March 2013
Message 69

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[Met-jobs] Post doc position: modelling the impact of storms in the land surface model ORCHIDEE (France)

From "Roger Brugge" <>
To "" <>
Date Tue, 26 Mar 2013 09:11:20 +0000

Post doc position: modelling the impact of storms in the land surface model 

Summary of post
We are recruiting for a new post-doctoral position to play a key part in 
building the capacity for modelling the impact of storms in the land surface 
model ORCHIDEE. The role is anticipated for a period of 24 months and is based 
at the LSCE in France. Research time needs to be spent in both France and 
Sweden as the successful candidate will be the integrator of this bilateral 

Capacity building for modelling the impact of storms is an exciting development 
to the land surface scheme ORCHIDEE. This task will involve: (1) downscaling 
high resolution wind fields for two regions in Europe, (2) developing a storm 
module for ORCHIDEE based the existing stand-level model ForestGALES, (3) 
modelling the structural and functional effects of wind storms including 
weathering, drainage and run-off in addition to the more typical effects on 
stand structure and validating the simulations against existing field 
observations, and (4) a regional attribution study of the effects of wind 
storms as a function of gap size and storm frequency.

Fuller description
Although Earth System Modelling groups dedicate considerable amounts of 
resources studying the effects of fires, shifting cultivation and more recently 
logging, storms are not yet explicitly dealt with in Earth System Models. 
However, storm-induced disturbances are likely to feedback to the climate 
system through direct effects such as increasing green house gase (GHG) 
emissions (CO2 and CH4) and changes in the energy budget and indirect effect 
such as increasing fire vulnerability, logging in subsequent years, increased 
weathering and increased C, N and cation leaching. The overall objective of 
this proposal is to bold together ongoing research efforts in France and Sweden 
to build the modelling capacity for attributing and prediction the impacts of 
wind storms in the Earth system.

Evaluating the impacts of wind storms on European forests between 1990 to 2010 
requires that the land surface model is forced by high resolution wind fields. 
Observational records allow to evaluate the ability of regional climate 
simulations, when forced by re-analyses, to properly simulate storms of the 
past 20 years. These simulations, made with the Weather Research and 
Forecasting (WRF) model will also be used to determine a feasible scale to 
which wind fields should be downscaled to obtain acceptable predictions of wind 

Currently, wind throw does not contribute to tree mortality in ORCHIDEE. 
Depending on the wind gusts, soil condition and characteristics, tree height, 
stand density, and topography, a given windstorm could result in no damage, 
small gaps (<0.01 km2)
or large gaps (>0.01 km2). Following wind throw, gap size will determine the 
growing environment for the regrowth. Quality of the simulated storm impacts 
depends on the ability to model the relationship between gusts and gaps and 
subsequently the biogeochemical and biophysical changes within the gaps. The 
relationship between gusts and gaps will be validated by making use of 
satellite-derived disturbance maps. Subsequently, observed and simulated 
gap-size and distribution for two test regions (see WP4) will be compared. 
FLUXNET observations will be used to validate the carbon and water fluxes and 
biophysical processes taking place within the gaps. Following the heavy storms 
Gudrun and Kyrill, flux towers have been erected in areas affected by 
windthrow, these observation allow a detailed validation of GHG, water and 
energy fluxes.

Recently data suggest that terrestrial processes may play a much more important 
role in the lateral C fluxes to the oceans through inland waters than 
previously thought. Slight changes in flow pathways or processes may switch 
ecosystems from being net sinks to net sources. Another important, but so far 
neglected feedback, is an indirect effect on long-term C fluxes during 
insufficient supply of base cations through weathering. We will explore how 
windfall and subsequent processes will affect the fluxes of carbon and base 
cations using existing watershed based models for both base cation and C 

Following validation, the newly acquired capacity will be demonstrated by two 
regional studies in Southern Sweden and South western France. These forest-rich 
regions were selected because, in addition to frequent small scale wind 
disturbance, both experienced a big storm in respectively 2005 (Gudrun) and 
2009 (Klaus). First, a factorial modelling experiment will be set-up with 
ORCHIDEE. This approach allows to attribute a fraction (positive or negative) 
of the current sink to wind throw. Second, an existing coupling between 
ORCHIDEE and WRF will be used to study the feedback between wind-disturbance 
and climate. To this aim virtual disturbance maps combing gap size
distributions and storm frequencies will be developed for the test regions. 
Combining maps with present climate will be the starting point for climate 
forecasting until 2050. Such a modelling experiment will help to establish 
whether wind throw has a positive or negative feedback on the climate system.

Home institution
>From an administrative point of view the position will be based at the 
>Laboratoire des Sciences du Climat et de l'Environnement (LSCE, 
>Orme-les-Merisiers, Gif-sur-Yvette, France). The successful candidate, 
>however, will be required to spend substantial time in Sweden at SLU (Uppsala 
>and Alnarp) and Lund University (Lund). As well as in France at the LSCE (Gif 
>sur Yvette) and INRA (Bordeaux).

Given the interdisciplinary nature of the research we are seeking for a highly 
motivated individual with a PhD degree in for example forestry, ecology, 
environmental modelling or  related topics. A broad interest in natural 
sciences more specifically terrestrial ecology and biogeochemistry is 
essential. Rather than for a specific training, we are looking for a candidate 
who is able to demonstrate her/his ability to understand coupled biogeochemical 
cycles and develop code (Fortran 90), publish manuscripts in peer review 
journals and establish and maintain communication between five researchers 
across two countries.

Required content of the application
Applications and inquiries should be sent to Sebastiaan Luyssaert 
( Applications should include:
(1) a curriculum vitae,
(2) statement of motivation,
(3) a short description (½ page no more than 1 page) of a recent scientific 
problem you successfully solved and
(4) names, addresses, phone numbers, and email addresses of at least two 

The position is available from September 1st and will remain open until filled 
with review of applications and interviews starting on April 21st. Salary 
follows national directives and is adjusted for work experience.

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