Retrieval of Sodium Number Density Profiles in the Mesosphere And

Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , 3 , T. Dunker 1 . The full width at half 3 − , V. V. Rozanov is observed. The high latitudes, 1 3 , where the maximum Na number − ◦ 5 7909 7910 , J. P. Burrows . At mid to high latitudes a clear seasonal varia- 2 3 − , and A. C. Aikin 4 , C. von Savigny 1,2 , M. Sinnhuber 3 ) number density profiles recently reported by Langowski et al.(2014). Monthly + The Na layer has a nearly constant altitude of 90–93 km for all latitudes and seasons, This discussion paper is/has beenTechniques under (AMT). review Please for refer the to journal the Atmospheric corresponding Measurement final paper in AMT if available. Institut für Umweltphysik, Universität Bremen,Institut Bremen, für Germany Physik, Ernst-Moritz-Arndt-Universität Greifswald,Department Greifswald, Germany of Physics and Technology, UiTInstitut The für Arctic Meteorologie University und of Klimaforschung Norway, Tromsø, – Norway Atmosphärische Spurengase und The Catholic University of America, Washington D.C., USA 1 2 3 4 Fernerkundung, Karlsruhe Institute5 of Technology, Karlsruhe, Germany Received: 15 June 2015 – Accepted: 6Correspondence July to: 2015 M. – Langowski Published: ([email protected]) 30 July 2015 Published by Copernicus Publications on behalf of the European Geosciences Union. Abstract An algorithm has been developedon for the a retrieval of latitude sodium andonance atom (Na) altitude fluorescence. number grid The density from resultsthe SCIAMACHY are resulting limb obtained global measurements seasonal betweenadapted of variations 50 from of the and that Na Na 150 used are km res- for(Mg analysed. altitude the The retrieval and retrieval of approach magnesium is atom (Mg) and magnesium ion densities are 3000–4000 atomscm mean values of Nawas are retrieved presented from as the asphere 4 function years and of lower of thermosphere altitude spectroscopic (MLT) and limb measurement latitude. mode. data This of data theand set SCIAMACHY has meso- a full widthations at in half Na maximum are of identified 5–15 for km. latitudes Small less but than substantial 40 seasonal vari- U.-P. Hoppe tion with a winter maximumwhich of are up only to measured 6000with atomscm in peak the densities Summermaximum being Hemisphere, of approximately the have peak 1000 lower Na variesmer atomscm number strongly mesopause, densities at high while latitudes itconcentration and at exceeds is high 5 10 latitudes km km and near atthat at the altitudes at lower polar below 88 sum- mid latitudes. km is latitudes. Inand significantly there The summer smaller is than results the overall a are Na good compared atom agreement with with these. other observations and models Retrieval of sodium number density profiles in the mesosphere andthermosphere lower from SCIAMACHY limb emission measurements M. P. Langowski Atmos. Meas. Tech. Discuss., 8, 7909–7952,www.atmos-meas-tech-discuss.net/8/7909/2015/ 2015 doi:10.5194/amtd-8-7909-2015 © Author(s) 2015. CC Attribution 3.0 License. 5 10 20 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ects and winds in the mesosphere ff 7912 7911 This manuscript is structured as follows: in Sect.2 the SCIAMACHY measurements In the last decade global satellite observations of Na with long time series have been As the metal layers reside at an altitude where the atmosphere is too thin for aircraft Na has a large number density compared to other metals in the MLT, and the lower There are two possible groups of Na sources for the upper atmosphere: terrestrial Meteoroids enter the Earth’s atmosphere at supersonic speed and are decelerated and the Na density retrievalties algorithm will are be explained. The presented results in for3, Sect. Na retrieved number densi- from both Na D lines at 589 nm. In Sect.4 SCIAMACHY instrument, theobservations measurements have of been which reported2007; areFan from used et OSIRIS al., in2007; onand thisHedin GOMOS the and study. (Fussen Gumbel, Odin et Other 2011), al., satellite SCIAMACHYSCIAMACHY2010). (Casadio (Gumbel Results limb et of MLT et al., the measurements2007) Na al., betweenstudy. number These 2008 density results retrieval and are from 2012 the compared are to presented other measurements in and this models. available. The first global(2004), space-based using the observations GOMOS were instrument reported on the by satelliteFussen Envisat. et Envisat also al. carries the observations, e.g. by lidar, yieldat good selected vertical locations. and time-resolved results, however, only to fly, but too denseare for satellites only to possible orbit forlocations with longer on time rockets, Earth periods, which and in-situ are can measurements expensive. Remote only sensing be methods are launched used at and ground a limited number of layer is the best understood metal layer in the MLT. atmosphere is nearly transparent589 at nm. the This wavelength simplifies of the the observation strongest from Na ground. transitions As at a result, the mesospheric Na formation impacts on ozonemetal compounds formation acting and as nucleation lossin nuclei the both for middle the in atmosphere formation (see, thetius of e.g., et gas aerosolsRapp and al., and phase clouds Thomas, ).2005 andin2006; A through theVoigt detailed et upper, al. understanding atmosphereand2005; of particlesCur- is the in required the origin upper toionospheric and atmosphere. sporadic understand Also, the E metal the reactions layers ions and formation are of metal the and metals ions principal loss are component found of of throughout ozone the ionosphere. and lower thermosphere (MLT).terial Furthermore, input the can total be amountmetals estimated of play from extraterrestrial an ma- measurements important of role these in metal upper layers. atmospheric Additionally, chemistry. Their chemical trans- and frictionally heated bymeteoric collisions ablation with of air metalsmetals molecules. and are These non transported processes metalsmetal lead and into layers to react the are the upper with formed atmosphere.e.g., thePlane, that The; 2003 ambient have ablated Plane neutral et peak al. , several atmosphere. densities thousand 2015 atomsfor As at a per a review). around cubic Althoughof centimeter result 85–95 the are km radiation metal low, concentrations altitude because these of metals they (see, fore, are have the strong large emitters metals are resonance readilyradiation fluorescence observed signal cross by and sections. remote their There- sensingas relatively methods. trace long species Due atmospheric to to investigate lifetime, their wave metal strong propagation species e are used sources, such as volcanic eruptions andtrial salt sources particles such from as the meteoroids oceans, and andare comet extraterres- the dusts. In most the likely upper sources atmosphere of meteoroids Na. 1 Introduction The metal sodium, Na, was first, (Davy isolated1808). in This the was laboratory achieved byide, by Sir NaOH, the Humphry with electrolysis Davy Na of in being very 1807 the collected dry at Earth’s molten the sodium atmospheric cathode. hydrox- MoreVesto Na Slipher than layerSlipher, ( one1929). hundred was years Theumn discovered later large of