Global Drought Monitoring Service through the GEOSS Architecture ...

Architectural Implementation Pilot, Phase 3 Version: 2.0
Global Drought Monitoring and European Drought
Observatory-Water SBA Engineering Report
Date: 11/Feb/2011
For example, lack of soil moisture availability is used to define conditions for
agricultural drought, and the shortage of ground-based in-situ soil moisture measurement
stations requires estimation of soil moisture over large land tracts using Land Surface Models
(such as the NCAR Community Land Model, or the ensemble National Land Data Assimilation
System (NLDAS within the USA) or distributed hydrological models (such as the Variable
Infiltration Capacity VIC model or LISFLOOD). Such models are linked systems of partial
difference equations that ingest multidimensional arrays of near-real-time or real-time
meteorological and precipitation data as functions of time. However, despite the fact that such
multi-dimensional data are solved across a lattice of grid cells that emulate spatial locations, the
output arrays for each respective area have to be geographically registered in order to be
imported into a Geographic Information System (GIS). In short, the complex land surface model
and Geographic Information System (GIS) are separate packages (applications). The advantage
of linking together the Land Surface Models or distributed hydrological models with a GIS is
that the soil moisture (as well as other water budget component and drought indicators) can then
be added together or republished as layers within a map, displayed with the drought impact
information, such as crops dependent upon green water. The soil moisture may then be
combined with different layers of information within the GIS, published as maps, and exchanged
using OGC Web Mapping Services (WMS) among individual national hydrometeorological
service drought monitors and the global drought monitor. This is the information system behind
the application (and the front end portal user interface), and this integrates the drought
information (indices and impact indicators) with maps of drought severity rankings and
vulnerability or impact factors. The observing system is comprised of the ground-based or
satellite-based observations used to derive the meteorological and precipitation forcing used in
the Land Surface Models or distributed hydrologic models.
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