Trends in diurnal variation of surface air temperatures over India during hot weather (April–June) season

• Published in: Natural hazards (Dordrecht) Vol. 114; no. 2; pp. 1815 - 1827
• Main Authors: Rohini, P., Rajeevan, M., Soni, V. K.
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01.11.2022; Springer Nature B.V
• Subjects: Aerosol content; Air temperature; Civil Engineering; Cooling effects; Daily temperatures; Diurnal variations; Earth and Environmental Science; Earth Sciences; Environmental Management; Geophysics/Geodesy; Geotechnical Engineering & Applied Earth Sciences; Heat waves; Hot weather; Hydrogeology; Minimum temperatures; Natural Hazards; Original Paper; Statistical analysis; Surface temperature; Surface-air temperature relationships; Temperature; Temperature data; Temperature extremes; Temperature trends; Trends; Turbidity; India; Aerosol loading; Diurnal temperature variation; Warm hours; Heat wave
• ISSN: 0921-030X; 1573-0840
• DOI: 10.1007/s11069-022-05447-z

The previous studies on temperature trends are based on temperatures observed at a fixed hour (maximum and minimum temperatures). In this study, trends in sub-daily (hourly) temperatures are examined using quality temperature data from 66 Indian stations spread over the country. The season April–May–June and the data period of 1975–2012 have been considered for this analysis. Analysis was made to see the differences in two phases, 1975–1993 and 1994–2012. Most parts of the country were warmer throughout the day during the period 1994–2012 compared to the earlier period 1975–1993. Increase in daytime temperatures over many stations in Central India is subdued due to the cooling effect caused by the increase in aerosol content. Turbidity has shown a significant increasing trend over central Indian station, and it is 0.06 per decade. A statistically significant (at the 5% significant level) warming trend in diurnal temperature is observed during night/early morning hours. Warm hours showed an increasing trend in all four homogenous regions with a significant increase over northwest India ~ 1.5 h per decade and northeast India ~ 2 h per decade. The increase in extreme temperature hours may lead to an increase in the duration of heat wave events in the future.