Role of Natural and Anthropogenic Loadings on Indian Temperature Trends

• Published in: Pure and applied geophysics Vol. 176; no. 11; pp. 5125 - 5140
• Main Authors: Padmavathi, B., Rekapalli, Rajesh, Tiwari, R. K.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.11.2019; Springer Nature B.V
• Subjects: Anthropogenic factors; Atmospheric processes; Carbon dioxide; Correlation analysis; Correlation coefficient; Correlation coefficients; Earth and Environmental Science; Earth Sciences; El Nino; El Nino phenomena; El Nino-Southern Oscillation event; Frequencies; Geophysics/Geodesy; Human influences; Oceans; Periodicities; Regression analysis; Sensitivity; Sensitivity analysis; Southern Oscillation; Spectral analysis; Spectrum analysis; Statistical analysis; Statistical methods; Temperature; Temperature effects; Temperature trends; Trends; AMO; ENSO; PDO; TSI; CO; NAO; Indian maximum and minimum temperature
• ISSN: 0033-4553; 1420-9136
• DOI: 10.1007/s00024-019-02247-8

We evaluate the impact of natural and anthropogenic loadings on Indian maximum ( T max ) and minimum ( T min ) temperature variabilities during 1901–2015 using multiple spectral and statistical analyses. We compare the significant eigenmodes of temperature with TSI, Ocean and Atmospheric Processes (OAP) such as ENSO, PDO, NAO, AMO and CO 2 data to understand their influence on temperature. The present analysis is based on new eigen-weighted correlation coefficient (EWCC) and regression analysis to assess the sensitivity of temperature to TSI, OAP and CO 2 . The first eigenmodes (EM) of T max and T min representing the long-term trend correlate well with the first EM of TSI (EWCC: 0.90 and 0.78) and CO 2 (EWCC: 0.95 and 0.72), respectively. The CO 2 residing throughout the day and night in the atmosphere may produce a similar linearly increasing trend in T max and T min . However, the trend test revealed non-stationarity in the trends of T max and T min . In addition, the regression analysis revealed high sensitivity of the T max and T min trend to TSI compared with CO 2 . Our study suggests that there is an intermittent change in the running mean of TSI between 1901 and 2015 resulting in observed changes in T max . In addition, spectral analysis of the T max and T min records revealed statistical significant  periodicities of ~ 2–7 years and 11 ± 2 years in T max and ~ 2–7 years and 50 ± 4 years in T min , which may be associated with OAP and TSI, respectively. Based on the present analyses, we conclude that there are combined responses of (1) intrinsic variation in TSI and CO 2 , which may be interpreted as the major loading factors on the trend of T max and T min , respectively; (2) periodic variabilities in different frequency bands may be associated with both solar and ocean atmospheric processes depending upon time scales.