Landscape Evaporative Response Index (LERI): A high resolution monitoring and assessment of evapotranspiration across the Contiguous United States|蒸散发监测数据集|干旱预警数据集

Landscape Evaporative Response Index (LERI) is remotely-sensed high-resolution information of the evaporative response from the land in near real time. LERI assesses anomalies in actual evapotranspiration (ETa), as percentiles, across the Contiguous US and northern Mexico at a 1-km spatial resolution. LERI is based on the ETa data produced by the U. S. Geological Survey using the operational Simplified Surface Energy Balance (SSEBop) model. SSEBop combines evapotranspiration fraction generated from remotely sensed MODIS thermal imagery, acquired every 8 days, with climatological atmospheric evaporative demand. To quantify LERI, a rank-based, non-parametric method is used to estimate percentiles of the SSEBop ETa, over a period of ETa accumulation, compared to the available period of record (January 2000 to present). LERI percentiles are also binned into four drought categories (LD0 - LD3) analogous to the US Drought Monitor (USDM) categories (i.e. D0-D3) and using the same percentile breaks that USDM considers for soil moisture. By its numerical design, LERI essentially represents the evaporative response of the landscape driven primarily by the anomalous state of soil moisture to meet the climatological atmospheric demand through a combination of evaporation (from soil and leaf surfaces) and transpiration (root-stomata-air) processes. Real-time and high-resolution assessment of this soil moisture state is extremely salient to understanding and forecasting ecological responses. LERI serves as an experimental drought-monitoring and early warning guidance tool and has the potential to inform research into understanding characteristics of Ecological Drought. Preliminary work finds LERI to closely track modeled moisture conditions in the upper soil layers (~10 cm). LERI can complement other drought-monitoring indices and modeled soil moisture products. Work is ongoing to assess LERI’s ability to capture signals of drought early warning, and its unique ability to assess land-surface moisture state. LERI maps, and spatial and historical time series data could be accessed at https://www.esrl.noaa.gov/psd/leri/.