Assessment of contemporary Arctic river runoff based on observational discharge records

We describe the contemporary hydrography of the pan-Arctic land area draini ng into the Arctic Ocean, northern Bering Sea, and Hudson Bay on the basis of observational records of river discharge and computed runoff. The Region al Arctic Hydrographic Network data set, R-ArcticNET, is presented, which i s based on 3754 recording stations drawn from Russian, Canadian, European, and U.S. archives. R-ArcticNET represents the single largest data compendiu m of observed discharge in the Arctic. Approximately 73% of the nonglaciate d area of the pan-Arctic is monitored by at least one river discharge gage giving a mean gage density of 168 gages per 10(6) km(2). Average annual run off is 212 mm yr(-1) with approximately 60% of the river discharge occurrin g from April to July. Gridded runoff surfaces are generated for the gaged p ortion of the pan-Arctic region to investigate global change signals. Siber ia and Alaska showed increases in winter runoff during the 1980s relative t o the 1960s and 1970s during annual and seasonal periods. These changes are consistent with observations of change in the climatology of the region. W estern Canada experienced decreased spring and summer runoff.