NLDAS VIC Land Surface Model L4 Hourly 0.125 x 0.125 degree V002 (NLDAS_VIC0125_H) at GES DISC

This data set contains a series of land surface parameters simulated from the VIC land-surface model (LSM) for Phase 2 of the North American Land Data Assimilation System (NLDAS-2). The data are in 1/8th degree grid spacing and range from Jan 1979 to the present. The temporal resolution is hourly. The file format is WMO GRIB-1.

Details about the NLDAS-2 configuration of the VIC LSM can be found in Xia et al. (2012). The version of the VIC model for the NLDAS-2 VIC data available from the NASA GES DISC is VIC-4.0.3; this version of the VIC model is the same as used in Sheffield et al. (2003).

The VIC model was developed at the University of Washington and Princeton University as a macroscale, semi-distributed, grid-based, hydrologic model [Liang et al., 1994; Wood et al., 1997]. The full water and energy balance modes of VIC were used for NLDAS-2. VIC uses three soil layers, with thicknesses that vary spatially. The root zone depends on the vegetation type and its root distribution, and can span all three soil layers. The VIC model includes a two-layer energy balance snow model [Cherkauer et al., 2003].

The VIC LSM was forced by the hourly NLDAS-2 forcing "File A" files, and contains forty-three fields. The data set applies a user-defined parameter table to indicate the contents and parameter number. The GRIBTAB file shows a list of parameters for this data set, along with their Product Definition Section (PDS) IDs and units.

For information about the vertical layers of the Soil Moisture Content (PDS 086), Soil Temperature (PDS 085), and Liquid Soil Moisture Content (PDS 151), please see the README Document or the GrADS ctl file.

本数据集收录了北美陆地数据同化系统第二阶段（NLDAS-2）中，由VIC陆地表面模型（Land Surface Model，LSM）模拟的一系列陆地表面参数。数据以1/8度网格间距进行排列，时间跨度自1979年1月起至当前。时间分辨率为每小时。数据文件格式为WMO GRIB-1格式。关于VIC LSM在NLDAS-2中的配置细节，可参考Xia等人在2012年的研究。可从NASA GES DISC获取的NLDAS-2 VIC数据所使用的VIC模型版本为VIC-4.0.3，该版本与Sheffield等人于2003年使用的模型版本相同。VIC模型由华盛顿大学和普林斯顿大学共同开发，是一种宏观、半分布式、基于网格的流域水文模型[李昂等人，1994；伍德等人，1997]。NLDAS-2中使用的VIC模型采用了完整的水和能量平衡模式。VIC模型采用三层土壤层，其厚度随空间而变化。根区依赖于植被类型及其根系分布，可跨越所有三层土壤层。VIC模型包含一个双层能量平衡雪模型[切卡乌尔等人，2003]。VIC LSM受到每小时NLDAS-2强迫文件“A”的驱动，并包含四十三项字段。数据集应用用户定义的参数表以指示内容和参数编号。GRIBTAB文件显示了该数据集的参数列表，以及它们的产物定义部分（Product Definition Section，PDS）ID和单位。关于土壤含水量（PDS 086）、土壤温度（PDS 085）和液态土壤含水量（PDS 151）的垂直层信息，请参阅README文档或GrADS ctl文件。