Analysis of the dynamics of the boundary layer of the atmosphere during the passage of mesoscale convective systems on the example of the city of Tomsk

2021 ◽  
Author(s):  
Vera A. Zhukova ◽  
Nikolay P. Krasnenko ◽  
Konstantin N. Pustovalov ◽  
Petr M. Nagorskiy ◽  
Tatyana S. Koshikova ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Mesoscale Convective Systems ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
The City

A Lagrangian perspective on cold pool collisions

2020 ◽  
Author(s):  
Giuseppe Torri ◽  
Zhiming Kuang
Keyword(s):  
Boundary Layer ◽  
Life Cycle ◽  
Spatial Scales ◽  
Mesoscale Convective Systems ◽  
Cold Pool ◽  
Convective Systems ◽  
Cold Pools ◽  
Mesoscale Convective ◽  
Temporal And Spatial ◽  
Convective Cells

<p>Collisions represent one of the most important processes through which cold pools—essential boundary layer features of precipitating systems—help to organize convection. For example, by colliding with one another, expanding cold pools can trigger new convective cells, a process that has been argued to be important to explain the deepening of convection and the maintenance of mesoscale convective systems for many hours. In spite of their role, collisions are an understudied process, and many aspects remain to be fully clarified. In order to quantify the importance of collisions on the life cycle of cold pools, we will present some results based on a combination of numerical simulations in radiative-convective equilibrium and a Lagrangian cold pool tracking algorithm. First, we will discuss how the Lagrangian algorithm can be used to estimate that the median time of the first collision for the simulated cold pools is under 10 minutes. We will then show that cold pools are significantly deformed by collisions and lose their circular shape already at the very early stages of their life cycle. Finally, we will present results suggesting that cold pools appear to be clustered, and we will provide some estimates of the associated temporal and spatial scales.</p>

scholarly journals Convective boundary layer characterization in the Amazon rainforest before and after the passage of Mesoscale convective systems

2020 ◽  
Vol 42 ◽  
pp. e2
Author(s):  
Vanessa Monteiro
Keyword(s):  
Boundary Layer ◽  
Convective Boundary Layer ◽  
Growth Rates ◽  
Mesoscale Convective Systems ◽  
Amazon Rainforest ◽  
Specific Humidity ◽  
Convective Boundary ◽  
Data Set ◽  
Convective Systems ◽  
Mesoscale Convective

This study describes thermodynamic variables (e.g., temperature and humidity) of the atmospheric convective boundary layer (CBL) and its growth rates preceding and following the passage of mesoscale convective systems (MCSs) in the Amazon rainforest. Using the data set provided by GoAmazon 2014/15, this study will address its objectives through the evaluation of case studies and an ensemble of days when there was the passage of MCSs. The results show that the convective boundary layer experiences reductions in the equivalent potential temperature within 2 to 8K and in the specific humidity up to 2 g kg-1 after the passage of a MCS, due to the cold and dry air brought to the surface by storms downdrafts. These two variables in addition to others (e.g., energy fluxes) are responsible for the low growth rates of the convective boundary layer, that were reduced by 100 m h-1 in the following two hours after the rainfall ceases, when compared to undisturbed conditions. Nonetheless, this work provides a quantitative evaluation of the thermodynamic features of the convective boundary layer under the passage of mesoscale convective systems in the Amazon rainforest.

Evaluating Diurnal and Semi-Diurnal Cycle of Precipitation in CMIP6 Models Using Satellite- and Ground-Based Observations

2021 ◽  
pp. 1-56
Author(s):  
Shuaiqi Tang ◽  
Peter Gleckler ◽  
Shaocheng Xie ◽  
Jiwoo Lee ◽  
Min-Seop Ahn ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Diurnal Cycle ◽  
Climate Models ◽  
Early Morning ◽  
Mesoscale Convective Systems ◽  
Convective Systems ◽  
Ensemble Mean ◽  
Mesoscale Convective ◽  
Diurnal Cycle Of Precipitation

