Development and Testing of Coupled Land-Surface, Pbl and Shallow/Deep Convective Parameterizations Within the Mm5 PDF Download
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Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781721938643
Category :
Languages : en
Pages : 224
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Book Description
The objective of this investigation was to study the role of shallow convection on the regional water cycle of the Mississippi and Little Washita Basins using a 3-D mesoscale model, the PSUINCAR MM5. The underlying premise of the project was that current modeling of regional-scale climate and moisture cycles over the continents is deficient without adequate treatment of shallow convection. It was hypothesized that an improved treatment of the regional water cycle can be achieved by using a 3-D mesoscale numerical model having a detailed land-surface parameterization, an advanced boundary-layer parameterization, and a more complete shallow convection parameterization than are available in most current models. The methodology was based on the application in the MM5 of new or recently improved parameterizations covering these three physical processes. Therefore, the work plan focused on integrating, improving, and testing these parameterizations in the MM5 and applying them to study water-cycle processes over the Southern Great Plains (SGP): (1) the Parameterization for Land-Atmosphere-Cloud Exchange (PLACE) described by Wetzel and Boone; (2) the 1.5-order turbulent kinetic energy (TKE)-predicting scheme of Shafran et al.; and (3) the hybrid-closure sub-grid shallow convection parameterization of Deng. Each of these schemes has been tested extensively through this study and the latter two have been improved significantly to extend their capabilities. Stauffer, David R. and Seaman, Nelson L. and Munoz, Ricardo C. Goddard Space Flight Center NAG5-6398
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
ISBN: 9781721938643
Category :
Languages : en
Pages : 224
Get Book Here
Book Description
The objective of this investigation was to study the role of shallow convection on the regional water cycle of the Mississippi and Little Washita Basins using a 3-D mesoscale model, the PSUINCAR MM5. The underlying premise of the project was that current modeling of regional-scale climate and moisture cycles over the continents is deficient without adequate treatment of shallow convection. It was hypothesized that an improved treatment of the regional water cycle can be achieved by using a 3-D mesoscale numerical model having a detailed land-surface parameterization, an advanced boundary-layer parameterization, and a more complete shallow convection parameterization than are available in most current models. The methodology was based on the application in the MM5 of new or recently improved parameterizations covering these three physical processes. Therefore, the work plan focused on integrating, improving, and testing these parameterizations in the MM5 and applying them to study water-cycle processes over the Southern Great Plains (SGP): (1) the Parameterization for Land-Atmosphere-Cloud Exchange (PLACE) described by Wetzel and Boone; (2) the 1.5-order turbulent kinetic energy (TKE)-predicting scheme of Shafran et al.; and (3) the hybrid-closure sub-grid shallow convection parameterization of Deng. Each of these schemes has been tested extensively through this study and the latter two have been improved significantly to extend their capabilities. Stauffer, David R. and Seaman, Nelson L. and Munoz, Ricardo C. Goddard Space Flight Center NAG5-6398
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 20
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Book Description
Accuracy of turbulence parameterization in representing Planetary Boundary Layer (PBL) processes in climate models is critical for predicting the initiation and development of clouds, air quality issues, and underlying surface-atmosphere-cloud interactions. In this study, we 1) evaluate WRF model-simulated spatial patterns of precipitation and surface fluxes, as well as vertical profiles of potential temperature, humidity, moist static energy and moisture tendency terms as simulated by WRF at various spatial resolutions and with PBL, surface layer and shallow convection schemes against measurements, 2) identify model biases by examining the moisture tendency terms contributed by PBL and convection processes through nudging experiments, and 3) evaluate the dependence of modeled surface latent heat (LH) fluxes onPBL and surface layer schemes over the tropical ocean. The results show that PBL and surface parameterizations have surprisingly large impacts on precipitation, convection initiation and surface moisture fluxes over tropical oceans. All of the parameterizations tested tend to overpredict moisture in PBL and free atmosphere, and consequently result in larger moist static energy and precipitation. Moisture nudging tends to suppress the initiation of convection and reduces the excess precipitation. The reduction in precipitation bias in turn reduces the surface wind and LH flux biases, which suggests that the model drifts at least partly because of a positive feedback between precipitation and surface fluxes. The updated shallow convection scheme KF-CuP tends to suppress the initiation and development of deep convection, consequently decreasing precipitation. The Eta surface layer scheme predicts more reasonable LH fluxes and the LH-Wind Speed relationship than the MM5 scheme, especially when coupled with the MYJ scheme. By examining various parameterization schemes in WRF, we identify sources of biases and weaknesses of current PBL, surface layer and shallow convection schemes in reproducing PBL processes, the initiation of convection and intra-seasonal variability of precipitation.
Author: Erich J. Plate
Publisher: Springer Science & Business Media
ISBN: 9401150583
Category : Science
Languages : en
Pages : 493
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Book Description
Studies of convection in geophysical flows constitute an advanced and rapidly developing area of research that is relevant to problems of the natural environment. During the last decade, significant progress has been achieved in the field as a result of both experimental studies and numerical modelling. This led to the principal revision of the widely held view on buoyancy-driven turbulent flows comprising an organised mean component with superimposed chaotic turbulence. An intermediate type of motion, represented by coherent structures, has been found to play a key role in geophysical boundary layers and in larger scale atmospheric and hydrospheric circulations driven by buoyant forcing. New aspects of the interaction between convective motions and rotation have recently been discovered and investigated. Extensive experimental data have also been collected on the role of convection in cloud dynamics and microphysics. New theoretical concepts and approaches have been outlined regarding scaling and parameterization of physical processes in buoyancy-driven geophysical flows. The book summarizes interdisciplinary studies of buoyancy effects in different media (atmosphere and hydrosphere) over a wide range of scales (small scale phenomena in unstably stratified and convectively mixed layers to deep convection in the atmosphere and ocean), by different research methods (field measurements, laboratory simulations, numerical modelling), and within a variety of application areas (dispersion of pollutants, weather forecasting, hazardous phenomena associated with buoyant forcing).
