CRN Workshop, March 3-5, 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

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

CRN Workshop, March 3-5, 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 : SURFRAD/CRN sites »Validation Needs for GIMPAP LST product SURFRAD/CRN data plays critical role in NPOESS and GOES-R Programs !!

CRN Workshop, March 3-5, 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

CRN Workshop, March 3-5, 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/ Grass Land 5 Boulder, CO 40.13/ Crop Land 6 Desert Rock, NV 36.63/ 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

CRN Workshop, March 3-5, 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 X3 pix STD, Visual 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

CRN Workshop, March 3-5, 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

CRN Workshop, March 3-5, 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

CRN Workshop, March 3-5, Data Sources (5) Month Site 1Site 2Site 3Site 4Site 5Site 6 DayNightDayNightDayNightDayNightDayNightDayNight Number of Match-up Dataset: and SURFRAD Number of Match-up Dataset: GOES-8 and SURFRAD Overall: Large number for statistical significance.

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

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

CRN Workshop, March 3-5, 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

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

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

CRN Workshop, March 3-5, 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) N/A Total RMS1.80/2.07*2.09/2.17* *weighted through each site

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

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

CRN Workshop, March 3-5, Results ---- Correlation Analyses Relative biasV(goes)V(surfrad)V (goes-surfrad)CV(goes, surfrad)  ( goes, surfrad) No  goes  surfrad  goes  surfrad Bondeville Site Case Study Samples for GOES-8 LST vs SURFRAD: Bondeville Site Case Study

CRN Workshop, March 3-5, 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

CRN Workshop, March 3-5, Backup slides

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

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

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

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

CRN Workshop, March 3-5, 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: View Zenith of GOES-10: View Zenith of GOES-8: View Zenith of GOES-10: Note the difference of the two sites

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

CRN Workshop, March 3-5, 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.

CRN Workshop, March 3-5, 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.

CRN Workshop, March 3-5, 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.