1. March 18, 2003 MODIS Atmosphere, St. Michaels MD Infrared Retrieval of Temperature, Moisture, Ozone, and Total Precipitable Water: Recent Update and Status of MOD07 Suzanne Wetzel Seemann a, Jun Li a, W. Paul Menzel b, Liam E. Gumley a, Kathleen I. Strabala a a Cooperative Institute for Meteorological Satellite Studies, University of Wisconsin-Madison b Office of Research and Applications, NOAA/NESDIS

2. March 18, 2003 MODIS Atmosphere, St. Michaels MD Retrievals are performed in 5x5 FOV (approximately 5km resolution) clear-sky radiances over land and ocean for both day and night. Algorithm is a statistical synthetic regression and has the option for a subsequent nonlinear physical retrieval. Regression predictors include MODIS infrared radiances from bands 24, 25, 27-36 (4.4 - 14.2  m). Clear sky determined by MODIS cloud mask (MOD35). MODIS Atmospheric Temperature and Moisture Profiles Product, MOD07

3. March 18, 2003 MODIS Atmosphere, St. Michaels MD Overview of MOD07 products Brief algorithm discussion Evaluation of MOD07 products (Collection 3 processed after May 1, 2002) Recent Update (March 14, 2003) MOD07 products include: Atmospheric precipitable water vapor (total, high, and low) Profiles of temperature and moisture Total column ozone Stability indices (lifted index, total totals)

4. March 18, 2003 MODIS Atmosphere, St. Michaels MD Hurricane Lili, 2 October 2002 Terra MODIS direct broadcast TPW (mm): Terra MODIS total precipitable water vapor Terra MODIS true color image

5. March 18, 2003 MODIS Atmosphere, St. Michaels MD Typhoon Sinlaku, 7 September 2002 Aqua MODIS TPW = 72.5 mm Aqua MODIS true color image Total Precipitable Water Vapor

6. March 18, 2003 MODIS Atmosphere, St. Michaels MD Terra MODIS Total Precipitable Water Vapor, 2 June 2001 0 6 12 18 24 30 36 42 48 54 60 66 72 TPW (mm):

7. March 18, 2003 MODIS Atmosphere, St. Michaels MD PW High 700-300 hPa PW Low 920 hPa - sfc PW (mm): 0 3 6 9 12 15 18

8. March 18, 2003 MODIS Atmosphere, St. Michaels MD Dobson Total Column Ozone, 2 October 2002 Terra MODIS direct broadcast

9. March 18, 2003 MODIS Atmosphere, St. Michaels MD Isobaric Surfaces/Profiles of Temperature 13 October 2002 Terra MODIS direct broadcast oKoK Temperature Pressure (hPa) 300 hPa 500 hPa 850 hPa

10. March 18, 2003 MODIS Atmosphere, St. Michaels MD Mixing Ratio (g/kg) Pressure (hPa) 300 hPa 500 hPa 850 hPa Isobaric Surfaces/Profiles of Mixing Ratio 13 October 2002 Terra MODIS direct broadcast

11. March 18, 2003 MODIS Atmosphere, St. Michaels MD p sfc p sfc I =  sfc B (T sfc )  (p sfc ) -  B (T(p)) [ d  (p) / dp ] dp + (1-  )  B d  o Algorithm Discussion Clear radiance exiting the atmosphere for a MODIS IR band with wavelength : I is measured by MODIS for = 4.4 - 14.2  m (I 24, I 25, I 27, … I 36 ) I can be considered a nonlinear function of the atmospheric properties including T, q, ozone, surface pressure, skin temperature, and emissivity. We can infer a synthetic regression relationship using calculated radiances from a global set of radiosonde profiles and surface data. Relationship is inverted to retrieve atmospheric properties from observed MODIS radiances.

12. March 18, 2003 MODIS Atmosphere, St. Michaels MD Global radiosondes: NOAA-88 data set containing 7500+ global radiosonde profiles of temperature, moisture, and ozone used for training data set. 800 additional radiosondes from north African desert were added. Skin temperature and emissivity must be assigned to each profile. RT model: Radiance calculations for each training profile are made using a 101 pressure layer transmittance model. MODIS instrument noise is added to calculated spectral band radiances. Radiosonde temperature-moisture-ozone profile / calculated MODIS radiance pairs are used to create the statistical regression relationship. Bias corrections are applied to the observed MODIS radiances to account for forward model error, spectral response uncertainty, and calibration error.

13. March 18, 2003 MODIS Atmosphere, St. Michaels MD Global Total Precipitable Water Comparison 22 May 2002 MODIS TPW SSM/I f-14 TPW Ascending and descending passes were averaged 0 6 12 18 24 30 36 42 48 54 60 66 72 TPW (mm):

14. March 18, 2003 MODIS Atmosphere, St. Michaels MD TPW (mm) for 2 June 2001 over North America MODIS Regression RetrievalMODIS Physical RetrievalGOES-8 and GOES-10 Day Night

15. March 18, 2003 MODIS Atmosphere, St. Michaels MD Comparison of TPW from MODIS (dots), GOES-8 (circles), and radiosonde (x) with SGP ARM-CART microwave radiometer 79 clear sky cases from April 2001 to October 2002 Sample of one case: Cases were - Manually selected by inspection of radiance images to insure no cloud contamination. More scatter is present if all retrieved pixels are included. - Rerun locally with the most recent algorithm, except this doesn’t include the latest bias corrections.

