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.

The Impact of El-Niño and La-Niña on the Pre-Monsoon Convective Systems over Eastern India

Abstract: El-Niño and La-Niña are believed to change the intensity and frequencies of extreme weather events globally. The present study aims to analyse the impact of El-Niño and La-Niña on the lightning activities of cloud systems and their associated precipitation and thermodynamic indices over the Eastern India regions (Odisha, Jharkhand, and West Bengal) during the pre-monsoon season (March–May). Eastern India receives catastrophic thunderstorm events during the pre-monsoon season. The results suggest that the number of lightning flashes was higher in the El-Niño years than in the La-Niña periods, which helps convective activities to be developed over the study region. The precipitation variations showed similar patterns during El-Niño and La-Niña periods, but the magnitudes were higher in the latter. Results from the analysis of thermodynamic indices show that, during the La-Niña phase, the convective available potential energy (CAPE), convective inhibition (CIN), severe weather threat index (SWEAT), humidity index (HI), and total totals index (TTI) values increased, while the cross total index (CTI) and K index (KI) decreased. In contrast, the vertical total index (VTI) and Boyden index (BI) values showed less significant changes in both El-Niño and La-Niña periods. The anomalies of flash rate densities over most parts of our domain were positive during the El-Niño years and negative during the La-Niña years. Precipitation anomalies had a higher positive magnitude during the La-Niña phase, but had spatial variability similar to the El-Niño phase. The anomalies of most of the thermodynamic indices also showed noticeable differences between El-Niño and La-Niña periods, except for the HI index. El-Niño periods showed higher lightning and increased values of associated thermodynamic indices over eastern India, indicating more pronounced convective systems.

Climatic factors contributing to long-term variations of fine dust concentration in the United States

Abstract: High concentration of dust particles can cause respiratory problems and increase non-accidental mortality. Studies found fine dust (with aerodynamic diameter less than 2.5 microns) is an important component of the total PM2.5 mass in the western and central U.S. in spring and summer and has positive trends. This work examines factors influencing long-term variations of fine dust concentration in the U.S. using station data from the Interagency Monitoring Protected Visual Environments (IMPROVE) network during 1990–2015. The variations of the fine dust concentration can be largely explained by the variations of precipitation, surface bareness, and 10 m wind speed. Moreover, including convective parameters such as convective inhibition (CIN) and convective available potential energy (CAPE) better explains the variations and trends over the Great Plains from spring to fall. While the positive trend of fine dust concentration in the Southwest in spring is associated with precipitation deficit, the increasing of fine dust over the central Great Plains in summer is largely associated with an enhancing of CIN and a weakening of CAPE, which are related to increased atmospheric stability due to surface drying and lower troposphere warming. The positive trend of the Great Plains low-level jet also contributes to the increasing of fine dust concentration in the central Great Plains in summer via its connections with surface winds and CIN. Summer dusty days in the central Great Plains are usually associated with a westward extension of the North Atlantic subtropical high that intensifies the Great Plains low-level jet and also results in a stable atmosphere with subsidence and reduced precipitation.

Numerical simulations and doppler radar data analysis of a hail process in huaihe river basin

Abstract: A hail process in Huaihe River Basin observed by CINRAD Doppler radar on 12May 2000 hasbeen simulated by using nonhydrostatic mesoscale numerical model MM5The simulated wind fieldis analyzed and compared with Doppler radar wind data,both of them show that there was ameso-β cyclone around the hail regionResults show that this meso-β cyclone existed below 3 kmin the troposphere and its cyclonic circulation was very obvious below 1 kmThe temperature andmoisture fields from the simulation are also analyzedFurthermore,the storm-relativeenvironmental helicity and CAPE(convective available potential energy)are discussed

Some Aspects of Post-Frontal Convective Areas Along the West Coast of the United States.

Abstract: : The European Center for medium-Range WEather Forecasts (ECMWF) Level III-b analyses are used to study cases of post-frontal convective areas that occurred off the West Coast of the United States A five-year climatology suggests than an average of about 13 convective events occurs each winter, and that two of three cases are likely to have intense and well-organized convection Five events that occurred during the First Special Observing Period of the First GARP Global Experiment are selected for detailed study, Associations are sought between the post-frontal convective areas and standard synoptic and dynamic variables The convection appears to be closely tied to the position of the upper level cold trough Cold advection aloft and low-level heating as the cold air streams over the warmer ocean contribute to maintenance of low static stability in the convective region The feasibility of diagnosing the location of the convective regions is explored with diabatic and frictional parameterizations of the Naval Operational Global Atmospheric Prediction System (NOGAPS) Wind, temperature, geopotential and moisture fields from the ECMWF are used to specify the large-scale forcing The cumulus precipitation diagnosed by the NOGAPS does agree surprisingly well with the post-frontal convective areas in these five cases (Author)

Direct Bayesian model reduction of smaller scale convective activity conditioned on large scale dynamics

Abstract: . We pursue a simplified stochastic representation of smaller scale convective activity conditioned on large scale dynamics in the atmosphere. For identifying a Bayesian model describing the relation of different scales we use a probabilistic approach (Gerber and Horenko, 2017) called Direct Bayesian Model Reduction (DBMR). The convective available potential energy (CAPE) is applied as large scale flow variable combined with a subgrid smaller scale time series for the vertical velocity. We found a probabilistic relation of CAPE and vertical up- and downdraft for day and night. The categorization is based on the5 conservation of total probability. This strategy is part of a development process for parametrizations in models of atmospheric dynamics representing the effective influence of unresolved vertical motion on the large scale flows. The direct probabilistic approach provides a basis for further research of smaller scale convective activity conditioned on other possible large scale drivers.