Humla, Western Nepal 223 Year Tree Ring Oxygen Isotope Data Sano, M.; Ramesh, R.; Sheshshayee, M.S.; Sukumar, R. Sano, M. Ramesh, R. Sheshshayee, M.S. Sukumar, R. Monsoon ABSB Abies spectabilis (D. Don) Spach silver fir East Himalayan fir earth science/paleoclimate/tree ring (delta 18O,cellulose,null,per mil VSMOW,null,tree ring,null,null,N,null) earth science/paleoclimate/tree ring (age,null,null,year Common Era,null,tree ring,null,null,N,null) earth science/paleoclimate/tree-ring (Humla>LATITUDE 29.85>LONGITUDE 81.93) A tree-ring d18O chronology of Abies spectabilis from the Nepal Himalaya was established to study hydroclimate in the summer monsoon season over the past 223 years (ad 1778-2000). Response function analysis with ambient climatic records revealed that tree-ring d18O was primarily controlled by the amount of precipitation and relative humidity during the monsoon season (June-September). Since tree-ring d18O was simultaneously correlated with temperature, drought history in the monsoon season was reconstructed by calibrating against the Palmer Drought Severity Index (PDSI). Our reconstruction that accounts for 33.7% of the PDSI variance shows a decreasing trend of precipitation/moisture over the past two centuries, and reduction of monsoon activity can be found across different proxy records from the Himalaya and Tibet. Spatial correlation analysis with global sea surface temperatures suggests that the tropical oceans play a role in modulating hydroclimate in the Nepal Himalaya. Although the dynamic mechanisms of the weakening trend of monsoon intensity still remain to be analyzed, rising sea surface temperatures over the tropical Pacific and Indian Ocean could be responsible for the reduction of summer monsoon. STUDY NOTES: Abies spectabilis tree-ring oxygen isotope (d18O) data from Humla, western Nepal, for the past 220 years. IITRDB26 NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Sano, M. Investigator : Ramesh, R. Investigator : Sheshshayee, M.S. Investigator : Sukumar, R. 2017-08-23 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/22547 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/asia/nepal/humla2012d18o.txt https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/asia/nepal/humla2012d18o.txt English https://www.ncdc.noaa.gov/paleo/study/22547 https://www1.ncdc.noaa.gov/pub/data/paleo/treering/isotope/asia/nepal/humla2012d18o.txt Masaki Sano, R Ramesh, MS Sheshshayee, R Sukumar2012Increasing aridity over the past 223 years in the Nepal Himalaya inferred from a tree-ring d18O chronologyThe Holocene227809-81710.1177/0959683611430338http://journals.sagepub.com/doi/full/10.1177/0959683611430338 START YEAR: 1778 AD * END YEAR: 2000 AD 81.93 29.85 81.93 29.85