16. March 18, 2003 MODIS Atmosphere, St. Michaels MD Mean difference MODIS - TOMS = 4.4 dob RMS = 27.4 dob mean abs % error: abs(M-T)/T = 5.9% N = 10,614 Total Ozone from MODIS (top) and TOMS (bottom) May 22, 2002 MODIS (dob) TOMS (dob) 240 260 280 300 320 340 360 380 400 420 440 Latitude ( o ) - 60 - 40 - 20 0 20 40 60 80 - 40 - 20 0 20 40 60 80 % Error (M-T)/T

17. March 18, 2003 MODIS Atmosphere, St. Michaels MD MODIS profiles agree well with radiosondes and NCEP-GDAS when the atmospheric temperature and moisture is fairly smooth and monotonic: But not so well with smaller-scale features, such as isolated dry or moist layers: MODIS GDAS Sonde Temperature Pressure (hPa) Mixing RatioTemperature Pressure (hPa) Mixing Ratio Temperature Pressure (hPa) Mixing Ratio Temperature Pressure (hPa) Mixing Ratio

18. March 18, 2003 MODIS Atmosphere, St. Michaels MD Recent Update (delivered 14 March 2003) Improved emissivity assigned to each training profile Radiance bias correction update Reduction of noise due to detector-to-detector differences and along-track noise New retrieved skin temperature variable saved to ‘Surface_Temperature’; previously it was a copy of the ancillary GDAS surface temperature Improved handling of surface level in integration of TPW

19. March 18, 2003 MODIS Atmosphere, St. Michaels MD Recent Update (delivered 14 March 2003) Improved emissivity assigned to each training profile Radiance bias correction update Reduction of noise due to detector-to-detector differences and along-track noise New retrieved skin temperature variable saved to ‘Surface_Temperature’; previously it was a copy of the ancillary GDAS surface temperature Improved handling of surface level in integration of TPW

20. March 18, 2003 MODIS Atmosphere, St. Michaels MD Original algorithm used MODIS bands 24, 25, and 27 through 36 as predictors (4.4 - 14.2  m). Skin temperature and emissivity in the training data set does not properly characterize desert surface conditions for the shortest wavelength bands 24 & 25 (4.4 & 4.5  m). 0 6 12 18 24 30 36 42 48 54 60 66 72 TPW (mm): Result: Algorithm retrieved too much moisture over deserts.

21. March 18, 2003 MODIS Atmosphere, St. Michaels MD New algorithm operational May 1, 2002 Instead of using the BT from bands 24 and 25 individually as predictors, we use the BT difference 4.5 minus 4.4  m. This removes the surface contributions from both bands since [  sfc B (T sfc )  (p sfc )] =4.5  m - [  sfc B (T sfc )  (p sfc )] =4.4  m  0

22. March 18, 2003 MODIS Atmosphere, St. Michaels MD Level 3 - TPW 1 Day Global Average Max value in 1 degree area Images curtesy of Paul Hubanks, from MODIS web Elevated TPW in some desert areas

23. March 18, 2003 MODIS Atmosphere, St. Michaels MD Terra daytime June 2001 Aqua daytime August 2002

24. March 18, 2003 MODIS Atmosphere, St. Michaels MD Original emissivity assigned to NOAA88b training profiles: two values 0.84 and 0.95 with std 0.15, 0.03. Linear interpolation for wavelengths in between. Measured emissivity from UCSB MODIS Land group’s Emissivity Library

25. March 18, 2003 MODIS Atmosphere, St. Michaels MD Desert Non-Desert Land Ice / Snow Seawater Ecosystem-based Emissivity

26. March 18, 2003 MODIS Atmosphere, St. Michaels MD Aqua August 24, 2002 New delivery March 14, 2003

27. March 18, 2003 MODIS Atmosphere, St. Michaels MD Recent Update (delivered 14 March 2003) Improved emissivity assigned to each training profile Radiance bias correction update Reduction of noise due to detector-to-detector differences and along-track noise New retrieved skin temperature variable saved to ‘Surface_Temperature’; previously it was a copy of the ancillary GDAS surface temperature Improved handling of surface level in integration of TPW

28. March 18, 2003 MODIS Atmosphere, St. Michaels MD Calculated: NCEP-GDAS profiles of temperature and moisture (interpolated spatially) and surface pressure MOD07 regression-based skin temperature Representative land, ocean, ice, and desert emissivity PFAAST forward model with HITRAN 2000 spectral database Observed: Level 1B radiances, averaged into 5x5 FOV where all 25 pixels in the 5x5 were assigned a 95% confidence of clear or better by the MODIS cloud mask. Sensor zenith angle was limited to 20 o. Night only to avoid reflection in band 24 and sun glint Ocean only to reduce uncertainty due to skin temperature and emissivity estimates.

