Current Website: http://www.hydro.washington.edu/forecast/monitor/

An Experimental Surface Water Monitoring System for Continental USAndy W. Wood, Ali S. Akanda, and Dennis P. Lettenmaier

OVERVIEW We have implemented an experimental real-time surface water

monitoring system that uses the Variable Infiltration Capacity (VIC) macroscale hydrology model (Liang et al., 1994) for real-time estimation of soil moisture and snow water equivalent (SWE) over the continental U.S. at 1/2 degree spatial resolution.

The monitoring system will stage the DROUGHT ANALYSIS PRODUCTS described in the accompanying poster (Andreadis et al.) in real-time, as well as maintain an archive of comparative products extending back to 1915.

The monitoring system is driven by daily precipitation & temperature minima and maxima from 2131 Coop stations, and has a 1-day update lag, with updates each day by 2 p.m. PST.

The system will also stage weekly outlooks based on similar methods to the ensemble forecasting techniques used in the UW west-wide seasonal hydrologic forecast system.

Surface Water Monitoring System Products

References / Acknowledgements

Andreadis, K.M., E.A. Clark, A.W. Wood, A.F. Hamlet, and D.P. Lettenmaier, 2004, 20th Century Drought in the Conterminous United States , Journal of Hydrometeorology (accepted).

Liang, X., D. P. Lettenmaier, E. F. Wood and S. J. Burges, 1994. A Simple hydrologically Based Model of Land Surface Water and Energy Fluxes for GSMs, J. Geophys. Res., 99(D7).

The authors acknowledge the support of NOAA/OGP and the NASA Seasonal-to-Interannual Prediction Project (NSIPP).

VIC Hydrologic Model(Liang et al., 1994)

Comparison with Other Datasets

improving spatial resolution of the overall monitoring system to 1/8 degree. completing the automation of the nowcast / real-time simulation / plot generations incorporating additional products (beyond percentiles), including runoff maps, cumulative

departures from normal, and recovery probabilities (derived from the outlook products) explore different PDF periods and station datasets. (It may be better to screen out more stations

to achieve greater consistency with the pre-1950 record).

Other Changes / Ongoing Work

Univ. of Washington

Index Station Forcing Approach

1

3

Methods

Examples of Current Products

5

4

From a qualitative standpoint, we find good agreement with current real-time CPC soil moisture monitoring tool(recent plots shown at right)

Real-time Nowcasting Information Flow

2

VIC Retrospective SimulationDaily, 1915 to Near Current

VIC Real-timeSimulation

(~1 month long)

HydrologicState

HydrologicState

(-1 Day)

NOAA ACISPrcp Tmax Tmin

Coop Stations

NOAA ACISPrcp Tmax Tmin

Coop Stations

Index Station Method Gridded Forcing Creation Index Meth.

Hydrologic values, anomalies, percentiles

w.r.t. retrospective PDF

climatology (PDF) ofhydrologic values

w.r.t. defined period

vals, anoms%-iles

w.r.t. PDF

1930s 1955+Nowcastproduced

with 1-2 daylag fromcurrent

NASA/NOAA Workshop: Predicting Drought on Seasonal to Decadal Timescales (Silver Spring, MD), May 2005

CPC UW

The Andreadis et al. retrospective soil moisture dataset

shows good spatial and temporal

consistency with the SW Monitor simulations

(temporal comparison, left)

(spatial comparison, right)

Colorado Cell (39.25, -108.25)Andreadis et al. SW Monitor Andreadis et al.

The change in conditions over the past week, 2 weeks and 1 month help to characterize the evolving water balance.

The “first-cut” implementation of the system has a limited set of products – the primary results shown currently are nowcasts (with a 1-2 day lag depending on time of day) of soil moisture and snow water equivalent percentiles. Other products are in development (see Section 5 at right).

A primary goal of this system was to ensure consistency between real-time and retrospective outputs, hence the input stations were limited to those with BOTH reliable real-time reporting and historical records extending back at least 40 years. Because this results in many fewer stations than are available with less stringent criteria, we use the input stations indirectly. First, we estimate precipitation percentile (for ~month long periods) and (daily) temperature anomalies and interpolate them to a 1/8 degree grid. Then we extract corresponding values from a 1/8 degree climatological forcing PDF created using a larger set of station inputs (e.g., not all reporting in real-time, taken from the Andreadis et al. effort described in an associated poster). Finally, temporal disaggregation of the precipitation period values is needed.Currently, the PDF is based on 1960-2003, and the stations are fairly consistent for this period; however, this choice may be revisited.

The recent trend in relative soil moisture and SWE is shown by the changes in their percentiles in the last week, 2 weeks and month.

An archive from 1915-present of soil moisture and SWE percentiles on Day 1 of each month is available, with a simple interface for navigation

In Development

ARCHIVESCHANGES IN CURRENT CONDITIONS

TIMESERIES ANAYSIS FORPIXELS OR REGIONS

July 2002: the western U.S. drought centers on Colorado

March 1997: La Nina conditions bring the highest recorded snowfall to the PNW

August 1993: the highest recorded flow on the Mississippi R.

March 2002: Virginia experiences severe drought, many

well failures

OUTLOOKS

For a pixel or region (e.g., Upper Colorado R. basin), one can track the current hydro-climatic conditions and contrast them with other water years or with the seasonal climatological PDF.

We plan to implement weekly outlooks based on similar methods to those used in the UW west-wide seasonal hydrologic forecast system (using CPC, CFS, NSIPP and/or ESP climate ensembles).

At right are shown a sample ESP 3-month outlook initialized February 1