1. Working Group on Seasonal-to-Interannual Prediction
Yvan J. ORSOLINI
NILU - Norwegian Institute for Air Research,
and University of Bergen, Norway
Collaborators:
R. Senan (U. of Oslo), R. E. Benestad (Norwegian Met. Inst.)
G. Balsamo, F. Vitart, A. Weisheimer (ECMWF, England)
F. Doblas-Reyes (ICREA, Spain)

2. Role of Eurasian snow on subseasonal-to-seasonal forecasts
Role of snowpack, in particular impact of snow initialisation, on subseasonal-to-seasonal forecasts
We made twin simulations using a modelling strategy similar to the one used for looking at soil moisture impact in the warm season (Koster et al. 2004; 2010) in the GLACE2 international modeling project
Actual predictability experiments for autumn (years ) : coupled ocean-atmosphere ECMWF forecasts at high resolution, with realistic snow initialisation
Impact on circulation (NAO, Siberian High,...) at mid and high latitudes, impact on skill
Orsolini, Y.J., Senan, R., Balsamo, G., Doblas-Reyes, F., Vitart, D., Weisheimer, A., Carrasco, A., Benestad, R. (2013), Impact of snow initialization on sub-seasonal forecasts , Clim. Dyn., DOI: /s

3. Negative NAO phase in very cold winter 2009/10
Most negative winter (DJF) NAO in 145-Year Record
T2m
SLP
200hPa winds
ensemble-mean (11 #)
Series 1 – Series 2
15-day lead
DEC 1, 2009 start date
Series1 (realistic snow) has more negative NAO index than Series2
-> closer to re-analyses
-> Snow contributes to maintaining negative NAO
-> one of the factors influencing negative NAO phase
Several studies examined factors leading to NAO- (Jung et al., 2011; Fereday et al., 2012; Cohen et al, )

4. Role of Snow in Seasonal Forecast
Coord.: F.J. Doblas-Reyes
ICREA and IC3, Barcelona, Spain
Role of Snow in Seasonal Forecast
New SNOWGLACE2 experiments, covering more years
and both autumn/spring (NILU-ECMWF, Meteo-France)
Task coordination (NILU, Norwegian Met. Institute) : Forecast quality comparison of numerical hindcasts with improved snow initial conditions and statistical hindcasts using initial snow as a predictor

5. Influence of springtime Himalayan-Tibetan Plateau snow on the
onset of the Indian summer monsoon
Yvan J. Orsolini1, Retish Senan2 and Frode Stordal2
1Norwegian Institute for Air Research - NILU, Kjeller, Norway
2Department of Geosciences, University of Oslo, Oslo, Norway
Collaborating Institute in India: Indian Institute of Tropical Meteorology (IITM), Pune
NORINDIA part of a cluster of projects funded by the Research Council of Norway
INDIA-NORWAY programme ( )
NORINDIA : Climate Change and its Impacts on Selected Indian Hydrological Systems using Earth System and High-Resolution Modeling )
Coordinators : Eystein Jansen and Michel Mesquita (University of Bergen)

6. Sea ice loss and recent Eurasian cold winters
Meiji Honda (GRL 2009) proposed a link between Arctic sea-ice reduction and cold Asian winter
“Warm Arctic-Cold continent” paradigm (Overland et al., 2010)
Many recent studies...
Implications for seasonal forecasting
Eurasia
Summer to winter connection
Next shows the following winter situations for each of the years.
Zonally oriented cold anomalies over Eurasia are clearly shown.
Considering these characteristics, we investigated statistic relationship between the summer Arctic sea ice and the winter Eurasian climate.
Arctic
Eurasia
Anomalously cold recent Eurasian winters
Arctic Sea ice reduction
In late summer

7. Sea ice loss and recent Eurasian cold winters
Impact of sea ice initialisation ECMWF coupled ensemble seasonal forecasts : case study 2007
Orsolini, Y.J., Senan, R., Benestad, R.E., Melsom, A. (2012) Autumn atmospheric response to the 2007 low Arctic sea ice extent in coupled ocean-atmosphere hindcasts. Clim. Dyn., 38,
Anomalous cold air outbreaks over Far East
Next shows the following winter situations for each of the years.
Zonally oriented cold anomalies over Eurasia are clearly shown.
Considering these characteristics, we investigated statistic relationship between the summer Arctic sea ice and the winter Eurasian climate.
Remote surface temperature influence of Arctic Sea ice reduction in late summer 2007

8. National project with 6 partners
Enhancing seasonal-to-decadal Prediction of climate for the North Atlantic Sector and Arctic
National project with 6 partners
Lead by Uni. Bergen (N. Keenlyside),
To investigate key mechanisms for seasonal-to-decadal predictability
Focus on North Atlantic and Nordic Seas
Teleconnections to SST, sea ice, and snow cover anomalies
Stratosphere-troposphere coupling
To develop the Norwegian Climate Prediction model (NorCPM)
Norwegian Earth System model (NorESM) with ensemble Kalman Filter assimilation
NorESM atmospheric component (NCAR/CAM), oceanic component (U Miami model)
Seasonal and decadal prediction experiments