REDUCING BIASES IN ESTIMATES OF PRECIPITATION OVER THE UNITED-STATES - PHASE 3 ADJUSTMENTS

Adjustment procedures for reducing the bias in precipitation point mea surements of standard U.S. rain gauges are discussed. The procedures p resented here employ information about wind speed variations over the gauge orifice during precipitation events and extensive metadata files which trace the history of precipitation measurements at each site th roughout the period of instrumental observations (gauge type, exposure , and site climatology). The metadata required for this more sophistic ated method has been compiled for about 1500 U.S. stations. A descript ion of this metadata is provided, and examples of the application of t his adjustment procedure are shown. However, reconstruction of precipi tation over rough terrain from a network of adjusted point precipitati on values still remains a problem for further studies.