Representation of the Heated Planetary Boundary Layer in Mesoscale Models with Coarse Vertical Resolution

Pielke, Roger A.; Mahrer, Y.

doi:10.1175/1520-0469(1975)032<2288:rothpb>2.0.co;2

Cited by 98 publications

(44 citation statements)

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“…PBL schemes are used to parameterize the subgrid turbulent vertical fluxes of heat, momentum, and moisture within the boundary layer and throughout the atmosphere (Pielke and Mahrer 1975). The PBL representation is a determinant factor in accurately simulating mesoscale weather phenomena owing to the critical role that these fluxes exert in the unfolding of severe phenomena.…”

Section: B Mps Experimentsmentioning

confidence: 99%

A Comparison of Ensemble Strategies for Flash Flood Forecasting: The 12 October 2007 Case Study in Valencia, Spain

Amengual

Carrió

Ravazzani

et al. 2017

Journal of Hydrometeorology

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On 12 October 2007, several flash floods affected the Valencia region, eastern Spain, with devastating impacts in terms of human, social, and economic losses. An enhanced modeling and forecasting of these extremes, which can provide a tangible basis for flood early warning procedures and mitigation measures over the Mediterranean, is one of the fundamental motivations of the international Hydrological Cycle in the Mediterranean Experiment (HyMeX) program. The predictability bounds set by multiple sources of hydrological and meteorological uncertainty require their explicit representation in hydrometeorological forecasting systems. By including local convective precipitation systems, short-range ensemble prediction systems (SREPSs) provide a state-of-the-art framework to generate quantitative discharge forecasts and to cope with different sources of external-scale (i.e., external to the hydrological system) uncertainties. The performance of three distinct hydrological ensemble prediction systems (HEPSs) for the small-sized Serpis River basin is examined as a support tool for early warning and mitigation strategies. To this end, the FlashFlood Event-Based Spatially Distributed Rainfall-Runoff Transformation-Water Balance (FEST-WB) model is driven by ground stations to examine the hydrological response of this semiarid and karstic catchment to heavy rains. The use of a multisite and novel calibration approach for the FEST-WB parameters is necessary to cope with the high nonlinearities emerging from the rainfall-runoff transformation and heterogeneities in the basin response. After calibration, FEST-WB reproduces with remarkable accuracy the hydrological response to intense precipitation and, in particular, the 12 October 2007 flash flood. Next, the flood predictability challenge is focused on quantitative precipitation forecasts (QPFs). In this regard, three SREPS generation strategies using the WRF Model are analyzed. On the one side, two SREPSs accounting for 1) uncertainties in the initial conditions (ICs) and lateral boundary conditions (LBCs) and 2) physical parameterizations are evaluated. An ensemble Kalman filter (EnKF) is also designed to test the ability of ensemble data assimilation methods to represent key mesoscale uncertainties from both IC and subscale processes. Results indicate that accounting for diversity in the physical parameterization schemes provides the best probabilistic high-resolution QPFs for this particular flash flood event. For low to moderate precipitation rates, EnKF and pure multiple physics approaches render undistinguishable accuracy for the test situation at larger scales. However, only the multiple physics QPFs properly drive the HEPS to render the most accurate flood warning signals. That is, extreme precipitation values produced by these convective-scale precipitation systems anchored by complex orography are better forecast when accounting just for uncertainties in the physical parameterizations. These findings contribute to the identification of ensemble strategies ...

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Section: B Mps Experimentsmentioning

confidence: 99%

A Comparison of Ensemble Strategies for Flash Flood Forecasting: The 12 October 2007 Case Study in Valencia, Spain

Amengual

Carrió

Ravazzani

et al. 2017

Journal of Hydrometeorology

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“…Tests with a nonhydrostatic MM4 with a 6-km inner mesh examined band development and morphology. The SUNY/ Oswego Mesoscale Model (Ballentine 1980;Ballentine et al 1992;Pielke and Mahrer 1975) was also used in LOWS to simulate the evolution of lake-effect storm bands, including surface fluxes, PBL height, and precipitation. A hydrostatic version is being tested with 10 layers extending up to 9500 m MSL (mean sea level), with a 10-km mesh covering the Lake Ontario area.…”

Section: ) Remote Sensingmentioning

confidence: 99%

The Lake Ontario Winter Storms (LOWS) Project

Reinking¹,

Caiazza²,

Kropfli³

et al. 1993

Bull. Amer. Meteor. Soc.

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Snowstorms generated over the Great Lakes bring localized heavy precipitation, blizzard conditions, and whiteouts to downwind shores. Hazardous freezing rain often affects the same region in winter. Conventional observations and numerical models generally are resolved too coarsely to allow detection or accurate prediction of these mesoscale severe weather phenomena. The Lake Ontario Winter Storms (LOWS) project was conducted to demonstrate and evaluate the potential for real-time mesoscale monitoring and location-specific prediction of lake-effect storms and freezing rain, using the newest of available technologies. LOWS employed an array of specialized atmospheric remote sensors (a dual-polarization short wavelength radar, microwave radiometer, radio acoustic sounding system, and three wind profilers) with supporting observing systems and mesoscale numerical models. An overview of LOWS and its initial accomplishments is presented.

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“…Similar approaches for the simulation of the heated boundary layer have been proposed by Mahrer (1975), andYu (1977). The present model, however, differs from these approaches both with respect to the profile formulations and the way the boundary layer height is determined.…”

Section: Amentioning

confidence: 89%