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dc.contributor.authorWile, Sean M.
dc.contributor.authorHacker, Joshua P.
dc.contributor.authorChilcoat, Kenneth H.
dc.date.accessioned2016-02-09T19:15:59Z
dc.date.available2016-02-09T19:15:59Z
dc.date.issued2015
dc.identifier.citationSean M. Wile, Joshua P. Hacker "The potential utility of high-resolution ensemble sensitivity analysis for observation placement during weak flow in complex terrain," Weather and Forecasting, 2015, v. 30, pp. 1521-1536en_US
dc.identifier.urihttp://hdl.handle.net/10945/47757
dc.descriptionThe article of record as published may be found at http://dx.doi.org/10.1175/WAF-D-14-00066.1en_US
dc.description.abstractExpansion in the availability of relocatable near-surface atmospheric observing sensors introduces the question of where placement maximizes gain in forecast accuracy. As one possible method of addressing observation placement, the performance of ensemble sensitivity analysis (ESA) is examined for high-resolution (Dx 5 4 km) predictions in complex terrain and during weak flow. ESA can be inaccurate when the underlying assumptions of linear dynamics (and Gaussian statistics) are violated, or when the sensitivity cannot be robustly sampled. A case study of a fog event at Salt Lake City International Airport (KSLC) in Utah provides a useful basis for examining these issues, with the additional influence of complex terrain. A realistic upper-air observing network is used in perfect-model ensemble data assimilation experiments, providing the statistics for ESA. Results show that water vapor mixing ratios over KSLC are sensitive to potential temperature on the first model layer tens of kilometers away, 6 h prior to verification and prior to the onset of fog. Potential temperatures indicate inversion strength in the Salt Lake basin; the ESA predicts southerly flow and strengthened inversions will increase water vapor over KSLC. Linearity tests show that the nonlinear response is about twice the expected response. Experiments with smaller ensembles show that qualitatively similar conclusions about the sensitivity pattern can be reached with ensembles as small as 48 members, but smaller ensembles do not produce accurate sensitivity estimates. Taken together, the results motivate a closer look at the fundamental characteristics of ESA when dynamics (and therefore correlations) are weak.en_US
dc.description.sponsorshipThis research was funded in part by the Office of Naval Research under the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program.en_US
dc.format.extent16 p.en_US
dc.publisherAmerican Meteorological Societyen_US
dc.rightsThis publication is a work of the U.S. Government as defined in Title 17, United States Code, Section 101. Copyright protection is not available for this work in the United States.en_US
dc.titleThe potential utility of high-resolution ensemble sensitivity analysis for observation placement during weak flow in complex terrainen_US
dc.typeArticleen_US
dc.contributor.corporateNaval Postgraduate School (U.S.)en_US
dc.contributor.departmentMeteorologyen_US


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