VIC

The VIC model is a large-scale, semi-distributed hydrologic model. As such, it shares several basic features with the other land surface models (LSMs) that are commonly coupled to global circulation models (GCMs):
The land surface is modelled as a grid of large (>1km), flat, uniform cells
Sub-grid heterogeneity (e.g. elevation, land cover) is handled via statistical distributions.
Inputs are time series of daily or sub-daily meteorological drivers (e.g. precipitation, air temperature, wind speed).
Land-atmosphere fluxes, and the water and energy balances at the land surface, are simulated at a daily or sub-daily time step
Water can only enter a grid cell via the atmosphere
Non-channel flow between grid cells is ignored
The portions of surface and subsurface runoff that reach the local channel network within a grid cell are assumed to be >> the portions that cross grid cell boundaries into neighboring cells
Once water reaches the channel network, it is assumed to stay in the channel (it cannot flow back into the soil)
This last point has several consequences for VIC model implementation:
Grid cells are simulated independently of each other
Entire simulation is run for each grid cell separately, 1 grid cell at a time, rather than, for each time step, looping over all grid cells
Meteorological input data for each grid cell (for the entire simulation period) are read from a file specific to that grid cell
Time series of output variables for each grid cell (for the entire simulation period) are stored in files specific to that grid cell
Routing of stream flow is performed separately from the land surface simulation, using a separate model (typically the routing model of Lohmann et al., 1996 and 1998)

VIC模型是一种大规模、半分布式的水文模型。因此，它与其他常与全球环流模型（GCM）耦合的土地表面模型（LSM）具有许多基本特征：

- 土地表面被模拟为一个大型的（>1公里）、平坦、均匀的网格。
- 通过统计分布处理子网格异质性（例如，高程、土地覆盖）。
- 输入为每日或亚日气象驱动因素的时间序列（例如，降水量、空气温度、风速）。
- 土地-大气通量以及土地表面的水、能量平衡在每日或亚日时间步长内进行模拟。
- 水只能通过大气进入网格单元。
- 忽略网格单元之间的非渠道流动。
- 假设到达网格单元内本地水道网络的表面和地下径流部分大于穿过网格单元边界进入相邻单元的部分。
- 一旦水到达水道网络，就假设它将停留在水道中（不能回流到土壤中）。

此最后一点对VIC模型实施产生了几个影响：

- 网格单元相互独立地进行模拟。
- 整个模拟针对每个网格单元单独运行，一次一个网格单元，而不是在每次时间步长中循环遍历所有网格单元。
- 每个网格单元（整个模拟周期）的气象输入数据从特定于该网格单元的文件中读取。
- 每个网格单元（整个模拟周期）的输出变量时间序列存储在特定于该网格单元的文件中。
- 流流路由是在土地表面模拟之外单独进行的，使用一个独立的模型（通常是Lohmann等人于1996年和1998年的路由模型）。