Transitioning from the Traditional Divisional Dataset to Global Historical Climatology Network-Daily Gridded Divisional Dataset

The National Climatic Data Center's Climate Monitoring Branch uses climate-division data to identify trends and significant climate events in its monthly suite of temperature, precipitation and drought products. These products, some of which are contained within the State of the Climate report, provide a variety of maps and graphics that are generated based on these climate-division scale data. These maps and graphics are produced from a well established network of surface stations that are comprised of National Weather Service First Order and Cooperative Observer Network (COOP) stations. These surface stations are used to generate average temperature and precipitation for climate divisions across the country. This new dataset is based on the Global Historical Climatological Network-Daily (GHCN-D). The GHCN-D gridded divisional dataset will be based on a similar station inventory, however new methodologies will be used to compute temperature and precipitation for United States climate divisions. These are expected to improve the data coverage and the quality of the dataset, while maintaining the current product stream. The primary focus of this discussion is to provide historical differences in the traditional and grid-based GHCN -D divisional datasets. A discussion of monthly, seasonal, and yearly climate trends in temperature and precipitation will be included.