1. CRN Workshop, March 3-5, 2009 1 An Attempt to Evaluate Satellite LST Using SURFRAD Data Yunyue Yu a, Jeffrey L. Privette b, Mitch Goldberg a a NOAA/NESDIS/StAR b NOAA/NESDIS/NCDC

2. CRN Workshop, March 3-5, 2009 2 Outlines   Motivation   Data Sources   Method   Results   Summary

3. CRN Workshop, March 3-5, 2009 3 Motivation  Satellite LST Validation Needs Needs »Over 30 years LST development at NOAA – Climate Data Record »Validation Needs for NPOESS/VIIRS LST Product – Five years Cal/Val plan: 2009 – 2013 – Core ground data source : 20 SURFRAD/CRN sites »Validation Needs for GOES-R/ABI LST Product – Pre-launch validation plan: 2009 – 2013 – Core ground data source : 10-15 SURFRAD/CRN sites »Validation Needs for GIMPAP LST product SURFRAD/CRN data plays critical role in NPOESS and GOES-R Programs !!

4. CRN Workshop, March 3-5, 2009 4 Motivation (2)  LST Validation Difficulties »In Situ data limitation – measurement difficulty: emissivity »Effect of cloud contamination – Partial or thin cloudy pixels »Spatial and temporal variations »Angle effect  New Method Exploration

5. CRN Workshop, March 3-5, 2009 5 Data Sources No. Site Location Lat/Lon Surface Type* 1 Pennsylvania State University, PA 40.72/77.93 Mixed Forest 2 Bondeville, IL 40.05/88.37 Crop Land 3 Goodwin Creek, MS 34.25/89.87 Evergreen Needle Leaf Forest 4 Fort Peck, MT 48.31/105.10 Grass Land 5 Boulder, CO 40.13/105.24 Crop Land 6 Desert Rock, NV 36.63/116.02 Open Shrub Land Duration of Data: Jan 1 – Dec 31, 2001 GOES-8 and GOES-10 Imager data were applied in validating the LST algorithm using ground data from SURFace RADiation (SURFRAD) budget network stations Satellite and Ground Datasets

6. CRN Workshop, March 3-5, 2009 6 Data Source (2) Geolocation Match-up SURFRAD Data Satellite Data Time Match-up (<15 mins) Time Series Smoothness Check: Upwelling, Downwelling Irradiances Spatial Difference Test: T 4 -- 3X3 pix STD, Visual -- 0.5 deg Channel BT Difference Test: (T s, T 4 ), (T 4, T 2 ) (T 4, T 5 ) Matched Dataset Manual Tuning Match-up Flow Chart

7. CRN Workshop, March 3-5, 2009 7 Data Sources (3) » »The difference between the top of the atmosphere channel 4 brightness temperature from GOES satellite for the spatially closest pixel and the land surface temperature derived from SURFRAD measurements should be generally 5 K or less for clear sky conditions. » »The standard deviation of the 3 by 3 pixel array GOES channel 4 brightness temperature should no exceed 1.5 K. » »The absolute difference between GOES channel 4 and channel 2 brightness temperatures should not exceed 5 K. » »The absolute difference between GOES channel 4 and channel 5 brightness temperatures should not exceed 1 K. » »The time series curves of solar irradiance should be smoothly varying without distortions. » »The time series curves of down-welling infrared irradiance also should be smoothly varying in time without any significant enhancement. » »The average reflectance for the spatially closest GOES-pixel should be generally less than 40% except for snow conditions which can be mostly identified from sequence of hourly GOES images. Snow is more static than clouds. » »Finally the 0.5 degree by 0.5 degree around the SURFRAD site must be visually clear of clouds to form coincident pairs of cloud-free SURFRAD and GOES data. Match-up Data Processing

8. CRN Workshop, March 3-5, 2009 8 Data Sources (4) Atmospheric profiles TOA radiances MODTRAN Input (looping) parameters Start Surface Type Configuration Algorithm Coeffs. Sensor Spectral Response Funs Sensor Brightness Temperatures Sensor Brightness Temperature Calculation Regression of LST Algorithms STD Error Of Algorithms Input parameters Filter of Data Distribution Algorithm Selected Accuracy Analysis Sensitivities Analysis tables plots Simulation Process Regression Process Analyzing Process Developing for Satellite LST Algorithm

9. CRN Workshop, March 3-5, 2009 9 Data Sources (5) Month Site 1Site 2Site 3Site 4Site 5Site 6 DayNightDayNightDayNightDayNightDayNightDayNight 116334669761545712484157113245 21745928368678139359596135 30033927094771252358145141 46684284263892564446711274 54069213110713490645143158190 626393754378327324964235189 7183456314814224834250226 8163335691247106 3964188195 946837011084102697697123226257 105677661011562133967287596152 11591188414847112329411017685147 12255435996114838133731245872 Number of Match-up Dataset: and SURFRAD Number of Match-up Dataset: GOES-8 and SURFRAD Overall: Large number for statistical significance.

