scholarly journals Use of ARM observations and numerical models to determine radiative and latent heating profiles of mesoscale convective systems for general circulation models

2013 ◽  
Author(s):  
Wei-Kuo Tao ◽  
Houze, Robert, A., Jr. ◽  
Xiping Zeng
Keyword(s):  
General Circulation ◽  
Numerical Models ◽  
General Circulation Models ◽  
Mesoscale Convective Systems ◽  
Latent Heating ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
Heating Profiles

scholarly journals The Role of Continental Mesoscale Convective Systems in Forecast Busts within Global Weather Prediction Systems

Atmosphere ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 681 ◽  
Author(s):  
Parsons ◽  
Lillo ◽  
Rattray ◽  
Bechtold ◽  
Rodwell ◽  
...  
Keyword(s):  
Great Plains ◽  
Numerical Models ◽  
Weather Prediction ◽  
Mesoscale Convective Systems ◽  
The Arctic ◽  
Convective Systems ◽  
Middle Latitudes ◽  
Medium Range ◽  
Mesoscale Convective ◽  
Prediction Systems

Despite significant, steady improvements in the skill of medium-range weather predictionsystems over the past several decades, the accuracy of these forecasts are occasionally very poor.These forecast failures are referred to as “busts” or “dropouts”. The lack of a clear explanationfor bust events limits the development and implementation of strategies designed to reduce theiroccurrence. This study seeks to explore a flow regime where forecast busts occur over Europe inassociation with mesoscale convective systems over North America east of the Rocky Mountains.Our investigation focuses on error growth in the European Centre for Medium-Range WeatherForecasting’s (ECMWF’s) global model during the summer 2015 PECAN (Plains Elevated Convectionat Night) experiment. Observations suggest that a close, but varied interrelationship can occurbetween long-lived, propagating, mesoscale convection systems over the Great Plains and Rossbywave packets. Aloft, the initial error occurs in the ridge of the wave and then propagates downstreamas an amplifying Rossby wave packet producing poor forecasts in middle latitudes and, in somecases, the Arctic. Our results suggest the importance of improving the representation of organizeddeep convection in numerical models, particularly for long-lived mesoscale convective systems thatproduce severe weather and propagate near the jet stream.

Using the Stochastic Multicloud Model to Improve Tropical Convective Parameterization: A Paradigm Example

2012 ◽  
Vol 69 (3) ◽  
pp. 1080-1105 ◽  
Author(s):  
Yevgeniy Frenkel ◽  
Andrew J. Majda ◽  
Boualem Khouider
Keyword(s):  
General Circulation ◽  
General Circulation Models ◽  
Tropical Convection ◽  
Convective Parameterization ◽  
Convective Systems ◽  
Squall Lines ◽  
Walker Cell ◽  
Single Column ◽  
Mesoscale Convective ◽  
Coarse Grids

Abstract Despite recent advances in supercomputing, current general circulation models (GCMs) poorly represent the variability associated with organized tropical convection. A stochastic multicloud convective parameterization based on three cloud types (congestus, deep, and stratiform), introduced recently by Khouider, Biello, and Majda in the context of a single column model, is used here to study flows above the equator without rotation effects. The stochastic model dramatically improves the variability of tropical convection compared to the conventional moderate- and coarse-resolution paradigm GCM parameterizations. This increase in variability comes from intermittent coherent structures such as synoptic and mesoscale convective systems, analogs of squall lines and convectively coupled waves seen in nature whose representation is improved by the stochastic parameterization. Furthermore, simulations with a sea surface temperature (SST) gradient yield realistic mean Walker cell circulation with plausible high variability. An additional feature of the present stochastic parameterization is a natural scaling of the model from moderate to coarse grids that preserves the variability and statistical structure of the coherent features. These results systematically illustrate, in a paradigm model, the benefits of using the stochastic multicloud framework to improve deterministic parameterizations with clear deficiencies.

scholarly journals Representation of Tropical Mesoscale Convective Systems in a General Circulation Model: Climatology and Response to Global Warming

