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Numerical Modeling Of Arctic Mixed Phase Layered Clouds
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Book Synopsis Numerical Modeling of Arctic Mixed-phase Layered Clouds by : Yaosheng Chen
Download or read book Numerical Modeling of Arctic Mixed-phase Layered Clouds written by Yaosheng Chen and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Arctic mixed-phase clouds are often multi-layered. Different cloud layers interact through radiation as well as ice precipitation falling from upper layer clouds into the lower layer clouds. The evolution of an Arctic mixed-phase stratiform cloud under prescribed perturbations from an overlaying cloud in the form of downwelling longwave radiation and ice precipitation was simulated and documented. The perturbations created regions with heterogeneous properties in the horizontal direction within the lower level cloud, the consequence of which was the development of a mesoscale circulation that propagated the perturbations well beyond the location of the initial perturbed region.In a separate study, we forward modeled radar Doppler spectra based on a large-eddy simulation (LES) model simulation of a single layer Arctic mixed-phase cloud and compared the modeled quantities with those retrieved from the observations. We show that there was a significant contribution from the microphysical broadening to the cloud radar Doppler spectral width in Arctic mixed-phase clouds. LES simulations configured with different ice particle characteristics captured different aspects of the observations in the simulated case, where a mixture of ice particles of different properties were likely present. The dynamics of the LES simulations, characterized with the total turbulent kinetic energy dissipation rate, agreed fairly well with the values retrieved from the observations. Due to significant numerical dissipation in the model for the case evaluated here, the TKE dissipation rate from the subgrid-scale model did not represent the dissipation rate in the model.
Book Synopsis Mixed-Phase Clouds by : Constantin Andronache
Download or read book Mixed-Phase Clouds written by Constantin Andronache and published by Elsevier. This book was released on 2017-09-28 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt: Mixed-Phase Clouds: Observations and Modeling presents advanced research topics on mixed-phase clouds. As the societal impacts of extreme weather and its forecasting grow, there is a continuous need to refine atmospheric observations, techniques and numerical models. Understanding the role of clouds in the atmosphere is increasingly vital for current applications, such as prediction and prevention of aircraft icing, weather modification, and the assessment of the effects of cloud phase partition in climate models. This book provides the essential information needed to address these problems with a focus on current observations, simulations and applications. Provides in-depth knowledge and simulation of mixed-phase clouds over many regions of Earth, explaining their role in weather and climate Features current research examples and case studies, including those on advanced research methods from authors with experience in both academia and the industry Discusses the latest advances in this subject area, providing the reader with access to best practices for remote sensing and numerical modeling
Book Synopsis Arctic mixed-phase clouds : Macro- and microphysical insights with a numerical model by : Loewe, Katharina
Download or read book Arctic mixed-phase clouds : Macro- and microphysical insights with a numerical model written by Loewe, Katharina and published by KIT Scientific Publishing. This book was released on 2017-09-15 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work provides new insights into macro- and microphysical properties of Arctic mixed-phase clouds: first, by comparing semi-idealized large eddy simulations with observations; second, by dissecting the influences of different surface types and boundary layer structures on Arctic mixed- phase clouds; third, by elucidating the dissipation process; and finally by analyzing the main microphysical processes inside Arctic mixed-phase clouds.
Book Synopsis Arctic Mixed-phase Clouds by : Katharina Loewe
Download or read book Arctic Mixed-phase Clouds written by Katharina Loewe and published by . This book was released on 2020-10-09 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work provides new insights into macro- and microphysical properties of Arctic mixed-phase clouds: first, by comparing semi-idealized large eddy simulations with observations; second, by dissecting the influences of different surface types and boundary layer structures on Arctic mixed- phase clouds; third, by elucidating the dissipation process; and finally by analyzing the main microphysical processes inside Arctic mixed-phase clouds. This work was published by Saint Philip Street Press pursuant to a Creative Commons license permitting commercial use. All rights not granted by the work's license are retained by the author or authors.
