Lab I: Conceptual Models of Cyclone Evolution
Due: Friday 24 January
Answer the following questions concerning the evolution of extratropical
cyclones. Be thorough in your explaination. To research your answers,
refer to Bjerknes and Solberg (1922), Godske et al. (1957), Reed (1990),
and Shapiro and Keyser (1990). These papers are available in the synoptic
meteorology notebook in the CVL.
Problem 1:
What did Bjerknes and Solberg assert was the source of the kinetic
energy of the extratropical cyclone? How in their view did the
kinetic energy and associated energy transformations change during
the course of a cyclone's life cycle?
Problem 2:
Identify and describe four modifications and extensions that should
be made to the Norwegian Cyclone model based on scientific
advances over the past 75 years. Also explain why these
modifications are necessary.
Problem 3:
On 20 January 1993 a major extratropical
cyclone developed over
the eastern Pacific and made landfall on the northern Washington/southern
British Columbia coast producing wind gusts of up to 88 miles per hour
in the Seattle Metropolitan area. Using output from a high resolution
mesoscale model, analyze the forecast frontal structure of the storm
at forecast hours 6, 9,
and 12 following the conceptual model of
Godske et al. (1957) or Shapiro and Keyser (1990). Choose the
conceptual model to use based on which one you believe best
fits the simulated evolution. Note that these are color plots of
sea level pressure (every 2 mb) and 900 mb temperature (every 2C;
not plotted where the 900 mb surface is under ground) that should be
spooled to color printer cirp-c.
Explain your choice of conceptual model. Some questions you might
want to address include: Does frontal fracture occur? Does
the cyclone exhibit a "T-bone-like" frontal structure with the cold
front moving perpendicular to the warm front or does the classic
process of occlusion appear to occur? Be sure to turn in your 3-hourly
frontal analyses with your write up.