in scattering Na cross in 1929 section thespectral by and upper atmospheric atmosphere American range. results col- Sydney astronomer in aatmospheric Chapman, relatively ozone, strong who emission proposed had in anomenon the previously visible and reaction-cycle worked the theory Na on to emissions explaining (see, explain e.g., upper theChapman, , 1938 night-glow1939). phe- 5 5 25 20 15 10 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , see Lan- retrieval by + + Mg / at 589.158 nm, which 2 with options 1, 2, 4, 5, 7 scial1c erent and the data set presented here ff at 589.756 nm and D 1 7914 7913 . An average for same latitude and local time of + 0.6 nm. ≈ ects in the retrieval for the outermost measurements on the altitude-latitude ff cient to resolve the two Na D lines, D erent tangent altitudes, resulting in an adequate vertical resolution in the scanned erences between results from both D lines are discussed and the results are com- ffi The highest tangent altitude of the nominal limb mode, which was performed daily In the occultation mode SCIAMACHY observes either the sun or the moon through The SCIAMACHY data set employed in this study is Level 1 data Version 7.03 and ff ff for one day of measurements every two weeks. As the ion layers (e.g., Mg gowski et al., 2015)was are decided to located exploit atof the slightly the MLT standard higher mode profiling of altitudes mode. SCIAMACHY However,limb than the first, MLT retrieval the results measurements prior from neutral should to the layers, not later nominal it limb be investigation and too di Langowski et al.(2015), becauseedge the e better signal togrid. noise ratio of Na produced less tion (also around 3.3 km) at the altitude of the metal atom and ion layers, was performed during the whole SCIAMACHY lifetime,Na is layer about peak. 91 However, km, from which thealtitude is range middle between just of 50 the 2008 and the altitude 150 limb km of in MLT the mode, 30 which steps of scans 3.3 the km with a good vertical resolu- points downward towards the Earth’stop surface of and scans the thecoverage. atmosphere. upwelling In radiation The at limb nadir the di mode mode the delivers instrument a points good tangentially latitudinal to andmode. the longitudinal Earth’s surface at will be extended later. Forthe each dark MLT limb signal scan, at there 350from km is the tangent an signal altitude. additional For at measurement Natangent the of this altitudes. other At dark tangent 590 signal, nm altitudes, whichsu SCIAMACHY is is has subtracted a much spectral weaker resolution than of the 0.44 nm. signal This at is MLT the up to 15 orbitsmonthly of means SCIAMACHY of data the is results formedNote for before the that the 2008–2012 retrieval. there data The is set multiannual Northern a are Hemisphere, formed larger because after latitudinal the the coverage northern retrieval. fer for from dayside the solar high straylight latitude Southern contaminations. measurements Hemisphereview This suf- of than is the the because instrument the (see sunThereLangowski is is et partly also al., a in2015; larger the, Langowski field coverage2015 of of for high more latitudes details). compared to the Mg the atmosphere at sunrise and moonrise, respectively. In nadir mode the instrument range of altitudes, but with a poorer latitudinal and longitudinal resolution than the nadir di a sun-synchronous, low Earth orbitcrossing with time) a at descending node around (southboundoccultation 10 a.m. local geometry. ESA equator local lost time. contact It with made Envisat measurements on the in 8 limb, April nadir 2012. and have a spectral seperation of and M-factors, which include optiondetails.). 3 The (see LevelSherbakov 1 and Lichtenberg, dataLangowski et2008 have al.(2015)for been for more averaged Mg using and Mg the same approach as used by pared to other measurementsare and investigated. Finally, model the results. findings The of this seasonal study and are annual summarized changes in Sect.5. 2 Instrument, retrieval algorithm and algorithm2.1 extension SCIAMACHY The limb observations ofScanning scattered Imaging solar Absorption electromagneticMACHY) Spectrometer radiation, on observed for board by the AtmosphericBurrows the Environmental et CHartographY al., Satellite1995; (SCIA- (Envisat)Bovensmannby et are the al., used1999 European forfor Space more this Agency details). ESA study Envisat on was (see launched an Ariane-5 rocket on 28 February 2002 into 7.04 and was calibrated with ESA’s calibration tool 5 5 25 25 20 15 20 15 10 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | . ) 2 2 3 θ i P E (1) ... 2 cal- f and is and j line has retrieval 1 and 3 1 are taken + E 1 ij λ Mg and the emis- / for D n 1 2 P ) (see, e.g., Cham- stands for both ab- 2 λ line has a mixture of ( a 2 s πF and self-absorption to the higher state cient, the probability of the i γ ffi , (2) . ff 1) while the D and are taken from Chandrasekhar states is highly improbable. The Na erent for both D lines. The D j = ff } P jk ∆ and transition wavelength 2 ji A E {z A ij k f P | are di 2 7915 7916 rel. Einstein coe E 0 and × 0.5. The wavelength integrated absorption cross = λ 1 and = d , which is furthermore attenuated by self-absorption ) . (3) E } . The changes with respect to the Mg 1 2 2 e 2 λ n s E ( E {z e . The relative Einstein coe cm | σ s 1 2 ) (note that it is convention to use is a linear combination of the phase function for Rayleigh . (4) × S )d λ 2 and an absorption part – along the line of sight (LOS) and 2 ) } a ( } 2 ij belongs to the symbol and is not meant as a factor 3.14 P E nm λ s λ n ( 2 π ij + {z πF )d f 0.5 and photons a 2 s cm πF | 2 , which is already considered in Eq. (1). The factors 1) s = ( Z π + {z n 1 πe mc ) × . The signal is the integrated product of the density ). Equation (1) is discretized on the 2-D latitude–altitude grid and E Z 0 f θ ( f ( , density f 2 1 γ π ) ) } e 4 | θ s ( ( {z (cos | P 1 γn E integ. abs. cross section in nm cm along the emission path Phase function 3 4 Z to the ground state 3 LOS = γ = = 2 λ = ) d is normalized to 4 θ The process causing the emission is resonance fluorescence. A solar photon is ab- The mathematical representation of the forward model is: s is calculated as follows: (see Eq.6 for γ ( σ πI |{z} photons section has to be distributed overresulting the correct absorption shape function cross of section thesolar emission profile line irradiance. is and This the multiplied product withcombination is the of then wavelength the integrated dependent second over and all third wavelengths factor yielding of the the emissivity true in Eq. (2). scattering and an isotropic part: P from the NIST atomic spectradependent database phase (Kramida function et al., 2012). The scattering angle specific parameters, i.e., oscillator strength depend on the change in angular momentum (1960) (see1).The Table factors with the solar irradiance berlain et al., ),1958 and for D resonant transition compared tolower all states, is other 1 possible for both transitionsas lines, upper from because states only the the and upper two the state lowest transition excited to states between are the involved P a purely isotropic phase function ( and Z sorbed by a Na atom, which is excited from the lower state spontaneously and immediately re-emitted, which returns the atom to the lower state both components The two relevant transitions are from the lowermost excited states 3 4 2.2 Retrieval algorithm and adaption toThe Na retrieval algorithm presented in nesiumLangowski atom et and al.