Focus on the United States Relocatable - High resolution models which do not cover a specific region. They have a limited range, but the tradeoff is the higher resolution Inputs Models require the use of specific input variable information in order to calculate output. The ETA model makes use of temperature, wind, moisture, ocean surface data, and precipitable water data as provided by rawinsondes, aircraft, wind profilers, and GOES satellite. The NGM model extends its use of variables by including precipitation, moisture, cloud coverage, u and v momentum, pressure, surface energy budget, and sub-soil temperatures. These instruments provide temperature, moisture, height, wind, dewpoint, altimeter setting, integrated precipitable water, and cloud drift wind data.
Bases forecasts on a database of previous forecasts.
The other models also make use of these variables, but they extend their use of parameters by including extra information. The NGM and the ETA models operate their analyses on an optimal interpolation system. The weights for the observed corrections are determined statistically and include the distance between observations, the distance between the observations and the analysis points, instrumentation accuracy, and first guess accuracy. This results in a smoother gradient for the initial spin-up cycle. The RUC also operates on an optimal interpolation system.