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180
170 W
160 W
150 W
140 W 130 W 120 W110 W 100 W 90 W
60 N
50 N
40 N
COASTAL ZONE
30 N
Fig. 23.1
The EnKF domain used in this study. The coastal zone used to identify land-falling
mid-latitude cyclones is outlined by the
thick black lines
and the North American coastline
1993
), the Noah land surface model (
Chen and Dudhia 2001
), WRF Single-
Moment 3-class microphysics (
Hong et al. 2004
), the Rapid Radiative Transfer
Model (RRTM) longwave radiation scheme (
Mlawer et al. 1997
), and the Dudhia
shortwave radiation scheme (
Dudhia 1989
).
23.3.2
Description of the Response Function
and Case Selection
The response function used in these experiments to diagnose land-falling cyclones
is the average sea-level pressure in a 216 km by 216 km box surrounding the 24-h
forecast ensemble mean cyclone center. Only cyclones that could be identified as
a local minimum and tracked back for the 24-h forecast period were included.
Observation targeting calculations based on the methodology of
Ancell and
Hakim
(
2007a
) are performed for every 24-h forecast cyclone that was found in
the coastal zone (outlined in Fig.
23.1
) over the 6-month duration of this study.
A total of 27 storms were found to impact the coastal zone over this time, which
is a typical frequency for wintertime land-falling cyclones. However, each storm
lasted for several days and its position at the 24-h forecast time would be within the
coastal zone over several consecutive forecast runs. Therefore, targeting calculations
were made several times for each storm, resulting in a total of roughly 200 cases.
Tab le
23.1
characterizes each forecast run of these storms with regard to their
deepening rate and direction of coastal approach, two aspects that are analyzed
later in this section. It should be noted that it was not possible to characterize each
of the 27 individual storms as deepening or decaying as a particular event may
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