Datalogger files are raw USCRN data. However, instead of being collected via satellite, the raw data are collected from station dataloggers (also referred to as PDAs--Personal Digital Assistant) in the field during site maintenance visits by NOAA/ATDD engineers. These data are uploaded to a site at Oak Ridge National Lab from where they are pulled by NCEI. These raw data are received as CSV formatted files--detailed documentation are required to read the data and will be provided to ingest. These files may not be available until months after the included observations are made.

The NOAA Monthly U.S. Climate Gridded Dataset (NClimGrid) consists of four climate variables derived from the GHCN-D dataset: maximum temperature, minimum temperature, average temperature and precipitation. Each file provides monthly values in a 5x5 lat/lon grid for the Continental United States. Data is available from 1895 to the present. In March 2015, new Alaska data was included in the nClimDiv dataset. The Alaska nClimDiv data were created and updated using similar methodology as that for the CONUS.

**Please note, this dataset has been superseded by a newer version (see below). Users should not use this version except in rare cases (e.g., when reproducing previous studies that used this version).** USCRN "Processed" Data (labeled as "uscrn-processed"): are interpreted values and derived geophysical parameters with other quality indicators processed from raw data (both Datalogger files and/or Raw Data from GOES and NOAAPort) by the USCRN Team.

The Global Data Assimilation System (GDAS) is the system used by the Global Forecast System (GFS) model to place observations into a gridded model space for the purpose of starting, or initializing, weather forecasts with observed data. GDAS adds the following types of observations to a gridded, 3-D, model space: surface observations, balloon data, wind profiler data, aircraft reports, buoy observations, radar observations, and satellite observations. GDAS data are available as both input observations to GDAS and gridded output fields from GDAS.

This dataset, DSI-6411 is comprised of soil moisture data and the accompanying information for the agricultural regions of Western Russia (west of ~ 60E) and The Ukraine for the period from 1992 to 1996. These data are collected routinely for agro-meteorological monitoring of these two countries and serve as an input for the in-situ assessment of the state of the major crops.

U.S. Enhanced Hourly Wind Station Data is digital data set DSI-6421, archived at the National Centers for Environmental Information (NCEI; formerly National Climatic Data Center, NCDC). During earlier work at NCDC, it was noted that anemometer elevations at U.S. weather stations (for which metadata related to anemometer height was available) varied widely with time. Between 1931 and 2000, there were up to 12 significant anemometer height changes at some of these stations, and on average there was one change per decade at any station with more than 10 years of record.

The Nested Grid Model (NGM) and Medium Range Forecast (MRF) Archive is historical digital data set DSI-6140, archived at the NOAA National Centers for Environmental Information (NCEI). The National Centers for Environmental Prediction (NCEP) of the National Weather Service (NWS) runs a series of computer analyses and forecasts operationally, which use or produce model data. This data set is one of several NCEP sets of model data archived at NCEI.

While the Fujita and Saffir-Simpson Scales characterize tornadoes and hurricanes respectively, there is no widely used scale to classify snowstorms. The Northeast Snowfall Impact Scale (NESIS) developed by Paul Kocin of The Weather Channel and Louis Uccellini of the National Weather Service characterizes and ranks high-impact Northeast snowstorms. These storms have large areas of 10 inch snowfall accumulations and greater. NESIS has five categories: Extreme, Crippling, Major, Significant, and Notable.

The Snowstorm Database is a collection of over 500 snowstorms dating back to 1900 and updated operationally. Only storms having large areas of heavy snowfall (10-20 inches or greater) are included. The spatial extent includes the contiguous U.S. but the most storms are in the eastern two thirds of the U.S. This is the only comprehensive data set with starting and ending dates along with daily and total storm snowfall for large snowstorms from 1900 to the present. The data is archived in shapefile format, one shapefile per storm.

The Regional Snowfall Index (RSI) is an index of significant snowstorms that impact the eastern two thirds of the U.S. The RSI ranks snowstorm impacts on a scale from 1 to 5, similar to the Fujita scale for tornadoes or the Saffir-Simpson scale for hurricanes. NCEI has analyzed and assigned RSI values to over 500 storms going as far back as 1900. New storms are added operationally. As such, RSI puts the regional impacts of snowstorms into a century-scale historical perspective. The RSI differs from other indices because it includes population.