Controls on the isotopic composition of daily precipitation characterized by dual moisture transport pathways at the monsoonal margin region of North-Western India

The Kashmir Valley represents a critical region for understanding isotopic changes in the atmospheric moisture sources since it is located at the intercept between the influences of mid-latitude westerlies and the southwest monsoon circulation. This study presents the variation in isotopic composition (delta O-18 and delta H-2) of daily precipitation samples collected from the Kashmir Valley, North-Western Himalaya, to quantify the effect of meteorological parameters, separately for the Southwest monsoon (SWM) season and the periods of Western Disturbances (WDs). The results suggest that precipitation isotopic composition is strongly modulated by temperature and relative humidity during the periods of WDs. Still, this dependency is weak in the case of the SWM season. Moisture transport pathways calculated from HYSPLIT back trajectory analysis shows a wide spatial variability during the monsoon season. On the other hand, the origin of moisture during the WD season was mostly restricted from the Mediterranean region, providing an explanation of a strong dependency between the precipitation isotopes and the meteorological parameters during the WD period. Such kind of relation may provide additional diagnostic for the WD events and may help in paleo-monsoon investigations.