Volume 3 • Issue 3 • 1000126 J Earth Sci Climate Change ISSN:2157-7617 JESCC, an open access journal Research Article Open Access Gopal Krishan et al., J Earth Sci Climate Change 2012, 3:3 http://dx.doi.org/10.4172/2157-7617.1000126 Research Article Open Access Earth Science & Climatic Change Keywords: Hydrology; Water cycle; Atmospheric vapour; Stable isotopes; Arabian Sea; Bay of Bengal; Mediterranean Sea Introduction Stable isotope hydrology received a big boost with the identiication of the co-variance of hydrogen and oxygen isotopes in precipitation irst by Friedman, 1953 [1] and later in the form of GMWL by Craig, 1961 [2]. A continental efect from as large as 45‰ per 100 km in δD on North coast of California to as little as 2‰ across the Great Basin in Northern Nevada was observed [3]. Values of elevation efect have been reported to be approximately 40‰ in δD per 1000m increase on the west slope of the Sierra Nevada [4]. Dansgaard, 1964 [5] reported a good world-wide correlation for coastal and polar stations between mean δD and δ 18 O values of precipitation and the mean annual air temperature (MAAT) with an average decrease of >5.6‰ for δD and 0.7‰ for δ 18 O per degree Celsius. hese observed variations are consistent with temperature dependence of equilibrium fractionation factor again indicating that condensation is an equilibrium process. he precipitation progressively decrease from <-2 ‰ along the northern part of the west coast to ~ –6 ‰ towards the east coast. In fact, rains over much of India have δ 18 O values between -2 ‰ to -4 ‰ [6]. he monsoon is a large scale wind circulation phenomenon that brings large amount of moisture on the Indian sub-continent during the period mid June to September. Earlier studies on monsoon dynamics mainly dealt with deviation of total precipitation from the normal, spatial variability in precipitation, extreme events and timing of onset of monsoon [7-9]. Most of these studies relied on conventional meteorological parameters such as temperature (Continental and sea surface), relative humidity, wind speed, wind direction, cloud pattern etc. However, suicient accuracy in onset of monsoon, its dynamics on the continent and the timing of its withdrawal is not well understood. he complexity of the phenomenon is due to link between mixing of sub-regional moisture with continental scale moisture arising directly from Arabian Sea and/or Bay of Bengal and/or Indian Ocean. Using the isotopic signatures of water molecules, it is possible to track the movement of air moisture. his is due to fact that with the onward movement of the air moisture heavy isotopes get systematically depleted and the recycling of moisture due to condensation and subsequent evaporation cause a diference in relative enrichment in deuterium and oxygen isotopic composition. In India, the Southwest (SW) monsoon begins from Lakshadweep, Minicoy and Kerala [10, 11] and it enters North India from Arabian Sea and Bay of Bengal. During the winter and springs, Northeast (NE) monsoon is prevalent in the Southeast (SE) parts of India, while the north and Northwest (NW) part of the country receives rains due to the Western Disturbances [10-12]. hus the sources of precipitation/ atmospheric vapor in India are mainly Arabian Sea and Bay of Bengal in Monsoon season. But during non-monsoon seasons the sources of precipitation/atmospheric vapor are local/regional derived vapors. he stable isotopes of oxygen and hydrogen ( 18 O and 2 H) can be used for tracking the sources of atmospheric vapor/precipitation due to the systematic mass-dependant partitioning of the three isotopomers 1 H 1 H 16 O, 1 H 2 H 16 O and 1 H 1 H 18 O among solid, liquid and gaseous phases as water passes through the hydrological cycle. he studies (15-21) were carried out in diferent parts of the World on the isotope data of surface vapor have a limited data and is not suicient to adequately explain the isotopic composition of atmospheric water vapor. No attempt has been made so far to identify the source of atmospheric vapor/precipitation at Roorkee, Uttarakhand, India using isotopic signature. herefore, the present study is carried out for identifying the sources of atmospheric vapor/precipitation at Roorkee using the isotopic signatures and the isotopic data has also been correlated with the wind trajectory and satellite data obtained from India Meteorological Department, New Delhi to establish the similarities among these. *Corresponding author: Gopal Krishan, Hydrological Investigation Division, National Institute of Hydrology, Uttarakhand, India, Tel: +919634254939; Fax: 01332-272123; E-mail: drgopal.krishan@gmail.com Received October 01, 2012; Accepted November 19, 2012; Published November 22, 2012 Citation: Gopal Krishan, Rao MS, Kumar B (2012) Application of Isotopic Signature of Atmospheric Vapor for Identifying the Source of Air Moisture-An Example from Roorkee, Uttarakhand, India. J Earth Sci Climate Change 3:126. doi:10.4172/2157-7617.1000126 Copyright: © 2012 Gopal Krishan, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract In the present study, the isotopic signature of atmospheric vapor/precipitation is used to identify the source of air moisture at Roorkee, Uttarakhand, India. The interpretation of the isotope data of atmospheric vapor for the years 2008-09 indicates that the seasonality effect divides the entire data spectrum into three sub-units as: monsoon water vapor (δ 18 O<-25, δD<-126) of Bay of Bengal (BoB)/oceanic origin are the most depleted; the most enriched vapors (δ 18 O>-5, δD>-6) of local origin and the vapors originating due to Western Disturbances (WD) have values (δ 18 O ~-15, δD~-53) between these two sources. The monsoon showers are isotopically the most depleted with the highest slope (7.78) of its characteristic line followed by winter rains which are marginally enriched. The pre-monsoon showers are the most enriched rains in the year. With these systematic it can be easily differentiated between pre- monsoon and monsoon rains and in identifying the true monsoon rains or onset of monsoon. Application of Isotopic Signature of Atmospheric Vapor for Identifying the Source of Air Moisture-An Example from Roorkee, Uttarakhand, India Gopal Krishan 1 *, M.S. Rao 1 and Bhishm Kumar 2 1 National Institute of Hydrology, Roorkee- 247667, Uttarakhand, India 2 IAEA, Vienna, Austria