Book Synopsis Simulations of Arctic Mixed-phase Clouds in Forecasts with CAM3 and AM2 for M-PACE. by :
Download or read book Simulations of Arctic Mixed-phase Clouds in Forecasts with CAM3 and AM2 for M-PACE. written by and published by . This book was released on 2008 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: [1] Simulations of mixed-phase clouds in forecasts with the NCAR Atmosphere Model version 3 (CAM3) and the GFDL Atmospheric Model version 2 (AM2) for the Mixed-Phase Arctic Cloud Experiment (M-PACE) are performed using analysis data from numerical weather prediction centers. CAM3 significantly underestimates the observed boundary layer mixed-phase cloud fraction and cannot realistically simulate the variations of liquid water fraction with temperature and cloud height due to its oversimplified cloud microphysical scheme. In contrast, AM2 reasonably reproduces the observed boundary layer cloud fraction while its clouds contain much less cloud condensate than CAM3 and the observations. The simulation of the boundary layer mixed-phase clouds and their microphysical properties is considerably improved in CAM3 when a new physically based cloud microphysical scheme is used (CAM3LIU). The new scheme also leads to an improved simulation of the surface and top of the atmosphere longwave radiative fluxes. Sensitivity tests show that these results are not sensitive to the analysis data used for model initialization. Increasing model horizontal resolution helps capture the subgrid-scale features in Arctic frontal clouds but does not help improve the simulation of the single-layer boundary layer clouds. AM2 simulated cloud fraction and LWP are sensitive to the change in cloud ice number concentrations used in the Wegener-Bergeron-Findeisen process while CAM3LIU only shows moderate sensitivity in its cloud fields to this change. Furthermore, this paper shows that the Wegener-Bergeron-Findeisen process is important for these models to correctly simulate the observed features of mixed-phase clouds.
Author :National Aeronautics and Space Administration (NASA) Publisher :Createspace Independent Publishing Platform ISBN 13 :9781721290482 Total Pages :36 pages Book Rating :4.2/5 (94 download)
Book Synopsis Cloud-Scale Numerical Modeling of the Arctic Boundary Layer by : National Aeronautics and Space Administration (NASA)
Download or read book Cloud-Scale Numerical Modeling of the Arctic Boundary Layer written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-06-19 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt: The research objective of this NASA grant-funded project was to determine in detail how large-scale processes. in combination with cloud-scale radiative, microphysical, and dynamical processes, govern the formation and multi-layered structure of Arctic stratus clouds. This information will be useful for developing and improving 1D (one dimensional) boundary layer models for the Arctic. Also, to quantitatively determine the effects of leads on the large-scale budgets of sensible heat, water vapor, and condensate in a variety of Arctic winter conditions. This information will be used to identify the most important lead-flux processes that require parameterization in climate models. Our approach was to use a high-resolution numerical model, the 2D (two dimensional) University of Utah Cloud Resolving Model (UU CRM), and its 1D version, the University of Utah Turbulence Closure Model (UU TCM), a boundary layer model based on third-moment turbulence closure, as well as a large-eddy simulation (LES) model originally developed by C.H. Moeng. Kruegen, Steven K. and Delnore, Victor E. (Technical Monitor) Langley Research Center
Book Synopsis Physical Processes in Clouds and Cloud Modeling by : Alexander P. Khain
Download or read book Physical Processes in Clouds and Cloud Modeling written by Alexander P. Khain and published by Cambridge University Press. This book was released on 2018-04-30 with total page 644 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the most comprehensive and systematic description currently available of both classical and novel theories of cloud processes, providing a much-needed link between cloud theory, observation, experimental results, and cloud modeling. This volume shows why and how modern models serve as a major tool of investigation of cloud processes responsible for atmospheric phenomena, including climate change. It systematically describes classical as well as recent advancements in cloud physics, including cloud-aerosol interaction; collisions of particles in turbulent clouds; and the formation of multiphase cloud particles. As the first of its kind to serve as a practical guide for using state-of-the-art numerical cloud models, major emphasis is placed on explaining how microphysical processes are treated in modern numerical cloud resolving models. The book will be a valuable resource for advanced students, researchers and numerical model designers in cloud physics, atmospheric science, meteorology, and environmental science.
