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Title: Using Remote Sensing and Radar MET Data to Support Watershed Assessments Comprising IEM

Author
item KIM, KEEWOK - Environmental Protection Agency (EPA)
item PRICE, KATIE - Environmental Protection Agency (EPA)
item WHELAN, GENE - Environmental Protection Agency (EPA)
item GALVIN, MICHAEL - Environmental Protection Agency (EPA)
item WOLFE, KURT - Environmental Protection Agency (EPA)
item DUDA, PAUL - Aqua Terra Consultants
item GRAY, MARK - Aqua Terra Consultants
item Pachepsky, Yakov

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/16/2014
Publication Date: 6/16/2014
Citation: Kim, K., Price, K., Whelan, G., Galvin, M., Wolfe, K., Duda, P., Gray, M., Pachepsky, Y.A. 2014. Using Remote Sensing and Radar MET Data to Support Watershed Assessments Comprising IEM. Meeting Proceedings. 7th International Congress on Environmental Modeling and Software: Bold Visions for Environmental Modeling, iEMSs 2014. 2:940-947.

Interpretive Summary: Hydrologic and fate-and-transport components of watershed models are driven by precipitation data. The primary source of this data is land-based precipitation gauges, usually part of a meterological (MET) station; although estimates may be obtained from Doppler weather radar. Many watersheds or catchments do not have MET stations or have MET stations that are too far away to adequately represent the spatial and temporal distribution of precipitation. The objective of this work was to compare precipitation data estimated with radar-based stations to that measured with ground-based gauge stations, and to evaluate the efficacy of using either one to support watershed modeling within an integrated environmental modeling context. Evaluations were performed in two areas: Manitowoc River Basin and Milwaukee area in Wisconsin, USA. Large differences between radar and gauge data, in terms of frequency and total precipitation, were found in the Manitowoc River Basin; although not the Milwaukee area. The discrepancy in the Manitoc River Basin was due to the occurrence of abnormally large precipitation intensity events (>100 mm/hr; total amount of 2815.6 mm) captured by the gauging station but not with radar. Results of this work will be useful to environmental scientists involved in watershed modeling projects.

Technical Abstract: Meteorological (MET) data required by watershed assessments that comprise Integrated Environmental Modeling (IEM) have traditionally been provided by land-based weather (gauge) stations; although these data may not be most appropriate for describing adequate spatial and temporal resolution if the MET stations are too few, too far away, or operating improperly. To complement land-based stations, remote sensing and radar satellite data are being increasingly used in obtaining synoptic data with the spatial and temporal resolution required for site-specific and/or event-based assessments. This study compares and contrasts the viability of automating the use of radar satellite data and land-based gauge stations to support MET data collection for IEM applications, especially at those locations where gauge stations prove to be inadequate. Specifically, the North American Land Data Assimilation System (NLDAS) and NEXRAD (NEXt generation RADar) Multisensor Precipitation Estimates (MPE) are compared with gauge data at Milwaukee and Manitowoc, Wisconsin USA. NLDAS contains automatic quality control (QC), uses hourly gauge station data and modeled precipitation, provides estimates at hourly intervals with a 1/8th-degree resolution, and provides time series at specified locations. MPE contains data QC’ed by human forecasters, combines radar-based estimates with hourly gauge station data on a 4-km grid, provides all spatial data by time increment, and is based on newer algorithms than NLDAS. Results of thecomparison showed excellent correlation between gauge and radar data at Milwaukee, while the Manitowoc results strongly suggested using radar over gauge data.