2021 ◽  
pp. 1-40
Author(s):  
Wenhao Dong ◽  
Ming Zhao ◽  
Yi Ming ◽  
V. Ramaswamy
Keyword(s):  
Global Warming ◽  
General Circulation ◽  
Circulation Model ◽  
Mesoscale Convective Systems ◽  
Geophysical Fluid Dynamics Laboratory ◽  
Strongly Correlated ◽  
Event Scale ◽  
Convective Systems ◽  
Mesoscale Convective

AbstractThe characteristics of tropical mesoscale convective systems (MCSs) simulated with a finer-resolution (~50-km) version of the Geophysical Fluid Dynamics Laboratory (GFDL) AM4 model are evaluated by comparing with a comprehensive long-term observational dataset. It is shown that the model can capture the various aspects of MCSs reasonably well. The simulated spatial distribution of MCSs is broadly in agreement with the observations. This is also true for seasonality and interannual variability over different land and oceanic regions. The simulated MCSs are generally longer-lived, weaker and larger than observed. Despite these biases, an event-scale analysis suggests that their duration, intensity and size are strongly correlated. Specifically, longer-lived and stronger events tend to be bigger, which is consistent with the observations. The same model is used to investigate the response of tropical MCSs to global warming using time-slice simulations forced by prescribed sea surface temperatures (SST) and sea-ice. There is an overall decrease in occurrence frequency, and the reduction over land is more prominent than over ocean.

scholarly journals A 17 year climatology of convective cloud top heights in Darwin

2018 ◽  
Author(s):  
Robert C. Jackson ◽  
Scott M. Collis ◽  
Valentin Louf ◽  
Alain Protat ◽  
Leon Majewski
Keyword(s):  
General Circulation ◽  
Convective Cloud ◽  
Active Phase ◽  
General Circulation Models ◽  
Convective System ◽  
Wet Season ◽  
Australian Monsoon ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
Cumulus Congestus

Abstract. The validation of convective processes in general circulation models requires the use of large datasets that provide long term climatologies of the spatial statistics of convection. To that regard, echo top heights (ETHs) retrieved from 17 years of data from C-band POLarization (CPOL) Radar are analyzed in varying phases of the Madden-Julian Oscillation (MJO) and Northern Australian Monsoon in order to provide ample validation statistics for the Department of Energy's next generation Earth Energy Exascale Model. In this paper, ETHs are retrieved using a novel methodology that uses the texture of radial velocity. Comparisons of retrieved ETHs against satellite retrieved cloud top heights from the split window technique show that the estimated ETH are correlated with, and, on average, are within 3 km of satellite retrieved cloud top heights. Using this technique gives comparable ETHs compared to using a reflectivity threshold. Bimodal distributions of ETH, likely attributable to the cumulus congestus and mature stages of convection, are more commonly observed when the active phase of the MJO is away from Australia. The presence of a convectively stable layer at around 5 km altitude over Darwin inhibiting convection past this level can explain the position of the modes at around 5 to 6 km and 12 to 13 km respectively. The spatial distributions show that Hector, a deep convective system that occurs almost daily during the wet season over the Tiwi Islands, and seabreeze convergence lines are likely more common in break conditions. Oceanic mesoscale convective systems (MCSes) are likely more common during the night. Unimodal distributions of ETH are more common during monsoon conditions and during an active MJO over Darwin, consistent with the presence of widespread MCSes that are commonly associated with both the MJO and the Northern Australian Monsoon. In general, the MJO is a greater control of the ETHs observed over Darwin, with generally both lower and more unimodal distributions of ETH when the MJO is active over Darwin.

A five-year climatological lightning characteristics of linear mesoscale convective systems over North China

2021 ◽  
Vol 256 ◽  
pp. 105580
Author(s):  
Dongxia Liu ◽  
Mengyu Sun ◽  
Debin Su ◽  
Wenjing Xu ◽  
Han Yu ◽  
...  
Keyword(s):  
North China ◽  
Mesoscale Convective Systems ◽  
Convective Systems ◽  
Mesoscale Convective
Sign in / Sign up

Export Citation Format

Share Document