## 4 Results and Discussion
### HiWATER-MUSOEXE Results  
Statistics of the comparisons between the HJ-1B/IRS LST, MODIS 1 km LST, and _in situ_ AMS measurements for each of the HiWATER sites shown in Figure 2 are summarized in Table 3. Although there are fewer days with HJ-1B/IRS data than with MODIS data, both comparisons with _in situ_ data yield similar results: the HJ-1B/IRS standard deviation (STD), RMSE, and linear correlation coefficient (R) values of HJ-1B/IRS _vs._ AMS are 2.45 K, 2.78 K, and 0.67 (with 204 samples), respectively, whereas those for the MODIS 1 km LST values are 4.07 K, 2.98 K, and 0.79 (with 886 samples), respectively. A single Taylor [32] diagram is shown in Figure 4 to summarize multiple aspects of the method performance. The labels are assigned to six cases of the available data listed in Table 3. The position of each label on the plot quantifies how closely the estimation matches the _in situ_ measurements. The RMSE (blue dotted semi-circle) between the estimated and _in situ_ measurements is the difference from the \"observed\" values, which are defined as the _in situ_ measurement STDs. The labels with a small  
Figure 3: Scatter plots of **(a)** the MOD05-WVC and _in situ_ CE318-WVC for cloud-free observations; **(b)** the difference between the MOD05-WVC and _in situ_ CE318-WVC compared with the CE318-WVC at the HiWATER sites from 19 June to 15 September 2012. The number of valid samples is 26.  
distance to the \"observed\" points (_i.e._, smaller values of \"observed\" contours) correspond to the estimates that agree well with the _in situ_ measurements. Most of these estimates have relatively high correlations and low RMSEs. The estimates that lie on or near the dashed arc have the correct STD. In Figure 4, it can be observed that label \"a\" (vegetables, HJ-1B/IRS) generally agrees better with the _in situ_ measurements and exhibits lower RMSE and higher correlation. For the other labels (maize and orchards), the results are not as good, as the RMSEs are larger than 1.5 K (outside the dotted semi-circle of 1.50) and the correlations are lower than 0.9 (outside the green line of 0.9). The vegetable site (AMS 1, labeled \"a\" in Figure 4) is a relatively flat area with an elevation of 1552.75 m. Figure 5a indicates good agreement between the site observations and the satellite estimates at the vegetable site, which are also shown in Figure 4 and Table 3.  
The 14 maize sites (AMS 2-AMS 3, AMS 5-AMS 16) are typical maize croplands in the HiWATER project. These sites are analyzed as a group in this study. The RMSE of 2.83 K in the maize area is acceptable due to the intercropping of certain croplands. The MODIS 1 km LST produces significant underestimations (the red ellipse in Figure 5b). These underestimations may partly be caused by the effect of clouds. It is difficult to efficiently exclude the clouds, especially in the partly cloudy pixels. The orchard site (AMS 17) is planted with apple trees and intercropping maize. Unlike the vegetable and maize sites, the landscape at this site is heterogeneous. However, the results at the orchard site are  
Figure 4: Taylor diagram that describes the performance of the LST retrieval from HJ-1B/IRS and MODIS over the HiWATER experiment sites in 2012. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Cropland** & **Product** & **Label (in Figure 4)** & **STD (K)** & **RMSE (K)** & **R** & **N (Samples)** \\ \hline \multirow{3}{*}{Vegetable} & HJ1B/IRS & a & 3.40 & 1.42 & 0.94 & 12 \\  & MODIS & A & 3.61 & 2.32 & 0.85 & 53 \\ \multirow{3}{*}{ Maize} & HJ1B/IRS & b & 2.58 & 2.83 & 0.67 & 180 \\  & MODIS & B & 4.06 & 3.01 & 0.79 & 778 \\ \multirow{3}{*}{Orchard} & HJ1B/IRS & c & 2.61 & 2.87 & 0.69 & 12 \\  & MODIS & C & 3.51 & 3.12 & 0.79 & 55 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Comparison of the HJ-1B/IRS and MODIS 1 km LST algorithm performance at the HiWATER sites (from June to September 2012). similar to those at the maize sites (Table 4 and Figure 4). This result is confirmed in Figure 5c.