A Study of Regional Precipitation Trends in Iceland Using a High-Quality Gauge Network and ERA-40

Abstract

The climatic variability and trends of precipitation in Iceland are examined for the period 1961?2000 using bias-corrected rain gauge data and precipitation forecasts from the 40-yr ECMWF Re-Analysis (ERA-40). Several quantities are studied: the monthly and annual precipitation amounts as well as the statistical characteristics of 12-hourly precipitation rate and the geometrical features of the precipitation fields. The study highlights the credibility of ERA-40 and its ability to capture in a realistic manner the climatic variability of precipitation in Iceland, despite local discrepancies related to the crude horizontal resolution of these data. The observed intra- and interannual variations in the precipitation characteristics can be linked to variations in size, location, and occurrence of the large-scale precipitation systems crossing Iceland that are in turn influenced by the strength of the North Atlantic Oscillation, especially in winter.