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Tropical cyclogenesis
Team Leader:
Robert Rogers (AOML/HRD)
Team members:
Michael Montgomery (Naval Postgraduate School, AOML/HRD)
Objective:
While forecasts of tropical cyclone track have shown significant
improvements in recent years, corresponding improvements in forecasts of
tropical cyclone intensity have been much slower. The lack of improvement
in intensity forecasting is the result of deficiencies in the numerical models
(e.g., resolution limitation and parameterization inadequacies), deficiencies
in the observations, and deficiencies in our basic understanding of the
physical processes involved. The problem becomes even more acute for
forecasting tropical cyclogenesis. While global models have shown some skill
in recent years in predicting tropical cyclogenesis, our understanding of the
physical processes involved remains limited, largely because observing genesis
events is a difficult task. However, a key aspect of the NOAA Intensity
Forecasting Experiment (IFEX) is the collection of observations during all
portions of a tropical cyclone's lifecycle, particularly on the early lifecycle
stages. This emphasis on the early stages of the lifecycle will provide an
opportunity to observe several genesis events and improve our understanding of
this key process, leading to better predictions of tropical cyclogenesis,
organization, and intensification.
Since both tropical cyclogenesis and tropical cyclone intensity change
can be defined by changes in low- and mid-level vorticity, knowledge of the
processes that play a significant role in genesis will also advance our
understanding of intensity change. A better understanding of the processes
that lead to an increase in low- and mid-level cyclonic vorticity will also
allow NHC to better monitor and forecast tropical cyclogenesis and intensity
change, improvements that would be especially valuable for those events that
threaten coastal areas. Data obtained by aircraft investigating potential
genesis events will positively impact operations and research in other ways as
well. The collection of three-dimensional data at all stages in a tropical
cyclone's lifecycle is one of the key requirements for NCEP as a part of the
IFEX experiment. Such data will provide information that will guide the
development of balance assumptions and error covariance matrices important in
the development of data assimilation schemes for models (i.e., HWRF) that will
be used in these environments. They will also provide important datasets for
evaluating the performance of HWRF. In addition to improving the understanding
and forecasting of tropical cyclogenesis and intensity change, the proposed
experiment will yield useful insight into the structure, growth and ultimately
the predictability of the systems responsible for almost all of the
weather-related destruction in the tropical Atlantic and East Pacific.
Investigation of systems that fail to complete the genesis process will also
result in a better understanding and prediction of easterly disturbances in
general so that distinction can be better made between developing and
non-developing tropical disturbances.
Milestones
- Collect radar, dropsonde, flight-level, and SFMR data within and around a
tropical disturbance undergoing genesis with near-continuous temporal coverage.
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Last modified: 8/28/2007
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