This document summarizes research evaluating uncertainties in comparing ground-measured land surface temperature (LST) to satellite-derived LST. The researchers used high-resolution ASTER imagery to characterize sub-pixel variability within low-resolution satellite pixels containing ground measurement sites. Preliminary analysis of four sites found mean differences between synthetic low-resolution pixels and in situ measurements of around 1K, with standard deviations of about 2K, indicating ground measurements can help validate satellite LST if accurate. However, systematic differences between sensor measurements were a major source of uncertainty. More data analysis is needed to better understand seasonal variability.

1. 07/26/10 Yunyue Yu 1 , Ming Chen 2 , Dan Tarpley 3 , Jeffrey L. Privette 4 , Miguel O. Roman 5 Present by Ming Chen 1 NOAA/NESDIS/STAR, 2 IMSG at NOAA/NESDIS, 3 Short & Associates, 4 NOAA/NESDIS/NCDC, 5 NASA/GSFC IGARSS 2010, Honolulu, Hawaii, USA

10. Enhanced Cloud Screening 07/26/10 Enhanced cloud filtering is needed for high quality satellite-ground match-up dataset Cloudy IGARSS 2010, Honolulu, Hawaii, USA

12. Stations and Match-up Datasets 07/26/10 IGARSS 2010, Honolulu, Hawaii, USA In addition to the candidate stations, shown in this map is the occurrence frequency of completely clear sky over US continent, which would affect the data size. Stations Latitude-Longitude Clear Cases By ASTER Cloud masks Clear Cases By Augmented Screening Desert Rock, Co 36.63 o N 116.02 o W 63 46 Bondville, IL 40.05 o N 105.24 o W 115 51 PennState,PA 40.72 o N 77.93 o W 61 20 Boulder, CO 40.13 o N 105.24 o W 35 13 Fort Peck, MT 48.31 o N 105.10 o W 12 8

13. Sample Scatter Plots 07/26/10 IGARSS 2010, Honolulu, Hawaii, USA DesertRock

14. Sample Statistics of Desert Rock Site 07/26/10 IGARSS 2010, Honolulu, Hawaii, USA Note that: E{Tc-Tg}: 1.81 K σ{ Tc-Tg}: 2.46 K Pixel ID Deg E{Tsat-Tc} σ{ Tsat-Tc} E{Tsat-Tg} σ{ Tsat-Tg} 0 C -0.04 0.69 1.78 2.13 1 0 0.01 0.60 1.82 2.26 2 45 -0.08 0.61 1.74 2.20 3 90 -0.20 0.92 1.61 1.99 4 135 -0.06 0.96 1.75 2.03 5 180 0.24 0.98 2.05 2.18 6 225 0.34 0.80 2.15 2.30 7 270 0.26 0.65 2.07 2.40 8 315 0.16 0.60 1.97 2.37

15. Topographic Feature and Mean Satellite-In Situ Difference 07/26/10 IGARSS 2010, Honolulu, Hawaii, USA Tsat-Tg is vectorized, where the modes are the absolute values of Tsat-Tg (Column 7 in Table) , and the directions are the surface site to the synthetic pixel centers. The contour shapes reflect the spatial structure of Tsat-Tg.

16. Aggregated Results 07/26/10 IGARSS 2010, Honolulu, Hawaii, USA 18 Station E{Tsat-Tc} σ{Tsat-Tc} E{Tc-Tg} σ {Tc-Tg} E{Tsat-Tg} σ {Tsat-Tg} DesertRock, NV 0.07 0.76 1.81 2.46 1.88 2.21 Boulder, CO 0.13 0.72 0.77 2.60 0.90 2.58 Fort Peck, MT 0.06 0.99 -0.20 3.36 -0.15 2.62 Bondville, IL 0.09 1.05 0.59 2.01 0.68 2.08 Penn State, PA 0.08 1.14 -0.25 2.09 -0.17 1.99

20. 07/26/10 Thank you for your attention ! IGARSS 2010, Honolulu, Hawaii, USA