REMOTE SENSING TOOLS FOR IMPROVING DROUGHT DECISION SUPPORT

Monitoring drought conditions and related impacts that occur in various sectors and on a variety of scales (from national to local) is a government activity at all levels as part of decision support for planning, risk management, and mitigation. Currently, there is revitalized interest in improving tools for drought decision support. This is evident in the 2004 Western Governors' Association report on the National Integrated Drought Information System and related discussions in the 2006 Congress.

In the past, climate and meteorological data have been the main sources for drought information and decision support. However, common limitations of climate-based indicators include gaps in coverage and the relatively coarse spatial detail of derived geospatial climate products. Also, climate-based indicators may not communicate the effects of drought on human and natural systems. Examples of these effects include declining forage production, lower crop yields, increased wildfire danger, deteriorating soil conditions, and diminishing water supply.

Frequent (e.g. daily) data collected from earth observing systems provide synoptic, near real-time measurements of surface conditions. One primary benefit of remotely sensed data is its inherent spatial detail for characterizing the land surface. Through a partnership, the USGS Center for EROS, the National Drought Mitigation Center, and the High Plains Regional Climate Center are developing and delivering tools that integrate climate, satellite, and biophysical information at a sub-county scale. The Vegetation Drought Response Index (VegDRI) is an indicator of vegetation condition (or stress) as the canopy responds to available soil moisture, solar energy, and other limiting factors. VegDRI has been provided to drought decision makers in a quasi-operational fashion since 2005. In 2006 - 2008, the project team is advancing toward providing this product in an operational mode.

Other tools with potential for drought decision support include passive microwave and calibrated Doppler radar reflectivity products. All remote sensing products require background to understand information content from the products and associated uncertainty. These and other issues are of critical importance to improve decisions made in response to or preparation for drought.