Midtropospheric CO 2 Concentration derived from infrared and microwave sounders. Application to the TOVS, AIRS/AMSU, and IASI/AMSU instruments.

Size: px

Start display at page:

Download "Midtropospheric CO 2 Concentration derived from infrared and microwave sounders. Application to the TOVS, AIRS/AMSU, and IASI/AMSU instruments."

Madlyn Warner
6 years ago
Views:

Scott, Gaelle Dufour, Raymond Armante and

1 ITSC XVI Angra dos Reis, 7-13 May 2008 Midtropospheric CO 2 Concentration derived from infrared and microwave sounders. Application to the TOVS, AIRS/AMSU, and IASI/AMSU instruments. Cyril Crevoisier, Alain Chédin, Noëlle A. Scott, Gaelle Dufour, Raymond Armante and Virginie Capelle Laboratoire de Météorologie Dynamique, CNRS, IPSL, Palaiseau

2 CO 2 from infrared/microwave sounders NOAA10/HIRS/MSU NOAAk/HIRS/AMSU AIRS/AMSU NASA/Aqua Since 2002 IASI/AMSU ESA/MetOp Since 2006 NOAA10 TOVS NOAAk ATOVS Time coverage May Oct Spectral resolution # IR/MW channels 19/4 19/15 Aqua AIRS/AMSU MetOp IASI/AMSU cm cm -1 (apodized) 2378/15 (324/15) 8461/15 (421/15) Local time

3 CO 2 seasonal cycle - Northern tropics [0-20 N] NOAA10 TOVS NOAA15 ATOVS* MetOp IASI/AMSU NOAA10: Chédin et al., JGR, 2003, NOAA15: Very preliminary results AIRS: Crevoisier et al., GRL, Aqua AIRS/AMSU

CO 2 seasonal cycle - Northern tropics [0-20 N] 380 370 360 350 340 87 89 91 93 95 97 99 01 03 05 07 NOAA10 TOVS NOAA15 ATOVS* MetOp IASI/AMSU

4 CO 2 seasonal cycle - Northern tropics [0-20 N] NOAA10 TOVS NOAA15 ATOVS* MetOp IASI/AMSU Difference between 7.30 am/pm observations Aqua AIRS/AMSU Diurnal Tropospheric Excess of CO 2 due to biomass burning emissions See Poster B12 [Chédin et al.]

5 Spectrum and sensitivity to atmospheric components Sensitivity of IASI T B to variations of atmospheric and surface variables (simulations with the 4A RT model) T B pert -TB ref (K) surface QuickTime and a TIFF (LZW) decompressor are needed to see this picture. O 3 CH 4 H 2 O CO 2 N 2 O CO CO 2 (1%) H 2 O (20%) O 3 (20%) CH 4 (20%) CO (40%) N 2 O (2%) Surface wavenumber (cm -1 ) 15 μm 10 μm 6 μm 4 μm 1 % of CO 2 variation 0.04% of T B variation 3ppmv 0.3 K The full information contained in the channels is needed to extract the CO 2 signal!

6 Spectrum and sensitivity to atmospheric components Sensitivity of IASI T B to variations of atmospheric and surface variables (simulations with the 4A RT model) T B pert -TB ref (K) surface QuickTime and a TIFF (LZW) decompressor are needed to see this picture. O 3 CH 4 H 2 O CO 2 N 2 O CO CO 2 (1%) H 2 O (20%) O 3 (20%) CH 4 (20%) CO (40%) N 2 O (2%) Surface wavenumber (cm -1 ) 15 μm 10 μm 6 μm 4 μm 1 % of CO 2 variation 0.04% of T B variation 3ppmv 0.3 K The full information contained in the channels is needed to extract the CO 2 signal!

7 Spectrum and sensitivity to atmospheric components Sensitivity of AIRS and IASI channels in the two CO 2 bands (simulations with the 4A RT model) AIRS IASI noise 15 μm H 2 O CO 2 O 3 T B pert -TB ref (K) 4 μm surface T CO noise CO wavenumber (cm -1 ) CO 2 (1%) CO (40%) H 2 O (20%) Surface T (1%) O 3 (20%) Surf. emissivity (5%) At 4 μm: Non-LTE Only nightime retrieval

8 Spectrum and sensitivity to atmospheric components Jacobians of two CO 2 AIRS channels Channel 80-15μm CO 2 Jacobian T Jacobian O 3 Jacobian Channel 261-4μm Channels at 4μm peak lower in the atmosphere.

Spectrum and sensitivity to atmospheric components Jacobians of two CO 2 AIRS channels and AMSU weighting functions Channel 80-15μm CO 2 Jacobian T Jacobian O 3

9 Spectrum and sensitivity to atmospheric components Jacobians of two CO 2 AIRS channels and AMSU weighting functions Channel 80-15μm CO 2 Jacobian T Jacobian O 3 Jacobian Channel 264-4μm 10 AMSU 10 AMSU AMSU 8 AMSU 7 AMSU Channels at 4μm peak lower in the atmosphere. AMSU channels bring the information on temperature.

CO 2 channel selection Aqua AIRS/AMSU: -15 AIRS channels (8 in the 15 μm band - 7 in the 4 μm band). -2 AMSU channels (6 and 8). MetOp IASI/AMSU: -14 IASI channels (all in the 15 μm band).

