Doctoral dissertation; Climate variability research cooperation between Norway, India and China

Dr. Lea Svendsen.Lea Svendsen defended her doctoral thesis Impact of Atlantic multi-decadal variability on the Indo-Pacific and Northern Hemisphere climate at the Nansen Center and Geophysical Institute, University of Bergen to day. The research provides new knowledge on the decadal variations in the sea surface temperature and its impact on climate variability. Dr. Svendsen has used proxy data, observations and NorESM modelling results back to the 15th Century. Specifically the dissertation addressed the teleconnection between decadal variations in the Atlantic Ocean and the global climate variability.

Figure 2 i PhD dissertation.Figure 2 i PhD dissertation.Dr. Svendsen concludes her doctoral research that the Atlantic multi-decadal variability (AMV) is a persistent signal in the climate system, but the impact on multi-decadal variability in the Indo-Pacific and the Northern Hemisphere may not be as string as previously suggested. AMV can modulate the inter-annual variability and the inter-basin teleconnections in the tropics. But the correlation with the Indian summer monsoon could be due to external forcing, and the Pacific seems to make a larger contribution to decadal trends in the Northern Hemisphere climate than the Atlantic.

The doctoral dissertation comprises of five publications:

  1. Svendsen, L., S. Hetzinger, N. Keenlyside, and Y. Gao (2014), Marine-based multiproxy reconstruction of Atlantic multidecadal variability, Geophysical Research Letters, 41(4), 2013GL059076.
  2. Sankar, S., L. Svendsen, G. Bindu, P. V. Joseph, and O. M. Johannessen, Teleconnections between Indian summer monsoon rainfall and Atlantic multidecadal variability over the last 500 years. Under review in TellusA.
  3. Luo F., Y. Gao, L. Svendsen, N. Keenlyside, S. Li and T. Furevik, External forcing synchronizes Atlantic multidecadal variability and the Indian summer monsoon (manuscript in preparation).
  4. Svendsen, L., N. G. Kvamstø, and N. Keenlyside (2013), Weakening AMOC connects equatorial Atlantic and Pacific interannual variability, Climate Dynamics, 43(11), 2931-2941.
  5. Svendsen, L., N. Keenlyside, I. Bethke, and Y. Gao, Investigating the role of the Atlantic and Pacific in the early 20th century warming trend (manuscript in preparation).

Her PhD work is a part of the Indo-Norwegian research project INDIA-CLIM: Decadal to multi-decadal variability in the Indian Monsoon Rainfall and teleconnection with Atlantic Multidecadal Oscillation funded by the Research Council of Norway. During her studies she has had several research visits to the Nansen Environmental Research Center – India (NERCI) Center in Cochin, resulting in one joint publication under review. Her resercah visits to India has been a part of the EU FP7 project Indo-European research Facilities for studies on Marine Ecosystem and climate in India (INDO-MARECLIM). Another paper due to be published is made in cooperation with scientists at the Nansen–Zhu International Research Center in Beijing.

Figure caption: Observed normalized and de-trended low-frequency filtered Northern Hemisphere surface temperature (blue line) from the GISTEMP data (Hansen et al. 2010), All India monsoon rainfall index (yellow line) from IITM (Parthasarathy et l. 19-94), the AMV-index (black line) and the 21-year running correlation between Atl3-index (3°N-3°S, 20°W-0°W) and Nino3-index (5°N-5°S, 90°W-150°W) (green line) from HadlSST data (Rayner et al., 2003).

Her supervisors have been professor Noel Keenlyside, Geophysical Institute University of Bergen and professor Yongqi Gao, Nansen Center. The opponents at the dissertation were Professor, ph.d. Mingfang Ting, Columbia University, USA, and Professor, ph.d. Axel Timmermann, University of Hawaii, USA, additional member of the committee was Professor, dr.scient. Tor Eldevik, Geophysical Institute, University of Bergen. The dissertation was lead by: Førsteamanuensis Jan Asle Olseth, University of Bergen.

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