Development of a 0.5 deg Global Monthly Raining Day Dataset from 1901-2010

While several long-term global datasets of monthly precipitation amount are available, precipitation frequency and intensity are also needed for the terrestrial water cycle study. The Climate Research Unit (CRU) provides the only long-term global monthly raining day number (N) data (i.e., daily precipitation frequency in a month), and it has been extensively used for evaluation and development of precipitation products. However, because CRU N is based on a limited number of gauges, it is found to perform poorly over data sparse regions.

By combining the CRU method with a short-term (20-year) gauge-satellite merged global daily precipitation dataset (CMORPH) and a global long-term monthly precipitation dataset (GPCC) with far more gauges than used in CRU, a new 0.5 deg global N dataset from 1901-2010 is developed. Our product differs significantly from CRU N. Compared with three independent regional daily precipitation products over U.S., China, and South America based on much denser gauge networks than used in CRU, the new product shows a significant improvement over CRU N. Our N product can be combined with the GPCC monthly P to quantify precipitation variability and change from 1901-2010. They can also be combined with various reanalysis precipitation products to reconstruct the 20th century daily precipitation.