资源环境科技发展态势分析平台

Paleoclimatic interpretation of stable isotope based proxies from India is complex due to lack of local amount effect (negative relation between rainfall and its heavy isotopic content observed over tropics) in most places. Recent studies revealed that regional or upstream rainfall/ convective activity plays a major role on daily rainfall O-18 variability. Here we extensively analyze the isotopic variability of Indian Summer Monsoon (ISM) rainfall of south western peninsular India. ISM rainfall O-18 of south western coast of India show significant correlation with the upstream convective activity and the associated rainfall over eastern Arabian Sea on daily, monthly and yearly time scales. A comparative dry-wet-dry (wet-dry-wet) rainfall pattern is observed over north eastern India, peninsular India and the equatorial Indian Ocean during the occurrence of low (high) values of rainfall O-18 at south western coast of India on all time scales. Thus the ISM rainfall O-18 of south western India captures not only the local or upstream convective activities, but reflects the rainfall pattern of a large domain including the Indian subcontinent and Indian Ocean. O-18 variations of climatic proxies from south western coast of India can be thus better interpreted in terms of these results.