(2014), ion whichgowski was retrievals used from et for the al., mag- SCIAMACHY limb2015),A MLT forward is measurements model used (Lan- forment and the of adjusted emission an orbit to signal ison the and set a absorption up specific 2-D and path latitude–altitude parameters inverted grid. of of for the each Na number limb densities atoms. measure- of the emitting species with emissivity the line from sunsorption to paths) the – point ofsivity scattering into the LOS (LFS) ( culation, while the rest ofchanges the (e.g., retrieval there algorithm is remained no unchanged, correctionγ beside for inelastic marginal scattering needed etc.). The emissivity f inverted for the numberdescribed density by Langowski et al.(2014) lie in the emissivity 5 5 10 20 15 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1 state S ect. The ff are normal- state, which e S x and x is used for the edge of state is stronger than the nm line the following parame- 2 2 1 1 , which leads to a hyperfine S photon 3 2 2 s cm = 14 . I 10 × . For the D 6 shifts line center − k lines each split into two groups of lines in 10 and the parameters 6 + . This can be explained phenomenologically Na and therefore has no isotope e − × 2 3 2 7918 7917 k P 23 11 is defined further below): 10 2 3.2 x × ( ± and D x line center 1 and 3 k line center 13.4 2 1 nm k − nm (see McNutt and, Mack 1963). = P 2 2 ˆ k is measured, which is a combination of the gravitational 2 σ 1 1 − 6 = − photon photon − scm scm 10 14 14 × 10 10 states, the D shifts) line the following values are used: × × − 2.7 0.228cm P 2 16 973cm of the intensity at the line center and the baseline intensity at the . (5) . = A 6 = − | e 5.44 5.44 x | 0 x I line center shifts 10 × × baseline k I e line center × ˆ line center σ k grav k × ( lines can be calculated for 0 line center I 2 − k 12.8 0.0495 0.0444 k = 2.14 2.16 line are shown in Fig.2. The Na density is large enough that a non-negligible part of ) = = The solar spectrum as well as the mesospheric absorption cross section for the Na Na has only one stable isotope, i.e., Wavenumber shifts between the solar spectrum and the absorption cross section in Following McNutt and(1963 ) Mack the solar irradiance in the vicinity of the Na D = = = = = 2 x e e ( 0 0 x A Because there are hyperfine splittingsaverage of for the both individual D line lines, wavelengths the and line strengths. center is the weighted splitting of the energy levels. The splitting for the lower 3 stable isotope has a nuclear angular momentum of leads to aa larger stronger overlap perturbation of of the the electron state. nucleus Due to and the electron stronger splitting wave of functions the and therefore D ters are used: I close spectral vicinity (thisThe is Doppler width called of a the Na “s-resolvedgroups lines blend” of in the in adjacent mesosphere linesMcNutt isHowever, have approximately and the 1.25 a lines pm., Mack inside separation The1963). a two of group about areexistence too 2 of narrow pm several to and be degenerate thus resolvedof lines, in can the however, the be is mesosphere. two The separated. important s-resolvedMcNutt for lines. and the This(1963); Mack correctFricke is, weighting and e.g., von well Zahn(1985). explained in Chamberlain et al.); (1958 splitting of the upper states 3 by the smaller distance of the valence electron and the nucleus incompared the to the the rotation of Earth andof the Earth change are of considered, the whicha Earth-sun-distance are combined along similar maximum the in amplitude elliptical magnitude of orbit as the constant shift and have I x red shift and other smaller shifts, e.g., pressure shifts. Additionally, Doppler shifts from and D The ratio A x The formula is givenized to for the wavenumbers wavenumber ofwavenumbers is the denoted line by center. The width parameter of thethe line mesosphere in are terms considered. of Here,line a center positive is shift moved value towardSince leads shorter to the wavenumbers a and, width red therefore, oflines longer shift the wavelengths. as in the the solar mesospheric Fraunhofer absorptioninfluence line on cross is the sections, emissivity. not In theseMcNutt much shiftslines and larger have(1963) of Mack a a than non-negligible constant the red shift width for of the solar the edge of the Fraunhofer linesSCIAMACHY is spectrum stated a in solarMcNutt irradiance and of(1963). 5.44 Mack To scale this to the the line: for the D I 5 5 15 25 20 10 10 20 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ect to ff because of n 1, which corresponds = . This takes into account f 1) − ) the retrieved peak density erent constraint parameters. ff 10 : − f . Note that the integral in Eq. (1) s 10 d × n R (albedo factor albedo factor + = to 5 old g P 7 − = 10 7920 7919 × new for the retrieval of Na were described. However, P + in Eq. (4). This approach is only reasonable if the 2 E , (6) . The equation is linearized employing an iterative approach λ f erently sensitive to self-absorption, another approach to de- ff d g line ) λ ( λ 2 σ )d − λ e ( × . As noted by Langowski et al.(2014), setting ) πF n retrieval by Langowski et). al.(2014 For Na the statistical errors are suf- λ ) ( ectively increases λ + as a linear factor, but also has a non-linear dependence on ( ff and the D σ πF n 1 ) R Mg λ D / ( erent correction methods for Na retrievals with OSIRIS are reported by Gum- σ ff R Di = a change of the albedo factor of 0.1 in Fig.4. The three highest constraint parameters retrieval result is nearlycal independent smoothing, of necessary the applied tothe constraint reduce Mg parameters oscillation (e.g., of verti- ficiently the small result). so This that isthen the not that Na of the retrieval Mg. case is However, theis for much dependence unfortunately less on the not sensitive variation to entirelythe of smoothing negligible, case the constraints constraint in especially parameter Fig.5. when TheLangowski the et meaning al.