29. March 18, 2003 MODIS Atmosphere, St. Michaels MD GDAS TPW Terra 2002236 GDAS TPW Aqua 2002236

30. March 18, 2003 MODIS Atmosphere, St. Michaels MD

31. Aqua Terra

32. March 18, 2003 MODIS Atmosphere, St. Michaels MD Aqua Terra

33. March 18, 2003 MODIS Atmosphere, St. Michaels MD Aqua Terra

34. March 18, 2003 MODIS Atmosphere, St. Michaels MD Aqua Terra

35. March 18, 2003 MODIS Atmosphere, St. Michaels MD Aqua Terra

36. March 18, 2003 MODIS Atmosphere, St. Michaels MD Terra Aqua 19,000 cases 14,000 cases

37. March 18, 2003 MODIS Atmosphere, St. Michaels MD Terra Radiance Bias at SGP-CART - Sample Individual Cases

38. March 18, 2003 MODIS Atmosphere, St. Michaels MD X X X X X X Terra Radiance Bias at SGP-CART, average of 70 cases Apr 01- Aug 02 Blue lines, calculated with approximated land emissivity Black lines, calculated with emissivity based on AERI measurements at the SGP-CART site and a function of julian day (Dave Tobin). Only significant Day/Night difference is in Band 24

39. March 18, 2003 MODIS Atmosphere, St. Michaels MD X X Terra Radiance Bias at SGP-CART, average of 70 cases Apr 01- Aug 02 Blue lines, calculated with approximated land emissivity Black lines, calculated with emissivity based on AERI measurements at the SGP-CART site and a function of julian day (Dave Tobin). Bias of bands 29, 31, and 32 becomes near-zero with the more accurate emissivity

40. March 18, 2003 MODIS Atmosphere, St. Michaels MD Discontinuity at 50 o N Previous radiance bias corrections were latitude dependent

41. March 18, 2003 MODIS Atmosphere, St. Michaels MD Global Average Radiance Bias (Observed minus Calculated) by Latitude Region +/- Standard Deviation (dotted)

42. March 18, 2003 MODIS Atmosphere, St. Michaels MD New Radiance Bias Corrections, delivery v.4.1.0 (March 14 2003) Can be a function of TPW (NCEP-GDAS) or BT. For each band: bias slope, y-intercept, max, and min are specified. An ancillary input ascii file for each Terra and Aqua contains this information, plus a flag specifying TPW or BT dependence. Input files can be updated regularly without redelivery. This allows us to accommodate changes due to monthly or seasonal bias variations, instrument changes, or improvements to the radiance bias calculations (profile input, surface characterization improvements).

43. March 18, 2003 MODIS Atmosphere, St. Michaels MD The Band 27 and 28 Problem Max = 1.2Max = 1.5

44. March 18, 2003 MODIS Atmosphere, St. Michaels MD Recent Update (delivered 14 March 2003) Improved emissivity assigned to each training profile Radiance bias correction update Reduction of noise due to detector-to-detector differences and along-track noise New retrieved skin temperature variable saved to ‘Surface_Temperature’; previously it was a copy of the ancillary GDAS surface temperature Improved handling of surface level in integration of TPW

45. March 18, 2003 MODIS Atmosphere, St. Michaels MD Sources of Noise in Retrieval Images: 1) Across track: Noisy or out-of-family detectors 2) Along track: Zenith angle dependent regression coefficients Sensor Zenith Actual MODIS sensor zenith n-1nn+1 Zenith angle formerly used for retrieval

46. March 18, 2003 MODIS Atmosphere, St. Michaels MD Sources of Noise in Retrieval Images: 1) Across track: Noisy or out-of-family detectors 2) Along track: Zenith angle dependent regression coefficients Sensor Zenith Actual MODIS sensor zenith n-1nn+1 New: perform two retrievals and average

47. March 18, 2003 MODIS Atmosphere, St. Michaels MD Terra 2001213 0505 Collection 3Recent Delivery

48. March 18, 2003 MODIS Atmosphere, St. Michaels MD Aqua 2002288 1925 Collection 3Recent Delivery

49. March 18, 2003 MODIS Atmosphere, St. Michaels MD Future Work Test use of TIGR training data set instead of NOAA-88 Improve surface characterization (emissivity, skin temperature) assigned to the training profiles Regression-based global radiance bias corrections Extend validation to other ARM CART sites, radiosondes, sun photometer network Applications to climate and weather studies See next

50. March 18, 2003 MODIS Atmosphere, St. Michaels MD IGBP Ecosystem Location of TIGR3 Profiles by Ecosystem Group

51. March 18, 2003 MODIS Atmosphere, St. Michaels MD Future Work Test use of TIGR training data set instead of NOAA-88 Improve surface characterization (emissivity, skin temperature) assigned to the training profiles Regression-based global radiance bias corrections Extend validation to other ARM CART sites, radiosondes, sun photometer network Applications to climate and weather studies See next

52. March 18, 2003 MODIS Atmosphere, St. Michaels MD http://cimss.ssec.wisc.edu/modis/mod07 http://modis-atmos.gsfc.nasa.gov/