Variability of lake surface water temperature: a case study during El Nino and La Nina events over the Himalayan lake region

ABSTRACT

Lake surface water temperature (LSWT) is sensitive to long-term changes in thermal structure of lakes. This paper investigates the association of LSWT with meteorological parameters and its impact during El Nino and La Nina events over the Himalayan lake region, using Moderate Resolution Imaging Spectroradiometer (MODIS) satellite data from 2001 to 2017. The observed daytime rates of change of LSWT was −0.05°C/year whereas it was +0.01°C/year for nighttime. The cooling of lake during daytime could be attributed to increase in rainfall and decrease in solar radiation, whereas increase in nighttime LSWT is due to increasing lowest temperature. The variability in LSWT with respect to meteorological variables during El Nino Southern Oscillation period was highest for cold phase than warm phase. There was only 1% increase in LSWT in the El Nino years (2002 and 2009), due to decreased rainfall by 95% and 56% respectively. On the other hand, the LSWT decreased in strong La Nina years of 2007 (2%) and 2010 (6%) due to the drastically increased rainfall, decreased maximum temperature and solar radiation. The correlation revealed that, in addition to the increase in temperature, the LSWT warming is consistent with the decrease in rainfall and increase in solar radiation.

KEYWORDS:

• El Nino
• La Nina
• LSWT
• rainfall
• solar Radiation
• Wular Lake

Acknowledgments

First, the authors would like to thank Land Processes Distributed Active Archive Center (LP DAAC) managed by the NASA Earth Science Data and Information System (ESDIS) project for making the MODIS data sets freely available. Also, the authors acknowledge the National Centers for Environmental Prediction (NCEP), Climate Forecast System Reanalysis (CFSR) dataset (globalweather.tamu.edu) for meteorological data. The authors are grateful to Science and Engineering Research Board (N-PDF), a statutory body of Department of Science & Technology (DST), Government of India for providing the financial assistance to carry out current research work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Science and Engineering Research Board (N-PDF), a statutory body of Department of Science & Technology (DST), Government of India [PFD/2017/0011227].