Observed Climatology and Trend in Relative Humidity, CAPE, and CIN over India

Abstract

Water vapor is the most dominant greenhouse gas in the atmosphere and plays a critical role in Earth’s energy budget and hydrological cycle. This study aims to characterize the long-term seasonal variation of relative humidity (RH), convective available potential energy (CAPE), and convective inhibition (CIN) from surface and radiosonde observations from 1980–2020. The results show that during the monsoon season, very high RH values are depicted while low values are depicted during the pre-monsoon season. West Coast stations represent large RH values compared to other stations throughout the year. Irrespective of the season, the coastal regions show higher RH values during monsoon season. Regardless of season, the coastal regions have higher RH values during the monsoon season. During the pre-monsoon season, the coastal region has high RH values, whereas other regions have high RH values during the monsoon season. The rate of increase in RH in North-West India is 5.4%, followed by the West Coast, Central, and Southern parts of India.. An increase in water vapor leads to raised temperature, which alters the instability conditions. In terms of seasonal variation, our findings show that CAPE follows a similar RH pattern. CAPE increases sharply in Central India and the West Coast region, while it declines in South India. Opposite features are observed in CIN with respect to CAPE variability over India. The results of the study provide additional evidence with respect to the role of RH as an influencing factor for an increase in CAPE over India.

Hot weather hazard analysis over India

“…The April and May month also see the increased RH due weights due to the increased thunderstorm activities over east and northeast India leading to increase in the Relative humidity. The relative humidity is seen to have less impact on aggravating impact of heat waves over plains of northwest India and adjoining central India, which is very well correlated with the climatological lower relative humidity values over these regions 41,42 . In the month of June, again the situation is similar to March and April with additional few areas in Vidarbha, southern parts of Rajasthan and adjoining Gujarat showing more impact of RH over Heat Wave.…”

Uncoupling of stomatal conductance and photosynthesis at high temperatures: mechanistic insights from online stable isotope techniques

“…An increasing number of studies have shown the significant role of temperature and LAVPD increases in climate‐change‐induced tree mortality and growth decline (Novick et al ., 2016; Grossiord et al ., 2020; Trotsiuk et al ., 2021; McDowell et al ., 2022). Still, uncertainty and potential heterogeneity in the future VPD trend exist, as there are reports of increasing, instead of decreasing, trends in surface RH with warming at regional scales (Singh et al ., 2008; Eludoyin et al ., 2014; Khan et al ., 2022). More importantly, the interconnected nature of temperature and LAVPD complicates efforts to better understand and model plant responses to a changing environment, which highlights the need to disentangle the effects of temperature and LAVPD (Smith et al ., 2020; Schönbeck et al ., 2022).…”