SymonsSymons Gold Gold Medal Medal Lecture 2019 Lecture 2019
A Century of Remote Measurements of the Atmosphere Clive Rodgers University of Oxford George James Symons
Elected a fellow of the Society in 1856 at age 17
President 1880 and 1900 Council member for 37 years Secretary for 24 years
Founder of the British Rainfall Organisation and the Meteorological Magazine James Glaisher and Henry Coxwell ballooning
5 Sep 1862 Teisserenc de Bort
1908 REMOTE SOUNDING
What can you measure without going there?
Globally? 1920 - Lindemann & Dobson
Symons x Density at appearance
• Density at disappearance
Extrapolation assuming 220K
Density from sondes Dobson’s Ozone Spectrometer
1924 - 1926
1938
Paul Götz – The Umkehr Method 1929
Götz found that by observing solar UV scattered from the zenith sky as the sun set, he could determine something about the vertical distribution of ozone. Hans Dütsch 1957
Developed a method to be used on a digital computer
Linearise the model equations, solved for nine layers. Recompute with the full equations, and iterate. Jean King 1956
Thermal infrared emission
“The emergent intensity is simply the Laplace Transform of the Planck intensity considered as a function of optical depth”
From: Scientific Uses of Earth Satellites, Ed J. A. Van Allen Univerity of Michigan Press Ann Arbor, Michigan, 1956 Lewis Kaplan 1959
Proposed looking at CO2 in several spectral locations where there are different absorption coefficients Dave Wark, 1961
Simulated this idea, retrieved two layer temperatures and lapse rates from three radiances. Giichi Yamamoto 1961
Nimbus 3 Two sounders - 1969 SIRS IRIS Nimbus B in test PI Rudolph Hanel NASA Goddard
Infra-Red Interferometer Spectrometer
P.I. David Q Wark NOAA SIRS Satellite Infra-Red Spectrometer
8 channel grating spectrometer
SIRS-B prototype, National Air & Space Museum
Harold W. Yates , Space Technology and the Optical Sciences APPLIED OPTICS/ Vol. 21, No. 2 / 15 January 1982 INNOVATIONS
Year Innovation Instrument Satellite 1969 Fourier Transform Spectrometer IRIS Nimbus 3 “ Grating Spectrometer SIRS 1970 Solar UV Scattering BUV Nimbus 4 “ Filter Radiometer SCR “ Gas Correlation SCR 1972 Off-Axis Scanning ITPR Nimbus 5 “ Microwave Radiometer NEMS “ First Operational Sounder VTPR NOAA-2 1975 Detector Cooling LRIR Nimbus 6 “ Limb View LRIR 1981 First Geostationary Sounder VAS GOES-4 1984 Solar Occultation SAGE II ERBS 1994 GPS Radio Occultation GPS/MET MicroLab-1 1994 Lidar LITE STS 2002 Stellar Occultation GOMOS Envisat PI Don Heath NASA Goddard
Backscatter Ultraviolet Radiometer Nimbus 4 1970
Nadir viewing grating spectrometer measuring scattered solar UV at 12 wavelengths to obtain the vertical profile of ozone
Had over 20 flights:
–1975 Atmosphere Explorer –1978 SBUV Nimbus 7 –SSBUV Shuttle flights –NOAA/POES series ongoing SBUV/2 Layer Ozone (Southern Hemisphere) 5 Dec 2019 Filter Radiometers John Houghton Oxford With a new idea - gas correlation
Match the spectral response of the 1990 (Church Times) radiometer to the spectrum of CO2
Desmond Smith Reading/Heriot Watt
Nimbus 4 Selective Chopper Radiometer Nimbus 4 1970 N6 PMR 1975 modulate gas pressure Weighting functions for three nadir sounding instruments
N4 SCR 1970 N5 SCR 1972 Move mirror Move gas cells From Nimbus 4 SCR Nimbus 4 SCR
