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Spatial Overview
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The California Irrigation Management Information System (CIMIS) currently manages over 130 active weather stations throughout the state. Archived data is also available for 75 additional stations that have been disconnected from the network for various reasons. Most of the CIMIS stations produce estimates of reference evapotranspiration (ETo) for the station location and their immediate surroundings. Because of California's diverse landmass and climate, many locations within the state lack a representative CIMIS station. Some counties, for example, do not have a CIMIS station and others have only one or two stations. As a result, there are significant spatial ETo data gaps. In an attempt to mitigate this problem, CIMIS initiated a study to investigate the possibility of coupling remotely sensed satellite data with point measurements from the CIMIS weather stations to generate spatially distributed ETo values (ETo maps).
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A contract was awarded to the University of California Davis (UCD) remote sensing group, lead by Professor Susan Ustin, to conduct the study. The Department of Water Resources (DWR) formed an advisory committee comprised of individuals with expertise in remote sensing, GIS, modeling, and water management from DWR and UCD. The committee met, on an as needed basis to discuss new developments and plan future actions. After a thorough research, the team decided to use combinations of data derived from satellites and interpolated between CIMIS station measurements to estimate ETo at a 2 km spatial resolution. The resulting product has been vigorously tested and has demonstrated a degree of accuracy that is acceptable for most applications. For a brief description of the methodology used to generate the ETo maps, click on the Spatial Model link on the left sidebar.
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We would like to inform CIMIS data users that this is a newly emerging technique and is in the process of being refined. Although the data quality presented here is acceptable for most applications, we do not guarantee its accuracy. Therefore, neither the CIMIS program, the Department of Water Resources (DWR), UC Davis, nor any other party who participated in the development of this product shall be responsible for errors in this data, and/or for any resulting consequences from using this data.
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