|From||"Roger Brugge" <firstname.lastname@example.org>|
|Date||Mon, 19 Sep 2011 13:01:33 +0000|
Forwarded from CLIMLIST... POSTDOCTORAL PROPOSITION Centre de Recherches de Climatologie, UMR5210 CNRS Bât. Sciences Gabriel, 6 blvd Gabriel, 21000 Dijon Teleconnexions between West African atmospheric conditions (Monsoon and Harmattan wind) and extratropical climate variability: diagnostic analysis and modeling West African climate is characterized by two different seasons, i.e. the monsoonal season from June to September and a dry season, both having strong impacts on society such as water resource during the rainy season and health impacts (for instance meningitis epidemics) linked with low humidity and dust load and transport during the dry season. The analysis of observations and regional model simulations since 2003 have shown robust teleconnexions between West African climate variability and mid-latitude atmospheric circulation, especially through different weather regimes (Jung et al., 2006). The role of the Mediterranean Basin in these teleconnexions has recently been shown. In fact, West African precipitation shows stronger correlation with Mediterranean Sea surface temperature than equatorial Atlantic (Feudale et Shukla, 2007; Martiny et al., 2009; Polo et al., 2011). Other studies have shown that the Harmattan winds, blowing from the east or northeast and bringing a large amount of desert dust coming from the Sahara and Sahel's arid soils (Martiny et al. 2007 ; Molesworth et al., 2009), that play an important role on February to April meningitis number of cases in West Africa, are highly dependent on the wintertime Mediterranean atmospheric dynamics (Fontaine et al., 2009). To decline those results in terms of vulnerability, impacts and adaptation for societies, it is essential to take into account the variability at small spatial scales. Two main integrated components will be considered : The first step will focuse on the study of the interactions between the mid-latitude climate dynamics and the climate variability associated with (i) the summertime West African monsoon and (ii) the wintertime Harmattan winds. The aim is especially to highlight the importance of the mid-latitude atmospheric dynamics but also the role of the Mediterranean Sea surface temperature on West African atmospheric conditions. The second step will focuses on the impact of this specific interactions on the modulation in the predictability of extreme events such as heavy rainfall and drought conditions. To do so, a diagnostic study of the interactions between mid-latitude and West African atmospheric variability will be performed (reanalyses, in-situ data) especially with multivariate statistical methods, including weather classification approaches (automatic classification, neural networks). Numerical simulation experiments will also be achieved based on the WRF regional climate model implemented at the CRC laboratory. The study will first concentrate on the simulation of extreme events in the contemporary period (second half of the 20th century) with a focus on the rain at the beginning and the end of monsoon, and on the temperatures, winds and humidity in the heart of the dry season (January-May) in West Africa in order to better understand the processes involved. The experimental set up will then focus on the response of West African climate variability to variations of the Mediterranean Sea surface temperature, but also through so-called guided experiments with different configurations (blocking, “Greenland Above” circulation) that often happened vertical to the Mediterranean Sea. Numerical simulations will finally be based on future climate forced by the possible evolution of some atmospheric parameters (under different scenarios of climate change) to estimate possible changes in the relationship between extratropical and Mediterranean / West African climate conditions. Different datasets will be used: • Atmospheric Reanalyses ERA (1950-today), ERA-interim (1989-today); • Global numerical simulations from ECHAM/MPI-OM from 1950 to 2100 (17 ensemble runs, A1b SRES scenario); • Global numerical simulations from ARPEGE from 1950 to 2100 (A2 ans B2 SRES scenarios); • CMIP-4 available numercial simulations; • Regional WRF numerical imulations (ensemble-runs computed at CRC); • Station data. Skills: • Multivariate statistics (CCA, EOFs) and Model Output Statistics; • Unix • Good skills in Matlab programation and netCDF operators • Good skills in numerical simulations; • Good knowledge in West-African and Mediterranean climate will be appreciated; • English Period: january 2011 – december 2012 (12 months) Salary: 2000 euros Contact CV + motivation letters at: email@example.com firstname.lastname@example.org
Go to: Periods · List Information · Index by: Date (or Reverse Date), Thread, Subject or Author.