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.

An analysis of the synoptic and dynamical characteristics of hurricane Sandy (2012)

Abstract: Hurricane Sandy affected the Caribbean Islands and the Northeastern United States in October 2012 and caused 233 fatalities, severe rainfalls, floods, electricity blackouts, and 75 billion U.S. dollars in damages. In this study, the synoptic and dynamical characteristics that led to the formation of the hurricane are investigated. The system was driven by the interaction between the polar jet displacement and the subtropical jet stream. In particular, Sandy was initially formed as a tropical depression system over the Caribbean Sea and the unusually warm sea drove its intensification. The interaction between a rapidly approaching trough from the northwest and the stagnant ridge over the Atlantic Ocean drove Sandy to the northeast coast of United States. To better understand the dynamical characteristics and the mechanisms that triggered Sandy, a non-hydrostatic mesoscale model has been used. Model results indicate that the surface heat fluxes and the moisture advection enhanced the convective available potential energy, increased the low-level convective instability, and finally deepened the hurricane. Moreover, the upper air conditions triggered the low-level frontogenesis and increased the asymmetry of the system which finally affected its trajectory.

Early Warnings of Severe Convection Using the ECMWF Extreme Forecast Index

Abstract: ECMWF provides the ensemble-based extreme forecast index (EFI) and shift of tails (SOT) products to facilitate forecasting severe weather in the medium range. Exploiting the ingredients-based method of forecasting deep moist convection, two parameters, convective available potential energy (CAPE) and a composite CAPE–shear parameter, have been recently added to the EFI/SOT, targeting severe convective weather. Verification results based on the area under the relative operating characteristic curve (ROCA) show high skill of both EFIs at discriminating between severe and nonsevere convection in the medium range over Europe and the United States. In the first 7 days of the forecast ROCA values show significant skill, staying well above the no-skill threshold of 0.5. Two case studies are presented to give some practical considerations and discuss certain limitations of the EFI/SOT forecasts and how they could be overcome. In particular, both convective EFI/SOT products are good at providing guidance f...

Simulated Sensitivity of Tropical Cyclone Size and Structure to the Atmospheric Temperature Profile

Abstract: This study uses the WRF ARW to investigate how different atmospheric temperature environments impact the size and structure development of a simulated tropical cyclone (TC). In each simulation, the entire vertical virtual temperature profile is either warmed or cooled in 1°C increments from an initial specified state while the initial relative humidity profile and sea surface temperature are held constant. This alters the initial amount of convective available potential energy (CAPE), specific humidity, and air–sea temperature difference such that, when the simulated atmosphere is cooled (warmed), the initial specific humidity and CAPE decrease (increase), but the surface energy fluxes from the ocean increase (decrease).It is found that the TCs that form in an initially cooler environment develop larger wind and precipitation fields with more active outer-core rainband formation. Consistent with previous studies, outer-core rainband formation is associated with high surface energy fluxes, which le...

Synoptic situations of severe local convective storms during the pre-monsoon season in Bangladesh

Abstract: This study examines synoptic situations of severe local convective storms (mesoscale severe weather associated with deep convections such as tornado and hail) during the pre-monsoon season (from March to May) in Bangladesh. We compared composite meteorological fields on severe local convective storm days (SLCSD) with those on non-severe local convective storm days (NSLCSD). Moisture inflow from the Bay of Bengal is enhanced with intensification of southwesterly wind at 950 hPa on SLCSD compared with NSLCSD. The temperature is higher at 800 hPa over the inland area of the Indian subcontinent including Bangladesh on SLCSD than NSLCSD. At 550 hPa, a trough over Bangladesh develops on SLCSD compared with NSLCSD. This leads to the development of a thermal trough over the inland area of the Indian subcontinent and enhancement of cold advection from the northwest into Bangladesh on SLCSD at this level. This synoptic situation produces great potential instability of the atmosphere in Bangladesh on SLCSD during the pre-monsoon season. Composite distributions of lifted index, precipitable water and convective available potential energy on SLCSD and NSLCSD over south Asia show distinct differences of these parameters between these two categories with statistical significance especially in and around Bangladesh. These differences indicate that the atmospheric environment has great potential instability especially in and around Bangladesh on SCLSD under the synoptic situations shown in this study. Copyright © 2012 Royal Meteorological Society

Premonsoon estimates of convective available potential energy over the oceanic region surrounding the Indian subcontinent

Abstract: [1] Convective available potential energy (CAPE) and convective inhibition energy (CIN) are important parameters in determining the stability of the atmosphere for moist convection. This paper presents the estimates of CAPE and CIN during the premonsoon season over the oceanic region surrounding the Indian subcontinent. The high-resolution radiosonde data used in this study were collected as a part of the Integrated Campaign for Aerosols gases and Radiation Budget (ICARB; March–May 2006), which covered the Bay of Bengal, Arabian Sea, and parts of North Indian Ocean. We discuss the spatiotemporal variability of CAPE and CIN during the premonsoon period and investigate the role of boundary layer, as well as free tropospheric parameters in controlling the CAPE and CIN values. During the convective event of 9 April the sensors on board the ship recorded 4 mm of rain and an overall reduction of CAPE by 620 J kg−1 was seen. This corroborates with the concept that CAPE generated by the nonconvective processes is consumed by the convection for its intensification. However, the observed reduction in CAPE after this convective event is much less compared to the monsoon season reported elsewhere. CIN was found to be anticorrelated with the free convection depth (FCD), which is the distance through which the parcel ascends by its own buoyancy. Thus the variability in CAPE and CIN is found to be interlinked through the FCD. Apart from this, contribution to total CAPE from various levels are also estimated, which shows that the CAPE in the middle levels contributes most toward the total CAPE. Our investigations show that although the CAPE and CIN are related to the tropospheric parameters like temperature lapse rate, the variability in CAPE and CIN is essentially determined by the moisture in the atmospheric boundary layer. As the equivalent potential temperature (θE) in the ABL increases, CAPE increases, favoring the development of convection.