10 CO 2 channel selection Aqua AIRS/AMSU: -15 AIRS channels (8 in the 15 μm band - 7 in the 4 μm band). -2 AMSU channels (6 and 8). MetOp IASI/AMSU: -14 IASI channels (all in the 15 μm band). -3 AMSU channels (6, 7, and 8). Sensitivity (K) IASI sensitivity (K) IASI - CO2 channel selection CO 2 (1%) H 2 O (20%) O 3 (20%) 10 CH4 4% CO 20% 100 N2O 1% O3 20% CO2 1% H2O 20% IASI CO 2 Jacobians AMSU 8 AMSU AMSU

11 The level1b validation suite at LMD See Poster B10 [Armante et al.] Colocation of radiosoundings/re-analyses ERA40 with IR/MW observations FTP «Clean» Radiosoundings Radiosoundings /Reanalysis (ERA-40) Quality control of the Radiosoundings Inter/extrapolation UGAMP climatology ECMWF Radiative biases between calculated and observed BT RT model (Stransac, 4A) Fixed CO 2 =372 ppmv Space and Time Colocation (100 Km, 3h) - Radiosoundings «ERA40» (23 Go from 1979 to 2007 ) -Re-analyses ERA-40 (79 Mo / day, 2 days /month) Example IASI/AMSU (MetOp) Satellite data :14 orbits/day 900 Mo/day; 421 IR, 15 MW L1B Satellite Data ( )

12 AIRS Radiative biases: Monthly evolution (5 years over the tropics) Calc.-Obs. (K) 0.8 AIRS 80 (15 μm) 1.6 AIRS 264 (4 μm) AMSU ~60 situations/month over sea ~30 situations/month over land

13 AIRS Radiative biases: Monthly evolution (5 years over the tropics) Calc.-Obs. (K) 0.8 AIRS 80 (15 μm) 1.6 AIRS 264 (4 μm) CO 2 slopes (mean over 5 years): AIRS 80: 2.16 ppmv.yr -1 AIRS 264: 2.39 ppmv.yr -1 Mauna Loa: 2.05 ppmv.yr AMSU 6 ~60 situations/month over sea ~30 situations/month over land

14 A stand-alone approach General features of the CO 2 retrieval scheme : non-linear regressions calc-obs bias removal «clear sky» detection Training data set (TIGR) Selection of a set of CO 2 channels Training of Neural Networks Non-linear inference scheme Off-line q CO2 Simultaneous use of IR and MW channels to decorrelate T/CO 2. IASI AMSU Retrieval limited to the tropical region. [Chédin et al., JGR, 2003; Crevoisier et al., GRL, 2004]

15 Evaluation of the inference scheme characteristics We retrieve a mid-to-upper tropospheric integrated content of CO 2. Mean CO 2 averaging kernel over TIGR atmospheric dataset for nadir observation 10 Pressure (hpa) km IASI/AMSU NOAA15 AIRS/AMSU 1000

16 CO 2 distribution from AIRS and IASI - Monthly average

Evaluation of IASI CO 2 JAL commercial airliners between Australia and Japan Aircraft [Matsueda et al.] -8-10 km -1-2 points/month -until March.

17 Evaluation of IASI CO 2 JAL commercial airliners between Australia and Japan Aircraft [Matsueda et al.] km -1-2 points/month -until March IASI CO 2 weighting function altitude of the aircraft IASI CO 2 -integrated content 5-15 km -monthly mean -period: July 2007-March

18 Seasonal cycle 2 Detrended CO 2 seasonal cycle as observed in situ by JAL aircraft for CO 2 (ppmv) Apr Jun Aug Oct Dec Feb

19 Seasonal cycle 2 Detrended CO 2 seasonal cycle as observed in situ by JAL aircraft for CO 2 (ppmv) IASI (07/07-08/03) -2 Apr Jun Aug Oct Dec Feb

20 Latitudinal variation CO 2 latitudinal variation in July 1 ppmv JAL aircraft (10 km) IASI (5-15 km) 30N-25N 25N-20N 20N-15N 15N-10N 10N-05N 05N-EQ EQ-05S 05S-10S 10S-15S 15S-20S 20S-25S

21 Conclusions We retrieve a mid-to-upper tropospheric integrated content of CO 2 from simultaneous IR/MW observations (TOVS, ATOVS, AIRS/AMSU, IASI/AMSU). The CO 2 signal is very low: The full information contained in the channels is needed (that excludes using PCA-like data). Good agreement of CO 2 distribution between IASI and AIRS but lower variability/uncertainty with IASI: -Reducing radiometric noise is as important as improving spectral resolution. -A good AMSU instrument is important. General good agreement with in-situ observation in terms of seasonal cycle and latitudinal gradients.

A view on mid- tropospheric CH 4 and CO 2 in the tropics: 6 years from MetOp- A/IASI

2013 EUMETSAT/AMS Conference Vienna, 16-20 September 2013 A view on mid- tropospheric CH 4 and CO 2 in the tropics: 6 years from MetOp- A/IASI C. Crevoisier 1, R. Armante 1, N. Meilhac 1, S. Massart 2,