scholarly journals Moisture Sources and Life Cycle of Convective Systems over Western Colombia

2011 ◽  
Vol 2011 ◽  
pp. 1-11 ◽  
Author(s):  
Meiry Sayuri Sakamoto ◽  
Tércio Ambrizzi ◽  
Germán Poveda
Keyword(s):  
Life Cycle ◽  
Sea Breeze ◽  
Boreal Summer ◽  
Boreal Winter ◽  
Trade Winds ◽  
Convective Systems ◽  
Moisture Sources ◽  
Tropical North Atlantic ◽  
Mesoscale Convective ◽  
Mcs Genesis

This paper describes life cycle and moisture sources of mesoscale convective systems (MCSs) observed over western Colombia. Results show that, in general, MCS are more frequent during boreal summer and autumn, and particularly, systems observed in summer season present longer life and larger extension. On the continent, MCS genesis is strongly affected by sea breeze and diurnal heating and presents a peak from 15 to 18 LST. For oceanic systems, the main genesis period is later, from 00 to 03 LST. Continental and oceanic systems present a tendency of westward displacement. Analysis using a Lagrangian approach implemented to estimate air parcel trajectories suggests that, during boreal winter, the main moisture sources are from the Caribbean Sea and tropical north Atlantic, possibly resulting from the moisture-laden trade winds and the land-ocean temperature contrast over northern South America. In summer, it is clear the influence of ITCZ positioning with moisture particles traveling from the tropical Atlantic over Amazonian river basin. In Autumn, Chilean-Peruvian Pacific is the main moisture source, confirming the importance of Chocó low level jet to MCS genesis.

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.

Life cycle of mesoscale convective systems

2009 ◽  
Vol 34 (5) ◽  
pp. 285-292 ◽  
Author(s):  
S. M. Abdullaev ◽  
A. A. Zhelnin ◽  
O. Yu. Lenskaya
Keyword(s):  
Life Cycle ◽  
Mesoscale Convective Systems ◽  
Convective Systems ◽  
Mesoscale Convective

scholarly journals A 17 year climatology of the macrophysical properties of convection in Darwin

2018 ◽  
Vol 18 (23) ◽  
pp. 17687-17704 ◽  
Author(s):  
Robert C. Jackson ◽  
Scott M. Collis ◽  
Valentin Louf ◽  
Alain Protat ◽  
Leon Majewski
Keyword(s):  
Climate Models ◽  
Global Climate ◽  
Sea Breeze ◽  
Active Phase ◽  
Global Climate Models ◽  
Convective System ◽  
Wet Season ◽  
Australian Monsoon ◽  
Convective Systems ◽  
Mesoscale Convective

Abstract. The validation of convective processes in global climate models (GCMs) could benefit from the use of large datasets that provide long-term climatologies of the spatial statistics of convection. To that regard, echo top heights (ETHs), convective areas, and frequencies of mesoscale convective systems (MCSs) from 17 years of data from a 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 GCM validation. The ETHs calculated using velocity texture and reflectivity provide similar results, showing that the ETHs are insensitive to various techniques that can be used. Retrieved ETHs are correlated with those from cloud top heights retrieved by Multifunctional Transport Satellites (MTSATs), showing that the ETHs capture the relative variability in cloud top heights over seasonal scales. Bimodal distributions of ETH, likely attributable to the cumulus congestus clouds and mature stages of convection, are more commonly observed when the active phase of the MJO is over Australia due to greater mid-level moisture during the active phase of the MJO. 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 2–4 km and 7–9 km. Larger cells were observed during break conditions compared to monsoon conditions, but only during the inactive phase of the MJO. The spatial distributions show that Hector, a deep convective system that occurs almost daily during the wet season over the Tiwi Islands, and sea-breeze convergence lines are likely more common in break conditions. Oceanic MCSs are more common during the night over Darwin. Convective areas were generally smaller and MCSs more frequent during active monsoon conditions. In general, the MJO is a greater control on the ETHs in the deep convective mode observed over Darwin, with higher distributions of ETH when the MJO is active over Darwin.

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 Basis for a Rainfall Estimation Technique Using IR–VIS Cloud Classification and Parameters over the Life Cycle of Mesoscale Convective Systems

2008 ◽  
Vol 47 (5) ◽  
pp. 1500-1517 ◽  
Author(s):  
G. Delgado ◽  
Luiz A. T. Machado ◽  
Carlos F. Angelis ◽  
Marcus J. Bottino ◽  
Á. Redaño ◽  
...  
Keyword(s):  
Life Cycle ◽  
Empirical Relationship ◽  
Estimation Method ◽  
Tropical Rainfall Measuring Mission ◽  
Rainfall Rate ◽  
Mesoscale Convective Systems ◽  
Rainfall Estimation ◽  
Convective Systems ◽  
Cloud Classification ◽  
Mesoscale Convective

Abstract This paper discusses the basis for a new rainfall estimation method using geostationary infrared and visible data. The precipitation radar on board the Tropical Rainfall Measuring Mission satellite is used to train the algorithm presented (which is the basis of the estimation method) and the further intercomparison. The algorithm uses daily Geostationary Operational Environmental Satellite infrared–visible (IR–VIS) cloud classifications together with radiative and evolution properties of clouds over the life cycle of mesoscale convective systems (MCSs) in different brightness temperature (Tb) ranges. Despite recognition of the importance of the relationship between the life cycle of MCSs and the rainfall rate they produce, this relationship has not previously been quantified precisely. An empirical relationship is found between the characteristics that describe the MCSs’ life cycle and the magnitude of rainfall rate they produce. Numerous earlier studies focus on this subject using cloud-patch or pixel-based techniques; this work combines the two techniques. The algorithm performs reasonably well in the case of convective systems and also for stratiform clouds, although it tends to overestimate rainfall rates. Despite only using satellite information to initialize the algorithm, satisfactory results were obtained relative to the hydroestimator technique, which in addition to the IR information uses extra satellite data such as moisture and orographic corrections. This shows that the use of IR–VIS cloud classification and MCS properties provides a robust basis for creating a future estimation method incorporating humidity Eta field outputs for a moisture correction, digital elevation models combined with low-level moisture advection for an orographic correction, and a nighttime cloud classification.

