scholarly journals Elucidating the Life Cycle of Warm-Season Mesoscale Convective Systems in Eastern China from the Himawari-8 Geostationary Satellite

2020 ◽  
Vol 12 (14) ◽  
pp. 2307
Author(s):  
Dandan Chen ◽  
Jianping Guo ◽  
Dan Yao ◽  
Zhe Feng ◽  
Yanluan Lin
Keyword(s):  
Life Cycle ◽  
Large Scale ◽  
Eastern China ◽  
Warm Season ◽  
Northern China ◽  
Early Morning ◽  
Geostationary Satellite ◽  
Mesoscale Convective Systems ◽  
Convective Systems ◽  
Mesoscale Convective

The life cycle of mesoscale convective systems (MCSs) in eastern China is yet to be fully understood, mainly due to the lack of observations of high spatio-temporal resolution and objective methods. Here, we quantitatively analyze the properties of warm-season (from April to September of 2016) MCSs during their lifetimes using the Himawari-8 geostationary satellite, combined with ground-based radars and gauge measurements. Generally, the occurrence of satellite derived MCSs has a noon peak over the land and an early morning peak over the ocean, which is several hours earlier than the precipitation peak. The developing and dissipative stages are significantly longer as total durations of MCSs increase. Aided by three-dimensional radar mosaics, we find the fraction of convective cores over northern China is much lower when compared with those in central United States, indicating that the precipitation produced by broad stratiform clouds may be more important for northern China. When there exists a large amount of stratiform precipitation, it releases a large amount of latent heat and promotes the large-scale circulations, which favors the maintenance of MCSs. These findings provide quantitative results about the life cycle of warm-season MCSs in eastern China based on multiple data sources and large numbers of samples.

scholarly journals Macrophysical, Microphysical, and Radiative Properties of Tropical Mesoscale Convective Systems over Their Life Cycle

2016 ◽  
Vol 29 (9) ◽  
pp. 3353-3371 ◽  
Author(s):  
Dominique Bouniol ◽  
Rémy Roca ◽  
Thomas Fiolleau ◽  
D. Emmanuel Poan
Keyword(s):  
Life Cycle ◽  
Large Scale ◽  
Radiative Heating ◽  
Radiative Properties ◽  
Mesoscale Convective Systems ◽  
Cloud Base ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
Polar Orbiting Satellite ◽  
The Impact

Abstract Mesoscale convective systems (MCSs) are important drivers of the atmospheric large-scale circulation through their associated diabatic heating profile. Taking advantage of recent tracking techniques, this study investigates the evolution of macrophysical, microphysical, and radiative properties over the MCS life cycle by merging geostationary and polar-orbiting satellite data. These observations are performed in three major convective areas: continental West Africa, the adjacent Atlantic Ocean, and the open Indian Ocean. MCS properties are also investigated according to internal subregions (convective, stratiform, and nonprecipitating anvil). Continental MCSs show a specific life cycle, with more intense convection at the beginning. Larger and denser hydrometeors are thus found at higher altitudes, as well as up to the cirriform subregion. Oceanic MCSs have more constant reflectivity values, suggesting a less intense convective updraft, but more persistent intensity. A layer of small crystals is found in all subregions, but with a depth that varies according to the MCS subregion and life cycle. Radiative properties are also examined. It appears that the evolution of large and dense hydrometeors tends to control the evolution of the cloud albedo and the outgoing longwave radiation. The impact of dense hydrometeors, detrained from the convective towers, is also seen in the radiative heating profiles, in particular in the shortwave domain. A dipole of cooling near the cloud top and heating near the cloud base is found in the longwave; this cooling intensifies near the end of the life cycle.

scholarly journals Characteristics of Mesoscale Convective Systems over China and Its Vicinity Using Geostationary Satellite FY2

2015 ◽  
Vol 28 (12) ◽  
pp. 4890-4907 ◽  
Author(s):  
Xiangrong Yang ◽  
Jianfang Fei ◽  
Xiaogang Huang ◽  
Xiaoping Cheng ◽  
Leila M. V. Carvalho ◽  
...  
Keyword(s):  
Warm Season ◽  
The United States ◽  
Geostationary Satellite ◽  
Mesoscale Convective Systems ◽  
Convective System ◽  
Convective Systems ◽  
Diurnal Cycles ◽  
Mesoscale Convective ◽  
Positive Correlations ◽  
Monthly Variations

