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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.


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TL;DR: In this article, the authors examined the behavior of observed radar and infrared satellite interest fields (IFs) in the 75-min time frame surrounding the first lightning initiation over Florida and Oklahoma.
Abstract: Lightning initiation (LI) events over Florida and Oklahoma are examined and statistically compared to understand the behavior of observed radar and infrared satellite interest fields (IFs) in the 75-min time frame surrounding LI. Lightning initiation is defined as the time of the first lightning, of any kind, generated in a cumulonimbus cloud. Geostationary Operational Environmental Satellite (GOES) infrared IFs, contoured frequency by altitude diagrams (CFADs) of radar reflectivity, and model sounding data, analyzed in concert, show the mean characteristics over time for 36 and 23 LI events over Florida and Oklahoma, respectively. CFADs indicate that radar echoes formed 60 min before Florida LI, yet Oklahoma storms exhibited a ;30-min delayed development. Large ice volumes in Florida developed from the freezing of loftedliquidhydrometeorsformedbylong-lived(;45 min) warm rain processes, whichare mostlyabsentin Oklahoma. However, ice volumes developed abruptly in Oklahoma storms despite missing a significant warm rain component. GOES fields were significantly different before 30 min prior to LI between the two locations. Compared to Florida storms, lower precipitable water (PW), higher convective available potential energy, and higher 3.9-mm reflectance in Oklahoma, suggest stronger and drier updrafts producing a greater abundance of small ice particles. Somewhat larger 15-min 10.7-mm cooling rates in Oklahoma confirm stronger updrafts, while clouds in the 60‐30-min pre-LI period show more IF variability (e.g., in the 6.5‐10.7-mm difference). Florida storms (high PW, slower growth) offer more lead time for LI predictability, compared to Oklahoma storms (low PW, explosive growth), with defined anvils being obvious at the time of LI.

25 citations

Journal ArticleDOI
TL;DR: In this paper, an attempt is made to study the thermodynamic structure of convective atmosphere during pre-monsoon season over southwest peninsular India utilizing satellite derived data and radiosonde data.
Abstract: The combined use of both radiosonde data and three-dimensional satellite derived data over ocean and land is useful for a better understanding of atmospheric thermodynamics. Here, an attempt is made to study the thermodynamic structure of convective atmosphere during pre-monsoon season over southwest peninsular India utilizing satellite derived data and radiosonde data. The stability indices were computed for the selected stations over southwest peninsular India viz: Thiruvananthapuram and Cochin, using the radiosonde data for five premonsoon seasons. The stability indices studied for the region are Showalter Index (SI), K Index (KI), Lifted Index (LI), Total Totals Index (TTI), Humidity Index (HI), Deep Convective Index (DCI) and thermodynamic parameters such as Convective Available Potential Energy (CAPE) and Convective Inhibition Energy (CINE). The traditional Showalter Index has been modified to incorporate the thermodynamics over tropical region. MODIS data over South Peninsular India are also used for the study. When there is a convective system over south peninsular India, the value of LI over the region is less than ?4. On the other hand, the region where LI is more than 2 is comparatively stable without any convection. Similarly, when KI values are in the range 35 to 40, there is a possibility for convection. The threshold value for TTI is found to be between 50 and 55. Further, we found that prior to convection, dry bulb temperature at 1000, 850, 700 and 500 hPa is minimum and the dew point temperature is a maximum, which leads to increase in relative humidity. The total column water vapor is maximum in the convective region and minimum in the stable region. The threshold values for the different stability indices are found to agree with that reported in literature.

24 citations

Journal ArticleDOI
TL;DR: In this article, the authors examined the temporal and spatial variability of cloud-to-ground lightning in a sector covering the Iberian Peninsula, the Balearic Islands and nearby seas (36-44° N, 10° W −5° E) in the period from 2003 to 2009 (7 yr).
Abstract: Cloud-to-ground lightning in a sector covering the Iberian Peninsula, the Balearic Islands and nearby seas (36–44° N, 10° W–5° E) is analysed in the period from 2003 to 2009 (7 yr) Two Iberian lightning detection networks, composed of 18 sensors over Portugal and Spain, are combined for the first time in the present study The selected characteristics are cloud-to-ground flashes (CGFs), first stroke peak current, polarity and multiplicity (number of strokes in a given flash) This study examines the temporal (on hourly, monthly and seasonal timescales) and spatial variability of CGFs The influence of five forcing factors on lightning (elevation, lifted index, convective available potential energy and daily minimum and maximum near-surface air temperatures) over the Iberian sector is also assessed For regional-scale assessments, six subsectors with different climatic conditions were analysed separately Despite important regional differences, the strongest lightning activity occurs from late spring to early autumn, and mostly in the afternoon Furthermore, CGFs are mainly located over high-elevation areas in late spring to summer, while they tend to occur over the sea in autumn The results suggest that (1) orographically forced thunderstorms over mountainous areas, mostly from May to September, (2) tropospheric buoyancy forcing over western-central and northern regions in summer and over the Mediterranean regions in autumn, and (3) near-surface thermal contrasts from October to February largely control the location of lightning in Iberia There is no evidence of different forcings by polarity A clear correspondence between summertime precipitation patterns and CGFs is also found

24 citations

Journal ArticleDOI
TL;DR: In this article, the relationship between the convective available potential energy (CAPE) and the surface pressure is exploited by a widely used algorithm for hurricane potential intensity (PI) for the observed atmosphere, the algorithm is shown to yield significantly weaker pressure intensity (20%−25%) and velocity intensity (5%−10%) than the most familiar analytical formulas.
Abstract: The theoretical minimum eyewall pressure of tropical cyclones can be computed from convective available potential energy (CAPE) if the buoyancy in the CAPE is allowed to feed back on the surface pressure via hydrostatic balance. The relationship between this so-called hurricane CAPE and the surface pressure is exploited by a widely used algorithm for hurricane potential intensity (PI). For the observed atmosphere, the algorithm is shown to yield significantly weaker pressure intensity (20%–25%) and velocity intensity (5%–10%) than the most familiar analytical formulas. This discrepancy is found to come mostly from thermodynamic approximations in the formulas.The CAPE–PI algorithm makes a significant adjustment to the hurricane CAPE by subtracting the environmental CAPE. Most of the environmental profile becomes irrelevant as a result. Other steady-state theories retain the influence of the full environmental column. The impact of this choice on the pressure and velocity PI is analyzed. Another imp...

24 citations

Journal ArticleDOI
TL;DR: In this paper, a new inhibition hypothesis explaining the expected characteristics of the spatial distribution of cumulus clouds is postulated, which can be parameterized in terms of a stabilization function representing the time rate of change of convective available potential energy.
Abstract: The spatial distribution of cumulus clouds is assumed to be the result of the effects of convective activity on the thermodynamic environment. The effects can be parameterized in terms of a stabilization function representing the time rate of change of convective available potential energy. Using these results, a new inhibition hypothesis explaining the expected characteristics of the spatial distribution of cumulus clouds is postulated. This paper performs a verification of the inhibition hypothesis on real and simulated cloud fields. In order to do so, an objective measure of the spatial characteristics of cumulus clouds is introduced. Multiple cloud experiments are performed with a three-dimensional numerical cloud model. Skylab pictures of real cumuli are also used in the verification. Results of applying this measure to simulated and observed cumulus cloud fields confirm the inhibition hypothesis.

24 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202365
202291
202151
202038
201932
201827