The University of Melbourne

Automatic Cyclone Tracking

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Latest News: Mar 29 2008: JRA25, NCEP and NCEP2 are updated to Feb 2008.

 

Introduction

This is the Home page for the University of Melbourne Automatic Cyclone Tracking web access.

We present the global statistics of cyclones that were tracked with the University of Melbourne automatic cyclone tracking scheme (Murray and Simmonds 1991, and subsequent papers). These are predominantly extratropical cyclones, although there is also some expression of tropical cyclones.

 

The primary purpose of this web site is to allow the wider community to access our cyclone statistics, which are available on a 2.5 x 2.5 degree latitude-longitude grid, and to perform a variety of tasks including the creation of plots, the saving of data and the computation of anomalies (difference) from a chosen reference data set e.g. a climatology.

 

Cyclone statistics based on 6 hourly mean sea level pressure (MSLP) are available for several reanalysis projects: ERA-40 Reanalysis (ERA40) (1957-2002), NCEP Reanalysis (NCEP) (1958- ongoing), NCEP Reanalysis 2 (NCEP2) (1979- ongoing) and JRA-25 Reanalysis (JRA25) (1979- ongoing).

A long term goal is to allow the user to access the tracks database from which the statistics are derived.

Details about our group are available here:

Meteorology Group, School of Earth Sciences, University of Melbourne

 

Cyclone statistics

This version (1.0) supersedes the beta version that has been operating since May 2006.  See the Help section for documentation. This mainly consists of Basic Help and an Example. The web site is designed to be fairly self-explanatory.

 

 

You may access the cyclone statistics web site at:

http://www.earthsci.unimelb.edu.au/tracks/cycstats/cycstats.php

 

 

Please Note: Our network is backed up nightly from 18:00-24:00 (UTC +10:00) and so there may be poor response at times during this period. Furthermore, the temporary directories created for a user are deleted at 17:10 each Tuesday, Thursday and Sunday.

                                                                                                                                                     

Please direct any questions or report any problems to Kevin Keay.

 

The University of Melbourne automatic cyclone tracking software

The cyclone tracking software is freely available from our group. It is written in Fortran 77 and should compile correctly on any platform with the GNU g77 compiler. To date it has been compiled successfully on systems running Solaris, Linux and Cygwin under Microsoft Windows 2000 (and presumably under Windows XP). The present version is designed for grids of the order of 1 degree or larger, including the widely-used 2.5 degree reanalysis pressure and geopotential height fields. There is also a new version that can accommodate grids between 0.25 and 1 degree. This has not been exhaustively tested by us but we have assisted a small number of users with data on a 0.25 degree grid and the results appear fine. The input data should be in a simple binary format that we refer to as ‘conmap’. Details of this format are given in the software documentation. We can provide some additional Fortran 77 software to assist in converting GRIB or NetCDF data to the conmap (CMP | CIF) format. At present there is no graphics capability for external users but we are looking into providing scripts for a freely available package such as GrADS.

 

The software may be obtained by contacting Ian Simmonds.

 

Please indicate the platform that you intend to run the software on. We recommend the g77 compiler but the software should compile with others but we can’t test these ourselves. In addition please tell us the resolution of the data that will be input to the software. Often a user will contact us again if they require any further assistance on matters such as choice of parameters or to convert NetCDF to conmap if no appropriate tools are available.

 

 

The animation at the top of this page

 

The animation at the upper right of this page shows cyclones that were identified on six-hourly mean sea level maps from the ERA-40 Reanalysis which is freely available from the ECMWF. See: http://data.ecmwf.int/data/d/era40_daily

 

The period July 1 2001 00UTC – July 4 2001 18UTC (16 maps) is shown. Different symbols depict the cyclone state as shown in this key:

 

 

The term ‘strong’ is relative. In this example it refers to cyclones with a mean Laplacian of pressure exceeding 0.2 hPa/(deg.lat.)2 but often one would choose a larger value e.g. 0.7, to highlight the stronger systems. Click here for a larger animation (1.1 MB).

 

 

Sources of Data

 

The cyclone statistics presented here are based on 6 hourly mean sea level pressure (MSLP) fields from several reanalysis projects. These are freely available from the following web sites (note that registration is required for access to JRA25 products):

 

1.                   ERA-40 Reanalysis  (ERA40) (1957-2002)

2.                   NCEP Reanalysis    (NCEP) (our statistics: 1958- ongoing)

3.                   NCEP Reanalysis 2 (NCEP2) (1979- ongoing)

4.                   JRA-25 Reanalysis  (JRA25) (1979- ongoing)

 

 

Copyright and Disclaimer

 

We use the cyclone statistics that are presented here in our published research. Although every effort has been made to ensure that they are correct we can not guarantee that the statistics or the data used to compute them are free from errors. Hence we take no responsibility for any negative consequences arising from their use by any party external to our group at the University of Melbourne.

 

The cyclone statistics, as data files or images, may be freely used for research and most publications including journals. However in the case of a reference book (e.g. an encyclopaedia) or a text book you should contact Ian Simmonds for clarification on any potential copyright issue relating to the University of Melbourne.

 

In any event it would be appreciated that you include an appropriate reference to this web site. For instance:

 

The cyclone statistics were obtained from the University of Melbourne Automatic Cyclone Tracking web page (http://www.earthsci.unimelb.edu.au/tracks/cychome.htm). These are computed using the automatic cyclone tracking scheme of Murray and Simmonds (Murray and Simmonds 1991a; Murray and Simmonds 1991b; Simmonds et al. 1999; Simmonds and Murray 1999; Simmonds et al. 2003; Lim and Simmonds 2007).