Abstract This study investigates mesoscale convective systems (MCSs) over China and its vicinity during the boreal warm season (May–August) from 2005 to 2012 based on data from the geostationary satellite Fengyun 2 (FY2) series. The authors classified and analyzed the quasi-circular and elongated MCSs on both large and small scales, including mesoscale convective complexes (MCCs), persistent elongated convective systems (PECSs), meso-β circular convective systems (MβCCSs), meso-β elongated convective system (MβECSs), and two additional types named small meso-β circular convective systems (SMβCCSs) and small meso-β elongated convective systems (SMβECSs). Results show that nearly 80% of the 8696 MCSs identified in this study fall into the elongated categories. Overall, MCSs occur mainly at three zonal bands with average latitudes around 20°, 30°, and 50°N. The frequency of MCSs occurrences is maximized at the zonal band around 20°N and decreases with increase in latitude. During the eight warm seasons, the period of peak systems occurrences is in July, followed decreasingly by June, August, and May. Meanwhile, from May to August three kinds of monthly variations are observed, which are clear northward migration, rapid increase, and persistent high frequency of MCS occurrences. Compared to MCSs in the United States, the four types of MCSs (MCCs, PECSs, MβCCSs, and MβECSs) are relatively smaller both in size and eccentricity but exhibit nearly equal life spans. Moreover, MCSs in both countries share similar positive correlations between their duration and maximum extent. Additionally, the diurnal cycles of MCSs in both countries are similar (local time) regarding the three stages of initiation, maturation, and termination.

scholarly journals A Simple Model of the Life Cycle of Mesoscale Convective Systems Cloud Shield in the Tropics

2017 ◽  
Vol 30 (11) ◽  
pp. 4283-4298 ◽  
Author(s):  
R. Roca ◽  
T. Fiolleau ◽  
D. Bouniol
Keyword(s):  
Life Cycle ◽  
Simple Model ◽  
Large Scale ◽  
Morphological Characteristics ◽  
Mesoscale Convective Systems ◽  
Boreal Summer ◽  
Maximum Extent ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
The Tropics

Abstract Mesoscale convective systems (MCSs) are important to the water and energy budget of the tropical climate and are essential ingredients of the tropical circulation. MCSs are readily observed in satellite infrared geostationary imagery as cloud clusters that evolve in time from small structures to well-organized large patches of cloud shield before dissipating. The MCS cloud shield is the result of a large ensemble of mesoscale dynamical, thermodynamical, and microphysical processes. This study shows that a simple parametric model can summarize the time evolution of the morphological characteristics of the cloud shield during the life cycle of the MCS. It consists of a growth–decay linear model of the cloud shield and is based on three parameters: the time of maximum extent, the maximum extent, and the duration of the MCS. It is shown that the time of maximum is frequently close to the middle of the life cycle and that the correlation between maximum extent and duration is strong all over the tropics. This suggests that 1 degree of freedom is left to summarize the life cycle of the MCS cloud shield. Such a model fits the observed MCS equally well, independent of the duration, size, location, and propagation characteristics, and its relevance is assessed for a large number of MCSs over three boreal summer periods over the whole tropical belt. The scaling of this simple model exhibits weak (strong) regional variability for the short- (long-) lived systems indicative of the primary importance of the internal dynamics of the systems to the large-scale environment for MCS sustainability.

scholarly journals The Life Cycle of Anvil Clouds and the Top-of-Atmosphere Radiation Balance over the Tropical West Pacific

2018 ◽  
Vol 31 (24) ◽  
pp. 10059-10080 ◽  
Author(s):  
Casey J. Wall ◽  
Dennis L. Hartmann ◽  
Mandana M. Thieman ◽  
William L. Smith ◽  
Patrick Minnis
Keyword(s):  
Life Cycle ◽  
Large Scale ◽  
Warm Pool ◽  
Mesoscale Convective Systems ◽  
Radiation Balance ◽  
Convective Systems ◽  
Cloud Radiative Effect ◽  
Mesoscale Convective ◽  
Sst Anomaly ◽  
Cloud Radiative Effects

Observations from a geostationary satellite are used to study the life cycle of mesoscale convective systems (MCS), their associated anvil clouds, and their effects on the radiation balance over the warm pool of the tropical western Pacific Ocean. In their developing stages, MCS primarily consist of clouds that are optically thick and have a negative net cloud radiative effect (CRE). As MCS age, ice crystals in the anvil become larger, the cloud top lowers somewhat, and cloud radiative effects decrease in magnitude. Shading from anvils causes cool anomalies in the underlying sea surface temperature (SST) of up to −0.6°C. MCS often occur in clusters that are embedded within large westward-propagating disturbances, and therefore shading from anvils can cool SSTs over regions spanning hundreds of kilometers. Triggering of convection is more likely to follow a warm SST anomaly than a cold SST anomaly on a time scale of several days. This information is used to evaluate hypotheses for why, over the warm pool, the average shortwave and longwave CRE are individually large but nearly cancel. The results are consistent with the hypothesis that the cancellation in CRE is caused by feedbacks among cloud albedo, large-scale circulation, and SST.

