Publications


Future changes in the East Asian rain band projected by global atmospheric models with 20-km and 60-km grid size

CLIMATE DYNAMICS 37 (2011) 2481-2493

S Kusunoki, R Mizuta, M Matsueda


Assessment of representations of model uncertainty in monthly and seasonal forecast ensembles

Geophysical Research Letters 38 (2011)

A Weisheimer, TN Palmer, FJ Doblas-Reyes

The probabilistic skill of ensemble forecasts for the first month and the first season of the forecasts is assessed, where model uncertainty is represented by the a) multi-model, b) perturbed parameters, and c) stochastic parameterisation ensembles. The main foci of the assessment are the Brier Skill Score for near-surface temperature and precipitation over land areas and the spread-skill relationship of sea surface temperature in the tropical equatorial Pacific. On the monthly timescale, the ensemble forecast system with stochastic parameterisation provides overall the most skilful probabilistic forecasts. On the seasonal timescale the results depend on the variable under study: for near surface temperature the multi-model ensemble is most skilful for most land regions and for global land areas. For precipitation, the ensemble with stochastic parameterisation most often produces the highest scores on global and regional scales. Our results indicate that stochastic parameterisations should now be developed for multi-decadal climate predictions using earth-system models. Copyright 2011 by the American Geophysical Union.


ECMWF seasonal forecast system 3 and its prediction of sea surface temperature

CLIMATE DYNAMICS 37 (2011) 455-471

TN Stockdale, DLT Anderson, MA Balmaseda, F Doblas-Reyes, L Ferranti, K Mogensen, TN Palmer, F Molteni, F Vitart


A CERN for climate change

PHYSICS WORLD 24 (2011) 14-15

T Palmer


Extended warming of the northern high latitudes due to an overshoot of the Atlantic meridional overturning circulation

Geophysical Research Letters 38 (2011) n/a-n/a

P Wu, L Jackson, A Pardaens, N Schaller


Decadal climate prediction with the European Centre for Medium-Range Weather Forecasts coupled forecast system: Impact of ocean observations

Journal of Geophysical Research: Atmospheres 116 (2011)

FJ Doblas-Reyes, MA Balmaseda, A Weisheimer, TN Palmer

Three 10 year ensemble decadal forecast experiments have been performed with the European Centre for Medium-Range Weather Forecasts coupled forecast system using an initialization strategy common in seasonal forecasting with realistic initial conditions. One experiment initializes the ocean in a standard way using an ocean-only simulation forced with an atmospheric reanalysis and with strong relaxation to observed sea surface temperatures. The other two experiments initialize the ocean from a similar ocean-only run that, in addition, assimilates subsurface observations. This is the first time that these experiments were performed. The system drifts from the realistic initial conditions toward the model climate, the drift being of the same order as, if not larger than, the interannual signal. There are small drift differences in the three experiments that reflect mainly the influence of dynamical ocean processes in controlling the adjustment between the initialized state and the model climate in the extratropics. In spite of the drift, the predictions show that the system is able to skillfully predict some of the interannual variability of the global and regional air and ocean temperature. No significant forecast quality benefit of the assimilation of ocean observations is found over the extratropics, although a negative impact of the assimilation of incorrect expendable bathythermograph profiles has been found for the global mean upper ocean heat content and the Atlantic multidecadal oscillation. The results illustrate the importance of reducing the important model drift and the ocean analysis uncertainty. Copyright 2011 by the American Geophysical Union.


Predictability of an atmospheric blocking event that occurred on 15 December 2005

