Palmer Modified Drought Index

Palmer Modified Drought Index The term "Palmer Drought Index" has been used collectively to represent multiple indices. This index is simply a water balance model which analyzes precipitation and temperature, and used as a tool to measure meteorological and hydrological drought across space and time. All versions of the index uses the Versatile Soil Moisture Budget to model the movement of water within the system, and a daily Priestly-Taylor model to estimate evapotranspiration. The Palmer Drought Index (PDI) uses monthly temperature and precipitation data to calculate a simple soil water balance. The index is a relative measure that typically ranges from -4 (extremely dry) to +4 (extremely wet) and represents how soil moisture availability differs from that expected for a given place and time of year. The PDI includes a "memory" component that considers past conditions and persistence of soil moisture surplus or deficit. The Modified Palmer Drought Index (PMDI) is obtained from the sum of the wet and dry terms weighted by probability values. The PMDI has the same value as the PDI during established dry or wet spells but can be different during transition periods. 2022-05-04 Agriculture and Agri-Food Canada agri-geomatics-agrog@agr.gc.ca Nature and EnvironmentScience and TechnologyPDIagclimatePMDIAgricultureCropsFarmlandsTemperaturePrecipitation Data Product Specification (English)PDF https://agriculture.canada.ca/atlas/supportdocument_documentdesupport/aafcAgClimate/en/ISO_19131_AgClimate_-_Data_Product_Specification.pdf Palmer Drought IndexWMS https://agriculture.canada.ca/atlas/services/app_agclimate_agclimat/agclimate_pdi/ImageServer/WMSServer?request=GetCapabilities&service=WMS Using AAFC Climate Services (French)PDF https://agriculture.canada.ca/atlas/supportdocument_documentdesupport/aafcAgClimate/fr/Utilisation_des_services_climatiques_dAAC.pdf Data Product Specification (French)PDF https://agriculture.canada.ca/atlas/supportdocument_documentdesupport/aafcAgClimate/fr/Donnees_agroclimat_-_SPC.pdf Agroclimate Interactive Maps (English)HTML https://agriculture.canada.ca/atlas/agclimate Agroclimate Interactive Maps (French)HTML https://agriculture.canada.ca/atlas/agclimat Pre-packaged GeoTIF files (No linguistic component)GeoTIF https://agriculture.canada.ca/atlas/data_donnees/cli/agClimate/tif/pdi/ Using AAFC Climate Services (English)PDF https://agriculture.canada.ca/atlas/supportdocument_documentdesupport/aafcAgClimate/en/Using_AAFC_Climate_Services.pdf Palmer Drought IndexESRI REST https://agriculture.canada.ca/atlas/rest/services/app_agclimate_agclimat/agclimate_pdi/ImageServer Palmer Drought IndexESRI REST https://agriculture.canada.ca/atlas/rest/services/app_agclimate_agclimat/agclimate_pdi/ImageServer

The term "Palmer Drought Index" has been used collectively to represent multiple indices. This index is simply a water balance model which analyzes precipitation and temperature, and used as a tool to measure meteorological and hydrological drought across space and time. All versions of the index uses the Versatile Soil Moisture Budget to model the movement of water within the system, and a daily Priestly-Taylor model to estimate evapotranspiration.

The Palmer Drought Index (PDI) uses monthly temperature and precipitation data to calculate a simple soil water balance. The index is a relative measure that typically ranges from -4 (extremely dry) to +4 (extremely wet) and represents how soil moisture availability differs from that expected for a given place and time of year. The PDI includes a "memory" component that considers past conditions and persistence of soil moisture surplus or deficit.

The Modified Palmer Drought Index (PMDI) is obtained from the sum of the wet and dry terms weighted by probability values. The PMDI has the same value as the PDI during established dry or wet spells but can be different during transition periods.

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Country: Canada

Electronic Mail Address: agri-geomatics-agrog@agr.gc.ca

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