(2014): densities of it are the defines how constraintin large, strong parameter the as the used retrieval smoothness is here of equation. the isFor Figure5 profile explained moderateshows is in weighted retrievals constraint for parameter di (1 the increased part of multiplytherefore scattered e radiation, which we assume is unpolarized and is nearly independent oforders the of choice magnitude. of A factor the of constraint 5–10 parameter in for the constraint approximately parameter two has a similar e altitude compared to straylight contamination.Na Because SCIAMACHY D can lines, resolve which both termine are the di amount of radiationEarth’s passing surface the and Earth’s then atmosphere, being beingpresented scattered reflected in into at Sect. the the.2.3.1 limb Unfortunately,results, field this so of that approach view another did of approach not the isin always presented instrumentHedin yield in is and Sect. reasonable Gumbel(2011),2.3.2, and which which is was similar to finally the2.3.1 used. one Total to single scattering ratio estimation from direct comparison ofThe the albedo factor isNa determined number as densities. For thefication typical factor of Na for the slant which optimal column both albedophase profiles D factor function shown is (Eq.4) lines in is illustrated yield Fig.3 changed in thethe to Fig.4. same identi- It should be noted that the with the integrated true slant column density the incoming solar irradiation is eitherof absorbed resonance along fluorescence, the or path along fromof the the sun emissivity line to is of the sight, considered point after in the the emission. self-absorption This factor reduction the single scattering approximationlengths for below about the 300 background nm.Earth’s signal In surface or is the scattered visible only back regiona valid from radiation result, for the may lower wave- a be atmospherejust part reflected into from once the of mesosphere. the and the As can,multiplied incoming therefore, to solar produce the solar more irradiation irradiance, emission. may which will This pass be is the called considered thebel grid by albedo et cells factor a in al.(2007) more factor thebackground following. than and signalHedin for and thegle Gumbel).(2011 limb scattering scan In radiative transfer atHedinthe model 40 and lowest km considering tangent tangent(2011) Gumbel Rayleigh altitude altitude scattering the approach of only. is cannot SCIAMACHY Because directly compared limb be to MLT used, measurements a because is sin- the at background 53 km, signal this is too small at this using the retrieved densitylinear of density the previous step in the non-linear part to2.3 retrieve the Extension for multiple scattering In the previous section the optimizationalgorithm and developed adaptation for of Mg the and single Mg scattering retrieval f the self-absorption factor to no self-absorption, is a good starting step for the iteration. contains 5 5 20 15 25 10 15 25 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | slant of the 2 b ). To deter- Fraunhofer ), which we λ λ and D α erent ground , ff 1 h ( ss density, so a sys- I 2 , while a part of the a could be compensated a and D 1 slant column densities were and wavelength 2 h line could yield larger densities 2 ected strongly by atmospheric ab- ff erences between the D ff erent behaviour and shows a nearly ex- ff above 20km altitude. Figure7 shows the a 7921 7922 or the di 1 ects the dark signal measurement at 350km tangent ) (with tangent altitude ff h ( with the multiplicative component b ss + ) aI λ , h ( erent tangent altitudes, as well as the ratio for the simulated total ff ss I ) show oscillations at high altitudes. Note that a stronger smoothing ) ) show too strong smoothing while the lowest constraint parameters h 5 10 ( − − a etc.). The estimated value for the total to single scattering ratio is the 10 = 10 even for albedo factors smaller than 1. However, although this algorithm b ) set to the radiance along with the exponential decrease of the Rayleigh × × λ 1 ff , –5 h –5 ( 7 9 single scattering limb radiance and measured limb radiance ) is proportional to the simulated single scattering radiance − − inc λ I , 10 10 h ( × × Unfortunately, this method failed quite often for the following reasons: The densities Any unwanted straylight also a inc used to calculate theapproach total to to obtain single the scattering albedoand ratio factor the for is limb a to radiance limb use calculatedmodel measurement. with the SCIATRAN A a ratio is simple radiative of able transfer the tomagnetic model. measured calculate radiation The limb radiative for the radiance transfer known single measurementFigure6 andshows geometries total the and Rayleigh ratio atmospheric scattered oftering parameters. electro- the radiance measured for limb di radiancescattered and the simulated simulated radiance single scat- and the single scattered radiance for di ponential increase in the total to single scattering ratio above 50 km altitude. The true The Rayleigh scattered background radiance in the vicinity of the Na D lines can be column densities initially were toothan large, the so that D thefailed D the matching of densitiesgood retrieved the from both calibration Na of lines the is data a and good the indicator used2.3.2 for radiative how transfer model Total work. to single scattering ratio estimation from comparison of simulated albedos. As was reportedtering by Oikarinen ratio et only al.(1999)limb shows the radiance, modelled a however, total weak has to a dependency single completely scat- on di the tangent altitude. The measured already larger than the ones for D were too small and insensitive to the albedo factor, the D tematic error in one propertywhich is results rather in reduced some than robustness increased in if the the other method. one is tuned, altitude, which is usually subtractedtitudes. from As the a limb consequence radiances this atconsiderations. dark the Instead 30 radiance of other is tangent not thisI al- simply we subtracted assume for the that following a part of the total incoming radiation Rayleigh-scattered limb radiance isaltitude roughly and proportional exponentially to decreasing the limbare density expected. radiances We at with assume that the increasing there tangent tangent altitudes is that altitudes a reaches small the straylight instrument component fromis for lower high only tangent tangent altitudes weakly and dependent thatnent this is on component on altitude. the Aboveand order becomes 50 km of much magnitude bigger this than asconstant additional the the o straylight actual actual Rayleigh compo- limb scatteredscattered component. radiance radiance This at nearly with this altitude tangentto explains altitude simulated the single nearly scattering exponentialsignificantly ratio. rise In influence of the the the troposphere radiancefails measured and there. and lower Therefore, the stratosphere we clouds assume simplea that region approach in where using a the region limb anto measurement above it’s albedo to 20 simulated simulated factor and value single with below scattering the 45 km, ratio right is there ground very is albedo. close sorption in the mesosphere and upper stratosphere, and includes the H mine the multiplicative andand additive 660 components nm the is wavelength used. region This between spectral 650 region is not a (5 leads to the need of a lower albedo factor to match the D line at 656nm, whichditive is component a is clear not solar an signature, ill so posed that problem fitting (where a the smaller multiplicative and ad- minimum of the multiplicative component call the multiplicative part light: by a higher (5 straylight component and the actual dark radiance is an additional component 5 5 20 15 10 25 15 10 25 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | (ln 200 B ± and close to ◦ at the highest 2 − cm N is about 93 km for ◦ 10 10 × )) is used. The altitude of the 2 D apart from high latitudes, which + 3 1 − (D ectively more weight on the matching 1 2 ff ) scattering angles. ◦ 7924 7923 . In the summer the maximum density decreases 3 − at high latitudes and up to 1 2 − cm 9 10 at high latitudes. The annual mean is shown in Fig. 11 and shows ) and high (around 