Murray, R. J., and I. Simmonds, 1991a: A numerical scheme for tracking cyclone centres from digital data. Part I: Development and operation of the scheme. Australian Meteorological Magazine, 39, 155–166.

Murray, R. J., and I. Simmonds, 1991b: A numerical scheme for tracking cyclone centres from digital data. Part II: Application to January and July general circulation model simulations. Australian Meteorological Magazine, 39, 167–180.

Simmonds, I., R. J. Murray, and R. M. Leighton, 1999: A refinement cyclone tracking methods with data from FROST. Australian Meteorological Magazine (Special ed.), 35–49.

Simmonds, I., and R. J. Murray, 1999: Southern extratropical cyclone behavior in ECMWF analyses during the FROST Special Observing Periods. Weather and Forecasting, 14, 878-891.

Simmonds, I., K. Keay and E.-P. Lim, 2003: Synoptic activity in the seas around Antarctica. Monthly Weather Review, 131, 272-288.

Lim, E.-P., and I. Simmonds, 2007: Southern Hemisphere winter extratropical cyclone characteristics and vertical organization observed with the ERA-40 reanalysis data in 1979-2001. Journal of Climate, 20, 2675-2690.

 

 

References

 

Rice, J., 1982: The Derivation of a Computer-based Synoptic Climatology of Southern Hemisphere Extratropical Cyclones. Honours Thesis, Department of Meteorology, The University of Melbourne, 113 pp.

 

Murray, R. J., and I. Simmonds, 1991: A numerical scheme for tracking cyclone centres from digital data. Part I: Development and operation of the scheme. Australian Meteorological Magazine, 39, 155–166.

 

Murray, R. J., and I. Simmonds, 1991: A numerical scheme for tracking cyclone centres from digital data. Part II: Application to January and July general circulation model simulations. Australian Meteorological Magazine, 39, 167–180.

 

Jones, D.A., and I. Simmonds, 1993: A climatology of Southern Hemisphere extratropical cyclones. Climate Dynamics, 9, 131–145.

 

Jones, D.A., and I. Simmonds, 1994: A climatology of Southern Hemisphere anticyclones. Climate Dynamics, 10, 333–348.

 

Jones, D.A., 1994. An objective study of Southern Hemisphere synoptic activity. PhD Thesis, School of Earth Sciences, University of Melbourne, Parkville, Australia, 392 pp.

 

Simmonds, I., and D. A. Jones, 1998: The mean structure and temporal variability of the semiannual oscillation in the southern extratropics. International Journal of Climatology, 18, 473–504.

 

Simmonds, I., and R. J. Murray, 1999: Southern extratropical cyclone behavior in ECMWF analyses during the FROST special observing periods. Weather and Forecasting, 14, 878–891.

 

Simmonds, I., R. J. Murray, and R. M. Leighton, 1999: A refinement cyclone tracking methods with data from FROST. Australian Meteorological Magazine (Special ed.), 35–49.

 

Simmonds, I., and K. Keay, 2000: Mean Southern Hemisphere extratropical cyclone behaviour in the 40-year NCEP-NCAR reanalysis. Journal of Climate, 13, 873-885.

 

Simmonds, I., and K. Keay, 2000: Variability of Southern Hemisphere extratropical cyclone behaviour 1958-97. Journal of Climate, 13, 550-561.

 

Keable, M., I. Simmonds and K. Keay, 2002: Distribution and temporal variability of 500 hPa cyclone characteristics in the Southern Hemisphere. International Journal of Climatology, 22,131-150.

 

Simmonds, I., Keay, K. and E.-P. Lim, 2003: Synoptic activity in the seas around Antarctica. Monthly Weather Review, 131, 272-288.

 

Simmonds, I., 2003: Modes of atmospheric variability over the Southern Ocean. Journal of Geophysical Research, 108, 8078, doi: 10.1029/2000JC000542.

 

Simmonds, I., and J. C. King, 2004: Global and hemispheric climate variations affecting the Southern Ocean. Antarctic Science, 16, 401-413.

 

Lim, E.-P., 2005: Global changes in synoptic activity with increasing atmospheric CO2. PhD Thesis, School of Earth Sciences, University of Melbourne, Australia, 381 pp.

 

Pezza, A. B., and I. Simmonds, 2005: The first South Atlantic hurricane: Unprecedented blocking, low shear and climate change. Geophysical Research Letters, 32, L15712, doi: 10.1029/2005GL023390.

 

Simmonds, I., A. Rafter, T. Cowan, A. B. Watkins and K. Keay, 2005: Large-scale vertical momentum, kinetic energy and moisture fluxes in the Antarctic sea-ice region. Boundary-Layer Meteorology, 117, 149-177.

 

Wassermann, S., C. Schmitt, C. Kottmeier and I. Simmonds, 2006: Coincident vortices in Antarctic wind fields and sea ice motion. Geophysical Research Letters, 33, L15810, doi:10.1029/2006GL026005.

 

White, W. B., and I. Simmonds, 2006: Sea surface temperature-induced cyclogenesis in the Antarctic circumpolar wave. Journal of Geophysical Research, 111, C08011, doi:10.1029/2004JC002395.

 

Krinner, G., O. Magand, I. Simmonds, C. Genthon and J.-L. Dufresne, 2007: Simulated Antarctic precipitation and surface mass balance at the end of the twentieth and twenty-first centuries. Climate Dynamics, 28, 215-230.

 

Lim, E.-P., and I. Simmonds, 2007: Southern Hemisphere winter extratropical cyclone characteristics and vertical organization observed with the ERA-40 reanalysis data in 1979-2001. Journal of Climate, 20, 2675-2690.

 

Last Update: March 29 2008

Maintained by: Kevin Keay