Topic
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.
Papers published on a yearly basis
Papers
More filters
••
TL;DR: In this paper, the effect of meteorological parameters and environmental pollution on thunderstorm and lightning activity over Kolkata (22.65° N, 88.45° E), India during the pre monsoon season (April-May) was analyzed with aerosol optical depth, cloud top temperature and lightning flash rate.
Abstract: The purpose of this study is to understand the effect of meteorological parameters and environmental pollution on thunderstorm and lightning activity over Kolkata (22.65° N, 88.45° E), India during the pre monsoon season (April–May). The aerosol optical depth, cloud top temperature and lightning flash rate are analyzed with 2004–2010 observations. The convective available potential energy (CAPE) and convective condensation level (CCL) are utilized to view the role of convective energy and level of cloud base in thunderstorm and lightning activities. The suspended particulate matter (SPM), sulfur oxides (SOx) and nitrogen oxides (NOx) are also considered for a precise understanding of the effects of all these parameters on thunderstorms and lightning activity. High variability in convective energy persists over Kolkata during the pre monsoon season. It is observed that high CAPE and lower CCL leads to maximum wind speed with thunderstorms. Irrespective of CCL heights the average concentration of SPM is observed to be high for increased lightning flash rate. It is revealed that increased surface pollution in a near storm environment can increase the lightning flash rate during thunderstorms. The result also shows that the enhanced lightning activity intensifies the production of tropospheric NO2.
20 citations
••
TL;DR: In this paper, the authors evaluated the precipitation diurnal cycles over East Asia during the summer of 2008 simulated with three convective available potential energy (CAPE) based closure assumptions, i.e., CAPE-relaxing (CR), quasi-equilibrium (QE), and free-troposphere QE (FTQE) and investigated the impacts of planetary boundary layer (PBL) mixing, advection, and radiation on the simulation by using the weather research and forecasting model.
Abstract: Closure assumption in convection parameterization is critical for reasonably modeling the precipitation diurnal variation in climate models. This study evaluates the precipitation diurnal cycles over East Asia during the summer of 2008 simulated with three convective available potential energy (CAPE) based closure assumptions, i.e. CAPE-relaxing (CR), quasi-equilibrium (QE), and free-troposphere QE (FTQE) and investigates the impacts of planetary boundary layer (PBL) mixing, advection, and radiation on the simulation by using the weather research and forecasting model. The sensitivity of precipitation diurnal cycle to PBL vertical resolution is also examined. Results show that the precipitation diurnal cycles simulated with different closures all exhibit large biases over land and the simulation with FTQE closure agrees best with observation. In the simulation with QE closure, the intensified PBL mixing after sunrise is responsible for the late-morning peak of convective precipitation, while in the simulation with FTQE closure, convective precipitation is mainly controlled by advection cooling. The relative contributions of different processes to precipitation formation are functions of rainfall intensity. In the simulation with CR closure, the dynamical equilibrium in the free troposphere still can be reached, implying the complex cause-effect relationship between atmospheric motion and convection. For simulations in which total CAPE is consumed for the closures, daytime precipitation decreases with increased PBL resolution because thinner model layer produces lower convection starting layer, leading to stronger downdraft cooling and CAPE consumption. The sensitivity of the diurnal peak time of precipitation to closure assumption can also be modulated by changes in PBL vertical resolution. The results of this study help us better understand the impacts of various processes on the precipitation diurnal cycle simulation.
20 citations
••
TL;DR: In this paper, the impact of haze radiative effect on summertime 24-h convective precipitation over North China was investigated using WRF model (version 3.3) through model sensitivity studies between scenarios with and without aerosol radiative effects.
