May 2012
Message 41

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[Met-jobs] University of Sheffield Shine Centre FUNDED PhD Studentship

From "Roger Brugge" <>
To "" <>
Date Tue, 22 May 2012 11:49:13 +0000
Shine Centre Studentship
The Northern Hemisphere polar jet stream and its effect on regional climate 
change during 1871-2100

The key motivation for this study is that over the last decade a tendency has 
developed for a more meridional jet-stream pattern than previously, which has 
led to unusual regional climate anomalies with severe socio-economic impacts 
across the Northern Hemisphere, including in 2010 record floods in Pakistan, 
intense heat waves and forest fires in Russia, and some enigmatically cold 
winter spells on both sides of the Atlantic in 2010 and 2011 (e.g. December 
2010 was the coldest December since 1890 in the Central England Temperature 
record) which caused severe socio-economic disruptions in the UK. While these 
regional climate anomalies are directly attributable to changes in the jet 
stream, the ultimate drivers of the changes in the jet stream itself have not 
been fully quantified. One of the main aims of the current project is to 
advance mathematical modelling (analytical and numerical) in order to make a 
leap forward in the understanding of jet streams and their effects on climate.

At the same time, Arctic sea-ice coverage - most notably in late summer - has 
reached and remained at record low levels. This may be linked with what 
Professor James E Overland, an international leading expert of the field, has 
dubbed 'Warm Arctic Cold Continents' - whereby, as a result of the polar 
amplification of global warming and thinning Arctic sea-ice, more heat is 
released from the polar ocean to the overlying atmosphere, which reduces the 
meridional surface temperature gradient and tends to weaken the mid-latitude 
westerly winds, with resulting jet-stream changes as noted above. Note however 
that Arctic Sea Ice is not the only driver of changes in the jet stream. 
Contemporaneous changes in solar output, the Pacific Ocean's El Nino - Southern 
Oscillation cycle, the state of the Atlantic Ocean and other factors linked to 
Northern European climate are all known to have additional impacts on the 
northern hemisphere jet stream and thereby impact Europe and other regional 
climates. Fluctuations in these additional factors are superimposed on top of 
the recent Arctic Sea Ice decline in the historical record and these varying 
drivers need to be unravelled for a more complete picture. This is a second 
main aim of the proposed project.

This project will analyse in details the historic observational records for 
evidence of similar sea ice changes to the recent period during the previous 
Arctic warm period of the 1930s/40s, to ascertain to what extent there is a 
consistent response and to what extent recent changes in the jet stream might 
be caused by natural climate variability. This will also allow us to constrain 
the likely future changes in jet-stream behaviour, and therefore regional 
disparities of climate change in the generally densely populated mid-latitude 
Northern Hemisphere continents during the coming decade and indeed the 
remainder of the Twenty First Century. The project will also analyse and model 
changes in the polar front jet stream configuration and strength in the 
Northern Hemisphere mid-high latitude atmosphere in response to ongoing climate 
change from global warming and other relevant factors. It will do so using 
state-of-the-art climate analyses including: Twentieth Century Reanalysis 
(1871-2008) and ECMWF ERA-40 and Interim Reanalysis (1957-2012) sea level 
pressure, winds, temperatures and geopotential height fields, and also the IPCC 
AR5 suite of GCM projections. The project will include analysis of Met Office 
climate model simulations: both backwards to 1871 (to assess GCM reliability 
against the observational record and for validating purposes our modelling) and 
forwards to 2100 and will interact with the Met Office's long range forecasting 
and climate change projection programs through active collaboration.

The project is a collaboration between Dr Edward Hanna (PI, Dept of Geography,<>) and Prof Robert von 
Fay-Siebenburgen (CoI, SoMaS,<>). Please direct 
informal queries to either of the above two people. The project will also have 
an external CoI, Dr Adam Scaife (Head, Monthly to Decadal Prediction; Met 
Office). During the project the student will spend the a short period of time 
at the Met Office in order to acquire the modelling skills necessary for a 
successful outcome.

Deadline: Tuesday 5th June 2012 or until filled.

How to apply: This project is administered through 
SOMAS<>. You can apply 
online<> for admission to 
the university, choosing SOMAS as your department of study.

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