Publications


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


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


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


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


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


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,


Gradient free descent: Shadowing, and state estimation using limited derivative information

Physica D: Nonlinear Phenomena 190 (2004) 153-166

K Judd, L Smith, A Weisheimer

Shadowing trajectories can play an important role in assessing the reliability of forecasting models, they can also play an important role in providing state estimates for ensemble forecasts. Gradient descent methods provide one approach for obtaining shadowing trajectories, which have been shown to have many useful properties. There remains the important question whether shadowing trajectories can be found in very high-dimensional systems, like weather and climate models. The principle impediment is the need to compute the derivative (or adjoint) of the system dynamics. In this paper we investigate gradient descent methods that use limited derivative information. We demonstrate the methods with an application to a moderately high-dimensional system using no derivative information at all. © 2003 Elsevier B.V. All rights rserved.


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,


Development of a European multimodel ensemble system for seasonal-to-interannual prediction (DEMETER)

BULLETIN OF THE AMERICAN METEOROLOGICAL SOCIETY 85 (2004) 853-+

TN Palmer, A Alessandri, U Andersen, P Cantelaube, M Davey, P Delecluse, M Deque, E Diez, FJ Doblas-Reyes, H Feddersen, R Graham, S Gualdi, JF Gueremy, R Hagedorn, M Hoshen, N Keenlyside, M Latif, A Lazar, E Maisonnave, V Marletto, AP Morse, B Orfila, P Rogel, JM Terres, MC Thomson


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


Numerical simulation of cloud- clear air interfacial mixing

Journal of the Atmospheric Sciences 61 (2004) 1726-1739

M Andrejczuk, WW Grabowski, SP Malinowski, PK Smolarkiewicz

This paper discusses results from a series of direct numerical simulations of the microscale cloud-clear air mixing, set forth in the idealized scenario of decaying moist turbulence. In the moist case, kinetic energy of microscale motions comes not only from the classical downscale energy cascade, but it can also be generated internally due to the evaporation of cloud droplets. Three sets of numerical simulations are performed for three intensities of initial large-scale eddies. In each set, a control dry simulation is performed, as well as two moist simulations applying either bulk or detailed representation of cloud microphysics. Model results suggest that, as far as the evolutions of enstrophy and turbulent kinetic energy are concerned, the most significant impact of moist processes occurs at the low intensity of initial large-scale eddies (the input turbulent kinetic energy of 2 X 10-4 m2 s-2 resulting in the maximum eddy dissipation rate of 5 X 10-4 m2 s-3). In such a case, mixing and homogenization are dominated by the kinetic energy generated as a result of evaporation of cloud water and its impact on the microscale buoyancy. Detailed microphysics, which explicitly treat the size dependence of cloud droplet sedimentation and evaporation, appear to have a comparatively small effect, although this result might be an artifact of a coarse grid resolution used in the simulations. High anisotropy, also observed in laboratory experiments with mixing, between cloudy and cloud-free air, prevails even at the high intensity of initial large-scale eddies (the input turbulent kinetic energy of 2 X 10-2 m2 s-2, the maximum eddy dissipation rate of 7 × 10-3 m2 s-3), despite the fact that mixing and homogenization proceed in a similar manner in moist and dry simulations. Impact on cloud microphysics is also quantified. Cloud droplet spectra at the end of simulations correspond to neither the extremely inhomogeneous nor homogeneous mixing scenarios-the two asymptotic limits where, respectively, either the cloud droplet size or the number of cloud droplets remain constant. The shift from low to high intensity of initial large-scale eddies shifts the mixing scenario toward the homogeneous case, corroborating the classical argument based on scale analysis. © 2004 American Meteorological Society.


Forcing singular vectors and other sensitive model structures

QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY 129 (2003) 2401-2423

J Barkmeijer, T Iversen, TN Palmer


Radar-echo tracking by use of invariant moments.

Appl Opt 42 (2003) 5891-5896

M Andrejczuk, S Moszkowicz, KE Haman, T Szoplik

A number of techniques to track rainfall patterns by use of radar observations have been developed over the years. We present a method for radar-echo tracking based on Hu invariant moments. The method has been tried on several sequences of test images, and the derived displacement fields were in good agreement with the real motions of the tested objects. For the real data obtained from the conventional meteorological radar in Legionowo the method occasionally failed when changes in the radar echo between observations were too large.


Validation of water vapour profiles from GPS radio occultations in the Arctic

FIRST CHAMP MISSION RESULTS FOR GRAVITY, MAGNETIC AND ATMOSPHERIC STUDIES (2003) 441-446

M Gerding, A Weisheimer


Benefits of increased resolution in the ECMWF ensemble system and comparison with poor-man's ensembles

QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY 129 (2003) 1269-1288

R Buizza, DS Richardson, TN Palmer