Regional and Local Impacts of the ENSO and IOD Events of 2015 and 2016 on the Indian Summer Monsoon—A Bhutan Case Study
Open Access
- 24 July 2021
- journal article
- research article
- Published by MDPI AG in Atmosphere
- Vol. 12 (8), 954
- https://doi.org/10.3390/atmos12080954
Abstract
The Indian Summer Monsoon (ISM) plays a vital role in the livelihoods and economy of those living on the Indian subcontinent, including the small, mountainous country of Bhutan. The ISM fluctuates over varying temporal scales and its variability is related to many internal and external factors including the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD). In 2015, a Super El Niño occurred in the tropical Pacific alongside a positive IOD in the Indian Ocean and was followed in 2016 by a simultaneous La Niña and negative IOD. These events had worldwide repercussions. However, it is unclear how the ISM was affected during this time, both at a regional scale over the whole ISM area and at a local scale over Bhutan. First, an evaluation of data products comparing ERA5 reanalysis, TRMM and GPM satellite, and GPCC precipitation products against weather station measurements from Bhutan, indicated that ERA5 reanalysis was suitable to investigate ISM change in these two years. The reanalysis datasets showed that there was disruption to the ISM during this period, with a late onset of the monsoon in 2015, a shifted monsoon flow in July 2015 and in August 2016, and a late withdrawal in 2016. However, this resulted in neither a monsoon surplus nor a deficit across both years but instead large spatial-temporal variability. It is possible to attribute some of the regional scale changes to the ENSO and IOD events, but the expected impact of a simultaneous ENSO and IOD events are not recognizable. It is likely that 2015/16 monsoon disruption was driven by a combination of factors alongside ENSO and the IOD, including varying boundary conditions, the Pacific Decadal Oscillation, the Atlantic Multi-decadal Oscillation, and more. At a local scale, the intricate topography and orographic processes ongoing within Bhutan further amplified or dampened the already altered ISM.Funding Information
- Vetenskapsrådet (2013-06476)
This publication has 66 references indexed in Scilit:
- Widespread Climate Change in the Himalayas and Associated Changes in Local EcosystemsPLOS ONE, 2012
- Expert views of climate change adaptation in least developed AsiaJournal of Environmental Management, 2012
- A prominent pattern of year-to-year variability in Indian Summer Monsoon RainfallProceedings of the National Academy of Sciences of the United States of America, 2012
- Abnormal monsoon years and their control on erosion and sediment flux in the high, arid northwest HimalayaEarth and Planetary Science Letters, 2005
- Extremes of the Indian summer monsoon rainfall, ENSO and equatorial Indian Ocean oscillationGeophysical Research Letters, 2004
- Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth centuryJournal of Geophysical Research: Atmospheres, 2003
- Winter surface pressure anomalies over Eurasia and Indian summer monsoonGeophysical Research Letters, 2002
- Teleconnection of OLR and SST anomalies over Atlantic Ocean with Indian summer monsoonGeophysical Research Letters, 2002
- Assessment of the impacts of the 1997–98 El Niño on the Asian‐Australia MonsoonGeophysical Research Letters, 1999
- Measuring the strength of ENSO events: How does 1997/98 rank?Weather, 1998