Updating the Meteorological Database for Basins 4.0

BASINS contains a national database of meteorological data that are essential to the successful application of BASINS assessment models. To be effective, these data need to be of high quality, have thorough spatial coverage, and be current. The BASINS 3.1 meteorological database contains data for nearly 500 stations for the period 1970 to 1996. As required by the BASINS models, each station in the database contains hourly values for precipitation, air temperature, dewpoint temperature, solar radiation, wind, evaporation, cloud cover, and potential evapotranspiration (PET). As part of the ongoing BASINS version 4.0 development, an updated version of the meteorological database has been compiled. This updated database brings all data up to the currently available time period and greatly expands the number of stations for which data are available. Though many of the expanded stations do not contain a complete set of meteorological constituents, the number of precipitation stations has more than doubled. The organization of the database was changed from its current manner (by state) to one that is more consistent with other BASINS data (by HUC-8). The most reliable collection of meteorological data for the U. S. comes from NOAA's National Climatic Data Center (NCDC). After acquiring the data, they were reviewed for quality. For existing BASINS stations, the period from 1997 to the present was reviewed to determine whether or not the station was still recording quality data. Stations not in the existing BASINS database were reviewed to determine their period of record and quality of their data. Only stations containing quality data (i.e.limited missing periods) for a significant time period (> 10 years) were added to the BASINS meteorological database. For the data that were added, correction of missing and accumulated periods was undertaken. This was done using valid data from nearby stations, filling missing periods with the nearest station's values and distributing accumulated values using the nearby station that was closest in proximity and data value. When possible, adjustments for spatial variation were made during the correction process. National databases with coverages of meteorological variability, such as the USDA's PRISM database, were used during the data correction process. Summary files of the correction process were produced, showing how the missing and accumulated periods were corrected. Another meteorological database added to BASINS was that of the CLIGEN weather generator. CLIGEN uses historic meteorological statistics to synthesize data constituents that could be of use in BASINS. CLIGEN contains a database of historical monthly averages for various meteorological constituents at over 2600 stations throughout the U. S. The majority of BASINS datasets are organized by HUC-8 with the major exception being the meteorological database. The updated database was reorganized by HUC-8, making it more compatible with other BASINS data. GIS coverages of HUC-8 boundaries and the updated met stations were overlaid to determine the stations included in each HUC-8. Along with the stations inside each HUC-8, those just outside the HUC-8 were also included. BASINS download support software was updated to handle the process of merging meteorological data from multiple HUC-8s, taking care to not store the same station multiple times. During the development of the updated database, care was taken to document each step in the process. Substantial use of VB. Net scripts aided in leaving a "track record" of the updating process and also allows for reproducing the steps for future updates. Detailed logs of the processes were generated by the scripts, adding another level of quality assurance documentation.