Convective available potential energy

About: Convective available potential energy is a research topic. Over the lifetime, 936 publications have been published within this topic receiving 43773 citations. The topic is also known as: CAPE.

Microwave Radiometric Observation of a Waterspout Over Coastal Arabian Sea

Abstract: This letter discusses the background thermodynamic conditions of a convective cloud during the occurrence of a waterspout This study is conducted using a very unique experimental observation of a ground-based multifrequency microwave radiometer which was set to scan the atmosphere in seven elevation angles The spatio-temporal variations of the cloud microphysical parameters during the evolution of a multicell convective cumulus system are studied Humidity and temperature anomalies deduced from the radiometric observation could clearly explain the convective processes like the formation of an intense updraft of moist air, convective heating due to large latent heat energy release, and cooling of the lower atmosphere below 2-km altitude by the downdrafting dry air The measurements from collocated IR radiometer, surface met sensors, and calculated CAPE showed the formation of an intense convection in a humid warm atmosphere over a shallow warm ocean (conducive to formation of a waterspout) Studies on the evolution of cloud parameters during the life cycle of convective precipitation are of great interest in weather forecasting

Early evolution of vertical vorticity in a numerically simulated idealized convective line

Abstract: The generation and organization of mesoscale convective vortices (MCVs) is a recurring theme in midlatitude and tropical meteorology during the warm season. In this work a simulation of a finite-length idealized convective line in a westerly shear environment is investigated in the absence of ambient vertical vorticity. An asymmetry in average vertical vorticity forms rapidly at early times in the present simulation. This study focuses on the formation and organization of vertical vorticity at these early simulation times. Previous simulations suggest that tilting of either ambient or storm-generated horizontal vorticity is the primary mechanism responsible for the formation, organization, and maintenance of MCVs. This study confirms recent work regarding the generation of vertical vorticity at early times in the simulation. A Lagrangian budget analysis of the vertical vorticity equation, however, shows that vorticity convergence becomes a comparable, and at times dominant, mechanism for the enhancement and long-term organization of vertical vorticity early in the simulation. Despite differences in the initial ambient horizontal vorticity, hodograph, and convective available potential energy, the Lagrangian budget analysis in the present midlatitude case is consistent with the Lagrangian budget results of a previous tropical squall line simulation. The study of idealized convective lines in midlatitude environmental conditions therefore provide valuable insight into understanding vertical vorticity production in tropical squall lines and their potential relevance to tropical cyclogenesis.

Ocean Convective Available Potential Energy. Part II: Energetics of Thermobaric Convection and Thermobaric Cabbeling

Abstract: The energetics of thermobaricity- and cabbeling-powered deep convection occurring in oceans with cold freshwater overlying warm salty water are investigated here. These quasi-two-layer profiles are widely observed in wintertime polar oceans. The key diagnostic is the ocean convective available potential energy (OCAPE), a concept introduced in a companion piece to this paper (Part I). For an isolated ocean column, OCAPE arises from thermobaricity and is the maximum potential energy (PE) that can be converted into kinetic energy (KE) under adiabatic vertical parcel rearrangements. This study explores the KE budget of convection using two-dimensional numerical simulations and analytical estimates. The authors find that OCAPE is a principal source for KE. However, the complete conversion of OCAPE to KE is inhibited by diabatic processes. Further, this study finds that diabatic processes produce three other distinct contributions to the KE budget: (i) a sink of KE due to the reduction of stratification by vertical mixing, which raises water column’s center of mass and thus acts to convert KE to PE; (ii) a source of KE due to cabbeling-induced shrinking of the water column’s volume when water masses with different temperatures are mixed, which lowers the water column’s center of mass and thus acts to convert PE into KE; and (iii) a reduced production of KE due to diabatic energy conversion of the KE convertible part of the PE to the KE inconvertible part of the PE. Under some simplifying assumptions, the authors also propose a theory to estimate the maximum depth of convection from an energetic perspective. This study provides a potential basis for improving the convection parameterization in ocean models.

Role of moisture patterns in the backbuilding formation of HyMeX IOP13 heavy precipitation systems

Abstract: Mediterranean regions are regularly affected by heavy convective precipitation. During the Hydrological Cycle in the Mediterranean Experiment Intensive Observation Period 13 (HyMeX-IOP13), the multi-platform observation strategy allowed analysing the backbuilding convective systems which developed on 14 October 2012 as well as the associated moisture structures in the environment upstream of convection. The numerical simulation at 2.5-km horizontal resolution succeeds in reproducing the location and time evolution of the observed heavy precipitation systems and the main characteristics of the marine air mass. Convection develops in Southeastern France over the foothills closest to the coast when a moist conditionally unstable marine boundary layer topped by particularly dry air masses is advected inland. Cold air formed by evaporative cooling under the precipitating cells flows down the valleys slowly shifting the location of the backbuilding convective cells from the mountainsides to the coast and over the sea. Surface observations confirm that these simulated backbuilding mechanisms describe realistically the processes involved in the maintenance of the heavy precipitation event. A lagrangian analysis shows that the moisture supply to the convective system is provided by the moist conditionally unstable marine boundary layer while the dry air masses above are involved in the cold pool formation. Four days before the event, both, the dry and the moist air masses, come from the Atlantic Ocean in the lower half of the troposphere. The dry air mass involved in the cold pool formation results from both the advection of mid-level air masses and the drying of low-level air masses lifted up over Spain. For the moist air mass feeding the backbuilding convective systems, most of the air parcels overpass France before travelling almost 48 hours in the lowest 1000m above the Mediterranean. About 50 % of the moisture supply to the precipitating system originates from the evaporation over the sea.