DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING 4. Satellite Validation Principle

C o r r e l a t i v e

D a t Day 4 Lecture 2 Instrument intercomparison – Paul Simona 1 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Atmospheric Remote Sensing Measurements

• Atmosphere is continuously changing in time and space. => No repeated measurements of the same quantity.

• Radiation field measurements are direct, all other are indirect

• Measurements probe large atmospheric volume => Large averaging and validation by in situ measurements difficult

Courtesy Erkki Kyrola

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 2 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Atmospheric Satellite Sensors

We launch a satellite sensor for dedicated purposes:

ƒ Meteorology, dynamical tracer, surface UV monitoring; ƒ Global climatology; ƒ Montreal and Kyoto Protocol related issues; ƒ Atmospheric processes: polar chemistry, etc.; ƒ Tropospheric issues like pollution, biomass burning, oxidizing capacity…; ƒ Radiative Transfer and Chemical Transport modelling.

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 3 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Satellite Validation Principles

Ideally,

the observations of atmospheric constituents must not be dependent on:

¾ the atmospheric temperature; ¾ the abundance of other species; ¾ the Sun elevation; ¾ the presence of clouds; ¾ the instrument degradation (aging); ¾ etc…

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 4 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Satellite Validation Principles

First issue: Remote sensing output is affected by:

ƒ Instrument degradation;

ƒ Calibration uncertainties;

ƒ Errors/assumptions on retrieval model (forward + inverse): radiative transfer codes, spectroscopic databases, atmospheric profile databases, surface albedo, treatment of clouds and aerosols.

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 5 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Satellite validation principles

Therefore:

¾ Validation is required to confirm error budgets derived from theoretical and laboratory studies, and identify new error sources.

¾ Quantitative validation must take into account both satellite and correlative data error sources.

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 6 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Satellite Validation Principles

Second issue: Remote sensing does not provide a direct measure of the number density, but:

ƒ Earth radiance and solar irradiance measurements

ƒ Horizontal resolution

ƒ Latitude/time sampling

ƒ The [measurement] + [retrieval algorithm] system is characterised by weighting functions determining altitude range, sensitivity, vertical resolution of the retrieved information

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 7 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Satellite Validation Principles

Therefore:

¾ Validation must characterise the real information content coming from the measurement, including sampling and smoothing aspects, and independency w.r.t. databases and assumptions.

¾ Satellite and ground-based data give a differently smoothed/sampled/truncated perception of the ozone field.

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 8 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Satellite Validation Principles

Third issue: Atmospheric ozone exhibits

9 Spatial structures;

9 Temporal variability at a hierarchy of scales;

9 Strong correlations with temperature, altitude/pressure, dynamics, etc.

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 9 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Satellite Validation Principles

Therefore:

¾ It is not a well mixed, homogeneous, like laboratory sample;

¾ No linearity;

¾ Differences in ozone field perception make comparisons and their interpretation difficult.

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 10 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Satellite Validation Principles

Conclusion: Proper validation is highly instrumental driven in:

9 Determining if, how and to what extent satellite data can meet the dedicated objectives

9 Pointing to defiances in calibration and retrieval algorithms

9 Improving data products

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 11 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Satellite Validation Principles

Validation goes well beyond a simple comparison exercise, in scope and in difficulty; ideally it should combine both qualitative and quantitative correlative studies with information content studies. Scientific/operational purposes must serve as a baseline. A few comparison pairs at a few stations during a limited campaign are by far not sufficient.

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 12 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING GOME GDP 2.7 versus Dobsons (4 years)

> +3% < -5% Lambert et al., al., et Lambert

> +3% ESA TN, < -6% > +5% 2002

However, annual means concluded to an excellent agreement !

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 13 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING T dependence of ozone cross-section GOME versus Dobsons and Brewers

GDP 3.0 GDP 4.0

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 14 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING T dependence of ozone cross-section TOMS versus Dobsons and Brewers

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 15 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Solar Zenith Angle dependence

40 Tropic of Capricorn Northern Mid-latitudes 30 60° North Arctic Polar Circle Northern Polar Latitudes 20

10

0 GDP 2.7 / 3.0 / 4.0

-10

-20 GDP 1.20 -30 SZA Dependence of GOME v2.0 Total Ozone 20 30w.r.t. 40 SAOZ 50 Network 60 Observations 70 80 90 100 Solar zenith(Jul angle - Nov of GOME1996) (deg) 20

15 GDP 2.0

10

5

0

-5 G / % O )/S O S (GO -10

-15 All latitudes excepted Antarctica Vertical error bars: standard deviation (2σ) -20 20 30 40 50 60 70 80 90 100 Solar zenith angle of GOME [deg.]

