Role of Natural and Anthropogenic Loadings on Indian Temperature Trends PADMAVATHI B., 1,2 RAJESH REKAPALLI, 1 and R. K. TIWARI 1 Abstract—We evaluate the impact of natural and anthro- pogenic loadings on Indian maximum (T max ) and minimum (T min ) temperature variabilities during 1901–2015 using multiple spec- tral 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 inter- mittent 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 signifi- cant 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 asso- ciated 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 , respec- tively; (2) periodic variabilities in different frequency bands may be associated with both solar and ocean atmospheric processes depending upon time scales. Key words: Indian maximum and minimum temperature, CO 2 , TSI, ENSO, PDO, NAO, AMO. 1. Introduction During the past several years, researchers have been discussing the possible role of various natural and anthropogenic loadings on Indian temperature variability. There are diverse opinions about the loadings from external solar, internal ocean-atmo- spheric and anthropogenic processes. In general, variation in solar radiation and oceanic atmospheric circulations can cause long-term continental-scale climate/temperature variations, whereas anthro- pogenic agents will induce local-scale changes. The analysis of the instrumental and proxy reconstructed temperature data from different parts of the globe revealed the annual to centennial-scale solar-induced cyclic pattern in the temperature/climate variability (Eddy 1988; Lean and Rind 1999; Rigozo et al. 2007; White and Liu 2008; Engels and van Geel 2012; Chowdary et al. 2014; Tiwari et al. 2016). Several researchers have demonstrated the presence of peri- odicities of the order of 11, 22, 56–60, 104–120 years, etc., in the terrestrial temperature records, which obviously attest to the role of solar variability on the global scale (Friis-Christensen and Svensmark 1997; Kasatkina et al. 2007; Gray et al. 2010; Tiwari et al. 2015, 2016). In addition, several researchers have also suggested a significant influ- ence of oceanic oscillations on global climate variability. Several global- and regional-scale studies have shown evidence for coupled influence of solar and oceanic circulation processes on climate change (Pant and Kumar 1997; Friis-Christensen and Svensmark 1997; Yousef 2000; Hu et al. 2003; Tiwari and Rao 2004; Rigozo et al. 2007; Singh and Singh 2006; Kothawale et al. 2010; Chowdary et al. 2014; Tiwari et al. 2015). In particular, there are studies suggesting the high sensitivity of the Indian climate system to the El Nin ˜o-Southern Oscillation Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00024-019-02247-8) contains sup- plementary material, which is available to authorized users. 1 CSIR-NGRI, Hyderabad, India. E-mail: rekapalli@gmail.com 2 AcSIR, CSIR-NGRI, Hyderabad, India. Pure Appl. Geophys. Ó 2019 Springer Nature Switzerland AG https://doi.org/10.1007/s00024-019-02247-8 Pure and Applied Geophysics