10. CRN Workshop, March 3-5, 2009 10 Data Source (6) LST estimation from SURFRAD measurement

11. CRN Workshop, March 3-5, 2009 11 Method  Direct Comparison »Scatter Plots »Table of Statistics  Correlation Analyses »Two-measurement Comparisons

12. CRN Workshop, March 3-5, 2009 12 Satellite LST: Algorithms applied to GOES-8/10 data Ground LST: Derived from SURFRAD site measurements Duration: Jan 1 – Dec 31, 2001 SURFRAD radiance Temperature :  emit  up  down  emit   Spectral Correction: T=T+dT pir - dT  dT pir =(d   pir /   )(T/4) dT  =(T/4)(d  ) GOES 8/10 data Cloud filter Match-up and Comparison Statistics Algorithm: LST Calculation Plots & Tables Method (2) of Procedure of Direct Comparison

13. CRN Workshop, March 3-5, 2009 13 Comparison of SURFRAD Estimated LSTs and GOES Retrieved LSTs Validation Results: FORT PECK, 2001 Results for GOES-8Results for GOES-10 Results ---- Direct Comparison

14. CRN Workshop, March 3-5, 2009 14 Comparison of SURFRAD Estimated LSTs and GOES Retrieved LSTs Validation Results: Boulder, 2001 Results for GOES-8Results for GOES-10 Results ---- Direct Comparison (2)

15. CRN Workshop, March 3-5, 2009 15 Validation Results: direct comparison summary Good: ● ● Statistical significance ● ● Two satellite validations ● ● Accuracy satisfaction (average RMS=2.1 K) Issues: ● ● Point-pixel difference ● ● Emissivity inaccuracy ● ● Cloud screen effectiveness Results ---- Direct Comparison (3) Site GOES-8GOES-10 Bias (K)STD (K)Bias (K)STD (K) 11.471.87N/A 21.062.26-0.412.27 30.151.31-0.841.53 4-0.272.10-0.971.87 5-0.591.67-1.371.91 6-1.631.69-1.691.30 Total-0.371.76-1.231.69 RMS1.80/2.07*2.09/2.17* *weighted through each site

16. CRN Workshop, March 3-5, 2009 16 Method (3) Two-Measurement Method

17. CRN Workshop, March 3-5, 2009 17 Method (3) Two-Measurement Method

18. CRN Workshop, March 3-5, 2009 18 Results ---- Correlation Analyses Relative biasV(goes)V(surfrad)V (goes-surfrad)CV(goes, surfrad)  ( goes, surfrad) 0.001739.97134.6452.09636.2600.974 No  goes  surfrad  goes  surfrad 11.051.3780.334 21.061.2390.661 31.071.0830.870 41.080.9001.035 51.090.6691.174 61.100.2931.230 Bondeville Site Case Study Samples for GOES-8 LST vs SURFRAD: Bondeville Site Case Study

19. CRN Workshop, March 3-5, 2009 19 Summary  SURFRAD ground station data were used for GOES-R LST algorithm evaluation.  GOES-8, -10 Imager data were used as proxies of GOES-R ABI.  LST algorithm coefficients were derived from a radiative transfer simulation model (MODTRAN).  Match-up dataset of satellite and ground data were created carefully.  Direct comparisons indicate a promising algorithm accuracy.  Correlation analyses showed good algorithm precision  Further works will be performed using three-measurement comparison

20. CRN Workshop, March 3-5, 2009 20 Backup slides

21. CRN Workshop, March 3-5, 2009 21 Two-directions from GOES Satellites 135° W 75°W

22. CRN Workshop, March 3-5, 2009 22 Difference of LSTs observed by GOES-10 and GOES-8 imager at the same location of SURFRAD station Desert Rock, NV, 36.63ºN, 116.02ºW. The simultaneous observation pairs are about 2096. View zenith of GOES-8: 60.14 0 View zenith of GOES-10: 46.81 0 LST Directional Effect in GOES-8 and -10 Imager

23. CRN Workshop, March 3-5, 2009 23 Goodwin Creek, MS, observation pairs are about 510. View Zenith of GOES-8/-10: 42.68 0 /61.89 0 LST Directional Effect in GOES-8 and -10 Imager (2)

24. CRN Workshop, March 3-5, 2009 24 Boulder, CO, observation pairs are about 510. View Zenith of GOES-8/-10: 42.68 0 /61.89 0 LST Directional Effect in GOES-8 and -10 Imager (3)

25. CRN Workshop, March 3-5, 2009 25 LST Directional Effect in GOES-8 and -10 Imager (4) Bondville, IL. Data pairs: 710 Fort Peck, MT. Data pairs: 912 View Zenith of GOES-8: 48.12 0 View Zenith of GOES-10: 66.14 0 View Zenith of GOES-8: 62.42 0 View Zenith of GOES-10: 62.36 0 Note the difference of the two sites

26. CRN Workshop, March 3-5, 2009 26 Daytime Scatter plot comparison of the GOES LST and the SURFRAD LST for all the match-up data in 2001, within 6 SURFRAD sites.

27. CRN Workshop, March 3-5, 2009 27 scatter plot comparison of the GOES LST and the SURFRAD LST for all the match-up data in 2001, within 6 SURFRAD sites. Nighttime scatter plot comparison of the GOES LST and the SURFRAD LST for all the match-up data in 2001, within 6 SURFRAD sites.

28. CRN Workshop, March 3-5, 2009 28 scatter plot comparison of the GOES LST and the SURFRAD LST for all the match-up data in 2001, within 6 SURFRAD sites. Dry atmos condition scatter plot comparison of the GOES LST and the SURFRAD LST for all the match-up data in 2001, within 6 SURFRAD sites.

29. CRN Workshop, March 3-5, 2009 29 scatter plot comparison of the GOES LST and the SURFRAD LST for all the match-up data in 2001, within 6 SURFRAD sites. Moist atmos condition scatter plot comparison of the GOES LST and the SURFRAD LST for all the match-up data in 2001, within 6 SURFRAD sites.