In recent years the frequency and intensity of cyclones and hurricanes have been increased manifold compared to the last decade. As a result, the necessity for the development of computer models to predict the track, intensity, and time of occurrence of cyclonic storms has increased to avoid loss of life and prevention of damages to public properties. In this presentaion I had tried to highlight the ten most used models in this aspect which are responsible for saving millions of life and their livelihood.

1. TEN MOST
POPULAR
SOFTWARE FOR
PREDICTION OF
CYCLONIC STORM
DR. MRINMOY
MAJUMDER

2. What is Cyclone ?
A general term for a weather system in which
winds rotate inwardly to an area of low
atmospheric pressure.
The circulation pattern is in counter clockwise
direction in the Northern Hemisphere and
clockwise direction in the Southern
Hemisphere.
There are three different types of cyclones
mainly observed in tropical and sub tropical
regions : tropical cyclones, extratropical
cyclones and tornadoes.
More detail description about cyclones can be
found at
https://wxguys.ssec.wisc.edu/2019/04/29/cyclo
ne/

3. How cyclones are formed ?
Tropical cyclones form only over warm ocean waters
near the equator.
Warm and moist air over the ocean rises upward from
near the surface.
Air from surrounding areas with higher air pressure
pushes in to the low pressure area.
This also becomes warm and moist and as a
consequence rises and this process repeats itself
forming a centrifugal movement.
The warmed and moist air rises and cools the water in
the air forms clouds. This system grows continuously.
“When the winds in the rotating storm reach 39
mph (63 kmph), the storm is called a “tropical
storm”. “
When the wind speeds reach 74 mph (119 kmph),
the storm is officially a “tropical cyclone” or
hurricane.
However, this system sequentially loses energy
when it come inland where it causes rainfall and
wind storm and then “vanishes into thin air”
More detailed explanation can be found from
https://sites.google.com/site/disasterportal/stroms_
cyclones/cyclone-formation

4. What is the
difference between
Hurricane and
Cyclones
They are all basically the same
thing, but are given different
names depending on where they
appear.
Hurricanes are tropical storms
that form over the North Atlantic
Ocean and Northeast Pacific.
Cyclones are formed over the
South Pacific and Indian Ocean.
The Saffir-Simpson Hurricane Scale
Source : https://sites.google.com/site/disasterportal/stroms_cyclones/cyclone-
formation

5. Major Cyclones/Hurricanes
1900 : Galveston Hurricane hit Galveston Island, on Texas' eastern coast, in
1900.
1979:The strongest tropical cyclone recorded worldwide, as measured by
minimum central pressure, which reached a pressure of 870 hPa (25.69 inHg)
on October 12, 1979.
2005: Hurricane Wilma is the strongest Atlantic hurricane ever recorded,
after reaching an intensity of 882 mbar (hPa; 26.05 inHg) in October 2005.
2020 : The first pre-monsoon cyclone in a century : Cyclone Amphan
followed by Cyclone Nisarga, (hit the financial capital of India)
2021: Out of 13 to 20 named storms (winds of 39 mph or higher) around
50% is expected to become hurricanes and about 25% will cause category 3,
4 or 5 level Hurricanes. NOAA provides these ranges with a 70% confidence.
Already two cyclones has created land fall in two peninsula of India : Cyclone
Taukait and Cyclone Yash.

6. Types of Computer Models Used for
Cyclone Prediction
Cyclones or Hurricanes can cause severe damage to life and livelihood of mankind.
As a result, it is important to anticipate the cyclones well in advance
That is why, various computer based models are prepared nowadays to approximate cyclones/hurricanes.
The models can be categorized with respect to its objective into three groups ::
to predict the time of occurrence of the cyclone
to estimate the intensity of cyclone and
to forecast the track of the cyclones.
Computer models currently do well in the speculation of the path of tropical cyclones, but they are not as
reliable in foretelling changes in intensity more than 24 hours in advance.
Once forecasters have calculated that a cyclone or hurricane is likely to make landfall, warnings are issued for
the areas that may be affected.
Ten Most popular and contemporary cyclone prediction computer models are discussed next.

7. Ten Most Popular Cyclone Prediction
Models
CLIPER
The Aviation Model
BAM (Beta and Advection Model)
The GFDL Model
VICBAR
NHC93
HWRF
Cyclocane Spaghetti Models
COAMPS-TC Ensemble
HMON

8. CLIPER
CLIPER is the only purely statistical model still in use.
The acronym stands for CLImatology and PERsistence.
The only inputs to CLIPER are the storm's current and previous positions, its motion and
intensity, and the time of the year.
Because CLIPER knows nothing about the meteorological situation, forecasters use it as a "no
skill" prediction against which other models are judged.
It is designed as a statistical regression equation based on past data and current
climatological data.
This was the major forecasting model used up until the 1980's.

9. The Aviation Model
The Aviation Model is a version of National Centers for Environmental
Prediction(NCEP)'s (formerly National Meteorological Center (NMC)'s) operational
forecast model.
It is a multilevel, global spectral model with T126 truncation, equivalent to 106 km
horizontal resolution.
Hurricane track forecasting capability is attained by inserting a synthetic vortex into
the initial analysis at the observed hurricane position and tracking the vortex motion
as the model calculation evolves.

10. BAM (Beta and Advection Model)
BAM (Beta and Advection Model) assumes that the hurricane moves with the
aviation model's winds (vertically averaged and filtered to remove the hurricane)
plus a drift toward the pole and westward due to the northward increase of the
Coriolis parameter (the "beta effect").
BAM comes in three versions, shallow, medium, and deep, depending upon the
depth over which the vertical average is computed.

