Linking variability of monsoon precipitation with satellite-based observations of stable water isotopes over Northeast I
- PDF / 3,569,121 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 0 Downloads / 242 Views
Ó Indian Academy of Sciences (0123456789().,-volV)(0123456789( ).,-volV)
Linking variability of monsoon precipitation with satellite-based observations of stable water isotopes over Northeast India ROHIT PRADHAN* , NIMISHA SINGH and RAGHAVENDRA P SINGH Land Hydrology Division, EPSA, Space Applications Centre (ISRO), Ahmedabad 380 015, India. *Corresponding author. e-mail: [email protected] MS received 31 May 2019; revised 9 September 2019; accepted 19 September 2019
Isotopic composition of atmospheric water vapor provides information on transport, mixing and phase change of water in the atmosphere. It provides a useful tool for understanding various aspects of the hydrological cycle. SCanning Imaging Absorption Spectrometer for Atmospheric CHartographY (SCIAMACHY) onboard ENVISAT-1 was a spectrometer designed to measure the composition of trace gases in troposphere and stratosphere. It provided global measurements of total columnar HDO and H2O concentrations using the spectral window between 2338.5 and 2382.5 nm. Temporal variability of columnar dD was studied over Northeast (NE) India and mean columnar dD for pre-monsoon and monsoon months were correlated with precipitation data obtained from Global System for Mapping of Precipitation (GSMaP). It was observed that dD during the pre-monsoon months of April–May showed good correlation (r [ 0.7, p \ 0.05) with total precipitation during June–August for the corresponding year over forested regions of Meghalaya and parts of Assam. Analysis was also carried out to understand the relationship between SCIAMACHY derived gridded monthly dD and Multivariate El-Nin ˜o Index (MEI) with zero and one month lag periods. Positive correlation was observed between dD and MEI over parts of Central India, Myanmar and Thailand. Isotope ratio of water vapor provides additional information compared to traditional meteorological observations and holds the potential to improve forecasting models. Keywords. Stable isotopes; SCIAMACHY; Northeast India; hydrology; ENSO.
1. Introduction Study of Indian Summer Monsoon (ISM) rainfall is essential in understanding the hydrological cycle of the country (Guhathakurta and Rajeevan 2008). Northeast (NE) Indian region receives some of the heaviest rainfall during ISM (around 1400 mm) as compared to other parts of Indian subcontinent (Prabhu et al. 2017). This area is dominated by dynamic weather arising due to its diverse orographic conditions (Mahanta et al.
2013). Both local and remote forces (Prabhu et al. 2017) govern ISM rainfall in the easternmost part of the country. In the last few decades, this region has experienced a decline in ISM rainfall (Preethi et al. 2017) leading to drought like conditions in different states of NE India. Western disturbance and Nor’westers are major phenomenon governing moisture transport over NE India during winter and pre-monsoon months, respectively (Laskar et al. 2015; Jeelani et al. 2018).
35
Page 2 of 9
Studying isotopic composition of water vapor provides information about the history of mixing a
Data Loading...
