An intercomparison of results from three trajectory models

Three three-dimensional trajectory models (LAGRANTO, TRAJKS and FLEXTRA), all driven with analysis wind fields from the European Centre for Medium-Range Weather Forecasts, are intercompared. The comparison has three parts: first, a case study of strong ascent in a warm conveyor belt is performed; second, a large set of back trajectories from the tropopause region over Europe and the mid-latitude Atlantic Ocean is investigated; third, a set of low-level trajectories is compared. The intercomparison shows that all three models have been implemented correctly. The degree of model accordance depends on the interpolation methods used. Deviations between the results from a single model using different interpolation schemes are of the same magnitude as the deviations of different models. If all models use linear spatial interpolation, their respective trajectories closely agree with each other, with deviations of 2% or less for the average distance between the starting and the ending positions in the free atmosphere after 48 h. Close to the surface, where the differences in the model formulations are largest, average horizontal position deviations may be up to 10%. Compared with other sources of errors, such as inaccuracies in the wind fields or insufficient temporal and spatial resolution of the data set, these differences are much smaller. Non-linear spatial interpolation leads to stronger vertical motions than linear interpolation and, in the case study, enhanced the quality of the results. Copyright © 2001 Royal Meteorological Society

[1]  D. Blake,et al.  TRACE A trajectory intercomparison: 2. Isentropic and kinematic methods , 1996 .

[2]  R. Draxler,et al.  Sensitivity of three-dimensional trajectories to the spatial and temporal densities of the wind field , 1990 .

[3]  H. Fuelberg,et al.  TRACE A trajectory intercomparison 1. Effects of different input analyses , 1996 .

[4]  J. Staehelin,et al.  Measurements of nitrogen oxides at the tropopause: Attribution to convection and correlation with lightning , 2000 .

[5]  Sverre Petterssen,et al.  Weather analysis and forecasting , 1940 .

[6]  An Intercomparison of Isentropic Trajectories over the South Atlantic , 1994 .

[7]  J. Walmsley,et al.  On the numerical accuracy of trajectory models for long‐range transport of atmospheric pollutants , 1983 .

[8]  Ying-Hwa Kuo,et al.  The Accuracy of Trajectory Models as Revealed by the Observing System Simulation Experiments , 1985 .

[9]  A. Stohl,et al.  A textbook example of long‐range transport: Simultaneous observation of ozone maxima of stratospheric and North American origin in the free troposphere over Europe , 1999 .

[10]  A. Simmons,et al.  Implementation of the Semi-Lagrangian Method in a High-Resolution Version of the ECMWF Forecast Model , 1995 .

[11]  A. Stohl,et al.  Accuracy of trajectories as determined from the conservation of meteorological tracers , 1998 .

[12]  Rainer Bleck,et al.  Modeling atmospheric transport to the Marshall Islands , 1985 .

[13]  Jonathan D. W. Kahl,et al.  Intercomparison of three long-range trajectory models applied to Arctic haze , 1989 .

[14]  Heini Wernli,et al.  A Lagrangian‐based analysis of extratropical cyclones. I: The method and some applications , 1997 .

[15]  A. Stohl,et al.  Interpolation Errors in Wind Fields as a Function of Spatial and Temporal Resolution and Their Impact on Different Types of Kinematic Trajectories , 1995 .

[16]  A. Simmons,et al.  An Energy and Angular-Momentum Conserving Vertical Finite-Difference Scheme and Hybrid Vertical Coordinates , 1981 .

[17]  A. Stohl.  Computation, accuracy and applications of trajectories—A review and bibliography , 1998 .

[18]  Petra Seibert.  Convergence and Accuracy of Numerical Methods for Trajectory Calculations , 1993 .