Book Synopsis Intercomparison of Model Simulations of Mixed-phase Clouds Observed During the ARM Mixed-Phase Arctic Cloud Experiment. Part II by :
Download or read book Intercomparison of Model Simulations of Mixed-phase Clouds Observed During the ARM Mixed-Phase Arctic Cloud Experiment. Part II written by and published by . This book was released on 2008 with total page 65 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a deep, multi-layered, mixed-phase cloud system observed during the ARM Mixed-Phase Arctic Cloud Experiment. This cloud system was associated with strong surface turbulent sensible and latent heat fluxes as cold air flowed over the open Arctic Ocean, combined with a low pressure system that supplied moisture at mid-level. The simulations, performed by 13 single-column and 4 cloud-resolving models, generally overestimate the liquid water path and strongly underestimate the ice water path, although there is a large spread among the models. This finding is in contrast with results for the single-layer, low-level mixed-phase stratocumulus case in Part I of this study, as well as previous studies of shallow mixed-phase Arctic clouds, that showed an underprediction of liquid water path. The overestimate of liquid water path and underestimate of ice water path occur primarily when deeper mixed-phase clouds extending into the mid-troposphere were observed. These results suggest important differences in the ability of models to simulate Arctic mixed-phase clouds that are deep and multi-layered versus shallow and single-layered. In general, models with a more sophisticated, two-moment treatment of the cloud microphysics produce a somewhat smaller liquid water path that is closer to observations. The cloud-resolving models tend to produce a larger cloud fraction than the single-column models. The liquid water path and especially the cloud fraction have a large impact on the cloud radiative forcing at the surface, which is dominated by the longwave flux for this case.
Book Synopsis Physical Processes in Clouds and Cloud Modeling by : Alexander P. Khain
Download or read book Physical Processes in Clouds and Cloud Modeling written by Alexander P. Khain and published by Cambridge University Press. This book was released on 2018-07-05 with total page 643 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides a comprehensive analysis of modern theories of cloud microphysical processes and their representation in numerical cloud models.
Book Synopsis Intercomparison of Model Simulations of Mixed-phase Clouds Observed During the ARM Mixed-Phase Arctic Cloud Experiment. Part I by :
Download or read book Intercomparison of Model Simulations of Mixed-phase Clouds Observed During the ARM Mixed-Phase Arctic Cloud Experiment. Part I written by and published by . This book was released on 2008 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt: Results are presented from an intercomparison of single-column and cloud-resolving model simulations of a cold-air outbreak mixed-phase stratocumulus cloud observed during the Atmospheric Radiation Measurement (ARM) program's Mixed-Phase Arctic Cloud Experiment. The observed cloud occurred in a well-mixed boundary layer with a cloud top temperature of -15 C. The observed liquid water path of around 160 g m−2 was about two-thirds of the adiabatic value and much greater than the mass of ice crystal precipitation which when integrated from the surface to cloud top was around 15 g m−2. The simulations were performed by seventeen single-column models (SCMs) and nine cloud-resolving models (CRMs). While the simulated ice water path is generally consistent with the observed values, the median SCM and CRM liquid water path is a factor of three smaller than observed. Results from a sensitivity study in which models removed ice microphysics indicate that in many models the interaction between liquid and ice-phase microphysics is responsible for the large model underestimate of liquid water path. Despite this general underestimate, the simulated liquid and ice water paths of several models are consistent with the observed values. Furthermore, there is some evidence that models with more sophisticated microphysics simulate liquid and ice water paths that are in better agreement with the observed values, although considerable scatter is also present. Although no single factor guarantees a good simulation, these results emphasize the need for improvement in the model representation of mixed-phase microphysics. This case study, which has been well observed from both aircraft and ground-based remote sensors, could be a benchmark for model simulations of mixed-phase clouds.