180 3 ◦ × − for the median nominal measurements is found. Between 50 and 70km . The resulting albedo factors show similarities to the simulated total to A AB N, which is a high latitude and covered by SCIAMACHY observations for ◦ 1000 cm ln nominal). Fitting the logarithm puts e ≈ B = ect is smallest there. The albedo factor for the MLT measurements is then given by The seasonal variation of the vertical profile for low, mid and high latitudes is shown This estimation, however, can only be done for the nominal SCIAMACHY limb mea- ff most months. Not only isbecomes the thinner: density from strongly reduced aautumn during full to summer, width only the at 7 profile kmother also half in width-defining maximum summer. parameters (FWHM) Qualitatively than ofmaximum a 50 % 11 similar etc.). km of reduction The the in is reduction maximumupper spring also value edge of and observed of (e.g. the the for 75, profile. profile 25,ferent Figure months width 515 % andshows occurs latitudes. of the The on vertical VCDsshown column both are in densities formed the (VCDs) Fig. by for lower integration10. dif- ofof and The the slightly vertical the VCDs below profiles also 1 show the seasonal cycle with a summer minimum several months during boreal summer. The peak altitude at 71 tween 80–105 km altitude, asfiles well as at the 71 seasonal variation of the normalized Na pro- latitudes covered in the winter hemisphere. in Fig. 12, and verticalAt profile shapes low for latitudes selected latitudes aserved. in semi-annual July This variation are variation shown with is in maxima(see, Fig. well in13. e.g., correlated Marchvon with and Savigny thetime. September and semi-annual is, Lednyts’kyy The variation2013), ob- in semi-annual which temperature oscillationet shows for al.(2013). a Na The maximum was during verticalFigure this also profiles14 found atshows in the high model seasonal latitudinal variation studies summer of by show theMarsh a Na reduced number width. density for the region be- are only measured in thedensities. The summer results period for and, both therefore, hemispheres only are show nearly the symmetric. small summer 1 for low (around 0 surements measuring from groundaround to 53km 90km altitude, altitude. so Thefound. that However, MLT the the measurements latitudinal minimum and start between longitudinal at co-locatedthe 20 nominal days and measurements of 45km from the can sameto not time to MLT-data directly period retrieve be the show albedo very factor.for similar Figure9 anshows profile the example shapes, final which measurement. fitMLT can First of measurements be the are the albedo fitted found. multiplicative factor The components median for for the all days in nominal the and same time period ( The monthly mean Na number densitiesin as Fig. a.10 function The of average latitude of and both altitude are retrieval shown results ( fit and Fig.8 theprofile. results of the multiplicative and additive component for one example orbits were used here)albedo of factor nominal limb measurements is formed for all altitudes. The of the lower albedo factore values at lower altitudes, whichthe considers that product the perturbing 3 Monthly averaged Na densities the logarithms of the nominal and the MLT measurements are fitted as factor single scattering ratios, which are high at scattering angles at around 90 MLT density maximum is about 92kma and varies seasonal only cycle by in a few numberwinter km density mid during latitudes with the of year. a up Na winter to shows 6000 maximum, cm with peak densities in the to only an average peak density of roughly 2000–4000 cm 5 5 15 20 10 15 20 10 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | er- ff erences of ff line only, Fig. 17 2 emission signal than 1 D / or the D 2 1 erences of up to 40 %. The large ff line is good, showing relative di 2 line having a slightly smaller error than 2 erences. For instance, the self-absorption ff 7926 7925 erences) and overall in quite good agreement. retrieval results erences are larger with absolute di ff ff 2 and the D erences for the VCDs of both lines. The overall ff 1 and D 1 erent reasons for the discrepancies, e.g., remaining issues with which correspond to relative di ff 2 − 10 % for most months and latitudes. However, for the highest latitudes N recorded between 2008 and 2013. The majority of these have been line with the current method. ± ◦ cm 1 9 10 erences between D × ff line. In the maximum number density region the relative error is roughly 10 %. 1 There may be di The SCIAMACHY and the ALOMAR results are similar and on the same order of discrepancies occur in ahigh. region where the Na density and therefore self-absorptionthe is calibration of the data.radiative Furthermore, transfer model small contribute inaccuracies to in the the di assumptions for the In the following, themeasurements. SCIAMACHY Figure data18 setshows isdar a compared comparison Observatory to to for ground- ground-basedNorway, and Middle at ALOMAR space-based 69 Atmosphere (Arctic Li- Research) lidar measurements at Andøya, magnitude (a factor 3 for the largest di approximation only considers losstiple along scattering the into linebroadened the of sight line mesospheric and of absorption noslightly sight. cross contribution change Furthermore, of with section a mul- temperature. isNa constant In also used; addition width shows to however, of a theet the the chemoluminescent resonance al., width Doppler- nightglow fluorescence).2012 (see, dayglow, can This e.g., 2,Fussen nightglow which et is shows al., not acence,2010 ; caused lower comparedPlane by to ratio self-absorption. the of resonance Thus,ties the for fluorescence, non-negligible the D could small D explain chemolumines- larger retrieved densi- 4.3 Comparison to independent data sets which is in good agreement withSCIAMACHY the error peak altitudes bars found are inThe the the errors SCIAMACHY standard data. bars The deviation of the ofdenote respective measurements the daily standard in mean deviation, each Na whichday. column month. is density a measured measure by of the the lidar geophysical variation on that In the summer months June and July the ALOMAR and SCIAMACHY measurements published by Dunker et al.(2015a) and show a mean peak altitude of around 92 km, 4 Error discussion and validation 4.1 Estimation of errors in theFour vertical to profile eight individualmonthly day averages shown measurements in have thediances been are previous linearly section. used propagated The to into errorsaverage the form of error SCDs. the the of As the measured multiannual SCDs the limberror to ra- estimate inversion propagation the step from error the of includeswe daily SCDs use non-linear the to operation, same the a Monte-Carlosian number approach error further densities as in linear isLangowski the eta not range(2014). al. daily of carried A average the out. random SCD typical Gaus- Instead a profile error large and of number a the of daily numberdard average times densities deviation SCD are (here profile of retrieved. 