Southern Hemisphere warming Sept 5 1970 10-1 mb thickness PI Bill Smith NOAA Cross-track Scanning Infrared Temperature Profile Radiometer Nimbus 5 1972
FOV 32 km, 14 views cross track
7 spectral channels: 19.7, 14.96, 14.5, 14.0, 13.4, 11.1, 3.7 µm
Followed by: VTPR NOAA 2-5 1973-79 Was an operational follow on to ITPR
HIRS Nimbus 6 1975 Also a follow on to ITPR: 17 spectral channels Field of view: 0.04 rad, 25 km at nadir, sidescan to 42 fov’s
500 mb Temperature 1200Z 6 March 1973
Intense low, North Pacific
NMC analysis –––––– ITPR suggested adjustment - - - - Followed by: VTPR NOAA 2-5 1973-79 HIRS Nimbus 6 1975 With 23 FOV’s cross track Also a follow on to ITPR: 17 spectral channels was an operational follow on to ITPR Field of view: 0.04 rad, 25 km at nadir, sidescan to 42 fov’s
VTPR (NOAA 2-5) Scan Pattern PI Dave Staelin Nimbus E Microwave Spectrometer MIT NEMS Nimbus 5 1972
Straightforward microwave receiver pointing downwards
FOV ~190 km
3 channels in the O2 band near 5mm for temperature
2 channels for water
Clouds are almost transparent in the microwave Waters et al, J Atmos Sci, 32 p1953 TOVS Scan Pattern HIRS and MSU on NOAA series PI John Gille NCAR
Limb Radiance Inversion Radiometer Nimbus 6 1975
New ideas: Measuring Temperature, • Limb scanning Ozone, Water • Cooled detector Comparison with radiosonde & rocketsonde Zonal mean cross section of LIMS V6 data for May 6, 1979.
(a) Temperature with contour increment of 5 K,
(b) ascending (daytime) ozone with contour increment of 0.5 ppmv.
Subsequent limb sounders
On Nimbus 7:
LIMS - update of LRIR
SAMS - a limb sounding version of SCR/PMR
On UARS:
CLAES, ISAMS, MLS, HALOE, HRDI, WINDII
On Envisat:
MIPAS, SCIAMACHY UARS
Upper Atmosphere Research Satellite 12 Sept 1991
CLAES - high spectral resolution limb sounding tuneable etalon
HALOE - solar occultation, gas correlation radiometer
ISAMS - Improved SAMS
MLS - Microwave Limb Sounder
WINDII - Limb interferometer measuring Doppler shift of airglow lines for mesosphere and thermosphere winds
HRDI - High Resolution Doppler Imager Mount Pinatubo
June 15 1991
We had not planned for this in the design of ISAMS…
Even so, our window channel was very useful.
Pat McCormick Solar Occultation NASA Langley
Oct 1978 Stratospheric Aerosol Measurement II (SAM II) Nimbus 7
Feb 1979 Stratospheric Aerosol and Gas Experiment (SAGE) on AEM-B Solar Occultation
1985 Atmospheric Trace Molecule Spectroscopy Experiment (ATMOS) on Spacelab and STS 1992-4
1991 Halogen Occultation Experiment (HALOE) on UARS HF, HCl, CH4, NO, H2O, O3, NO2 and pressure
2003 ACE - Atmospheric Chemistry Experiment Fourier Transform Spectrometer Polar orbiter
2002 SCIAMACHY - Envisat Occultation & Scattering Rick Anthes NCAR Radio Occultation
GPS/MET flown on a tiny satellite MicroLab-1 1995
COSMIC-1 2016 COSMIC-2a 2019
Cluster of six satellites
daily geographic coverage provided by COSMIC-2. The locations of radio occultation profiles are shown in green, ground based radiosonde locations are in red. Stellar Occultation Global Ozone Monitoring by Occultation of Stars (GOMOS) on Envisat 2002
Spatio-temporal observations of the tertiary ozone maximum, Sofieva V, Kyrölä E, Verronen P et al. Atmospheric Chemistry and Physics (2009) 9(13) 4439-4445 Data Analysis How was all this data analysed?