Book Synopsis Simulating Mixed-phase Arctic Stratus Clouds by :
Download or read book Simulating Mixed-phase Arctic Stratus Clouds written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phase cloud processes in the GISS GCM we use the GISS single-column model coupled to a bin resolved microphysics (BRM) scheme that was specially designed to simulate mixed-phase clouds and aerosol-cloud interactions. Using this model with the microphysical measurements obtained from the DOE ARM Mixed-Phase Arctic Cloud Experiment (MPACE) campaign in October 2004 at the North Slope of Alaska, we investigate the effect of ice initiation processes and Bergeron-Findeisen process (BFP) on glaciation time and longevity of single-layer stratiform mixed-phase clouds. We focus on observations taken during October 9th-10th, which indicated the presence of a single-layer mixed-phase clouds. We performed several sets of 12-hour simulations to examine model sensitivity to different ice initiation mechanisms and evaluate model output (hydrometeors concentrations, contents, effective radii, precipitation fluxes, and radar reflectivity) against measurements from the MPACE Intensive Observing Period. Overall, the model qualitatively simulates ice crystal concentration and hydrometeors content, but it fails to predict quantitatively the effective radii of ice particles and their vertical profiles. In particular, the ice effective radii are overestimated by at least 50%. However, using the same definition as used for observations, the effective radii simulated and that observed were more comparable. We find that for the single-layer stratiform mixed-phase clouds simulated, process of ice phase initiation due to freezing of supercooled water in both saturated and subsaturated (w.r.t. water) environments is as important as primary ice crystal origination from water vapor. We also find that the BFP is a process mainly responsible for the rates of glaciation of simulated clouds. These glaciation rates cannot be adequately represented by a water-ice saturation adjustment scheme that only depends on temperature and liquid and solid hydrometeors contents as is widely used in bulk microphysics schemes and are better represented by processes that also account for supersaturation changes as the hydrometeors grow.
Book Synopsis Simulating Mixed-phase Arctic Stratus Clouds by :
Download or read book Simulating Mixed-phase Arctic Stratus Clouds written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The importance of Arctic mixed-phase clouds on radiation and the Arctic climate is well known. However, the development of mixed-phase cloud parameterization for use in large scale models is limited by lack of both related observations and numerical studies using multidimensional models with advanced microphysics that provide the basis for understanding the relative importance of different microphysical processes that take place in mixed-phase clouds. To improve the representation of mixed-phase cloud processes in the GISS GCM we use the GISS single-column model coupled to a bin resolved microphysics (BRM) scheme that was specially designed to simulate mixed-phase clouds and aerosol-cloud interactions. Using this model with the microphysical measurements obtained from the DOE ARM Mixed-Phase Arctic Cloud Experiment (MPACE) campaign in October 2004 at the North Slope of Alaska, we investigate the effect of ice initiation processes and Bergeron-Findeisen process (BFP) on glaciation time and longevity of single-layer stratiform mixed-phase clouds. We focus on observations taken during 9th-10th October, which indicated the presence of a single-layer mixed-phase clouds. We performed several sets of 12-h simulations to examine model sensitivity to different ice initiation mechanisms and evaluate model output (hydrometeors concentrations, contents, effective radii, precipitation fluxes, and radar reflectivity) against measurements from the MPACE Intensive Observing Period. Overall, the model qualitatively simulates ice crystal concentration and hydrometeors content, but it fails to predict quantitatively the effective radii of ice particles and their vertical profiles. In particular, the ice effective radii are overestimated by at least 50%. However, using the same definition as used for observations, the effective radii simulated and that observed were more comparable. We find that for the single-layer stratiform mixed-phase clouds simulated, process of ice phase initiation due to freezing of supercooled water in both saturated and undersaturated (w.r.t. water) environments is as important as primary ice crystal origination from water vapor. We also find that the BFP is a process mainly responsible for the rates of glaciation of simulated clouds. These glaciation rates cannot be adequately represented by a water-ice saturation adjustment scheme that only depends on temperature and liquid and solid hydrometeors contents as is widely used in bulk microphysics schemes and are better represented by processes that also account for supersaturation changes as the hydrometeors grow.
