VARIABLE: CLEAR SKY LAND SURFACE TEMPERATURE (LST) Observed temporal variations of LST y(t) can be expressed as sum of the time-dependent expected value Y(t), the weather/climate-related anomaly y'(t) and random error of observation δ(t): y(t) = Y(t) + y'(t) + δ(t). (2) Expected value Y(t) can be approximated as: (3) Where T=1year, H=1day, K=N=2. Land Surface Temperature (T ) ground truth can be obtained from observation of upward (Uup) and downward (Udw) broadband infrared fluxes over land at Surface Radiation (SURFRAD) stations: δσT4 = Uup - (1-ε)Udw . (1) Land surface emissivity (ε) is assumed to be known, and σ is the Stefan-Boltzmann constant. GOES-10 Observed 2001 Diurnal/Seasonal cycle of LST (ºC) at location of SURFRAD stations: The amplitude of the diurnal cycle of LST is very large, almost twice as large as the amplitude of the diurnal cycle of Surface Air Temperature.

Clear sky LST GOES-8-SURFRAD GOES-10-SURFRAD GOES-10-GOES-8 Estimates of seasonal and diurnal variations of cloud free LST (ºC) at SURFRAD stations Y1(t), and systematic differences in expected values Y2(t)-Y1(t), Y3(t)-Y1(t), Y3(t)-Y2(t) of LST observed at SURFRAD stations (1), GOES-8 (2), and GOES-10 (3) satellites. Dashed lines display sunrise and sunset times. SURFRAD

Empirical estimates of Lag-correlation function of weather related component in GOES-10 observed clear sky LST in vicinity of three SURFRAD stations.

Systematic Error, Δi,j, ºC List of selected SURFRAD stations with their coordinates; Numbers of used observations coincided in time at SURFRAD stations, GOES-8 and GOES-10 satellites; Annual mean LST a00; Standard Errors of LST observation δi; Standard Deviation σ of weather related component of LST; Correlation between residuals of LST approximation, COR (yi-Yi,yj-Yj); Mean differences Δi,j between nighttime observed LST. Index i,j=1,2,3 means: 1 - SURFRAD station, 2 - GOES-8, and 3 – GOES-10 satellite observation. SURFRAD Network Coordinates Obser- vations Number Annual Mean, a00ºC Standard Error SD COR (yi-Yi,yj-Yj) Systematic Error, Δi,j, ºC Station Name Lat. º N Lon. º W i=1 i=2 i=3 δ1 ºC δ2 δ3 σ r1,2 r1,3 r2,3 Δ2,1 Δ3,1 Δ3,2 Goodwin Creek, MS 34.25 89.87 510 14.3 13.0 0.6 0.8 0.7 3.7 .96 .97 -0.2 -0.9. Desert Rock, NV 36.63 116.02 3190 21.5 19.7 19.9 1.2 3.0 .92 .94 .90 -2.3 -2.0 0.3 Bondville, IL 40.05 88.37 1160 9.5 11.2 9.2 1.3 3.5 -1.2 -1.6 Boulder, CO 40.13 105.24 1350 10.8 10.4 9.6 0.9 1.0 4.3 .95 .93 -0.7 -1.1 -0.4 Fort Peck, MT 48.31 105.10 1360 6.2 5.9 5.1 1.1 -0.5 -0.9