1000 is the This repetitionsso applied is large were determined to repeated number used). standard of The deviationmethod quantifies mean Monte is the and Carlo shown error in the realizations Fig. of stan- the are16. the region The determined. between profile. error 80 The The is and result smaller 100 km, of than with the this the measured D number density in the D In Fig. 16 both Nabe lines agree discussed very in well, the however, next this section. is not always the4.2 case, which will Di For a comparison of theshows individual the results absolute based on andagreement the of relative D the di results for the D ences of only in southern hemispheric winter the di up to 3 5 5 10 15 25 20 10 15 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 3 − er- ff in December. Again 2 − cm erence. The largest di 9 ff 10 × and 7 9 10 × 7928 7927 on upper atmospheric chemistry. . The latter is favored by low temperatures in 3 + erent techniques is clear. ff between December and February. In their Fig. 7, Dunker 2 − cm 9 N. The overall agreement of the seasonal variation and density is 10 ◦ × In the future, the SCIAMACHY Na data product will be extended to the period from The peak altitude obtained by She et al.(2000) is also 90–92 km. The full width The data set of She et al. (2000) was also used for comparison with other global Figure 19 shows a comparison to ground based lidar-measurements by She et al. The ALOMAR VCDs are larger in April and September than in June and July, and by Marsh et(2013) al. (their Fig.agreement 10). in There seasonal is a variation good(2010) with qualitative and and measurement quantitativeHedin results global and reported(2013). Gumbel (2011) The by reductionFussen as of et well thetatively al. as profile explained width model by in withMarsh theedge et results summer and high al.(2013) by northern the byMarsh latitudes Na an et is reaction increased al. ten- into ionization NaHCO rate at the upper data, using the results of the MLT retrieval as a-priori information. 2002 to 2012 by applying the retrieval algorithm also to the nominal SCIAMACHY limb and shows a clearlatitudes. seasonal The cycle retrieved with SCIAMACHY asurements data summer and minimum set most is models. pronounced inunderstanding This at of good data high the agreement role set with ofmetal provides other meteoroids and and a mea- metal their ions, unique release e.g., of set Mg Na and of coupled Mg with data the for other testing our at half maximum (FWHM)smaller of than the the peaklarger is 11–14 km volume 9–10 km for of (not space, SCIAMACHY. shown which However, here), SCIAMACHY might which in scans part is a slightly explain much this di satellite measurements by Fussen et al.(2010) (their Fig. 7) and the WACCM model quite good. ences between SCIAMACHY andabout the 20 % the from values July to presented November. by She et al.(2000) are the polar summer mesopauseat region the at bottom the edge, bottom whichof edge. is, e.g., atomic A shown Na further by by reductionGardnerperatures NLC et process so al.(2005), or that Fig. smaller both 9, ice reduction isdistinguishable. processes particles. the at This uptake the process lower edge also are depends correlated on and low hardly tem- 5 Conclusions The extension of a retrievalmagnesium, approach to previously the used for retrievalsented. the of Monthly retrieval mean Na of Na mesospheric numberfrom number density densities the profiles on SCIAMACHY a inThe latitudinal limb the Na and MLT MLT peak vertical measurements region has gridsmallest is from a retrieved at FWHM pre- 2008 summer of at to 5–15 high km 2012 latitudes. which The are depends peak on presented. density varies latitude from and 1000 season to and 6000 cm is (2000) at around 40 VCDs of around 5 et al.(2013, )2015b show VCDs betweenthe 3 seasonal cycle for the two di thus are in general agreementfor the with winter the month SCIAMACHY at Andoya seasonal are variation. available from LidarTilgner results and von Zahn(1988) showing of Na column density sometimessmaller agree, but or on much several larger days values. ALOMAReach The measures time ALOMAR much Na a lidar sporadic measureshappens Na larger during layer the column appears night density (see, in e.g., timeHeinrich the of et lidar’s observation al., observation (11),2008 a.m.). but volume. The not This transiencephysical during of variation SCIAMACHY’s usually sporadic in Na layers the results red inthe larger symbols cases geo- of when those ALOMAR particularto observed nights (a) much adsorption in smaller or Fig. column absorption18.and density of We (b) than Na attribute the atoms SCIAMACHY temperature onbalance in NLC with particles the less and coldest atomic smaller phasethese Na ice of strong particles and a variations, more because gravity Na the wavethe compounds. measurement leading lidar’s, SCIAMACHY and volume to does because is a not SCIAMACHY much chemical detect averages larger in than longitude. that of 5 5 25 20 20 10 15 25 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 7930 7929 N during the Geminids meteor shower 2010”, published in Ann. ◦ resonance line of sodium by lidar, J. Atmos. Terr. Phys., 47, 499–512, We wish to thank the AFOSR and the EOARD for the financial support 2 N during the Geminids meteor shower 2010, Ann. Geophys., 31, 61–73, ◦ Geophys., 31, 61–73, 2013, Ann. 2015b. Geophys.,7927 33, 197–197, doi:10.5194/angeo-33-197-2015, surements of thedoi:10.5194/acp-7-4107-2007, global 2007. mesospheric7912 sodium layer, Atmos. Chem.structure Phys., of 7, the 4107–4115, D 1985. 7918 nen, S., Seppälä,nard, A., J.-B., Fraisse, Verronen,let, R., P., M., Bertaux, Fanton Koopman, R., d’Andon, J.-L., Snoeij,sodium O., P., and Hauchecorne, layer Barrot, Saavedra, by L.: A., the G., Globaldoi:10.1029/2004GL021618, star measurement Dalaudier, Mangin, 2004. occultation of F., A.,7912 the instrument mesospheric Re- Théodore, GOMOS, Geophys. B., Res. Guir- Lett., 31,Kyrölä, L24110, E., Tamminen, J.,rot, Sofieva, G., V., Blanot, Hauchecorne, L.,global A., Fanton climatology Dalaudier, d’Andon, F., of O., Bertaux, the Fehr, J.-L., T., mesospheric Bar- Saavedra, sodium L., layer Yuan, from T., and GOMOS She, data C.-Y.: A during the 2002– sphere derived fromdoi:10.5194/acp-5-3053-2005, in 2005. situ7912 particle measurements, Atmos. Chem.electricity, particularly Phys., the 5, decomposition 3053–3069, substances of which the constitute their fixed bases; alkalies, andT. and on R. the the Soc. general Lond., exhibition nature 98, of of alkaline 1–44, the bodies, 1808. new Philos. 7911 layer at 69 doi:10.5194/angeo-31-61-2013, 2013. 7927 sodium properties measured withSol.-Terr. the Phy., 127, ALOMAR 111–119, Na, doi:10.1016/j.jastp.2015.01.003 lidar 2015a. compared7926 with WACCM, J. Atmos. spheric Na layer at 69 Chance, K. V., andmodes, J. Goede, Atmos. A. Sci., 56, P. 127–150, H.: 1999. SCIAMACHY:7913 missionimaging objectives absorption and spectrometer measurement for451, 1995. atmospheric7913 chartography, Acta Astronaut., 35, 445– mesospheric sodium densitiesSymposium, from Montreux, SCIAMACHY Switzerland, 23–27 daytime April limb 2007. spectra,7912 in:sodium-IV Proc. abundance Envisat of sodium in7918 twilight, J. Atmos. Terr. Phys., 12, 153–165, 1958. 