Monthly Weather Review 139 (2011) 2455-2470

M Matsueda, M Kyouda, Z Toth, HL Tanaka, T Tsuyuki

Atmospheric blocking occurred over the Rocky Mountains at 1200 UTC 15 December 2005. The operational medium-range ensemble forecasts of the Canadian Meteorological Center (CMC), the Japan Meteorological Agency (JMA), and the National Centers for Environmental Prediction (NCEP), as initialized at 1200UTC10 December 2005, showed remarkable differences regarding this event. All of the NCEP members failed to predict the correct location of the blocking, whereas almost all of the JMA members and most of the CMC members were successful in predicting the correct location. The present study investigated the factors that caused NCEP to incorrectly predict the blocking location, based on an ensemble-based sensitivity analysis and the JMA global spectral model (GSM) multianalysis ensemble forecasts with NCEP, regionally amplified NCEP, and globally amplified NCEP analyses. A sensitive area for the blocking formation was detected over the central North Pacific. In this area, the NCEP control analysis experienced problems in the handling of a cutoff cyclone, and the NCEP initial perturbations were ineffective in reducing uncertainties in the NCEP control analysis. The JMA GSM multianalysis ensemble forecasts revealed that regional amplification of initial perturbations over the sensitive area could lead to further improvements in forecasts over the blocking region without degradation of forecasts over the Northern Hemisphere (NH), whereas the global amplification of initial perturbations could lead to improved forecasts over the blocking region and degraded forecasts over the NH. This finding may suggest that excessive amplification of initial perturbations over nonsensitive areas is undesirable, and that case-dependent rescaling of initial perturbations may be of value compared with climatology-based rescaling, which is widely used in current operational ensemble prediction systems. © 2011 American Meteorological Society.


Verification of medium-range MJO forecasts with TIGGE

GEOPHYSICAL RESEARCH LETTERS 38 (2011) ARTN L11801

M Matsueda, H Endo


Predictability of Euro-Russian blocking in summer of 2010

GEOPHYSICAL RESEARCH LETTERS 38 (2011) ARTN L06801

M Matsueda


Accuracy of climate change predictions using high resolution simulations as surrogates of truth

Geophysical Research Letters 38 (2011)

M Matsueda, TN Palmer

How accurate are predictions of climate change from a model which is biased against contemporary observations? If a model bias can be thought of as a state-independent linear offset, then the signal of climate change derived from a biased climate model should not be affected substantially by that model's bias. By contrast, if the processes which cause model bias are highly nonlinear, we could expect the accuracy of the climate change signal to degrade with increasing bias. Since we do not yet know the late 21st Century climate change signal, we cannot say at this stage which of these two paradigms describes best the role of model bias in studies of climate change. We therefore study this question using time-slice projections from a global climate model run at two resolutions - a resolution typical of contemporary climate models and a resolution typical of contemporary numerical weather prediction - and treat the high-resolution model as a surrogate of truth, for both 20th and 21st Century climate. We find that magnitude of the regionally varying model bias is a partial predictor of the accuracy of the regional climate change signal for both wind and precipitation. This relationship is particularly apparent for the 850 mb wind climate change signal. Our analysis lends some support to efforts to weight multi-model ensembles of climate change according to 20th Century bias, though note that the optimal weighting appears to be a nonlinear function of bias. Copyright © 2011 by the American Geophysical Union.


Decadal climate prediction with the European Centre for Medium-Range Weather Forecasts coupled forecast system: Impact of ocean observations

JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 116 (2011) ARTN D19111

FJ Doblas-Reyes, MA Balmaseda, A Weisheimer, TN Palmer


On the predictability of the extreme summer 2003 over Europe

Geophysical Research Letters 38 (2011)

A Weisheimer, FJ Doblas-Reyes, T Jung, TN Palmer

The European summer 2003 is a prominent example for an extreme hot and dry season. The main mechanisms that contributed to the growth of the heat wave are still disputed and state-of-the-art climate models have difficulty to realistically simulate the extreme conditions. Here we analyse simulations using recent versions of the European Centre for Medium-Range Weather Forecasts seasonal ensemble forecasting system and present, for the first time, retrospective forecasts which simulate accurately not only the abnormal warmth but also the observed precipitation and mid-tropospheric circulation patterns. It is found that while the land surface hydrology plays a crucial role, the successful simulations also required revised formulations of the radiative and convective parameterizations. We conclude that the predictability of the event was less due to remote teleconnections effects and more due to in situ processes which helped maintain the dry surface anomalies occurring at the beginning of the summer. Copyright 2011 by the American Geophysical Union.


