A Large-Droplet Mode and Prognostic Number Concentration of Cloud Droplets in the Colorado State University Regional Atmospheric Modeling System (RAMS). Part II: Sensitivity to a Colorado Winter Snowfall Event

2005 ◽  
Vol 44 (12) ◽  
pp. 1912-1929 ◽  
Author(s):  
Stephen M. Saleeby ◽  
William R. Cotton
Keyword(s):  
Cloud Droplet ◽  
Atmospheric Modeling ◽  
Large Droplet ◽  
State University ◽  
Regional Atmospheric Modeling System ◽  
Cloud Droplets ◽  
Colorado State University ◽  
Droplet Nucleation ◽  
Snowfall Event ◽  
Regional Atmospheric Modeling

Abstract This paper is the second in a two-part series describing recent additions to the microphysics module of the Regional Atmospheric Modeling System (RAMS) at Colorado State University. These changes include the addition of a large-cloud-droplet mode (40–80 μm in diameter) into the liquid-droplet spectrum and the parameterization of cloud-droplet nucleation through activation of cloud condensation nuclei (CCN) and giant CCN (GCCN). The large-droplet mode was introduced to represent more precisely the natural dual mode of the cloud-droplet distribution. The parameterized droplet nucleation replaces the former estimation of cloud-droplet formation solely from supersaturation calculations. In Part I of this series, details of the improvements to the microphysics were presented, including the set of equations governing the development of cloud droplets in the Lagrangian parcel model that was employed to parameterize this complex process. Supercell simulations were examined with respect to the model sensitivity to the presence and concentration of large cloud droplets, CCN, and GCCN. Part II examines the sensitivity of the model microphysics to imposed aerosol variations in a wintertime snowfall event that occurred over Colorado on 28–29 February 2004. Model analyses and sensitivity are compared with the real-time forecast version 4.3 of RAMS as well as selected snowpack telemetry (SNOTEL) accumulated precipitation data and surface data from Storm Peak Laboratory in Steamboat Springs, Colorado.

scholarly journals Aerosol Impacts on the Microphysical Growth Processes of Orographic Snowfall

2013 ◽  
Vol 52 (4) ◽  
pp. 834-852 ◽  
Author(s):  
Stephen M. Saleeby ◽  
William R. Cotton ◽  
Douglas Lowenthal ◽  
Joe Messina
Keyword(s):  
Growth Process ◽  
Spillover Effect ◽  
Supercooled Liquid ◽  
Atmospheric Modeling ◽  
Regional Atmospheric Modeling System ◽  
Growth Processes ◽  
Cloud Droplets ◽  
Microphysical Processes ◽  
Orographic Cloud ◽  
Regional Atmospheric Modeling

AbstractThe Regional Atmospheric Modeling System was used to simulate four winter snowfall events over the Park Range of Colorado. For each event, three hygroscopic aerosol sensitivity simulations were performed with initial aerosol profiles representing clean, moderately polluted, and highly polluted scenarios. Previous work demonstrates that the addition of aerosols can produce a snowfall spillover effect, during events in which riming growth of snow is prevalent in the presence of supercooled liquid water, that is due to a modified orographic cloud containing more numerous but smaller cloud droplets. This study focuses on the detailed microphysical processes that lead to snow growth in each event and how these processes are modulated by the addition of hygroscopic aerosols. A conceptual model of hydrometeor growth processes is presented, along a vertical orographic transect, that reveals zones of vapor deposition of ice and liquid, riming growth, evaporation, sublimation, and regions in which the Wegener–Bergeron–Findeisen (WBF) snow growth process is active. While the aerosol-induced spillover effect is largely determined by the degree of reduction in ice particle riming, an enhancement in the WBF snow growth process under more polluted conditions largely offsets the loss of rime growth, thus leading to a minimal net change in the regional precipitation.