7915, atmosphere measurements in theRa., ultraviolet, visible 111, and 1289–1295, 2010. near infrared,7934 J. Quant. Spectrosc. bach, M., Schiller, C., Roiger,of A., meteoric Schlager, material H., and Dreiling, implications V., and for Borrmann, aerosol S.: nucleation Observations in the winter Arctic lower strato- Fan, Z. Y., Plane, J. M. C., Gumbel,Fricke, J., K. Stegman, H. J., and von and Zahn, Llewellyn, U.: Mesopause E. temperatures J.: derived Satellite fromFussen, probing mea- the D., hyperfine Vanhellemont, F., Bingen, C., Kyrölä, E., Tamminen, J., Sofieva, V., Hassi- Fussen, D., Vanhellemont, F., Tétard, C., Mateshvili, N., Dekemper, E., Loodts, N., Bingen, C., Davy, H.: The Bakerian lecture, on some new phenomena of chemical changes produced by Dunker, T., Hoppe, U.-P., Stober, G., and Rapp, M.:Dunker, Development T., Hoppe, of U.-P., Feng, the W., Plane, mesospheric J., Na and Marsh, D.: Mesospheric temperaturesDunker, T., Hoppe, and U.-P., Stober, G., and Rapp, M.: Corrigendum to ”Development of the meso- Acknowledgements. Burrows, J. P., Hölzle, E., Goede, A. P. H., Visser, H., and Fricke,Casadio, W.: S., SCIAMACHY–scanning Retscher, C., Lang, R., di Sarra, A., Clemesha, B.,Chamberlain, and J. Zehner, W., C.: Hunten, Retrieval of D. M., and Mack, J. E.:Chance, K. Resonance and Kurucz, scattering R. by L.: An atmospheric improved high-resolution solar reference spectrum for earth’s Chandrasekhar, S.: Radiative Transfer, Dover Publ.,Chapman, New S.: Tork, USA, Atmospheric 1960. sodium, Meteorl.7916, Chapman, Mag.,7933 S.: 73, Notes 137–139, on 1938. atmosphericCurtius, sodium,7911 J., Astrophys. Weigel, J., R., 90, Vössing, 309–316, H.-J., 1939. Wernli,7911 H., Werner, A., Volk, C.-M., Konopka, P., Krebs- of the projectmany, granted the Netherlands by and grant# Belgium.men This FA8655-09-1-3012. and work SCIAMACHY was Ernst-Moritz-Arndt-University is in ofby part jointly the Greifswald. supported European funded SCIAMACHY by Space data Agency the bysearch (ESA). University was Ger- Ulf-Peter of Council kindly Hoppe Bre- of and provided Tim Norway Dunker208020/F50 for are and funding grateful 216870/F50. the to the Na Re- lidar measurements at ALOMAR through grants References Bovensmann, H., Burrows, J. P., Buchwitz, M., Frerick, J., Noël, S., Rozanov, V. V., 5 5 20 15 25 30 10 15 25 10 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | = W), Geophys. Res. Lett., ◦ N, 105 ◦ erent vibrational levels, Geophys. Res. ff 7932 7931 DLFE-518.pdf, 2008. 7914 = N latitude in winter, J. Geophys. Res., 97, 8439–8454, doi:10.1029/JD093iD07p08439, ◦ try, J. Geophys. Res., 104, 31261–31274, 1999. 7921 sodium D line emission2012. in7926 the terrestrial nightglow, J. Atmos. Sol.-Terr.2003. Phy., 74,7911 181–188, changes, Chem. Rev., 115, 4497–4541, doi:10.1021/cr500501m, 2015. 7911 ment of current capabilities,doi:10.1016/j.jastp.2005.10.015 2006. and7912 basic sensitivities, J. Atmos. Sol.-Terr. Phy.,Krueger, 68, D. 715–744, A.: Eight-yearmesopause climatology region (80 of to nocturnal 105 km) temperature over Fort and Collins, sodium CO (41 density in the 27, 3289–3292, 2000. 7927, 7952 DLR-SCIA-0071, Issue 2/B,fenhofen, Deutsches Germany, Zentrum available at: fürhttps://earth.esa.int/c/document_library/get_file?folderId Luft- und Raumfahrt e.V., Oberpfaf- Lett., 40, 5821–5825, 2013. 7924 25566&name 41, 262–263, 1929. 7911 at 69 1988. 7927 Borrmann, S., Davies, S.,hydrate Konopka, (NAT) formation P., Schiller, at C.,Atmos. low Shur, Chem. NAT G., Phys., supersaturation 5, and in 1371–1380, Peter, Polar, doi:10.5194/acp-5-1371-2005 T.: Stratospheric 2005. Nitric Clouds7912 Acid (PSCs), shifts Tri- between OH Meinel bands originating from di 2008 period, Atmos. 7912, Chem.7926, Phys.,, 7927 10,7928, 7952 9225–9236,, doi:10.5194/acp-10-9225-2010 2010. variations of the Naistry and and Fe general layers,doi:10.1029/2004JD005670 2005. at circulation7928 the of South the Pole polar and their mesosphere,Plane, implications J. J. for M. Geophys. the C.:Geophys. Res., chem- Res. Retrieval 110, Lett., of 34, D10302, global L04813, doi:10.1029/2006GL028687 , mesospheric 2007. sodium7912, densities7919 2004–2009, J. from Atmos. the Sol.-Terr. Phy., 73, 2221–2227, Odin7912, , doi:10.1016/j.jastp.2010.10.008 satellite, 2011. , 7919 7920, 7928 Na number density enhancements measuredphys., with 26, the 1057–1069, ALOMAR, doi:10.5194/angeo-26-1057-2008 Weber 2008. Na7927 Lidar, Ann. Geo- (Version 5.0), National Institute od Standards7916 and Technology, Gaithersburg, MD, USA, 2012. mosphere, PhD thesis, University of Bremen, Bremen, Germany, in preparation,rithm 2015. for densities7914 of mesosphericsatellite-borne and lower limb thermospheric emission metal signals, atom2014, and Atmos. 2014. ion Meas. species Tech.,7910, from 7,7915, 29–48,7919 , doi:10.5194/amt-7-29- 7920, 7925 Janches, D., Sinnhuber, M., Aikin, A.and C., ion and Liebing, layers P.: Globaland using investigation WACCM-Mg model of SCIAMACHY/Envisat results, the Atmos. observations Mg Chem.2015, atom Phys., between 15, 2015. 273–295, 707914, doi:10.5194/acp-15-273- 7915 and 150 km altitude Geophys. Res.-Atmos., 118, 11442–11452,, doi:10.1002/jgrd.50870 2013. , 7924 7928 , 7952 hofer D lines, J. Geophys. Res., 68, 3419–3429, 1963. 7917, 7918 , 7934 Oikarinen, L., Sihvola, E., and Kyrölä, E.: MultiplePlane, scattering J., radiance Oetjen, in limb-viewing H., geome- der Miranda, M., Sais-Lopez, A., Gausa,Plane, M., J. and M. Williams, C.: B.: Atmospheric On chemistry the Plane, of J. M. meteroric C., metals, Feng, W., Chem. and Dawkins, Rev., E. 103, C.Rapp, 4963–4984, M.: M. The and Thomas, mesosphere G. and E.: metals: Modeling chemistry the and microphysics of mesospheric ice particles: assess- She, C. Y., Chen, S., Hu, Z., Sherman, J., Vance, J. D., Vasoli, V., White, M. A., Yu, J., and Sherbakov, D. and Lichtenberg, G.: SCIAMACHY Command Line Tool SciaL1c, ENV-SUM- Slipher, V. M.: Emissions in the spectrum of theTilgner, C. light and of von Zahn, the U.: night Average properties sky, Publ. of Astron. the sodium Soc. density Pac., distribution as observed Voigt, C., Schlager, H., Luo, B. P., Dörnbrack, A., Roiger, A., Stock, P., Curtius, J., Vössing, H., von Savigny, C. and Lednyts’kyy, O.: On the relationship between atomic oxygen and vertical Gardner, C. S., Plane, J. M. C., Pan, W., Vondrak, T., Murray, B. J.,Gumbel, and J., Chu, Fan, Z. X.: Y., Seasonal Waldemarsson, T., Stegman, J., Witt, G., Llewellyn, E., She,Hedin, C.-Y., and J. and Gumbel, J.: The global mesospheric sodium layer observed byHeinrich, Odin/OSIRIS D., in Nesse, H., Blum, U., Acott, P., Williams, B., andKramida, Hoppe, A., U.-P.: Ralchenko, Summer Y., sudden Reader, J., and NIST ASD Team: NIST Atomic Spectra Database Langowski, M.: Investigation of metal atom and ionLangowski, layers M., in Sinnhuber, M., the Aikin, mesosphere A. and C., lower von Savigny, ther- C., and Burrows, J. P.: Retrieval algo- Langowski, M. P., von Savigny, C., Burrows, J. P., Feng, W., Plane, J. M. C., Marsh, D.Marsh, R., D. R., Janches, D., Feng, W., and Plane, J. M.McNutt, C.: A D. global P. and model Mack, of meteoric J. sodium, E.: J. Telluric absorption, residual intensities, and shifts in the Fraun- 5 5 10 15 30 20 25 10 25 30 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , nm 2 photon s cm 14 10 × (from , Chandrasekhar j ∆ 1) 1) 1) + 1) + − j 7) 1) j j + + + 2 5 j 2 j j ( + + 1)(2 (2 E j 2 2 (6 j + j j j j 3 10 10 3(2 3(6 10(

