## 3 Results
### Testing Noah-MP Model in the Irtysh River Basin  
From the simulation results at the Kuwei site, the simulation accuracy of SFC1 STC1 and SFC2 STC1 is better than that of SFC1 STC2 and SFC2 STC2. At another site in the Irtysh River Basin, [PERSON] et al. [40] also proposed that the SFC1 STC1 scheme has the best simulation accuracy for snow depth and snow water equivalent. Combined with the test results of this study at the Kuwei site, we chose the SFC1 STC1 AB2 SNF1 scheme to simulate the snow depth and snow water equivalent at the whole basin, and the other eight schemes  
Figure 2: Modeling snow depth (**a**,**c**,**e**) and snow water equivalent (**b**,**d**,**f**) using Noah-MP model at Kuwei site. SFC1 STC1 means the surface layer drag coefficient uses the M-O scheme, and snow/soil temperature time uses the semi-implicit scheme. Similarly, the parameterization schemes selected by SFC1 STC2, SFC2 STC1, SFC2 STC2, SFC1 STC1 AB1, SFC1 STC1 AB2, SFC1 STC1 AB2 SNF1, and SFC1 STC1 AB2 SNF3 can be obtained.  
adopted the default selection of the model. Considering that the Noah-MP model requires a long time to reach equilibrium state [50; 51; 52], this study refers to the method proposed by [PERSON] et al. [53], and uses the forcing data from 1 January 2000 to 30 August 2001 to spin-up the model. Through the simulation, we get the simulation results of snow depth and snow water equivalent at a 3 h time scale in the Irtysh River Basin from September 2001 to December 2018. In order to evaluate the accuracy of the model simulation results, we process the snow depth data from all sources to the same time resolution as the GDSD data, and give the time series of the average snow depth in the Irtysh River Basin (Figure 3). As can be seen from Figure 3c,d, the accuracy of snow depth simulated by the Noah-MP model is distinctly higher than that obtained based on microwave remote sensing inversion in the Irtysh River Basin. In years with small snow depth, the snow depth recorded by LSD and CSS data is highly consistent with GDSD data. However, in years with high snow depth, such as 2002, 2006, 2008, 2009, 2010, and 2012, LSD and CSS snow depth are seriously underestimated. The snow depth series simulated based on the CMFD and ERA-Interim data were in good agreement with the GDSD data. Through the calculation results of MD and RMSE (Table 3), it is found that the MD and RMSE values between Noah_CMFD and GDSD are smaller than those between Noah_ERA and GDSD. Therefore, the results obtained by using CMFD as the driving simulation in Irtysh River Basin are the most accurate.  
\begin{table}
\begin{tabular}{c c c} \hline \hline  & **[PERSON]\_CMFD vs. GDSD** & **[PERSON]\_ERA vs. GDSD** \\ \hline _MD_ & 5.07 & 10.27 \\ _RMSE_ & 6.47 & 11.32 \\ \hline \hline \end{tabular}
\end{table}
Table 3: _MD_ and _RMSE_ values between Noah_CMFD, Noah_ERA, and GDSD snow depth.  
Figure 3: Average snow depth (SD) of each five-day period in the Irtysh River Basin from September 2001 to August 2014 based on GDSD data and CMFD simulation (**a**), GDSD data and ERA-Interim simulation (**b**), GDSD and LSD data (**c**), GDSD and CSS microwave remote sensing data (**d**). [PERSON]_CMFD represents the SD series by Noah-MP simulation with CMFD as the driving data and Noah_ERA represents the SD series by Noah-MP simulation with ERA-Interim as the driving data.