TY - JOUR
T1 - Isotopic fingerprinting of dual monsoon moisture sources, evapotranspiration process and microclimate manifestation over the tropical rainforest region, western part of the Western Ghats, India
AU - Tripti, M.
AU - Lambs, L.
AU - Gurumurthy, G. P.
AU - Moussa, I.
AU - Balakrishna, K.
N1 - Funding Information:
The authors acknowledge the funding support from PICS-CNRS grants for the field work and sample analysis. The authors also thank NOAA Air Resources Laboratory for accessibility to HYSPLIT Trajectory model and NRSC for the access to Bhuvan thematic datasets. TM thanks the Indian National Science Academy (INSA) and Department of Science and Technology (DST), Government of India for the INSPIRE Faculty fellowship (IFF), and funding the present research on the Western Ghats (DST/INSPIRE/04/2017/002651). TM also acknowledges the support of former Director (Dr. N. Purnachandra Rao, presently Chief Scientist, NGRI, Hyderabad), NCESS, Thiruvananthapuram to implement IFF in the institute and present Director (Prof. J.S. Ray), NCESS for research encouragement. The Editor (Prof. H. Guo), the Associate Editor (Dr. P. Négrel) and the anonymous reviewers constructive comments and suggestions on the initial submitted manuscript are greatly acknowledged.
Funding Information:
The authors acknowledge the funding support from PICS-CNRS grants for the field work and sample analysis. The authors also thank NOAA Air Resources Laboratory for accessibility to HYSPLIT Trajectory model and NRSC for the access to Bhuvan thematic datasets. TM thanks the Indian National Science Academy (INSA) and Department of Science and Technology (DST), Government of India for the INSPIRE Faculty fellowship (IFF), and funding the present research on the Western Ghats (DST/INSPIRE/04/2017/002651). TM also acknowledges the support of former Director (Dr. N. Purnachandra Rao, presently Chief Scientist, NGRI, Hyderabad), NCESS, Thiruvananthapuram to implement IFF in the institute and present Director (Prof. J.S. Ray), NCESS for research encouragement. The Editor (Prof. H. Guo), the Associate Editor (Dr. P. Négrel) and the anonymous reviewers constructive comments and suggestions on the initial submitted manuscript are greatly acknowledged.
Publisher Copyright:
© 2022 Elsevier B.V.
PY - 2022/9
Y1 - 2022/9
N2 - The changes in precipitation pattern provide an understanding on the hydroclimatic response to global warming during the Anthropocene. The present study investigates sources of precipitation moisture for the Indian Monsoon and the local environmental mechanisms controlling its distribution over the southwest coast of India. This is achieved by the characterization of stable isotope ratios of oxygen (δ18O) and hydrogen (δ2H) in rainwater samples collected from a high humid tropical setting (Swarna-Madisal river basin) of the Western Ghats, South India and another station further south (Bakrabail, southern edge of Nethravati river basin). This study contributes to the detailed investigation on rainwater isotopic composition and microclimate characteristics which is lacking in the humid west coast region. The rainwater isotopic composition of coast was close to that of the Arabian Sea water and reflected the first condensate of vapours which were originally formed under fast evaporation at the nearby ocean. In inland location, the higher d-excess values reflect continental moisture recycling. Evapotranspiration has led to higher kinetic fractionation effect in the inland region. The isotopic storm effect during winter monsoon season suggested the rain distribution from saturated air masses formed under deep convective effect in the Bay of Bengal. The overall local meteoric water line (LMWL) in the Swarna-Madisal basin was found to be δ2H = {(7.2 × δ18O) + 7.5}, R2 = 0.98. Further south, the LMWL of Bakrabail was, δ2H = {(8.19 × δ18O) + 16.1}, R2 = 0.98 for annual observation and displayed minimal variability for inter-seasonal slopes (7.73 for summer monsoon, 8.48 for winter monsoon and 8.36 for pre-monsoon) and intercepts (15.6 for summer monsoon, 17.8 for winter monsoon and 15.5 for pre-monsoon). In regions of vegetation dominance and humid climate, the prevailing local air mass masked the rain-out effect of marine air mass as well as the amount effect which support microclimatic settings at the local precipitation sites in southwest India. The time and space variability of regional moisture circulation in controlling atmospheric water balance has been deduced in this study. Thus, the high efficacy of stable isotopes in tracing the manifestation of microclimate in the humid tropics has been demonstrated.
AB - The changes in precipitation pattern provide an understanding on the hydroclimatic response to global warming during the Anthropocene. The present study investigates sources of precipitation moisture for the Indian Monsoon and the local environmental mechanisms controlling its distribution over the southwest coast of India. This is achieved by the characterization of stable isotope ratios of oxygen (δ18O) and hydrogen (δ2H) in rainwater samples collected from a high humid tropical setting (Swarna-Madisal river basin) of the Western Ghats, South India and another station further south (Bakrabail, southern edge of Nethravati river basin). This study contributes to the detailed investigation on rainwater isotopic composition and microclimate characteristics which is lacking in the humid west coast region. The rainwater isotopic composition of coast was close to that of the Arabian Sea water and reflected the first condensate of vapours which were originally formed under fast evaporation at the nearby ocean. In inland location, the higher d-excess values reflect continental moisture recycling. Evapotranspiration has led to higher kinetic fractionation effect in the inland region. The isotopic storm effect during winter monsoon season suggested the rain distribution from saturated air masses formed under deep convective effect in the Bay of Bengal. The overall local meteoric water line (LMWL) in the Swarna-Madisal basin was found to be δ2H = {(7.2 × δ18O) + 7.5}, R2 = 0.98. Further south, the LMWL of Bakrabail was, δ2H = {(8.19 × δ18O) + 16.1}, R2 = 0.98 for annual observation and displayed minimal variability for inter-seasonal slopes (7.73 for summer monsoon, 8.48 for winter monsoon and 8.36 for pre-monsoon) and intercepts (15.6 for summer monsoon, 17.8 for winter monsoon and 15.5 for pre-monsoon). In regions of vegetation dominance and humid climate, the prevailing local air mass masked the rain-out effect of marine air mass as well as the amount effect which support microclimatic settings at the local precipitation sites in southwest India. The time and space variability of regional moisture circulation in controlling atmospheric water balance has been deduced in this study. Thus, the high efficacy of stable isotopes in tracing the manifestation of microclimate in the humid tropics has been demonstrated.
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U2 - 10.1016/j.jhydrol.2022.128239
DO - 10.1016/j.jhydrol.2022.128239
M3 - Article
AN - SCOPUS:85134892947
SN - 0022-1694
VL - 612
JO - Journal of Hydrology
JF - Journal of Hydrology
M1 - 128239
ER -
