An official website of the United States government.

We've made some changes to EPA.gov. If the information you are looking for is not here, you may be able to find it on the EPA Web Archive or the January 19, 2017 Web Snapshot.

HMS: Hydrologic Micro Services

Meteorology - Wind

Obtaining NCEI Station IDs

A map of NCEI Stations can be found here. The Station ID, Name, Location, and Dates can be found by clicking on the map icon. Some stations may not show up until the map is zoomed into that location. It is recommended that you use NCEI Stations that support the 'Normals Daily' Precipitation Dataset, although stations that support the 'Precipitation Hourly' dataset will work as well.

Handling Missing Data

Occasionally, some NCEI Stations will have periods of missing or invalid data. Days with missing data will be indicated in the output time series with values of -9999. However, days with missing data will be excluded for all datasets when calculating statistics. For extreme event aggregation, missing data will be replaced by the mean of the other datasets, or with 0 if the mean is negative.

NCEI Wind

The National Centers for Environmental Information (NCEI) provides wind data recorded at rain gauge stations. Stations are identified by their Station ID which includes the type of station and the station number. Some stations have been recording data as far back as 1901 to present day. NCEI data are reported in local time zone.

NLDAS Wind

The North American Land Data Assimilation System (NLDAS) combines North American radar data and satellite data from CMORPH (https://www.cpc.ncep.noaa.gov/products/janowiak/cmorph_description.html). NLDAS has a one-hour time step on a 0.125-degree grid of North America, with an average time delay of four days for data retrieval. NLDAS has data coverage from January 1, 1979 to the present. NLDAS data are reported in UTC (GMT). Wind data are available as two components: 10-m above ground zonal and 10-m above ground meridional. Zonal direction is North-South and meridional direction is East-West. Wind speed is calculated as Sqrt(zonal2 + meridional2).

GLDAS Wind

The Global Land Data Assimilation System (GLDAS) combines satellite data and ground-based observational data to provide wind and other meteorological parameters. GLDAS has a three-hour time step on a global 0.25-degree grid. GLDAS-2.1 provides data coverage from January 1, 2000 to present, with an average time delay of one month for data retrieval. GLDAS data are reported in UTC (GMT).

Temporal Aggregations

The available temporal aggregations are dependent upon the native timestep size of the data source. Possible options include 'daily', for those sources which are not by default daily, and 'monthly'. Aggregated wind data are the averages over these time periods and provided in the aggregated timeseries. Monthly aggregations correspond to the calendar month, and require the entire month to be specified in the date time span.