Developments in the CSU-RAMS Aerosol Model: Emissions, Nucleation, Regeneration, Deposition, and Radiation

2013 ◽  
Vol 52 (12) ◽  
pp. 2601-2622 ◽  
Author(s):  
Stephen M. Saleeby ◽  
Susan C. van den Heever
Keyword(s):  
Deep Convection ◽  
Cloud Droplet ◽  
Atmospheric Modeling ◽  
Sea Salt ◽  
State University ◽  
Aerosol Model ◽  
Colorado State University ◽  
Lower Cloud ◽  
Orographic Clouds ◽  
Aerosol Effects

AbstractThe Colorado State University (CSU) Regional Atmospheric Modeling System (RAMS) has undergone development focused on improving the treatment of aerosols in the microphysics model, with the goal of examining the impacts of aerosol characteristics, scavenging, and regeneration processes, among others, on precipitation processes in clouds ranging from stratocumulus to deep convection and mixed-phase orographic clouds. Improvements in the representation of aerosols allow for more comprehensive studies of aerosol effects on cloud systems across scales. In RAMS there are now sub- and supermicrometer modes of sulfate, mineral dust, sea salt, and regenerated aerosol. All aerosol species can compete for cloud droplet nucleation, and they are regenerated via hydrometeor evaporation. A newly applied heterogeneous ice nuclei parameterization accounts for deposition nucleation and condensation and immersion freezing of aerosols greater than 0.5-μm diameter. There are also schemes for trimodal sea salt emissions and bimodal dust lofting that are functions of wind speed and surface properties. Aerosol wet and dry deposition accounts for collection by falling hydrometeors as well as gravitational settling of aerosols on water, soil, and vegetation. Aerosol radiative effects are parameterized via the Mie theory. An examination of the simulated impact of aerosol characteristics, sources, and sinks reveals mixed sensitivity among cloud types. For example, reduced aerosol solubility has little impact on deep convection since supersaturations are large and nearly all accumulation-mode aerosols activate. In contrast, reduced solubility results in reduced aerosol activation in precipitating stratocumulus. This leads to lower cloud droplet concentration, larger droplet size, and more efficient warm rain processes.

Investigation of the Summer Climate of the Contiguous United States and Mexico Using the Regional Atmospheric Modeling System (RAMS). Part II: Model Climate Variability

2007 ◽  
Vol 20 (15) ◽  
pp. 3866-3887 ◽  
Author(s):  
Christopher L. Castro ◽  
Roger A. Pielke ◽  
Jimmy O. Adegoke ◽  
Siegfried D. Schubert ◽  
Phillip J. Pegion
Keyword(s):  
United States ◽  
Climate Model ◽  
Weather Prediction ◽  
Regional Climate ◽  
Summer Rainfall ◽  
Atmospheric Modeling ◽  
Regional Atmospheric Modeling System ◽  
Prediction Mode ◽  
Regional Atmospheric Modeling ◽  
Seasonal Weather

Abstract Summer simulations over the contiguous United States and Mexico with the Regional Atmospheric Modeling System (RAMS) dynamically downscaling the NCEP–NCAR Reanalysis I for the period 1950–2002 (described in Part I of the study) are evaluated with respect to the three dominant modes of global SST. Two of these modes are associated with the statistically significant, naturally occurring interannual and interdecadal variability in the Pacific. The remaining mode corresponds to the recent warming of tropical sea surface temperatures. Time-evolving teleconnections associated with Pacific SSTs delay or accelerate the evolution of the North American monsoon. At the period of maximum teleconnectivity in late June and early July, there is an opposite relationship between precipitation in the core monsoon region and the central United States. Use of a regional climate model (RCM) is essential to capture this variability because of its representation of the diurnal cycle of convective rainfall. The RCM also captures the observed long-term changes in Mexican summer rainfall and suggests that these changes are due in part to the recent increase in eastern Pacific SST off the Mexican coast. To establish the physical linkage to remote SST forcing, additional RAMS seasonal weather prediction mode simulations were performed and these results are briefly discussed. In order for RCMs to be successful in a seasonal weather prediction mode for the summer season, it is required that the GCM provide a reasonable representation of the teleconnections and have a climatology that is comparable to a global atmospheric reanalysis.