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 16 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Ozone Profile Validation

Similar problems as with ozone column validation plus: 9 Importance of absolute radiometric calibration; 9 Polarization aspects (instrument + atmosphere); 9 Vertical smoothing issues; 9 Retrieved value is a mix of measured information and a priori information (first guess, constraints); 9 Geolocation and time mismatches; 9 Upper stratosphere: diurnal variation of ozone, …

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 17 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Collocation

Are we trying to integrate apples and bananas? What does "collocation" mean? Day 4 Lecture 2 Instrument intercomparison – Paul Simon 18 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Error Budget of a Comparison

Error covariance matrix: Five covariance contributions 1. Measurements errors 2. Errors associated with measurement parameters 3. Retrieval parameter errors 4. Vertical smoothing error 5. Horizontal smoothing error (or “collocation” errors)

S= SM + SB + SSA + SSV + SSH

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 19 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING ErrorBudget of a Comparison Dependent on: – technique, – constituent, – atmospheric state (variability, profile shape, temperature, surface …) … –andintended use !

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 20 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

OZONE Profile Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 21 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Ozone Profile Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 22 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Ozone Sondes & Lidar Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 23 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Ozone LIDAR Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 24 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 25 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 26 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 27 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Satellite Validation by Microwave Radiometer SOMARA

• Averaging kernel smoothing has been applied • Horizontal distance < 800 km from SOMORA in Payerne • Time difference < 1h between ground and satellite data • Time intervals of satellites data are quite different

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 28 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Satellite Validation by Microwave Radiometer

good agreement of all instruments at altitudes < 45 km

SOMORA

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 29 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING MIPAS Ozone Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 30 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

TemperatureValidation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 31 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Validation of MIPAS Temperature

Ridolfi et al., ACP (to be submitted) Day 4 Lecture 2 Instrument intercomparison – Paul Simon 32 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

NO2 Validation

NO2 Diurnal variation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 33 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

Geophysical Validation of MIPAS NO2

MIPAS OL 4.61 vs. NDACC/UVVIS NO2 column

Wetzel et al., ACP (to be submitted)

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 34 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

GOME and SCIAMACHY BrO product

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 35 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING GOME & SCIAMACHY BrO Validation

•Ground-based DOAS evaluated at noon for comparison with GOME/SCIAMACHY (daily averages)

•Excellent agreement of GOME and GB DOAS (day-to-day and seasonal variations)

•Good agreement with BIRA-IASB SCIA BrO evaluations

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 36 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING Trend of stratospheric BrO

•Removal of seasonal variation using empirical model •Long-term variations of stratospheric BrO column controlled by variations in total inorganic bromine (Bry) •Maximum of bromine load observed in early 2000, consistent with reduction of sources initiated by Montreal Protocol

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 37 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING NDACC FTIR Stations for SCIAMACHY Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 38 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING NDACC FTIR Stations for SCIAMACHY Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 39 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

MIPAS HNO3 FTIR Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 40 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING MIPAS HNO3 Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 41 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

MIPAS N2O FTIR Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 42 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING NDACC FTIR Time Series

N2O

6.50E+18

6.00E+18

5.50E+18

5.00E+18

Ny A l_TC 4.50E+18 Kiruna Izana Hares tua 4.00E+18 Jungfraujoch Zugspitze 3.50E+18 -2500 -1500 -500 500 1500 2500

Trend: significantly positive, in agreement with the surface trend of +(0.25 ± 0.05) %/yr reported in IPCC 2003 based on in-situ observations

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 43 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

MIPAS N2O FTIR Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 44 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

MIPAS N2O FTIR Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 45 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

MIPAS CH4 FTIR Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 46 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

MIPAS CH4 FTIR Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 47 DRAGON ADVANCED TRAINING COURSE IN ATMOSPHERE REMOTE SENSING

MIPAS CH4 FTIR Validation

Day 4 Lecture 2 Instrument intercomparison – Paul Simon 48