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Latest News: Sep 24
2009: Vertical tracing software now available. |
Introduction
This
is the Home page for
the
We present
the global
statistics of cyclones that were tracked with the
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,
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.
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You may
access the cyclone statistics web site at: http://www.earthsci.unimelb.edu.au/tracks/cycstats/cycstats.php |
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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
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 cant 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
It is now possible
to perform cyclone tracking at a set of levels (such as MSLP and various
geopotential heights) and then vertically trace a cyclone through the
atmosphere.
The software
is freely available from our group and may be obtained by contacting Ian Simmonds.
For more information refer to the Vertical Tracing
Software Home Page.
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.
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
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
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
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, 155166.
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, 167180.
Simmonds,
Simmonds,
Simmonds,
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
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, 155166.
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, 167180.
Jones, D.A., and I.
Simmonds, 1993: A climatology of Southern Hemisphere
extratropical cyclones. Climate Dynamics, 9, 131145.
Jones, D.A., and
Jones, D.A., 1994. An objective study of Southern Hemisphere synoptic activity.
PhD Thesis,
Simmonds,
Simmonds,
Simmonds,
Simmonds,
Simmonds,
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,
Simmonds,
Simmonds,
Lim, E.-P., 2005:
Global changes in synoptic activity with increasing atmospheric CO2. PhD Thesis,
Pezza, A. B., and I.
Simmonds, 2005: The first
Simmonds,
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,
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: September 24 2009
Maintained
by: Kevin Keay