Publications


Multi-Center Grand Ensemble using Three Operational Ensemble Forecasts

SOLA Meteorological Society of Japan 2 (2006) 33-36

M Matsueda, M Kyouda, HL Tanaka, T Tsuyuki

In this study, we investigate the impact of Multi-Center Grand Ensemble (MCGE) forecasts, consisting of three operational ensemble forecasts by the Japan Meteorological Agency (JMA), the National Centers for Environmental Prediction, and the Canadian Meteorological Center. We verified the skill of MCGE forecasts in comparison with that of JMA ensemble forecast using root mean square error, anomaly correlation, and Brier skill score for 500 hPa geopotential height and 850 hPa temperature in the Northern Hemisphere (20°N-90°N) in September 2005.Our results show that MCGE forecasts are more skillful than single-center ensemble forecast without considering weight among ensemble members and bias corrections. This implies that considering weight or bias corrections may result in further improvement of MCGE forecasts, specifically in probabilistic forecasts.


Changing frequency of occurrence of extreme seasonal temperatures under global warming (vol 32, art no L20721, 2005)

GEOPHYSICAL RESEARCH LETTERS 33 (2006) ARTN L07712

A Weisheimer, TN Palmer


Erratum: "Changing frequency of occurrence of extreme seasonal temperatures under global warming" (Geophysical Research Letters (2005) vol. 32 10.1029/2005GL023365)

Geophysical Research Letters 33 (2006)

A Weisheimer, TN Palmer


Malaria early warnings based on seasonal climate forecasts from multi-model ensembles

NATURE 439 (2006) 576-579

MC Thomson, FJ Doblas-Reyes, SJ Mason, R Hagedorn, SJ Connor, T Phindela, AP Morse, TN Palmer


Impact of increasing greenhouse gas concentrations in seasonal ensemble forecasts

GEOPHYSICAL RESEARCH LETTERS 33 (2006) ARTN L07708

FJ Doblas-Reyes, R Hagedorn, TN Palmer, JJ Morcrette


More power needed to probe cloud systems

NATURE 434 (2005) 271-271

TN Palmer


Representing model uncertainty in weather and climate prediction

ANNUAL REVIEW OF EARTH AND PLANETARY SCIENCES 33 (2005) 163-193

TN Palmer, GJ Shutts, R Hagedorn, E Doblas-Reyes, T Jung, M Leutbecher


Probabilistic prediction of climate using multi-model ensembles: from basics to applications.

Philos Trans R Soc Lond B Biol Sci 360 (2005) 1991-1998

TN Palmer, FJ Doblas-Reyes, R Hagedorn, A Weisheimer

The development of multi-model ensembles for reliable predictions of inter-annual climate fluctuations and climate change, and their application to health, agronomy and water management, are discussed.


Changing frequency of occurrence of extreme seasonal temperatures under global warming

Geophysical Research Letters 32 (2005) 1-5

A Weisheimer, TN Palmer

Using a multi-model multi-scenario ensemble of integrations made for the forthcoming fourth assessment report of the Intergovernmental Panel on Climate Change, the frequency of occurrence of extreme seasonal temperatures at the end of the 21st Century is estimated. In this study an extreme temperature is defined as lying above the 95 percentile of the simulated temperature distribution for 20th Century climate. The model probability of extreme warm seasons is heterogeneous over the globe and rises to over 90% in large parts of the tropics. This would correspond to an average return period of such anomalous warm seasons of almost one year. The reliability of these results is assessed using the bounding box technique, previously used to quantify the reliability of seasonal climate forecasts. It is shown that the dramatic increase in extreme warm seasons arises from the combined effect of a shift and a broadening of the temperature distributions. Copyright 2005 by the American Geophysical Union.


A forecast quality assessment of an end-to-end probabilistic multi-model seasonal forecast system using a malaria model

TELLUS SERIES A-DYNAMIC METEOROLOGY AND OCEANOGRAPHY 57 (2005) 464-475

AP Morse, FJ Doblas-Reyes, MB Hoshen, R Hagedorn, TN Palmer


The rationale behind the success of multi-model ensembles in seasonal forecasting - II. Calibration and combination

TELLUS SERIES A-DYNAMIC METEOROLOGY AND OCEANOGRAPHY 57 (2005) 234-252

FJ Doblas-Reyes, R Hagedorn, TN Palmer


Recurrent climate winter regimes in reconstructed and modelled 500 hPa geopotential height fields over the North Atlantic/European sector 1659-1990