Composite Life Cycle of Maritime Tropical Mesoscale Convective Systems in Scatterometer and Microwave Satellite Observations

2009 ◽  
Vol 66 (1) ◽  
pp. 199-208 ◽  
Author(s):  
Brian Mapes ◽  
Ralph Milliff ◽  
Jan Morzel
Keyword(s):  
Life Cycle ◽  
Large Scale ◽  
Surface Wind ◽  
Precipitable Water ◽  
Satellite Observations ◽  
Mesoscale Convective Systems ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
The Common ◽  
Cloud Tops

Abstract This study examines scatterometer-observed surface wind divergence and vorticity, along with precipitable water (PW), across the life cycle of tropical maritime mesoscale convective systems (MCSs) as resolved in 0.5° data. Simple composites were constructed around first appearances of cold (<210 K) cloud tops in infrared (IR) data at 3-hourly resolution. Many thousands of such events from the tropical Indo-Pacific in 2000 were used. Composites of subpopulations were also constructed by subdividing the dataset according to IR event size and duration, as well as by prevailing values of PW and vorticity at a 5° scale. The composite MCS life cycle here spans about a day and covers a few hundred kilometers, with a remarkable sameness across subpopulations. Surface wind convergence and PW buildup lead cold cloud appearance by many hours. Afterward there are many hours of divergence, indicative of downdrafts. Contrary to motivating hypotheses, the strength of this divergence relative to convergence is scarcely different in humid and dry subpopulation composites. Normalized time series of composite vorticity show an evolution that seems consistent with vortex stretching by this convergence–divergence cycle, with peak vorticity near the end of the period of convergence (3 h prior to cold cloud appearance). In rotating conditions, the common 1-day MCS life cycle is superposed on large-scale mean vorticity and convergence, approximately in proportion, which appear to be well scale-separated (covering the whole of the 48-h and 5°–10° averages) and are as strong as or stronger than the MCS signature.

Lake-effect rains over Lake Victoria and their association with Mesoscale Convective Systems

2021 ◽  
Author(s):  
Sharon E. Nicholson ◽  
Douglas Klotter ◽  
Adam T. Hartman
Keyword(s):  
Large Scale ◽  
Lake Victoria ◽  
Ground Truth ◽  
Mesoscale Convective Systems ◽  
Convective Systems ◽  
Lake Effect ◽  
Mesoscale Convective ◽  
Strong Convection ◽  
Short Rains ◽  
Lake Catchment

AbstractThis article examined rainfall enhancement over Lake Victoria. Estimates of over-lake rainfall were compared with rainfall in the surrounding lake catchment. Four satellite products were initially tested against estimates based on gauges or water balance models. These included TRMM 3B43, IMERG V06 Final Run (IMERG-F), CHIRPS2, and PERSIANN-CDR. There was agreement among the satellite products for catchment rainfall but a large disparity among them for over-lake rainfall. IMERG-F was clearly an outlier, exceeding the estimate from TRMM 3B43 by 36%. The overestimation by IMERG-F was likely related to passive microwave assessments of strong convection, such as prevails over Lake Victoria. Overall, TRMM 3B43 showed the best agreement with the "ground truth" and was used in further analyses. Over-lake rainfall was found to be enhanced compared to catchment rainfall in all months. During the March-to-May long rains the enhancement varied between 40% and 50%. During the October-to-December short rains the enhancement varied between 33% and 44%. Even during the two dry seasons the enhancement was at least 20% and over 50% in some months. While the magnitude of enhancement varied from month to month, the seasonal cycle was essentially the same for over-lake and catchment rainfall, suggesting that the dominant influence on over-lake rainfall is the large-scale environment. The association with Mesoscale Convective Systems (MCSs) was also evaluated. The similarity of the spatial patterns of rainfall and MCS count each month suggested that these produced a major share of rainfall over the lake. Similarity in interannual variability further supported this conclusion.

scholarly journals Lightning and precipitation produced by severe weather systems over Belém, Brazil

2014 ◽  
Vol 29 (spe) ◽  
pp. 41-59 ◽  
Author(s):  
Wanda Maria do Nascimento Ribeiro ◽  
José Ricardo Santos Souza ◽  
Márcio Nirlando Gomes Lopes ◽  
Renata Kelen Cardoso Câmara ◽  
Edson José Paulino Rocha ◽  
...  
Keyword(s):  
Large Scale ◽  
Electric Activity ◽  
Weather Conditions ◽  
Rain Gauge ◽  
Mesoscale Convective Systems ◽  
Major Influence ◽  
Rainfall Events ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
Cg Lightning

CG Lightning flashes events monitored by a LDN of the Amazon Protection System, which included 12 LPATS IV VAISALA sensors distributed over eastern Amazonia, were analyzed during four severe rainstorm occurrences in Belem-PA-Brazil, in the 2006-2007 period. These selected case studies referred to rainfall events, which produced more than 25 mm/hour, or more than 40 mm/ 2 hours of precipitation rate totals, registered by a tipping bucket automatic high-resolution rain gauge, located at 1º 47' 53" S and 48º 30' 16" W. Centered at this location, a 30 ,10 and 5 km radius circles were drawn by means of a geographic information system, and the data from lightning occurrences within this larger area, were set apart for analysis. During these severe storms the CG lightning events, occurred almost randomly over the surrounding defined circle, previously covered by mesoscale convective systems, for all cases studied. This work also showed that the interaction between large-scale and mesoscale weather conditions have a major influence on the intensity of the storms studied cases. In addition to the enhancement of the lightning and precipitation rates, the electric activity within the larger circles can precede the rainfall at central point of the areas

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