Book Synopsis The Arctic Clouds from Model Simulations and Long-term Observations at Barrow, Alaska by : Ming Zhao
Download or read book The Arctic Clouds from Model Simulations and Long-term Observations at Barrow, Alaska written by Ming Zhao and published by . This book was released on 2012 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Arctic is a region that is very sensitive to global climate change while also experiencing significant changes in its surface air temperature, sea-ice cover, atmospheric circulation, precipitation, snowfall, biogeochemical cycling, and land surface. Although previous studies have shown that the arctic clouds play an important role in the arctic climate changes, the arctic clouds are poorly understood and simulated in climate model due to limited observations. Furthermore, most of the studies were based on short-term experiments and typically only cover the warm seasons, which do not provide a full understanding of the seasonal cycle of arctic clouds. To address the above concerns and to improve our understanding of arctic clouds, six years of observational and retrieval data from 1999 to 2004 at the Atmospheric Radiation Management (ARM) Climate Research Facility (ACRF) North Slope of Alaska (NSA) Barrow site are used to understand the arctic clouds and related radiative processes. In particular, we focus on the liquid-ice mass partition in the mixed-phase cloud layer. Statistical results show that aerosol type and concentration are important factors that impact the mixed-phase stratus (MPS) cloud microphysical properties: liquid water path (LWP) and liquid water fraction (LWF) decrease with the increase of cloud condensation nuclei (CCN) number concentration; the high dust loading and dust occurrence in the spring are possible reasons for the much lower LWF than the other seasons. The importance of liquid-ice mass partition on surface radiation budgets was analyzed by comparing cloud longwave radiative forcings under the same LWP but different ice water path (IWP) ranges. Results show the ice phase enhance the surface cloud longwave (LW) forcing by 8~9 W m−2 in the moderately thin MPS. This result provides an observational evidence on the aerosol glaciation effect in the moderately thin MPS, which is largely unknown so far. The above new insights are important to guide the model parameterizations of liquid-ice mass partition in arctic mixed-phase clouds, and are served as a test bed to cloud models and cloud microphysical schemes. The observational data between 1999 and 2007 are used to assess the performance of the European Center for Medium-Range Weather Forecasts (ECMWF) model in the Arctic region. The ECMWF model-simulated near-surface humidity had seasonal dependent biases as large as 20%, while also experiencing difficulty representing boundary layer (BL) temperature inversion height and strength during the transition seasons. Although the ECMWF model captured the seasonal variation of surface heat fluxes, it had sensible heat flux biases over 20 W m−2 in most of the cold months. Furthermore, even though the model captured the general seasonal variations of low-level cloud fraction (LCF) and LWP, it still overestimated the LCF by 20% or more and underestimated the LWP over 50% in the cold season. On average, the ECMWF model underestimated LWP by ~30 g m−2 but more accurately predicted ice water path for BL clouds. For BL mixed-phase clouds, the model predicted water-ice mass partition was significantly lower than the observations, largely due to the temperature dependence of water-ice mass partition used in the model. The new cloud and BL schemes of the ECMWF model that were implemented after 2003 only resulted in minor improvements in BL cloud simulations in summer. These results indicate that significant improvements in cold season BL and mixed-phase cloud processes in the model are needed. In this study, single-layer MPS clouds were simulated by the Weather Research and Forecasting (WRF) model under different microphysical schemes and different ice nuclei (IN) number concentrations. Results show that by using proper IN concentration, the WRF model incorporated with Morrison microphysical scheme can reasonably capture the observed seasonal differences in temperature dependent liquid-ice mass partition. However, WRF simulations underestimate both LWP and IWP indicating its deficiency in capturing the radiative impacts of arctic MPS clouds.
Book Synopsis Cloud Dynamics by : Robert A. Houze Jr.
Download or read book Cloud Dynamics written by Robert A. Houze Jr. and published by Academic Press. This book was released on 2014-07-08 with total page 457 pages. Available in PDF, EPUB and Kindle. Book excerpt: As models of the Earth/atmosphere system and observations become ever more sophisticated, and concerns about climate change and societal impacts of extreme weather and its forecasting grow, understanding the role of clouds in the atmosphere is increasingly vital. Cloud Dynamics, Second Edition provides the essential information needed to understand how clouds affect climate and weather. This comprehensive book examines the underlying physics and dynamics of every specific type of cloud that occurs in the Earth's atmosphere, showing how clouds differ dynamically depending on whether they occur over oceans or mountains, or as parts of atmospheric storms, such as thunderstorms, tropical cyclones, or warm and cold fronts. Covering both the microphysical and macrophysical aspects of clouds, the book treats all of the physical scales involved in cloud processes, from the microscale of the individual drops and ice particles up to scales of storms in which the clouds occur. As observational technology advances with increasingly sophisticated remote sensing capabilities, detailed understanding of how the dynamics and physics of clouds affect the quantities being measured is of paramount importance. This book underpins the work necessary for proper interpretation of these observations, now and in the future. Provides the holistic understanding of clouds needed to pursue research on topics vital to life on Earth Provides in-depth understanding of all types of clouds over all regions of Earth, from the poles to the equator Includes detailed physical and dynamical insight into the entire spectrum of clouds populating Earth's atmosphere