CLIMATE DYNAMICS 24 (2005) 809-822

C Casty, D Handorf, CC Raible, JF Gonzalez-Rouco, A Weisheimer, E Xoplaki, J Luterbacher, K Dethloff, H Wanner


The rationale behind the success of multi-model ensembles in seasonal forecasting - I. Basic concept

TELLUS SERIES A-DYNAMIC METEOROLOGY AND OCEANOGRAPHY 57 (2005) 219-233

R Hagedorn, FJ Doblas-Reyes, TN Palmer


Quantum reality complex numbers, and the meteorological butterfly effect

BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY 86 (2005) 519-+

TN Palmer


Influence of a stochastic parameterization on the frequency of occurrence of North Pacific weather regimes in the ECMWF model

GEOPHYSICAL RESEARCH LETTERS 32 (2005) ARTN L23811

T Jung, TN Palmer, GJ Shutts


A new view of seasonal forecast skill: Bounding boxes from the DEMETER ensemble forecasts

Tellus, Series A: Dynamic Meteorology and Oceanography 57 (2005) 265-279

A Weisheimer, LA Smith, K Judd

Insight into the likely weather several months in advance would be of great economic and societal value. The DEMETER project has made coordinated multi-model, multi-initial-condition simulations of the global weather as observed over the last 40 years; transforming these model simulations into forecasts is non-trivial. One approach is to extract merely a single forecast (e.g. best-first-guess) designed to minimize some measure of forecast error. A second approach would be to construct a full probability forecast. This paper explores a third option, namely to see how often this collection of simulations can be said to capture the target value, in the sense that the target lies within the bounding box of the forecasts. The DEMETER forecast system is shown to often capture the 2-m temperature target in this sense over continental areas at lead times up to six months. The target is captured over 95% of the time at over a third of the grid points and maintains a bounding box range less than that of the local climatology. Such information is of immediate value from a user's perspective. Implications for the minimum ensemble size as well as open foundational issues in translating a set of multi-model multi-initial-condition simulations into a forecast are discussed; in particular, those involving 'bias correction' are consider. Copyright © Blackwell Munksgaard, 2005.


Improved radio occultation sounding of the Arctic atmosphere using simulations with a high resolution atmospheric model

Physics and Chemistry of the Earth 29 (2004) 277-286

V Kunitsyn, V Zakharov, K Dethloff, A Weisheimer, M Gerding, R Neuber, A Rinke, I Hebestadt

Radio occultation experiments have been simulated for the Arctic region on the basis of the regional atmospheric model HIRHAM4. Irregular structures in the atmosphere produce a violation of the quasi-sphericity in the radio signal propagation and exert a strong influence on the accuracy of atmospheric profiles retrieved by the radio occultation technique. Errors in radio occultation data are spatially localised and associated with gradients in atmospheric structures. Local errors reach 2% in retrieved profiles of refractivity corresponding to an error of 6 K in temperature. Therefore mesoscale variations in atmospheric parameter gradients in a specified region must be taken into account when interpreting radio occultation data. We show, that a correction functional can be developed using the refractivity index field calculated from the regional model in order to improve the radio occultation retrieval of atmospheric parameters. This functional is constructed from instantaneous model outputs, as well as from temporally averaged fields of refractivity using data of the HIRHAM4 model for the Arctic atmosphere. The correction functional derived from monthly averaged data reduced the retrieval errors of refractivity, temperature, and pressure in the troposphere, in particular, temperature retrieval errors are reduced up to 1 K. Application of this kind of functional depends on whether the model used for the construction of the functional is able to simulate the real mesoscale atmospheric structures. © 2004 Elsevier Ltd. All rights reserved.


Internal climate variability in global and regional climate models

CLIMATE IN HISTORICAL TIMES: TOWARDS A SYNTHESIS OF HOLOCENCE PROXY DATA AND CLIMATE MODELS (2004) 365-382

D Handorf, W Dorn, K Dethloff, A Rinke, A Weisheimer,


Nonlinear dynamics of the climate system

CLIMATE IN HISTORICAL TIMES: TOWARDS A SYNTHESIS OF HOLOCENCE PROXY DATA AND CLIMATE MODELS (2004) 13-41

K Dethloff, A Rinke, D Handorf, A Weisheimer, W Dorn,


A granular permutation-based representation of complex numbers and quaternions: elements of a possible realistic quantum theory

PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES 460 (2004) 1039-1055

TN Palmer