scholarly journals The Mars Regional Atmospheric Modeling System (MRAMS): Current Status and Future Directions

Atmosphere ◽  
2019 ◽  
Vol 10 (12) ◽  
pp. 747 ◽  
Author(s):  
Scot Rafkin ◽  
Timothy Michaels
Keyword(s):  
Numerical Experiments ◽  
Atmospheric Modeling ◽  
Lessons Learned ◽  
Current Status ◽  
Regional Atmospheric Modeling System ◽  
Future Directions ◽  
Current State ◽  
Development Plans ◽  
Regional Atmospheric Modeling ◽  
Physical Parameterizations

The Mars Regional Atmospheric Modeling System (MRAMS) is closing in on two decades of use as a tool to investigate mesoscale and microscale circulations and dynamics in the atmosphere of Mars. Over this period of time, there have been numerous improvements and additions to the model dynamical core, physical parameterizations, and framework. At the same time, the application of the model to Mars (and related code for other planets) has taught many lessons about limitations and cautions that should be exercised. The current state of MRAMS is described along with a review of prior studies and findings utilizing the model. Where appropriate, lessons learned are provided to help guide future users and aid in the design and interpretation of numerical experiments. The paper concludes with a discussion of future MRAMS development plans.

scholarly journals The Brazilian developments on the Regional Atmospheric Modeling System (BRAMS 5.2): an integrated environmental model tuned for tropical areas

2016 ◽  
Author(s):  
Saulo R. Freitas ◽  
Jairo Panetta ◽  
Karla M. Longo ◽  
Luiz F. Rodrigues ◽  
Demerval S. Moreira ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
South America ◽  
Atmospheric Chemistry ◽  
Amazon Basin ◽  
Carbon Dioxide Concentration ◽  
Atmospheric Modeling ◽  
Tracer Transport ◽  
Regional Atmospheric Modeling System ◽  
Near Surface ◽  
Regional Atmospheric Modeling

Abstract. We present a new version of the Brazilian developments on the Regional Atmospheric Modeling System where different previous versions for weather, chemistry and carbon cycle were unified in a single integrated software system. The new version also has a new set of state-of-the-art physical parameterizations and greater computational parallel and memory usage efficiency. Together with the description of the main features are examples of the quality of the transport scheme for scalars, radiative fluxes on surface and model simulation of rainfall systems over South America in different spatial resolutions using a scale-aware convective parameterization. Besides, the simulation of the diurnal cycle of the convection and carbon dioxide concentration over the Amazon Basin, as well as carbon dioxide fluxes from biogenic processes over a large portion of South America are shown. Atmospheric chemistry examples present model performance in simulating near-surface carbon monoxide and ozone in Amazon Basin and Rio de Janeiro megacity. For tracer transport and dispersion, it is demonstrated the model capabilities to simulate the volcanic ash 3-d redistribution associated with the eruption of a Chilean volcano. Then, the gain of computational efficiency is described with some details. BRAMS has been applied for research and operational forecasting mainly in South America. Model results from the operational weather forecast of BRAMS on 5 km grid spacing in the Center for Weather Forecasting and Climate Studies, INPE/Brazil, since 2013 are used to quantify the model skill of near surface variables and rainfall. The scores show the reliability of BRAMS for the tropical and subtropical areas of South America. Requirements for keeping this modeling system competitive regarding on its functionalities and skills are discussed. At last, we highlight the relevant contribution of this work on the building up of a South American community of model developers.

scholarly journals Estimativa de radiação solar via modelagem atmosférica de mesoescala aplicada à região nordeste do Brasil

