In the Global Climate division, large-scale climate variability is studied, including the effects of climate change. The research activities in the group focus on quantifying decadal to centennial climate variability, studying feedbacks in the earth system, development of global climate scenario’s and development of monthly, seasonal and decadal predictions. The group maintains global climate models of intermediate complexity and develops a state-of-the-art earth system model (EC-EARTH) as research tool and as tool for developing climate scenario’s. The group is internationally recognized in the fields of climate extremes, thermohaline circulation, tropical variability, atmospheric dynamics and land processes.

02-01-2012: Acceleration of land surface model devlopement over a decade of GLASS. Bart van den Hurk et al, Bulletin of the American Meteorological Society; doi: 10.1175/BAMS-D-11-00007.1

The Global Land Atmosphere System Study has ushered in an era in which LSMs for numerical weather and climate prediction now incorporate complex vegetation responses, detailed hydrology, dynamic snowpack evolution, urban processes, and more. This overview paper gives a historical overview of the GLASS panel activities and its current and future role in land surface model development and evaluation.

02-01-2012: Soil moisture effects on seasonal temperature and precipitation forecast scores in Europe. Van den Hurk, B.J.J.M., F. Doblas-Reyes, G. Balsamo, R.D. Koster, S.I. Seneviratne en H. Camargo Jr,; Clim. Dyn., 2010, doi:10.1007/s00382-010-0956-2.

The Second Global Land Atmosphere Coupling Experiment (GLACE2) is designed to explore the improvement of forecast skill of summertime temperature and precipitation up to 8 weeks ahead by using realistic soil moisture initialization. We show that for temperature the skill does indeed increase up to 6 weeks, but areas with (statistically significant) lower skill also exist at longer lead times for the European continent. The skill improvement is smaller than shown earlier for the US, partly because of a lower potential predictability of the European climate at seasonal time scales. Selection of extreme soil moisture conditions or a subset of models with similar initial soil moisture conditions does improve the forecast skill, and sporadic positive effects are also demonstrated for precipitation. Using realistic initial soil moisture data increases the interannual variability of temperature compared to the control simulations in the South-Central European area at longer lead times. Also better temperature forecasts are generated in a remote area in Western Europe. However, the covered range of forecast dates (1986 – 1995) is too short to isolate a clear physical mechanism for this remote correlation.

24-05-2011: The construction of a Central Netherlands temperature, G. van der Schrier(1), A. van Ulden(*), and G. J. van Oldenborgh(1)
(1)KNMI, P.O. Box 201, 3730 AE De Bilt, The Netherlands; (*) †

Abstract. The Central Netherlands Temperature (CNT) is a monthly daily mean temperature series constructed from homogenized time series from the centre of the Netherlands. The purpose of this series is to offer a homogeneous time series representative of a larger area in order to study large-scale temperature changes. It will also facilitate a comparison with climate models, which resolve similar scales. 
Read more on http://www.clim-past.net/7/527/2011/cp-7-527-2011.html

23-05-2011: Krimpend ijs op Arctische eilanden hoofdrolspeler in zeespiegelstijging, A.S. Gardner (DOASS) and B. Wouters (KNMI).

Smeltende gletsjers en ijskappen op de Canadese arctische eilanden spelen een veel grotere rol in de hedendaagse zeespiegelstijging dan tot zover werd aangenomen, volgens een internationale studie die op 20 April in Nature is verschenen. Tijdens de eerste drie jaar van de studie, van 2004 tot 2006, verloren de gletsjers en ijskappen in de regio jaarlijks gemiddeld 30 kubieke kilometer aan water. Dit verdrievoudigde zich tussen 2006 en 2009 tot 90 kubieke kilometer, oftewel 90 biljoen liter water per jaar. Tijdens de hele 6 jaar van de studie steeg de zeespiegel door het verdwijnende ijs wereldwijd gemiddeld met 1 millimeter.

14-04-2011: Regionale zeespiegelveranderingen in de eenentwintigste eeuw, C. Katsman (KNMI), A. Slangen (IMAU/UU), R. van de Wal (IMAU/UU), B. Vermeersen, R. Riva (TU Delft).

04-01-2011: EC-Earth: A seamless prediction system in action, W. Hazeleger et al, Bulletin of American Meteorological Society
http://journals.ametsoc.org/doi/abs/10.1175/2010BAMS2877.1

In a recent paper in BAMS we publish the project, the consortium and the model EC-Earth. EC-Earth is a state-of-the-art climate model based on ECMWFs seasonal forecast system. We present a seamless prediction strategy in which numerical weather forecasting strategies and climate predictions and projections are linked. The strategy of model development is illustrated by upgrading EC-Earth using both new model cycles of ECMWF and by including new earth system components developed at universities and institutions. We show that the coupled model performs well compared to CMIP3 models, in particular the atmospheric states. We also indicate that the slight changes that we implemented to get stable radiation balance did not affect the medium range weather forecasting capabilities. An example of a new snow scheme that is developed in the EC-Earth framework and that is now implemented in the ECMWF model is shown. The model is used for climate research and generating climate projections and predictions.