Abstract: The impact of haze radiative effect on summertime 24-h convective precipitation over North China was investigated using WRF model (version 3.3) through model sensitivity studies between scenarios with and without aerosol radiative effects. The haze radiative effect was represented by incorporating an idealized aerosol optical profile, with AOD values around 1, derived from the aircraft measurement into the WRF shortwave scheme. We found that the shortwave heating induced by aerosol radiative effects would significantly reduce heavy rainfalls, although its effect on the post-frontal localized thunderstorm precipitation was more diverse. To capture the key factors that determine whether precipitation is enhanced or suppressed, model grids with 24-h precipitation difference between the two scenarios exceeding certain threshold (>30 mm or<–30 mm) were separated into two sets. Analyses of key meteorological variables between the enhanced and suppressed regimes suggested that atmospheric convection was the most important factor that determined whether precipitation was enhanced or suppressed during summertime over North China. The convection was stronger over places with precipitation enhancement over 30 mm. Haze weakened the convection over places with precipitation suppression exceeding 30 mm and caused less water vapor to rise to a higher level and thus further suppressed precipitation. The suppression of precipitation was often accompanied with relatively high convective available potential energy (CAPE), relative humidity (RH) and updraft velocities.
20 citations
••
TL;DR: In this article, the long-term trends of the parameters related to convection and instability obtained from 27 radiosonde stations across six subdivisions over the Indian region during the period 1980-2016 are presented.
Abstract: . Long-term trends
of the parameters related to convection
and instability obtained from 27 radiosonde stations across six subdivisions
over the Indian region during the period 1980–2016 are presented. A total of
16 parcel and instability parameters along with moisture content, wind shear,
and thunderstorm and rainfall frequencies have been utilized for this
purpose. Robust fit regression analysis is employed on the regional average
time series to calculate the long-term trends on both a seasonal and a yearly
basis. The level of free convection (LFC) and the equilibrium level (EL) height
are found to ascend significantly in all Indian subdivisions. Consequently,
the coastal regions (particularly the western coast) experience increases
in severe thunderstorms (TSS) and severe rainfall (SRF) frequency in the
pre-monsoon period, while the inland regions (especially Central India) experience an
increase in ordinary thunderstorms (TSO) and weak rainfall (WRF) frequency during
the monsoon and post-monsoon periods. The 16–20-year periodicity is found to
dominate the long-term trends significantly compared to other periodicities
and the increase in TSS, and convective available potential energy (CAPE) is
found to be more severe after the year 1999. The enhancement in moisture transport
and associated cooling at 100 hPa along with the dispersion of boundary layer
pollutants are found to be the main causes for the increase in CAPE, which leads
to more convective severity in the coastal regions. However, in inland
regions, moisture-laden winds are absent and the presence of strong capping
effect of pollutants on instability in the lower troposphere has resulted in
more convective inhibition energy (CINE). Hence, TSO and occurrences of WRF have increased particularly in these regions.
19 citations
••
20 Mar 2020
TL;DR: In this article, the role of the vertical wind shear in the lower and middle troposphere, in terms of low-level shear and deep level shear, and of the convective available potential energy (CAPE) as possible precursors of significant tornadoes is statistically investigated.
Abstract: In this study, mesoscale environments associated with 57 significant tornadoes occurring over Italy in the period 2000–2018 are analyzed. The role of the vertical Wind Shear in the lower and middle troposphere, in terms of low-level shear (LLS) and deep-level shear (DLS), and of the convective available potential energy (CAPE) as possible precursors of significant tornadoes is statistically investigated. Wind shear and CAPE data are extracted from the ERA-5 and ERA-Interim reanalyses. Overall, the study indicates that: (a) values of these variables in the two uppermost quartiles of their statistical distribution significantly increases the probability of tornado occurrences; (b) the probability increases for increasing values of LLS and DLS, and (c) is maximum when either wind shear or CAPE are large. These conclusions hold for both the reanalysis datasets and do not depend upon the season and/or the considered area. With the possible exception of weak tornadoes, which are not included in our study, our results show that large wind shear, in the presence of medium-to-high values of CAPE, are reliable precursors of tornadoes.
19 citations