Multi-model Ensemble Based Extended Range Forecast of Tropical Cyclogenesis over the North Indian Ocean - Monitoring and Prediction of Tropical Cyclones in the Indian Ocean and Climate Change - page 200

using the latest generation of global numerical weather prediction systems
particularly in the extended range, although few studies (Pattanaik et al., 2003;
Roy Bhowmik, 2003; Kotal et al., 2009) have demonstrated the large difference
between the genesis potential parameter of developing and non-developing
system in the short to medium range time scale (3 to 5 days). In addition, very
few studies have been devoted to assessing the performance of ensemble
prediction systems for TCs. A recent study by Belanger et al. (2010) have
shown some skill in forecasting TCs using dynamically based ensemble
products from European Centre for Medium Range Weather Forecasting
(ECMWF) monthly forecast system. Their study also found that the
predictability of TC activity is sensitive to the phase and intensity of the
Madden-Julian oscillation (MJO) at the time of model initialization. Fu and
Hsu (2011) using a conventional atmosphere-ocean coupled system initialized
with NCEP's (National Centre for Environmental Prediction) FNL (Final)
analysis has successfully predicted a tropical cyclogenesis event in the NIO
with a lead time of two weeks. They also showed that a realistic MJO/ISV
(MJO/Intra Seasonal Variability) prediction will make the extended-range
forecasting of tropical cyclogenesis possible and also calls for improved
representation of the MJO/ISV in contemporary weather and climate forecast
models. Pattanaik et al. (2013) in their recent study have also demonstrated
useful skill in predicting tropical cyclogenesis over the NIO using present
generation coupled models. While analyzing the cyclogenesis based on the
coupled models forecast for 2010 post- monsoon season they found that the
model forecasts anomaly of weekly cyclonic vorticity maximum of about 2.5
× 10 -5 sec -1 combined with a low level convergence anomaly of about -0.8 to
-1.0 × 10 -5 sec -1 may lead to formation of a TC. Their study further indicated
that though the forecast had false alarm on one occasion, probability of
cyclogenesis was indicated correctly on five occasions.
Mohapatra and Adhikary (2011) have examined the relationship of MJO
with the cyclogenesis and further intensification over the NIO and found that
the MJO index in phase, 3 and 4 (east equatorial Indian Ocean and adjoining
maritime continent as defined by Wheeler and Hendon (2004)) is significantly
linked with cyclogenesis (formation of depression) in about 37% of the cases
in the NIO during October-December. There is no relationship between genesis
and MJO index in other phases. The frequency of genesis is very negligible
(about 10%) when the MJO with amplitude of <0.5 lies in the favourable phases
of 3 and 4 during October-December. The probability of intensification and
duration in cyclone stage and hence life period of cyclone is higher with MJO
in phases 3 and 4 and less with MJO in phases 1 and 7. There is no relationship,
when the MJO lies in 2, 5 and 6. The probability of intensification increases
with increase in amplitude of MJO in favourable phases.
Regional Specialised Meteorological Centre (RSMC), India Meteorological
Department (IMD), New Delhi issues a daily tropical weather outlook, which
assesses the possibility of tropical depression development in the Bay of Bengal