scholarly journals Mesoscale Convective Systems in Relation to African and Tropical Easterly Jets

2014 ◽  
Vol 142 (9) ◽  
pp. 3224-3242 ◽  
Author(s):  
L. Besson ◽  
Y. Lemaître
Keyword(s):  
Life Cycle ◽  
Deep Convection ◽  
Mesoscale Convective Systems ◽  
Convective Systems ◽  
African Easterly Jet ◽  
Interaction Processes ◽  
Tropical Easterly Jet ◽  
Mesoscale Convective ◽  
Jet Streaks

This paper documents the interaction processes between mesoscale convective systems (MCS), the tropical easterly jet (TEJ), and the African easterly jet (AEJ) over West Africa during the monsoon peak of 2006 observed during the African Monsoon Multidisciplinary Analyses (AMMA) project. The results highlight the importance of the cloud system localization relative to the jets in order to explain their duration and life cycle. A systematical study reveals that intense and long-lived MCSs correspond to a particular pattern where clouds associated with deep convection are located in entrance regions of TEJ and in exit regions of AEJ. A case study on a particularly well-documented convective event characterizes this link and infers the importance of jet streaks in promoting areas of divergence, favoring the persistence of MCSs.

scholarly journals Statistical Analysis of the Life Cycle of Isolated Tropical Cold Cloud Systems Using MTSAT-1R and TRMM Data

2012 ◽  
Vol 140 (11) ◽  
pp. 3552-3572 ◽  
Author(s):  
Keiji Imaoka ◽  
Kenji Nakamura
Keyword(s):  
Life Cycle ◽  
Tropical Rainfall Measuring Mission ◽  
Delayed Response ◽  
Cloud Systems ◽  
Convective Systems ◽  
Mature Phase ◽  
Mesoscale Convective ◽  
Radar Echo ◽  
The Difference ◽  
Rain Rates

Abstract Observations from the Multifunctional Transport Satellite-1R (MTSAT-1R) and the Tropical Rainfall Measuring Mission (TRMM) satellites are analyzed to show the universal view of the cloud life cycle, including the changes of vertical structure of rainfall, over the Maritime Continent and a part of the tropical western Pacific, with a focus on the isolated cold cloud systems. Temporally connected cold cloud systems are identified by a cloud tracking procedure and compared with the collocated observations from TRMM. Clear life cycle changes of the average reflectivity profile from the Precipitation Radar (PR), such as those of radar echo height and the brightband feature, are statistically confirmed over the ocean area. Systems with a lifetime of 5 h show a behavior similar to those of typical mesoscale convective systems, with an extension of anvil clouds up to an area of about 6000 km2 as a delayed response to the earlier intense convection, indicated by the peaks of rain rates and radar echo height at the early stages. In contrast, the 2-h lifetime systems decay rapidly and do not produce an extension of cloud and precipitation. The results also show that the difference between rainfall estimates of the TRMM Microwave Imager (TMI) and PR depends on the phase in the lifetime. TMI tends to provide higher conditional average rain rates at the mature phase than that of PR.

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 Spatiotemporal Characteristics and Large-Scale Environments of Mesoscale Convective Systems East of the Rocky Mountains

2019 ◽  
Vol 32 (21) ◽  
pp. 7303-7328 ◽  
Author(s):  
Zhe Feng ◽  
Robert A. Houze ◽  
L. Ruby Leung ◽  
Fengfei Song ◽  
Joseph C. Hardin ◽  
...  
Keyword(s):  
Great Plains ◽  
Rocky Mountains ◽  
Large Scale ◽  
Mesoscale Convective Systems ◽  
Rain Area ◽  
Stratiform Rain ◽  
Convective Systems ◽  
Mesoscale Convective ◽  
The U.S ◽  
Mcs Genesis

ABSTRACT The spatiotemporal variability and three-dimensional structures of mesoscale convective systems (MCSs) east of the U.S. Rocky Mountains and their large-scale environments are characterized across all seasons using 13 years of high-resolution radar and satellite observations. Long-lived and intense MCSs account for over 50% of warm season precipitation in the Great Plains and over 40% of cold season precipitation in the southeast. The Great Plains has the strongest MCS seasonal cycle peaking in May–June, whereas in the U.S. southeast MCSs occur year-round. Distinctly different large-scale environments across the seasons have significant impacts on the structure of MCSs. Spring and fall MCSs commonly initiate under strong baroclinic forcing and favorable thermodynamic environments. MCS genesis frequently occurs in the Great Plains near sunset, although convection is not always surface based. Spring MCSs feature both large and deep convection, with a large stratiform rain area and high volume of rainfall. In contrast, summer MCSs often initiate under weak baroclinic forcing, featuring a high pressure ridge with weak low-level convergence acting on the warm, humid air associated with the low-level jet. MCS genesis concentrates east of the Rocky Mountain Front Range and near the southeast coast in the afternoon. The strongest MCS diurnal cycle amplitude extends from the foothills of the Rocky Mountains to the Great Plains. Summer MCSs have the largest and deepest convective features, the smallest stratiform rain area, and the lowest rainfall volume. Last, winter MCSs are characterized by the strongest baroclinic forcing and the largest MCS precipitation features over the southeast. Implications of the findings for climate modeling are discussed.

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