Relations between the summer rainfall in India and the weather in the Atlantic

 Lead by Dr. Syam Sankar scientists at the Nansen Centers in Cochin, India and in Bergen have published a joint paper on The relationship between Indian summer monsoon rainfall and Atlantic multidecadal variability over the last 500 years. The paper is published in Tellus A.

a) Instrumental AMV and ISMR, (b) proxy reconstructed AMV (Gray-AMV, Mann-AMV and Svendsen-AMV) and (c) proxy reconstructed ISMR (KTRC, SASMI and SMMR). All the time series data are normalised and smoothed using an 11-yr moving average, except Mann-AMV which is only available as a filtered product.a) Instrumental AMV and ISMR, (b) proxy reconstructed AMV (Gray-AMV, Mann-AMV and Svendsen-AMV) and (c) proxy reconstructed ISMR (KTRC, SASMI and SMMR). All the time series data are normalised and smoothed using an 11-yr moving average, except Mann-AMV which is only available as a filtered product.Several studies have shown a statistically significant correlation between Atlantic multidecadal variability (AMV) and Indian summer monsoon rainfall (ISMR) since 1871 when instrumental data are available. In the instrumental records, both ISMR and North Atlantic sea surface temperatures (SSTs) have multidecadal variability with a period close to 60 yr, where periods of warm (cold) North Atlantic SSTs are accompanied by periods of wetter (dryer) ISMR and lower (higher) frequencies of dry years. The group of Indo-Norwegian scientists have studied both AMV and ISMR for the period from 1481 to present using several proxy reconstructions from both regions, as well as an extended instrumental data set for ISMR, to investigate multidecadal variability in the ISMR and the teleconnection to AMV. Previous studies investigating the relationship between AMV and ISMR in instrumental data have only used the period from 1871 onwards, whereas rain gauge data from the year 1844 are studied here, extending the instrumental record by 26 yr. Sankar et al.  find that the observed link between AMV and ISMR is present in the extended instrumental data. They also found that multidecadal variability is present in the ISMR in all proxy records; however, all the proxy records for both ISMR and AMV diverge before the 1800s. In addition, the observed correlation between AMV and ISMR has weakened in the last decade. These results emphasise that it is not appropriate to use single proxy reconstructions to study past climates.

The publication is a part of the project Indo-Norwegian research project INDIA-CLIM: Decadal to multi-decadal variability in the Indian Monsoon Rainfall and teleconnection with Atlantic Multidecadal Oscillation aiming at exploring the decadal to multi-decadal variations in Indian Monsoon during the last 500 years. In INDIACLIM the remote causes from Atlantic Multi-decadal Oscillation (AMO) on variations in temperature and precipitation patterns affecting water availability in India was investigated in order to contribute to better prediction of Indian Monsoon Rainfall (IMR). INDIA-CLIM was funded by the Research Council of Norway.

Publications from the INDIA-CLIM project includes:

  1. Abish, B., P. V. Joseph, and O. M. Johannessen, (2015): Climate change in the subtropical jetstream during 1950– 2009. Adv. Atmos. Sci., 32(1), 140–148, doi: 10.1007/s00376-014-4156-6.
  2. Abish, B., P.V. Joseph and O.M. Johannessen, (2013): Weakening Trend of the Tropical Easterly Jetstream of the Boreal Summer Monsoon season 1950 - 2009, Journal of Climate.
  3. Cui, X.D., Gao, Y.Q., Sun, J.Q. (2014): The response of the East Asian summer monsoon to strong tropical volcanic eruptions. Adv. Atmos. Sci., 31(6), 1245-1255, doi: 10.1007/s00376-014-3239-8
  4. Cui, X.D., Gao, Y.Q., Sun, J.Q., Guo, D., Li, S.L., Johannessen, O.M. (2014): Role of external forcing factors in modulating the Indian summer monsoon rainfall, the North Atlantic Oscillation and their relationship on inter-decadal timescale Climate Dynamics, 43, 2283-2295, DOI: 10.1007/s00382-014-2053-4
  5. Gong, D.Y., Gao, Y.Q., Guo, D., Mao, R., Yang, J., Hu, M., Gao, M.N., (2013): Interannual linkage between Arctic/North Atlantic Oscillation and tropical Indian Ocean precipitation during boreal winter. Climate Dynamics, 42, 1007-1027, DOI 10.1007/s00382-013-1681-4
  6. Joseph, P.V., G. Bindu and N. Preethi, (in press, 2016): Impact of the upper tropospheric cooling trend over the central Asian on the Indian summer monsoon rainfall and the Bay of Bengal cyclone tracks. Current Science. J. of the Indian Academy of Sciences.
  7. Joseph, P.V., G. Bindu, A. Nair, S. Wilson, 2013: Variability of summer monsoon rainfall in India on in- ter-annual and decadal time scales, Atmos. Oceanic Sci. Lett., 6, 398‒403, doi:10.3878/j.issn.1674-2834.13.0044.
  8. Luo, Feifei, Yongqi Gao, Lea Svendsen, Noel Keenlyside, Shuanglin L. and Tore Furevik (in prep. 2016): External forcing synchronizes the Atlantic Multidecadal Variability and the Indian Summer Monsoon. To be submitted to Geophys. Research Letters.
  9. Sankar, Syam, Lea Svendsen, Bindu G., and P. V. Joseph, and Ola M. Johannessen (2016): Teleconnections of Indian Summer Monsoon Rainfall with Atlantic Multidecadal Variability from 1400 to present. Tellus A 2016, 68, 31717,
  10. Svendsen, L., S. Hetzinger, N. Keenlyside, and Y. Gao (2014): Marine-based multiproxy reconstruction of Atlantic multidecadal variability, Geophysical Research Letters, 41, doi:10.1002/2013GL059076.
  11. Svendsen, Lea, 2016: Impacts of Atlantic multi-decadal variability on the Indo-Pacific and Northern Hemisphere climate. Doctoral Thesis, Geophysical Institute, University of Bergen. June 2016.
  12. Svendsen, Lea, Nils Gunnar Kvamstø, and Noel Keenlyside (2013): Weakening AMOC connects Equatorial Atlantic and Pacific interannual variability, Climate Dynamics, doi:10.1007/s00382-013-1904-8
  13. Wilson, Shinu Sheela, Joseph P.V, K. Mohanakumar, and Ola M. Johannessen, 2016: Temporal and Spatial Variability of the Low Level Jetstream of Asian Summer Monsoon. Under review Climate Dynamics.
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