Download or read book Cloud Dynamics written by PRUPPACHER and published by Birkhäuser. This book was released on 1976 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis An Observation and Modeling Study of Arctic Multilayered Mixed-phase Boundary Layer Clouds by : Hui Lai
Download or read book An Observation and Modeling Study of Arctic Multilayered Mixed-phase Boundary Layer Clouds written by Hui Lai and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To better understand the dynamic and thermodynamic processes that form and maintain Arctic multilayered mixed-phase clouds, Moderate Resolution Imaging Spectroradiometer (MODIS) radiances, High Spectral Resolution Lidar (HSRL) backscatter, and Ka-band ARM zenith radar (KAZR) returns along with balloon-borne sounding thermodynamic profiles, were analyzed from 1-3 May 2013. The observations, together with ERA-Interim Reanalysis data, indicate that three cloud regimes were present during this period. Frontal clouds occurred in a north to south band with Barrow located on their eastern edge at 00:00 UTC 2 May. By mid-day the frontal clouds had moved into the Barrow region. A broad low-altitude stratus deck existed to the west and north of Barrow, advecting into the Barrow region by the end of 2 May as the frontal clouds cleared the region. The stratus deck remained over Barrow throughout 3 May and several days beyond it. Boundary layer cellular convection was the predominant cloud type in the vicinity of the low pressure to the east and north of Barrow on 1-2 May.On 2 May 2013 shallow single- and multi-layered, mixed-phase clouds observed by the HSRL and KAZR were present above Barrow, Alaska, leading at various times to pristine crystals, rimed crystals and aggregates of crystals at the surface. During this case study period, a weak surface trough was located to the north and east of Barrow with a high pressure ridge to its west. The associated surface front was located over Barrow and extended to the north over the Arctic Ocean. High spatial (250-m) pixel resolution MODIS radiances show low level cloud streets in the vicinity of Barrow and just to its east oriented perpendicular to the mean wind around 00:00 UTC 2 May. Low altitude cloud streets also existed to the west of Barrow at this time, though oriented parallel to the mean wind. Finally, additional cloud streets to the southwest of Barrow and perpendicular to the mean wind also were present but in the higher altitude frontal clouds. The low altitude cloud streets just to the east and west of Barrow, and under the frontal cloud layer, were the source of the multilayered clouds on this day; this study focused on the ones to the west. These cloud streets formed in an environment of strong vertical wind shear with an underlying shallow buoyant layer near the surface.The Weather and Research Forecasting (WRF) model was used to conduct mesoscale simulations for this day and the two surrounding ones. For the three-day period from 1-3 May 2013 the 27-km spatial grid spacing WRF model reproduced mesoscale geopotential height, wind, relative humidity and sea-level pressure fields similar to those contained in the (0.75 lat/lon) ERA-Interim Reanalysis. Moreover, the model was able to reproduce the three cloud systems evident in the observations: the low cloud-liquid stratus to the west of Barrow, the deep frontal cloud layer in the vicinity of Barrow, and the more convective cloud cells with heights in-between to the east of Barrow.In the WRF modeling approach six nested domains were used with horizontal grid spacings starting from 27 km and scaling down in ratios of 3 to 1, with the finest domain run in large eddy simulation mode at 111-m horizontal grid spacing in an attempt to capture the short (~ 1.5-km) wavelength of the cloud streets apparent in the satellite data. Model results show that warm air advection and surface radiative heating created enhanced near surface instability, providing the buoyancy necessary to drive the initial convection. These buoyant parcels entered the region of strong vertical shear, leading to Richardson numbers around 0.2 and the conditions favorable for the formation of roll clouds. The wavelengths of the roll clouds produced by the inner four nested domains varied from 33 km for the outermost 3-km domain to 1 km for the finest 0.111-km grid spacing domain. The finest grid spacing domain roll-cloud wavelengths were comparable to those observed by MODIS, illustrating the necessity of using a grid spacing sufficiently small to place at least 7 to 10 grid points across a roll in order to resolve it.
Book Synopsis Arctic Mixed-phase Clouds from the Micro- to the Mesoscale - Insights from High-resolution Modeling by : Gesa K. Eirund
Download or read book Arctic Mixed-phase Clouds from the Micro- to the Mesoscale - Insights from High-resolution Modeling written by Gesa K. Eirund and published by . This book was released on 2019 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