As Dütsch had found with ozone in 1957, the obvious method wasn’t easy
It usually turned out to be very ill-conditioned Classic Paper: Sean Twomey US Weather Bureau On the Numerical Solution of Fredholm Integral Equations of the First Kind by the Inversion of the Linear System Produced by Quadrature Journal of the ACM Volume 10 Issue 1, Jan. 1963 pp 97-101
Jointly minimised:
The fit of the solution to the measurements, plus some smoothness criterion,
e.g. squared second differences of the profile, or squared departure from some a priori profile
Book: Introduction to the mathematics of inversion in remote sensing and indirect measurements Elsevier Science & Technology, 1977 Carl Mateer
Empirical orthogonal functions - Lorenz 1956
(Factor Analysis - Spearman 1904, Singular Vector Decomposition)
“There are at most four pieces of information about the vertical distribution to be obtained” square roots
1 0.88 2 0.40 3 0.17 4 0.13 5 0.08
Eigenvalues of a sample of about 100 measurements George Backus and Freeman Gilbert Scripps Institute of Oceanography
Uniqueness in the Inversion of Inaccurate Gross Earth Data Phil Trans 266 p 123-192 March 1970
The Averaging Kernel describes how the retrieval is related to the actual profile Miscellaneous approaches to finding a solution e.g.
Smoothest ‘exact’ linear solution - turns out to be a linear combination of weighting functions
Ad Hoc relaxation methods, e.g. Chahine 1968
Direct multiple regression: using a set of computed radiances (or a sample of coincident direct measurements to get coefficients). Rodgers 1966, Smith, Woolf & Jacob 1970
Onion Peeling - for limb sounding, work down from the top. Russell & Drayson 1972
Optimal Estimation: Combining the measured quantities with a properly characterised prior estimate in a statistically optimal way, e.g. using Bayes Theorem
Review: Rodgers (1976) Retrieval of Atmospheric Temperature and Composition from Remote Measurements of Thermal Radiation Rev Geophys and Space Phys 14 p609 Rod Jones We can divide the problem into :
Finding a profile or set of profiles that fit the measurements (a) exactly or (b) within the noise
Characterising the set of profiles that fit the measurements within the noise i.e. a proper error analysis, identifying different types of errors
Understanding how the solution relates to the true profile Assimilation of Remote Measurements
Jonathan Robert Eyre, Stephen J. English, Mary Forsythe, QJRMetS, Sept 2019 Assimilation of satellite data in numerical weather prediction. Part I: The early years
1970s: Assimilating retrievals as if they were radiosondes Not much effect in northern hemisphere, greater improvements in southern hemisphere
1990s: The move to assimilating radiances has eliminated much of the misuse of satellite information!
A century of progress End Year of Grating FT Filter Satellite Microwave Other launch Spectrometer Interferometer Radiometer 1969 Nimbus 3 SIRS IRIS 1970 Nimbus 4 SIRS, BUV IRIS SCR* 1972 Nimbus 5 ITPR, SCR/2* NEMS NOAA 2-5 1972-5 VTPR series HIRS, LRIR†, 1975 Nimbus 6 SCAMS PMR* 1978 Nimbus 7 SBUV LIMS†, SAMS*†, 1978 Tiros-N HIRS, SSU* MSU 1978-81 NOAA 6,7 HIRS, SSU* MSU 1983-94 NOAA 8-14 SBUV/2 HIRS/2, SSU* CLAES, HALOE*, 1991 UARS ISAMS*†, MLS WINDII 1992-4 STS/Atlas1-3 ATMOS 1995 Orbview-1 GPS/MET 1998-09 NOAA 15-17 HIRS/3 AMSU 1999 Terra (EOS) MOPITT* 2002 Aqua (EOS) AIRS AMSU-A 2004 Aura (EOS) TES HIRDLS† MLS† OMI 2006 METOP-A IASI HIRS/4 AMSU-A GOME/2, GRAS 2012 METOP-B IASI HIRS/4 AMSU-A GOME/2, GRAS 2018 METOP-C IASI AMSU-A GOME/2, GRAS
* gas correlation †Limb view Thanks to Alyn Lambert & Don Grainger