1) 3) 2) 1) + 1) + j 1) + − j 7934 7933 + j j + j 1 j ( 1)(2 5)( 3)( (2 j 1)(2 j + + − − j j j 10 j 10 (2 (2 (2 10( j E 1 1 0 ∆ + − depend on the change of angular momentum 2 E lines taken from McNutt and(1963). Mack Note that the approximate formula 2 and

1 Data of the solar extraterrestrial spectrum in the region 586–594 nm measured by E and D 1 by McNutt and(1963) Mack resolved is Na only Fraunhofer valid lines closethe are to SCIAMACHY much the spectrum. deeper center than of the the lines Fraunhofer in lines. the The SAO fully 2010 spectrum and which agrees for both,right is ﬁgure used shows in thethe the D SAO approximate 2010 formula spectrum by comparedMcNutt to and(1963). Mack the The fully resolved approximation of Figure 1. SCIAMACHY on 3 Juneand 2010, Kurucz 2010). and The from Fraunhofer lines the areSCIAMACHY and readily Smithsonian the observed Astrophysical SAO and 2010 Observatory the spectrum, left (Chance from ﬁgure which shows the both baseline the value of 5.44 1960). Table 1. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper |

er-

ﬀ

nm s phcm in irradiance Solar

−1 −1 −2 13 2.5 11 1.1 1.1 1.2 1.2 1.3 1.3 3.5 3 2.5 2 1.5 1 0.5 0 5 4.5 4 x 10

1 2 1 2 1 2 x 10 N) for three di ◦ 33 Na D Na D Na D Na D Na D Na D 2 220 K and solar irradiance = 22 T −2 1.5 Red shift only Doppler Red + max Red − max Doppler 11 line are smaller, because of stronger self- 2 1 00 7936 7935 line at temperature 2 wavelength in pm ∆ 0.5 −1−1 Slant column density in cm cient for the D −2−2 0 ﬃ −11 −3−3 erent shifts. x 10

ﬀ 1 0

90 80 70 60 50 −0.5 0.6 0.4 0.2 1.2 0.8

Na cross section in cm in section cross Na 110 100 150 140 130 120

10 10 10 10 10 10 10 10 10 10 10 10 10 10 7000 × × × × × × × × × × × × × × 1.1 1.1 1.2 1.2 1.3 1.3 5 5 5 5 5 5 5 5 5 5 1 1 5 5 1 2 1 2 1 2 1 1 2 1 2 2 1 2 1 2 1 2 1 2 erent constraint pa- Na D Na D Na D Na D Na D Na D Na D Na D Na D Na D Na D Na D Na D Na D ﬀ Na D Na D Na D Na D Na D Na D 6000

line shows higher densities. 8000 1 5000 −3 7000 lines and for di 2 6000 −3 4000 and D 1 5000 7938 7937 3000 4000 Number density in cm line shows higher densities. For the optimum albedo factor 2 3000 2000 Number density in cm 2000 1000 1000

0 0

90 80 70 60 50 95 90 85 80 75

150 140 130 120 110 100 110 105 100 Altitude in km in Altitude Altitude in km in Altitude Vertical Na density profiles for the D Vertical Na number density profile retrieved from the SCD profiles shown in Fig.3. Figure 5. rameters (Same conditions as invalue). Fig.3, albedo factor 1.2, see legend for constraint parameter Figure 4. For too large albedo factors the densities are smaller and the D For a too small albedo(here factor 1.2) the both D Na lines yield the same densities. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | line at α erent ground ff erent tangent altitudes of a series ff 7940 7939 Fit of the multiplicative and additive radiation component around the H Measured radiance to single scattering ratio for di Figure 7. 656nm. of nominal limb measurements as well as total to single scattering ratio for di Figure 6. albedos simulated with SCIATRAN. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2.20). = AB ( AB B=1.45 × 7941 7942 Altitude of lowest nominal value A=1.52 Average MLT profile nominal Average nominal profile Average nominal profile Limb signal / simulated single scattered signal 1 10 100 0

90 80 70 60 50 40 30 20 10

100 Fit results for the multiplicative and additive component as well as the simulated km in altitude Tangent Measured radiance to simulated single scattering ratio calculation for a MLT and co-located nominal limb measurements. The albedo factor is the product of Figure 9. Figure 8. values for the same ground albedo as in Fig.6.

Number density in cm in density Number Number density in cm in density Number

3 3 − − N/S. > 6000 6000 5000 4000 3000 2000 1000 500 250 100 50 0 < 0 No data ◦ > 6000 6000 5000 4000 3000 2000 1000 500 250 100 50 0 < 0 No data −82−60−40−20 0 20 40 60 82 7944 7943 Latitude in deg N Latitude in deg N −82−60−40−20 0 20 40 60 82 JanApr FebJul Mai Mar Oct Aug Jun Nov Sep Dec −82 −60 −40 −20 0 20 40 60 82 −82−60−40−20 0 20 40 60 82 90 80 70 60 50

90 80 70 60 50 90 80 70 60 50 90 80 70 60 50 90 80 70 60 50 Annual mean Na distribution. Note that the high latitudes are only measured in the Latitude–altitude distribution of the monthly mean Na densities. The average of the

150 140 130 120 110 100

150 140 130 120 110 100 150 140 130 120 110 100 150 140 130 120 110 100 150 140 130 120 110 100 Altitude in km in Altitude Altitude in km in Altitude hemispheric summer. Figure 11. Figure 10. results for both Na lines is used. Note that the highest covered latitude is at 82

Number density in cm in density Number

3 − > 6000 6000 5000 4000 3000 2000 1000 500 250 100 50 0 < 0 No data N S ° ° N ° 80 0 40 JFMAMJJASONDJ 7946 7945 Month Normalized Na density 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 JFMAMJJASONDJ 50−80 N 50−80 S 25−50 N 25−50 S 0−25 N 0−25 S 95 90 85 80 75 70 65 60 55 50

150 145 140 135 130 125 120 115 110 105 100

Normalized vertical Na proﬁle at selected latitudes in July. The densities are nor- 90 80 70 60 50 90 80 70 60 50 90 80 70 60 50 Seasonal variation of the vertical Na density proﬁle for low, mid and high latitudes.

150 140 130 120 110 100 150 140 130 120 110 100 km in Altitude 150 140 130 120 110 100 Altitude in km in Altitude malized to the peak value. Figure 13. Figure 12.

cm 10 in density column Vertical

2 9 − > 10.0 10.0 9.0 8.0 7.0 6.0 5.0 4.0 3.0 2.0 1.0 0.5 0.0 < 0.0 No data N. Right: proﬁles of the left ﬁgure ◦

7948 7947 Month Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan 0

Left: monthly mean Na number densities at 71

4000 line retrieval for the Na D1 Na D2 2 and D erence of the Na VCDs re- 1 ﬀ 3000 −3 ) di 2 2 D D − + 1 1 D D 2000

7949 7950 ) and relative (right, 2 Na number density in cm 2 1000 D − 1 lines. 2 and D 0 1

70 60 50 90 80

Absolute (left, D 120 110 100 150 140 130 Mean and standard deviation (error bars) of the Na D Altitude in km in Altitude Figure 17. equatorial SCIAMACHY measurements on 20 March 2010. trieved from the D Figure 16. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | N and the results from She ◦ N with lidar observations at ◦

SCIAMACHY ALOMAR Month 7952 7951

Mar Apr Mai Jun Jul Aug Sep Oct

8 7 6 5 4 3 2 1 0

Vertical column density in 10 in density column Vertical cm (10 m

) Comparison of the SCIAMACHY VCD proﬁle at 69

Left: comparison of the SCIAMACHY VCD proﬁle at 40

9 2 13 2 − − et al.(2000). Right: comparison(their Fig. of 7) the and sameMarsh et proﬁles al.(2013) with (their Fig. proﬁles 10). from Fussen et al.(2010) Figure 19. Andøya, Norway. Figure 18.