Toward a new generation of world climate research and computing facilities

Bulletin of the American Meteorological Society 91 (2010) 1407-1412

J Shukla, TN Palmer, R Hagedorn, B Hoskins, J Kinter, J Marotzke, M Miller, J Slingo

National climate research facilities must be enhanced and dedicated multi-national facilities should be established to accelerate progress in understanding and predicting regional climate change. In addition to the merits of running climate models at a resolution comparable with that of NWP models, the continual confrontation of an NWP model with observations can provide important constraints when the same model is used for much longer-time-scale climate predictions. Short-range forecast models give encouraging results using grid lengths of close to 1 km, without parameterizing deep convection. Prediction uncertainty, a key variable can be estimated by making an ensemble of forecasts with varying initial conditions, model equations, and other input fields such as greenhouse gas concentrations. The new generation of models will yield improved statistics of daily weather and, therefore, better predictions of regional climate variations on seasonal time scales.


Understanding the Anomalously Cold European Winter of 2005/06 Using Relaxation Experiments

MONTHLY WEATHER REVIEW 138 (2010) 3157-3174

T Jung, TN Palmer, MJ Rodwell, S Serrar


EXTENDED-RANGE PROBABILISTIC FORECASTS OF GANGES AND BRAHMAPUTRA FLOODS IN BANGLADESH

BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY 91 (2010) 1493-U121

PJ Webster, J Jian, TM Hopson, CD Hoyos, PA Agudelo, H-R Chang, JA Curry, RL Grossman, TN Palmer, AR Subbiah


Forecast quality assessment of the ENSEMBLES seasonal-to-decadal Stream 2 hindcasts. ECMWF Tech Memo.

ECMWF (2010) 621

FJ Doblas-Reyes, A Weisheimer, TN Palmer, JM Murphy, D Smith


Decadal climate prediction with the ECMWF coupled forecast system: Impact of ocean observations. ECMWF Tech Memo.

(2010) 633

FJ Doblas-Reyes, MA Balmaseda, A Weisheimer, TN Palmer


Future change in Southern Hemisphere summertime and wintertime atmospheric blockings simulated using a 20-km-mesh AGCM

GEOPHYSICAL RESEARCH LETTERS 37 (2010) ARTN L02803

M Matsueda, H Endo, R Mizuta


EC-Earth: A seamless Earth-system prediction approach in action

Bulletin of the American Meteorological Society 91 (2010) 1357-1363

W Hazeleger, C Severijns, T Semmler, S Ştefǎnescu, S Yang, X Wang, K Wyser, E Dutra, JM Baldasano, R Bintanja, P Bougeault, R Caballero, AML Ekman, JH Christensen, B Van Den Hurk, P Jimenez, C Jones, P Kållberg, T Koenigk, R McGrath, P Miranda, T Van Noije, T Palmer, JA Parodi, T Schmith, F Selten, T Storelvmo, A Sterl, H Tapamo, M Vancoppenolle, P Viterbo, U Willén

The EC-Earth consortium is a grouping of meteorologists and Earth-system scientists from 10 European countries, put together to face the challenges of climate and weather forecasting. The NWP system of the European Centre for Medium-Range Weather Forecasts (ECWMF) forms the basis of the EC-Earth Earth-system model. NWP models are designed to accurately capture short-term atmospheric fluctuations. They are used for forecasts at daily-to-seasonal time scales and include data assimilation capabilities. Climate models are designed to represent the global coupled ocean-atmosphere system. The atmospheric model of EC-Earth version 2, is based on ECMWF's Integrated Forecasting System (IFS), cycle 31R1, corresponding to the current seasonal forecast system of ECMWF. The EC-Earth consortium and ECMWF are collaborating on development of initialization procedures to improve long-term predictions. The EC-Earth model displays good performance from daily up to inter-annual time scales and for long-term mean climate.


Impact of 2007 and 2008 Arctic ice anomalies on the atmospheric circulation: Implications for long-range predictions

QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY 136 (2010) 1655-1664

MA Balmaseda, L Ferranti, F Molteni, TN Palmer