The subject of this web site is the near-real time monitoring of pan- Arctic water budgets and river discharge to the Arctic Ocean. The geography and dynamics of water across this region are important elements of the larger Earth System especially given growing evidence of the vulnerability of the Arctic climate and terrestrial biosphere to global change. The Arctic freshwater cycle figures prominently in any analysis of these dynamic systems.

At the same time, real-time river discharge data has been underutilized within the ocean-atmosphere modeling community with typical 3-5 year delays in data posting. There also has been deterioration in gauge networks even in previously well-monitored parts of the globe. The situation is particularly troublesome across the Russian Arctic. In contrast, there are reliable sources of operational meteorological and oceanological data for the purposes of weather forecasting. The mismatch between river discharge and meteorological data availability interferes with the construction of validated pan-Arctic water budgets. The timely identification and interpretation of changing Arctic hydrology is becoming increasingly difficult. Despite these problems, the Arctic appears to be an ideal setting to develop an integrated water cycle monitoring capacity since most of the river discharge into the Arctic Ocean is delivered through but a small number of large rivers. Only 12 hydrological gauges are required to capture 91% of total monitored area and 85 % of discharge.

A spatially and temporally-harmonized data set for pan-Arctic hydrology and meteorology will be essential to any future monitoring of global hange in this region. There are two primary goals:

• Goal 1 To develop and implement Arctic-RIMS (Rapid Integrated Monitoring System) for acquiring near-real time data and producing "quick-look" outputs that characterize terrestrial and aerological water budgets across the pan-Arctic drainage region.



• Goal 2 To create hydrologically-based re-analysis products using Arctic-RIMS and to analyze these time series in our continuing work on spatial and temporal variability of the pan-Arctic land mass.

Arctic-RIMS integrates several well-established data sets and tools developed by the co-Investigators to produce time-varying, region-wide aerological and land surface water budgets including river inputs to the Arctic Ocean and its 18 subsidiary seas. We couple algorithms developed at Ohio State University and University of Colorado for computing vapor flux convergence and other fields through the Vapor Transport Analysis System (VTAS), the NSIDC NISE satellite-derived snow product, the University of New Hampshire/AARI Permafrost Water Balance Model (P/WBM), the UNH Water Transport Model (WTM) and simulated river networks (STN-30). The algorithms is integrated within the UNH Global Hydrological Archive and Analysis System to provide a coherent geographic and temporal framework.

Both an operational capacity (Goal 1) and scientific analysis (Goal 2) are sought. Provisional data sets will be released in near-contemporary time (1-2 month delay) and re-analyzed at yearly intervals to produce higher quality output fields. Operational and re-analysis products will include all components of the water cycle across the entire pan-Arctic land mass (atmospheric convergence, precipitation, evapotranspiration, change in soil, snowpack, and shallow groundwater, runoff, and river discharge) plus estimates of potential error. Nominal resolution is 25 km (NSIDC EASE-Grid) with daily time steps. Arctic-RIMS reflects our ongoing commitment to make available Arctic data sets freely and without restriction.