Influence of large-scale variations in convective available potential energy (CAPE) and solar cycle over temperature in the tropopause region at Delhi (28.3°N, 77.1°E), Kolkata (22.3°N, 88.2°E), Cochin (10°N, 77°E), and Trivandrum (8.5°N, 77.0°E) using radiosonde during 1980–2005

Abstract

We have shown the relationship between seasonal, annual, and large-scale variations in convective available potential energy (CAPE) and the solar cycle in terms of temperature at the 100-hPa pressure level using daily radiosonde data for the period 1980 • N, 77. • E) and Trivandrum (8.5• N, 77.0 • E), India. In general, there was a tendency for increases in CAPE to be associated with decreases in temperature at the 100-hPa pressure level on all time scales. Decreasing linear trends in temperature were found at Delhi and Kolkata over the period [1990][1991][1992][1993][1994][1995][1996][1997][1998][1999][2000][2001][2002][2003][2004][2005][2006]. Our analysis suggests that the trend towards increasing convective activity in the troposphere leads-at least partly-to the trend towards cooling in the tropopause region. High CAPEs are, in general, associated with high rainfall. The minimum annual temperatures were observed almost simultaneously with enhanced annual CAPE during the northern summer, with a larger anti-correlation (−0.62) over Delhi than at other stations. The influence of the solar cycle on the control of temperature was significant (∼4-5• C) only around 8-10• N. Temperature variations in the upper troposphere are viewed as being jointly controlled by CAPE and the solar cycle, with the respective contribution of each being location-dependent.

Lightning and convective rain over Indian peninsula and Indo-China peninsula

“…Surface temperature does not show any role on convective rain in R 1 region, although positive role is observed in R 2 region. Present results are consistent with that of Dhaka et al (2010) who showed that high CAPE is associated with high rainfall and that of Roy Bhowmik et al (2008) who reported high value of CAPE during the pre-monsoon period.…”

Long-term trends of instability and associated parameters over the Indian region obtained using a radiosonde network

“…Hence, to find out the periodicities in the average long-term trends, the time series of all regions are averaged and then subjected to the EMD technique, which reveals the existence of four main periodicities, namely 1.5-2.5 years, corresponding to the QBO, 4-6 years, corresponding to ENSO, 10-12 years, corresponding to the solar cycle, and 16-20 years. A similar multi-decadal climatic oscillation was also reported by Dhaka et al (2010). Hence for simplicity, this periodicity has been renamed as the Multi-decadal Climatic Oscillation (MCO).…”

“…found to strongly influence the convective strengths over the Indian region (Manohar et al, 1999;Dhaka et al, 2010).…”

“…Over the Indian region, Manohar et al (1999) studied the latitudinal variation and distribution of thunderstorm frequency and CAPE over 78 Indian stations during 1970Indian stations during -1980 and they postulated that the ambient temperature at the 100 hPa pressure level has a strong relationship with it. Dhaka et al (2010) utilized radiosonde observations during 1958-1997 and they obtained very prominent anticorrelations on both a yearly and a seasonal basis between convection strength (CAPE) and upper-troposphere temperatures at 100 hPa (T 100). Later, Murugavel et al (2012) studied the long-term trends of CAPE from 32 radiosonde stations during 1984-2008 and revealed an alarming growth in monsoon CAPE over India, with a slope of 38 J kg −1 year −1 .…”

Retrieval of convective available potential energy from INSAT-3D measurements: comparison with radiosonde data and their spatial–temporal variations

“…Arakawa and Schubert, 1974;Moncrieff and Miller, 1976;Washington and Parkinson, 2005). Many of the cumulus parameterization schemes make use of CAPE in constructing closures (Donner and Phillips, 2003). The diurnal variation of CAPE is of primary importance for understanding the sensitivity of convection schemes in the model for producing the diurnal cycle of precipitation (Lee et al, 2007).…”