MAT, MAP, Z-Elevation

Daily air temperature, precipitation, and elevation of the rain-snow transition (Z-elevation) for each of the 60 elevation zones were used as inputs to the data-driven models. These elevation zone-average meteorological inputs, derived from gridded sources using spatial means, were provided by the CNFRC and are the same inputs used for their SNOW-17 and SAC-SMA models. The temperature data were from the Analysis of Record for Calibration (AORC, Kitzmiller et al. 2018). AORC is a gridded record of near-surface weather conditions covering the continental United States and Alaska, on a 0.008-degree grid mesh and one-hour temporal resolution. The precipitation data was derived from historical mean annual precipitation until WY 2003; after WY2003 precipitation is drawn from operational forcing, which is an internally adjusted dataset derived from National Center for Environmental Information’s Cooperative Observer Network and Natural Resources Conservation Service’s Snow Telemetry gages. The Z-elevation was from ERA5.研究以60个海拔分区各自的日气温、降水量及雨雪过渡带海拔（Z-elevation）作为数据驱动模型的输入变量。上述通过格点数据源经空间平均方法得到的海拔分区平均气象输入数据由CNFRC提供，且为其SNOW-17与SAC-SMA模型所使用的同源输入。气温数据源自校准记录分析数据集（Analysis of Record for Calibration，AORC），相关研究详见Kitzmiller等（2018）。AORC是覆盖美国本土与阿拉斯加地区的近地表气象条件格点数据集，其格网分辨率为0.008度，时间分辨率为1小时。2003水文年（Water Year，WY）之前，降水数据采用历史多年平均降水量；2003水文年之后的降水数据则取自业务化强迫场数据集，该数据集由美国国家环境信息中心（National Center for Environmental Information）合作观测网络与美国自然资源保护局（Natural Resources Conservation Service）雪量遥测站数据经内部校正生成。Z-elevation数据源自ERA5再分析数据集。