Long-term variations in outgoing long-wave radiation (OLR), convective available potential energy (CAPE) and temperature in the tropopause region over India

Abstract

Relationship of outgoing long-wave radiation (OLR) with convective available potential energy (CAPE) and temperature at the 100-hPa pressure level is examined using daily radiosonde data for a period 1980-2006.1 • E) and Kolkata (22.3 • N, 88.2 • E), and during 1989-2005 over Cochin (10 • N, 77 • E) and Trivandrum (8.5 • N, 77.0 • E), India. Correlation coefficient (R xy ) between monthly OLR and CAPE shows a significant (∼−0.45) anti-correlation at Delhi and Kolkata suggesting low OLR associated with high convective activity during summer (seasonal variation). Though, no significant correlation was found between OLR and CAPE at Cochin and Trivandrum (low latitude region); analysis of OLR and temperature (at 100-hPa) association suggests that low OLR peaks appear corresponding to low temperature at Delhi (R xy ∼ 0.30) and Kolkata (R xy ∼ 0.25) during summer. However, R xy between OLR and temperature becomes opposite as we move towards low latitudes (∼8 • -10 • N) due to strong solar cycle influence. Large scale components mainly ENSO and quasi-biennial oscillaton (QBO) that contributed to the 100-hPa temperature variability were also analyzed, which showed that ENSO variance is larger by a factor of two in comparison to QBO over Indian region. ENSO warm conditions cause warming at 100-hPa over Delhi and Darwin. However, due to strong QBO and solar signals in the equatorial region, ENSO signal seems less effective. QBO, ENSO, and solar cycle contribution in temperature are found location-dependent (latitudinal variability) responding in consonance with shifting in convective activity regime during El Niño, seasonal variability in the tropical easterly jet, and the solar irradiance.

Observation of Atmospheric and Ionospheric Anomalies before the Nepal Earthquakes on 25th April and 12th May 2015

“…The next day, April 26, 2015, also shows a high OLR value in the range of 280-290 watts/m 2 . The possibilities for enhancement in OLR are due to two reasons [52]:…”

Validation of ground-based microwave radiometer data and its application in verifying atmospheric stability over Mahbubnagar during 2011 monsoon and post-monsoon seasons

“…Atmospheric instability/processes, mainly development of convection, can often lead to formation of clouds and precipitation, release of latent heat, etc. Several studies have reported on the seasonal and longterm variation in various atmospheric parameters such as outgoing longwave radiation (OLR), sea surface temperature (SST), precipitable water, and clouds, which have effects on convective activity over different regions (Dai 2001;Gettelman et al 2002;Ueno and Aryal 2008;Sapra et al 2011;Venkat Ratnam et al 2013). Few studies have investigated the diurnal variation in convection.…”

Variability in the onset of summer monsoon over Gangetic West Bengal, India: an investigation with climatology of tropopause characteristics

“…The number of days with OLR ≤ 180 W m ‐2 is closely related to the number of days with precipitation ≥10 mm (Sandeep and Strodal, ). The relationship among OLR, convective available potential energy and temperature was examined at the 100 hPa pressure level over Delhi, Kolkata, Cochin and Trivandrum, India (Sapra et al, ) and observed a positive correlation between OLR and temperature at Delhi and Kolkata. On the other hand, an investigation was carried out on the association between mid‐latitude circulations and rainfall over Indian region on an intra‐seasonal timescale by considering 11 years (1974–1984) of Northern Hemisphere 500 hPa geo‐potential height and rainfall data for Indian summer monsoon months (Kriplani et al, ).…”