ECCC-CMC extra-tropical and tropical cyclone tracking algorithm for NWP

Algorithm description

This tracking algorithm is based on code originally developed by:

• Sinclair, M. R., 1997: Objective identification of cyclones and their circulation intensity, and climatology. Wea. Forecasting, 12, 595-612.

E-T cyclones are tracked based on either their minimum central mean sea level pressure (MSLP) or on their maximum values of gradient wind vorticity.

For vorticity-based tracking, cyclones (i.e. vorticity maxima) must reach a given user-specified threshold value. Vorticity fields are smoothed using a Cressman filter to remove (real and ficticious) small scale details and retain only the synoptic scale features.

For pressure-based traking, cyclone centers are determined from filtered MSLP fields. However, it is possible to extract the raw (i.e. unfiltered) minimum central pressure value.

The tropical cyclone tracking algorithm uses the same core than the extra-tropical pressure-based tracking algorithm. However, in order to identify cyclones with tropical characteristics, 4 additional parameters are considered:

a) 850-hPa relative vorticity filtered with a Cressman filter using a 300-km radius b) 250-850 hPa thickness c) Surface (10 m) wind speed d) Low level baroclinicity (noted B) measured in terms of asymetry of the 600-900 hPa thickness field. The definition of B employed follows:

• Sinclair, M. R., 2004: Extratropical Transition of Southwest Pacific Tropical Cyclones. Part II: Midlatitude Circulation Characterisitcs, Mon. Wea. Rev., 132, p. 2149.

Real-time applications using this algorithm can be found on https://meteocentre.com/cyclone-tracking/index_e.html

How to build the program at CMC

Build dependencies

• CMake 3.12+

Note: cmake_rpn is included as a submodule. Please clone with the --recursive flag or run git submodule update --init --recursive in the git repo after having cloned.

Environment

Source the right file depending on the architecture you need from the $ECCI_ENV variable. This will load the specified compiler and define the ECCI_DATA_DIR variable for the test datasets

• Example for PPP5:

. $ECCI_ENV/latest/ppp5/inteloneapi-2022.1.2.sh

• Example for CMC network and gnu 7.5:

. $ECCI_ENV/latest/ubuntu-18.04-amd-64/gnu-7.5.0.sh

Build and install

mkdir build
cd build
cmake ../
make
make package

How to build the program outside CMC (External users)

Build dependencies

• CMake 3.12+
• librmn 20.0.0+

Note: cmake_rpn is included as a submodule. Please clone with the --recursive flag or run git submodule update --init --recursive in the git repo after having cloned.

Build and install

mkdir build
cd build
cmake .. -Drmn_ROOT=[librmn path] -DCMAKE_INSTALL_PREFIX=[install path]
make
make test 
make install

To run the test suite (make test), you will have to run the script test/download-dbase.sh first to import the test database.