AbstractThe diurnal and semi-diurnal cycle of precipitation simulated from CMIP6 models during 1996-2005 are evaluated globally between 60°S and 60°N, as well as at ten selected locations representing three categories of diurnal cycle of precipitation: (1) afternoon precipitation over land, (2) early morning precipitation over ocean, and (3) nocturnal precipitation over land. Three satellite-based and two ground-based rainfall products are used to evaluate the climate models. Globally, the ensemble mean of CMIP6 models shows a diurnal phase of 3 to 4 hours earlier over land and 1 to 2 hours earlier over ocean, when compared with the latest satellite products. These biases are in line with what were found in previous versions of climate models but reduced compared to the CMIP5 ensemble mean. Analysis at the selected locations complimented with in-situ measurements further reinforces these results. Several CMIP6 models have shown a significant improvement in the diurnal cycle of precipitation compared to their CMIP5 counterparts, notably on delaying afternoon precipitation over land. This can be attributed to the use of more sophisticated convective parameterizations. Most models are still unable to capture the nocturnal peak associated with elevated convection and propagating mesoscale convective systems, with a few exceptions that allow convection to be initiated above the boundary layer to capture nocturnal elevated convection. We also quantify an encouraging consistency between the satellite- and ground-based precipitation measurements despite differing spatiotemporal resolutions and sampling periods, which provides confidence in using them to evaluate the diurnal and semi-diurnal cycle of precipitation in climate models.

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

scholarly journals An Observational Study of Mesoscale Convective Systems with Heavy Rainfall over the Korean Peninsula

2006 ◽  
Vol 21 (2) ◽  
pp. 125-148 ◽  
Author(s):  
Hyung Woo Kim ◽  
Dong Kyou Lee
Keyword(s):  
Observational Study ◽  
Korean Peninsula ◽  
Wind Shear ◽  
Heavy Rainfall ◽  
Vertical Wind Shear ◽  
Vertical Wind ◽  
Mesoscale Convective Systems ◽  
Low Level ◽  
Convective Systems ◽  
Mesoscale Convective

Abstract A heavy rainfall event induced by mesoscale convective systems (MCSs) occurred over the middle Korean Peninsula from 25 to 27 July 1996. This heavy rainfall caused a large loss of life and property damage as a result of flash floods and landslides. An observational study was conducted using Weather Surveillance Radar-1988 Doppler (WSR-88D) data from 0930 UTC 26 July to 0303 UTC 27 July 1996. Dominant synoptic features in this case had many similarities to those in previous studies, such as the presence of a quasi-stationary frontal system, a weak upper-level trough, sufficient moisture transportation by a low-level jet from a tropical storm landfall, strong potential and convective instability, and strong vertical wind shear. The thermodynamic characteristics and wind shear presented favorable conditions for a heavy rainfall occurrence. The early convective cells in the MCSs initiated over the coastal area, facilitated by the mesoscale boundaries of the land–sea contrast, rain–no rain regions, saturated–unsaturated soils, and steep horizontal pressure and thermal gradients. Two MCSs passed through the heavy rainfall regions during the investigation period. The first MCS initiated at 1000 UTC 26 July and had the characteristics of a supercell storm with small amounts of precipitation, the appearance of a mesocyclone with tilting storm, a rear-inflow jet at the midlevel of the storm, and fast forward propagation. The second MCS initiated over the upstream area of the first MCS at 1800 UTC 26 July and had the characteristics of a multicell storm, such as a broken areal-type squall line, slow or quasi-stationary backward propagation, heavy rainfall in a concentrated area due to the merging of the convective storms, and a stagnated cluster system. These systems merged and stagnated because their movement was blocked by the Taebaek Mountain Range, and they continued to develop because of the vertical wind shear resulting from a low-level easterly inflow.

Precipitation charge and size measurements in the stratiform region of two mesoscale convective systems

1995 ◽  
Vol 100 (D8) ◽  
pp. 16341 ◽  
Author(s):  
Monte G. Bateman ◽  
W. David Rust ◽  
Bradley F. Smull ◽  
Thomas C. Marshall
Keyword(s):  
Mesoscale Convective Systems ◽  
Convective Systems ◽  
Stratiform Region ◽  
Mesoscale Convective
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