2009 ◽  
Vol 24 (3) ◽  
pp. 339-345 ◽  
Author(s):  
Otacilio Leandro De Menezes Neto ◽  
Alexandre Araújo Costa ◽  
Fernando Pinto Ramalho
Keyword(s):  
Atmospheric Modeling ◽  
Regional Atmospheric Modeling System ◽  
Regional Atmospheric Modeling

A utilização de fontes alternativas de energias, como a solar, a eólica e a biomassa, vem crescendo significativamente nos últimos anos, sendo a energia solar, em particular, uma fonte abundante na região Nordeste do Brasil. O conhecimento preciso da radiação solar incidente é, assim, de grande importância para o planejamento energético brasileiro, servindo de base para o desenvolvimento de futuros projetos de plantas fotovoltaicas e de aproveitamento da energia solar. Este trabalho apresenta uma metodologia para o mapeamento da energia solar incidente ao nível do solo para a região Nordeste do Brasil, utilizando um modelo atmosférico de mesoescala (Regional Atmospheric Modeling System - RAMS), validado e ajustado por meio dos dados medidos pela rede de plataformas de coleta de dados (PCDs) da Fundação Cearense de Meteorologia e Recursos Hídricos (FUNCEME). Os resultados mostraram que o modelo apresenta erros sistemáticos, sobreestimando a radiação na superfície, porém após as devidas correções estatísticas, utilizando-se uma relação entre a fração de cobertura de nuvens prevista pelo modelo e a radiação observada na superfície e estimada no topo da atmosfera, encontram-se correlações de 0,92 com intervalos de confiança de 13,5 W/m² para dados com base mensal. Usando essa metodologia, a estimativa do valor médio anual (após ajustes) da radiação solar incidente no estado do Ceará é de 215 W/m² (máximo em outubro: 260 W/m²).

scholarly journals The Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS) – Part 1: Model description and evaluation

2009 ◽  
Vol 9 (8) ◽  
pp. 2843-2861 ◽  
Author(s):  
S. R. Freitas ◽  
K. M. Longo ◽  
M. A. F. Silva Dias ◽  
R. Chatfield ◽  
P. Silva Dias ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Carbon Monoxide ◽  
Biomass Burning ◽  
Transport Model ◽  
Aerosol Particles ◽  
Atmospheric Modeling ◽  
Tracer Transport ◽  
Regional Atmospheric Modeling System ◽  
Biomass Burning Aerosol ◽  
Regional Atmospheric Modeling

Abstract. We introduce the Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS). CATT-BRAMS is an on-line transport model fully consistent with the simulated atmospheric dynamics. Emission sources from biomass burning and urban-industrial-vehicular activities for trace gases and from biomass burning aerosol particles are obtained from several published datasets and remote sensing information. The tracer and aerosol mass concentration prognostics include the effects of sub-grid scale turbulence in the planetary boundary layer, convective transport by shallow and deep moist convection, wet and dry deposition, and plume rise associated with vegetation fires in addition to the grid scale transport. The radiation parameterization takes into account the interaction between the simulated biomass burning aerosol particles and short and long wave radiation. The atmospheric model BRAMS is based on the Regional Atmospheric Modeling System (RAMS), with several improvements associated with cumulus convection representation, soil moisture initialization and surface scheme tuned for the tropics, among others. In this paper the CATT-BRAMS model is used to simulate carbon monoxide and particulate material (PM2.5) surface fluxes and atmospheric transport during the 2002 LBA field campaigns, conducted during the transition from the dry to wet season in the southwest Amazon Basin. Model evaluation is addressed with comparisons between model results and near surface, radiosondes and airborne measurements performed during the field campaign, as well as remote sensing derived products. We show the matching of emissions strengths to observed carbon monoxide in the LBA campaign. A relatively good comparison to the MOPITT data, in spite of the fact that MOPITT a priori assumptions imply several difficulties, is also obtained.

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