This website presents a near real-time daily analysis of hydrologic conditions throughout the continental U.S. The objective of the site is to monitor departures from normal conditions (anomalies) that may help characterize evolving drought and/or flood risks. The analysis was initially implemented in 2005 at a 1/2 degree (latitude/longitude) resolution, with a limited number of analysis products.
The daily updates of soil moisture, runoff and snow water equivalent (SWE) are simulated by the VIC macroscale hydrologic model. The detailed, physically-based VIC model is driven by observed daily precipitation and temperature maxima and minima from approximately 2130 stations, selected for reporting reliably in real-time and for having records of longer than 45 years (and various other criteria). These are obtained from the NOAA Applied Climate Information System (ACIS). Typically, the data for the previous day are downloaded by 9 am PST, and the simulation and website update are completed by around noon pm PST, hence at the time of update the lag is 1 day. Since May 2005, all aspects of the work leading to the analyses & data posted online have been completely automated.
An extended abstract (Wood, 2008) for the 2008 AMS Conference on Hydrology provides a detailed description of the SW Monitor system and summarizes products as of January, 2008.
New Developments:In mid-2007, SW Monitor creator (Dr. Wood) obtained funding support from the NOAA Transition of Research Applications to Climate Services (TRACS) Program for additional developmental work and efforts to transition SW Monitor products to appropriate agency release points such as CPC and NDMC. Associated with this work, the following additions to the SW Monitor have, as of January 2008, been implemented:
- analyses for cumulative runoff and cumulative precipitation - for periods of 1, 2, 3, 6, 9, 12, 18, 24, 36, 48, and 60 months.
- 3-month ensemble forecasts of soil moisture and runoff, with derived probabilistic variables. The forecasts are based on ESP and on ENSO-conditioned subsets of ESP using similar approaches to those of the Westwide Forecast System.
- drought indexes -- model variables are used to derive drought related indexes. The first of these are the standardized precipitation index (SPI; McKee et al., 1993) and the standardized runoff index (SRI; Shukla and Wood, 2008; Mo, 2008).
- multi-model soil moisture analyses will be integrated by Dennis Lettenmaier and Ted Bohn.
In March 2008, Dr. Wood left U. Washington to join 3TIER, Inc. (Seattle), and turned over responsibility for the SW Monitor system to Dr. Lettenmaier, who also assumed PI-ship of the above-mentioned NOAA TRACS grant.
ReferencesMcKee, T. B., N. J. Doesken, and J. Kleist, 1993. The relationship of drought frequency and duration to timescales. 8th Conference on Applied Climatology, Anaheim, Calif., 17-22 January.
Mo, K., 2008. Model-based drought indices over the United States, J. Hydrometeorology (in review).
Shukla, S., and A. W. Wood, 2008. Use of a standardized runoff index for characterizing hydrologic drought, Geophys. Res. Lett., 35,L02405, doi:10.1029/2007GL032487.
Wood, A.W., 2008. The University of Washington Surface Water Monitor: An experimental platform for national hydrologic assessment and prediction. Proceedings of the AMS 22nd Conference on Hydrology, New Orleans, January 20-24, 13 pages.
Last modified: Wed Oct 20 11:51:01 PDT 1999