11. The GFDL Model
The Geophysical Fluid Dynamics Laboratory(GFDL) Model is a full physics model,
developed as a research tool at the Geophysical Fluid Dynamics Laboratory, that has
become fully operational.
With its fine resolution (about 19km) and other special adaptations to the hurricane
problem, it have an excellent forecasting record.

12. VICBAR
VICBAR is a specialized forecast model developed at Hurricane Research
Division(HRD)/Atlantic Oceanographic & Meteorological Laboratory(AOML).
It replaces the complex dynamics of the atmosphere with a layer of fluid with
constant density, representing the average motions between 850 and 200 hPa.
Despite its simplified dynamics and 50 km resolution, it is also a powerful forecast
model.

13. NHC93
NHC93 was developed at National Hurricane Centre(NHC) in National Oceanic and
Atmospheric Administration(NOAA).
It is the only statistical-dynamical model now in use.
It uses the output from the aviation model in a series of statistical regression
relations to predict hurricane motion.

14. More details about the six models
More details about CLIPER, Aviation Model, BAM, GFDL,VICBAR and NHC93 can be
found at the source as given below :
Hurricane Research Division,2014,HURRICANE TRACK PREDICTION MODELS, Retrieved from
https://www.aoml.noaa.gov/hrd/hrd_sub/models.html as on 27th May 2021

15. HWRF
HWRF is the driving dynamical model of the Real-Time Hurricane Forecast
Improvement Project Corrected Consensus Approach (HCCA) for Tropical Cyclone
Intensity Guidance at the National Hurricane Center, and has become the flagship
intensity prediction tool for hurricane forecasting at the National Weather Service.
Reference : Hurricane Weather Research and Forecasting Model(HWRF), Retrieved
from http://www.aoml.noaa.gov/hrd/project2005/HWRF.html on 27.05.202

16. Cyclocane Spaghetti Models
Cyclocane Spaghetti models (also called spaghetti plots) is the nickname given to the group
of computer models that show potential tropical cyclone paths.
When shown together, the individual model tracks can somewhat resemble strands of
spaghetti. In short, it gives you a way to see where a tropical storm or hurricane may head.
It can also give insight into whether the models are in agreement on the path of the storm
(for instance, all models show Florida in the path of a hurricane) or if there is a wide differing
opinion on where the storm may go.
Reference : Croft,H.,2021,Cyclocane,Retrieed from https://www.cyclocane.com/spaghetti-
models/ on 27052021.

17. COAMPS-TC Ensemble
The 11-member Coupled Ocean–Atmosphere Mesoscale Prediction System-Tropical Cyclones (COAMPS-TC)
ensemble has been developed by the Naval Research Laboratory (NRL) to produce probabilistic forecasts of
tropical cyclone (TC) track, intensity and structure. All members run with a storm-following inner grid at
convection-permitting 4-km horizontal resolution.
The COAMPS-TC ensemble is constructed via a combination of perturbations to initial and boundary conditions,
the initial vortex, and model physics to account for a variety of different sources of uncertainty that affect track
and intensity forecasts.
Unlike global model ensembles, which do a reasonable job capturing track uncertainty but not intensity, mesoscale
ensembles such as the COAMPS-TC ensemble are necessary to provide a realistic intensity forecast spectrum.
The ensemble-mean track and intensity forecast is superior to the unperturbed control forecast at all lead times,
demonstrating a clear advantage to running an ensemble versus a deterministic forecast.
Reference :Komaromi, William A., Patrick A. Reinecke, James D. Doyle, and Jonathan R. Moskaitis. " The Naval
Research ,Retrieved from https://doi.org/10.1175/WAF-D-20-0038.1

18. HMON
Hurricanes in a Multi-scale Ocean-coupled Non-hydrostatic model or HMON is
relatively new Hurricane forecast system running operationally at NCEP.
It has been coupled to the HYCOM ocean model for North Atlantic, Eastern and
Central Pacific basins.
It is developed for prediction of both track and intensity of hurricanes.
HMON v3.0.0 is the latest version.
For more details visit
https://nomads.ncep.noaa.gov/txt_descriptions/HMON_doc.shtml

19. Conclusion
To predict the path of a storm, meteorologists uses multiple models which are also known
as ensemble.
The original best model was CLIPER (Climate and Persistence which was the major
forecasting model used up until the 1980’s.
However with the advent of sophisticated computational systems such models get
improved and presently highly advanced models are developed which not only uses
meteorological data but also include remotely sensed imageries and various image
processing algorithms to analyse and forecast the track of cyclones.
Due to this immense advance in recent years , a cyclone alert (or cyclone watch) can be
issued 48 hours in advance of any expected storm and a cyclone warning within 24 hours in
advance.
Although, much more improvement can be imbibed.
Intensive research and their researchers need to be encouraged by the governments of
specially those countries, where massive damages are incurred by such storms every year.
Due to the impact of climate change and rapid urbanization. Such occurrence of severe
storms are increasing day by day.

20. Thank you
My ResearchGate Id : Mrinmoy_Majumder
Home Page: http://www.mrinmoymajumder.com
Author of: Lecture Notes on MCDM
Indian Link: https://www.instamojo.com/baipatra/lecture-notes-on-
mcdm/ ; Global Link: https://gum.co/zuPVt
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