Most of these indices were designed to detect meteorological and/orhydrological drought without incorporating vegetation responses todrought.Common Drought Severity IndicesDrought Indices Input Data• Palmer Drought Severity Index (PDSI)• Palmer Hydrological Drought Index (PHDI)• Crop Moisture Index (CMI)• Surface Water Supply Index (SWSI)Precipitation, Temperature(T), Soil Moisture• Percent of Normal Precipitation (PNP)• Deciles• Standardized Precipitation Index (SPI)PrecipitationReclamation Drought Index (RDI) Precipitation and PETU.S. Drought Monitor 6 key indicators & manysupplementary indicatorsEvaporative Drought Index T, Rh, MODIS Rsw & NDVIDrought indices integrate large amounts of data such as precipitation, snowpack,streamflow and other water supply indicators to monitor drought severity in acomprehensive framework, and to measure how much the climate in a given timeperiod has deviated from historically established normal conditions.
PENMAN-MONTEITH equation for EvapotranspirationWindspeed( ) ( )( ) iesatpnerreeCGRrE⋅+∆+⋅−⋅+−⋅⋅∆=γγρλ0Solar radiation HumidityAirTemperatureLand Water Balance = Precipitation – EvapotranspirationTHE PROBLEMTemperature + Precipitationdoes NOT show the landscape aridityVeg Leaf AreaFairbanks and Tucson have nearly identical annual precipitation,The difference is potential evaporation!
Global annual DSI over 2000-2011(-) Drier than normal(+) Wetter than normal
Monthly DSI over continental USA in 2012Strong drought impacts across US Corn-belt region in mid to late summer
MODIS ET and Landscape-ScaleClimate Data for MontanaAvg. July ET: 2000-2012Jared W. OylerPhD Student, Software EngineerNumerical TerradynamicSimulation Group (NTSG),Montana Climate OfficeCollege of Forestry andConservation,University of Montana
Remote Sensing of ET:MODIS ET• Penman-Monteith approach• ET = sum of:– Soil surface E– Canopy intercepted water E– VegetationT• 8-day, monthly, annual products• 1-km resolution• Main advantages– Generalized model that can be run globally– 8-day temporal resolution– Relatively straightforward to operationalize• Main disadvantages– Generalized model– Spatial resolutionAvg. July ET: 2000-2012
Data InputsMODIS 1-km products•LAI (8-day)•% Veg Cover (8-day)•Albedo (16-day)•Land Cover (Static)Daily weather data•1/2° x 2/3°•~ 56 km x 51 km•Temperature•Humidity (RH,VPD)•RadiationModel Params by LC•Used in calculations ofconductances andresistances•9 totalMODISP-M ETModel8-day1-km ET Estimates