# A New Approach to Defining Uncertainties for MODIS Land Surface Temperature
## 3 Validation
### Product Validation  
Figure 3 shows the validation for the GlobTemperature Aqua-MODIS product (GT_MYD_2P) at each of the seven sites over a full year of observations (2011). Corresponding validation is also shown for the level-2 operational Aqua-MODIS Collection 5 LST product (MYD11_L2) in Figure 4. Table 2 details the statistics of the validation. We use a three-sigma Hampel filter using robust statistics [67] to limit the number of outliers primarily caused by undetected clouds. This has been used in previous LST validation studies [68; 69]. A general finding is that better agreement against the in situ data is found for GT_MYD_2P compared with MYD11_L2. Figure 3: LST validation for the GlobTemperature Aqua-MODIS LST product (GT_MYD_2P) over seven SURFRAD validation sites: (**a**) Table Mountain, (**b**) Penn State University, (**c**) Bondville, (**d**) Desert Rock, (**e**) Goodwin Creek, (**f**) Sioux Falls, (**g**) Fort Peck; covering the year of 2011. Daytime matchups are in red, and nighttime matchups are in blue. The overall statistics for GT_MYD_2P show mean daytime bias of 0.37 K and an average daytime standard deviation per site of 1.53 K. For nighttime these values are 0.73 K and 1.21 K respectively. The corresponding statistics for MYD11_L2 show mean daytime bias of 1.33 K and average daytime standard deviation per site of 1.43 K. For nighttime, these values are 0.92 K and 1.09 K respectively. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Site**} & \multirow{2}{*}{**LST Product**} & \multicolumn{5}{c}{**Day**} & \multicolumn{5}{c}{**Night**} \\ \cline{3-10}  & & **n** & \(\mu\)**(K)** & \(\sigma\)**(K)** & **RMSE (K)** & **n** & \(\mu\)**(K)** & \(\sigma\)**(K)** & **RMSE (K)** \\ \hline \multirow{3}{*}{Bondville} & MYD11\_L2 & 74 & \(-\)1.16 & 1.74 & 2.09 & 92 & \(-\)0.51 & 1.38 & 1.47 \\ \cline{2-10}  & GT\_MYD\_2P & 84 & 0.08 & 1.66 & 1.66 & 93 & 0.02 & 1.33 & 1.33 \\ \hline \multirow{3}{*}{Desert Rock} & MYD11\_L2 & 101 & \(-\)1.57 & 0.85 & 1.78 & 16 & \(-\)2.36 & 0.23 & 2.37 \\ \cline{2-10}  & GT\_MYD\_2P & 219 & 0.87 & 1.48 & 1.71 & 270 & \(-\)0.88 & 1.17 & 1.46 \\ \hline \multirow{3}{*}{Fort Peck} & MYD11\_L2 & 116 & \(-\)0.68 & 1.60 & 1.74 & 167 & \(-\)0.63 & 1.06 & 1.23 \\ \cline{2-10}  & GT\_MYD\_2P & 107 & 0.28 & 1.43 & 1.46 & 166 & \(-\)0.42 & 1.09 & 1.17 \\ \hline Goodwin Creek & MYD11\_L2 & 113 & \(-\)1.91 & 1.06 & 2.18 & 90 & \(-\)0.08 & 1.41 & 1.41 \\ \hline \multirow{3}{*}{Penn State} & MYD11\_L2 & 82 & \(-\)2.20 & 1.67 & 2.76 & 76 & 0.75 & 1.47 & 1.65 \\ \cline{2-10}  & GT\_MYD\_2P & 91 & \(-\)0.28 & 1.66 & 1.68 & 73 & 1.85 & 1.37 & 2.31 \\ \hline \multirow{3}{*}{Sioux Falls} & MYD11\_L2 & 110 & \(-\)0.84 & 1.69 & 1.89 & 139 & \(-\)0.88 & 1.27 & 1.55 \\ \cline{2-10}  & GT\_MYD\_2P & 120 & 0.35 & 1.63 & 1.67 & 142 & \(-\)0.29 & 1.26 & 1.30 \\ \hline \multirow{3}{*}{Table Mountain} & MYD11\_L2 & 87 & \(-\)0.96 & 1.40 & 1.70 & 121 & \(-\)1.23 & 0.84 & 1.49 \\ \cline{2-10}  & GT\_MYD\_2P & 102 & \(-\)0.40 & 1.45 & 1.50 & 136 & \(-\)0.77 & 1.06 & 1.31 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: In situ validation statistics during 2011 for both GlobTemperature Aqua-MODIS LST retrievals (GT_MYD_2P) and operational Aqua-MODIS LST retrievals (MYD11_L2) with respect to the seven SURFRAD sites. Number of matchups (n), median (\(\mu\)) differences, robust standard deviations (\(\sigma\)) and root-mean-square errors (RMSEs) are presented for both day and night observations. Figure 4: LST validation for the operational Aqua-MODIS Collection 5 Level-2 LST product (MYD11_L2) over seven SURFRAD validation sites: (**a**) Table Mountain, (**b**) Penn State University, (**c**) Bondville, (**d**) Desert Rock, (**e**) Goodwin Creek, (**f**) Sioux Falls, (**g**) Fort Peck; covering the year of 2011. Daytime matchups are in red, and nighttime matchups are in blue.