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New Products from combined MODIS/AIRS

This article introduces new products for IMAPP from combined MODIS/AIRS data, including MODIS classification mask, AIRS sub-pixel cloud detection products, and cloud property products from AIRS radiances with the help of MODIS cloud masks. The article also discusses the validation of these products through comparisons with MODIS imagery, ground measurements, and lidar observations.

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New Products from combined MODIS/AIRS

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  1. New Products from combined MODIS/AIRS Jun Li, Chian-Yi Liu, Allen Huang, Xuebao Wu, and Liam Gumley Cooperative Institute for Meteorological Satellite Studies Space Science and Engineering Center University of Wisconsin-Madison 1225 West Dayton Street, Madison, Wisconsin International EOS/NPP Direct Readout Meeting, 3 – 6 October 2005 Benevento, Italy

  2. New products for IMAPP from combined MODIS/AIRS • MODIS classification mask • AIRS sub-pixel cloud detection products using MODIS data (Li et al. 2004a -JAM) • Single FOV Cloud/Aerosol property products from AIRS radiances (Li et al. 2004b - JAM; 2005a - JAM) with the help of MODIS (cloud mask, cloud phase mask, cloud classification mask, etc.) • AIRS cloud-clearing radiance products using multi-band MODIS clear radiances (Li et al. 2005b – IEEE TGARS)

  3. AIRS sub-pixel cloud detection and characterization using MODIS (Li et al. 2004a - JAM). • Use MODIS cloud mask (1 km) for AIRS single field-of-view (SFOV) clear mask • Use MODIS cloud phase mask (1 km) for AIRS SFOV cloud phase mask • Use MODIS cloud classification mask (1 km) for AIRS SFOV cloud classification mask Aqua MODIS RGB Natural Color; 17 September 2003: Hurricane Isabel

  4. AIRS clear coverage Clear Cloudy MODIS confident clear pixels are counted for AIRS clear coverage ! MODIS 1 km cloud mask

  5. Unknown Mixed Phase Ice Clouds Water Clouds Clear AIRS cloud phase mask with 13.5 km resolution (mixed phase clouds appear frequently !) MODIS cloud phase mask with 1 km spatial resolution

  6. F3 F2 F1 AIRS Window BT(K) Water Land L. Cld Mid Cld L. Cld H. Cld H. Cld Mid Cld Mid. Cld MODIS 1km classification mask superimposed to the AIRS footprints of the study area. The MODIS classification mask gives the cloud layer information with each AIRS footprint.

  7. Cloud property products from AIRS radiances (Li et al. 2004b - JAM; 2005a - JAM) with help of MODIS • MODIS cloud mask is used for AIRS SFOV clear/cloudy detection • MODIS cloud phase mask is used for AIRS SFOV phase determination • Cloud properties are retrieved from from AIRS radiances with a physical algorithm (Minimum Residual Method)

  8. Minimum Residual (MR) algorithm for cloud property retrieval (Li et al. 2004b - JAM; 2005a - JAM) Observed HES Radiance Measurements Cost function Fast Cloudy Radiative Transfer Model CTP: Cloud-Top Pressure; ECA: Effective Cloud Amount at 10 wavenumbers CPS: Cloud Particle Size in diameter; COT: Cloud Optical Thickness at 0.55µm clear COT, CPS (window region): 790 – 1130 cm-1 CTP and ECA (CO2 region): 670 – 790 cm-1 cloudy

  9. COT=0.05 COT=1.0 COT=5.0 COT=10.0

  10. CPS=10 CPS=20 CPS=30 CPS=50

  11. F1: Thick ice clouds 1km MODIS classification mask superimposed to AIRS footprints AIRS BT(K) @ 901.69 cm-1

  12. F1: CTP=258, CPS=33.90, COT=1.62

  13. AIRS window BT image over North America region

  14. AIRS cloud-top pressure retrieval with help of MODIS cloud mask

  15. AIRS cloud optical thickness retrieval with help of MODIS cloud mask and cloud phase mask

  16. Validation of cloud properties • Compare with MODIS natural color image • Compare with MODIS classification results • Ground measurements • Lidar observation

  17. MODIS/AIRS Spatial resolution: MODIS CTP: 5 km AIRS CTP: 13.5 km GOES CTP: 10 km

  18. AIRS CTH (m) Box A Barrow MPACE: Mixed Phase Artic Cloud Experiment Granule 223, 17 October 2004

  19. CTP comparison with Lidar AIRS time is 22:17:32 MODIS CTH=5.5 km; AIRS CTH=7.6 km

  20. AIRS OD=1.44 Vertical Layers AIRS Effective Radius=38.6 um AIRS time = 22:17:32 UTC

  21. Desert Vs Dust aerosol Dust Desert MODIS (BT11 - BT12) AIRS window BT MODIS Natural color

  22. Dust/aerosol Negative slope between 11 and 12 um Desert Low surface emissivity @ 8.9 um over desert Synergy of MODIS/AIRS is expected to improved aerosol/dust products which are useful for regional applications

  23. Derive AIRS cloud-cleared radiances using MODIS/AIRS cloud-clearing algorithm • MODIS multi-spectral IR clear radiances within AIRS sub-pixel are used for AIRS cloud-clearing on SFOV basis (Li et al. 2005b, IEEE-TGARS) • MODIS clear radiances within AIRS sub-pixel are used for Quality Control (QC) on AIRS cloud-clearing

  24. Aqua MODIS IR SRF Overlay on AIRS Spectrum Direct spectral relationship between IR MODIS and AIRS provides unique application of MODIS in AIRS cloud_clearing !

  25. Optimal imager/sounder cloud-clearing Methodology (Li et al. 2005; IEEE Trans. On Geoscience and Remote sensing, June issue). 3 5 8 7 2 1 6 4 • CCR is obtained on single footprint basis (3 by 3 box moves by single footprint • MODIS clear radiances are used for QC N* is solved from 9 MODIS band (22, 24, 25, 28, 30, 31, 32, 33, 34) are used

  26. AIRS clear (13.5 km) AIRS clear + CC-S (13.5 km) MODIS clear (1 km)

  27. AIRS single FOV profile retrieval versus ECMWF analysis Water Vapor Mixing Ratio Temperature Clear neighbor Cloud contaminated Cloud-cleared

  28. Temperature RMS difference between AIRS and ECMWF~ 250 thin cloud FOVs Contaminated by thin clouds !! Clear Neighbor Cloud-cleared (MODIS/AIRS)

  29. Summary • There are potential new products from combined MODIS/AIRS, especially the SFOV cloud property products that include AIRS cloud mask, cloud phase mask, cloud layer information mask, etc. • AIRS SFOV cloud-cleared radiances will be derived using MODIS/AIRS cloud-clearing approach. • Efforts are also on deriving AIRS SFOV sounding products under both clear and cloudy skies with help of existing MODIS products.

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