Author: Joseph Anthony Santanello
Publisher:
ISBN:
Category :
Languages : en
Pages : 282
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Book Description
Abstract: The convective planetary boundary layer (PBL) integrates land-atmosphere interactions over regional spatial scales and diurnal temporal scales. Previous attempts to infer surface energy and water budgets from observations of the PBL have been constrained by difficulties in monitoring and estimating the processes that control PBL evolution. This research presents an empirical and modeling investigation of land-atmosphere interactions focusing on the utility of remote sensing of the PBL. An energy conservation approach applied to 132 sets of daily PBL and land surface observations from the Atmospheric Radiation Measurement Cloud and Radiation Test Bed in the Southern Great Plains (ARM-SGP) reveals limitations to using energy budget methods to estimate surface fluxes on diurnal time scales. At the same time, statistical analyses demonstrate that observable properties of the PBL are directly related to land surface conditions and a methodology is established to estimate surface fluxes and moisture conditions that does not require detailed land surface models or parameterizations. These relationships vary as a function of surface properties and atmospheric conditions and are examined in detail using a coupled PBL/land-surface model in association with observational data. More importantly, the results from these analyses identify feedbacks in the land-atmosphere system that are not included in current models of the PBL. The feedbacks and relationships also provide insight regarding the link between surface fluxes and PBL structure, and can be used to estimate surface conditions from routine observations of the PBL.
Author: David J. Stensrud
Publisher: Cambridge University Press
ISBN: 0521865409
Category : Science
Languages : en
Pages : 408
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Book Description
Contents: 1.
Author: Chao Jih-Ping
Publisher:
ISBN:
Category : Cloud physics
Languages : en
Pages : 152
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Book Description
Author: Kerry Emanuel
Publisher: Springer
ISBN: 1935704133
Category : Science
Languages : en
Pages : 242
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Book Description
This book presents descriptions of numerical models for testing cumulus in cloud fields. It is divided into six parts. Part I provides an overview of the problem, including descriptions of cumulus clouds and the effects of ensembles of cumulus clouds on mass, momentum, and vorticity distributions. A review of closure assumptions is also provided. A review of "classical" convection schemes in widespread use is provided in Part II. The special problems associated with the representation of convection in mesoscale models are discussed in Part III, along with descriptions of some of the commonly used mesoscale schemes. Part IV covers some of the problems associated with the representation of convection in climate models, while the parameterization of slantwise convection is the subject of Part V.
Author: E.F. Wood
Publisher: Springer Science & Business Media
ISBN: 9400921551
Category : Science
Languages : en
Pages : 302
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Book Description
It is well known that the interactions between land surfaces and the atmosphere, and the resulting exchanges in water and energy have a tremendous affect on climate. The inadequate representation of land-atmosphere interactions is a major weakness in current climate models, and is providing the motivation for the HAPEX and ISLSCP experiments as well as the proposed Global Energy and Water Experiment (GEWEX) and the Earth Observing System (EOS) mission. The inadequate representation reflects the recognition that the well-known phys ical relationships, which are well described at small scales, result in different relationships when represented at the scales used in climate models. Understanding this transition in the mathematical relationships with increased space-time scales appears to be very difficult, and has led to different approaches; at one extreme, the famous "bucket" model where the land-surface is a simple one layer storage without vegetation; the other extreme may be Seller's Simple Biosphere Model (Sib) where one big leaf covers the climate model grid. Given the heterogeneous nature of landforms, soils and vegetation within a climate model grid, the development of new land surface parameterizations, and their verification through large scale experiments is perceived to be a challenging area of research for the hydrology and meteorology communities. This book evolved from a workshop held at Princeton University to explore the status of land surface parameterizations within climate models, and how observa tional data can be used to assess these parameterizations and improve models.
Author: Daniel Chau
Publisher:
ISBN:
Category :
Languages : en
Pages : 328
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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The specific purpose of the research is to evaluate the performance of the MM5 model in the forecasting of near-surface parameters, such as 2-meter temperature, 2-meter dew point, and 1000-850 mb thickness. The evaluation will include a comparison of the MM5 against the Eta model, and a comparison of the forecasting skill of the MM5 with three different land-surface parameterization schemes. Three different soil moisture scaling techniques will be applied to the MM5, and their forecasts will be evaluated against observations taken from 7-9 December 2001. The MM5 displayed an inability to capture the full magnitude of the diurnal cycle of 2-meter temperature and dew point. The Eta model performed better than the MM5 in the forecasts of near-surface parameters. The MM5 forecasts of near-surface parameters can be improved by adjusting the vertical profile of the soil moisture in the model initial conditions. By removing soil moisture from the initial conditions of the MM5, a more realistic Bowen ratio was simulated, leading to an improved forecast of the diurnal cycle of temperature and dew point. The results of this research suggest that the cause of the damped diurnal cycle in the MM5 forecasts may be inadequate ventilation of the upper planetary boundary layer, an inaccurate representation of surface evapotranspiration, or incorrect assignment of soil type and land use categories.
