12.310
Assignment 2: The Geostrophic Wind
1. Reading & problems from Meteorological Manual
Read and complete problems from handouts of the
Meteorological Manual:
Ex 5. Fronts and Extra-tropical Cyclones and Ex.6 Upper Air Flow.
2. Current weather on the web
Practice
looking at the most recent surface and upper air maps using the PAOC
Synoptic Laboratory web
(http://paoc.mit.edu/synoptic)
Present Weather
Station Obs--Surface –
click on USA
(in the right hand column) and
print the latest USA map of surface observations and mean sea level
pressure. Complete and hand in the following:
a) Note
locations of high and low pressure
b) Note the direction of the wind around a low and a high
c) Where is the strongest wind on the map? What's the value? How does pressure vary
across this region?
d) What
is the surface pressure over the Boston area? (Switch to Massachusetts
map for a better reading)
Station Obs--Upper – print the latest 500 mb map.
The plot contains
individual station reports along with contours of the height of the
500mb surface and temperature.
e) Identify
large-scale troughs and ridges
f) Note the direction and strength of the upper level jet.
g) Write down the wind speed and direction over the New England
region.
The 500
mb winds are much stronger than the surface winds and are responsible
for the movement of the storms.
Do not forget to include date and time of observations in your
report.
Boston
Forecast
Check
on the weather forecast for Boston for the next few days by clicking
on:
Forecasts--US
– view the
surface forecast map from one of the model:
GFS
- surface
It
shows surface pressure and precipitation forecast over the US region
for next few days. What
would you expect to happen over
the Boston area for the weekend? Write a paragraph with
your description.
Do not forget to include date and time of when you prepared your
forecast.
3.
A case study: January 8, 2008
In this
second part of the assignment we will study the connection between
the wind and the pressure field on the large-scale, the so-called
‘geostrophic relationship’, using upper air and surface data from
the case of January 8, 2008, when a low pressure system was
affecting much of the Eastern US region.
For more on the rotating tank experiment we
performed in class, see the
balanced motion project in the "Weather in a Tank"
labguide.
Note: you don't need the web for this part of the Assignment. Use
the hand out given in class.
NOTE. This is what is expected from Assignment II:
Part 1- Reading
Reading + problems from 2 handouts:
Ex 5. Fronts and Extra-tropical Cyclones and Ex.6 Upper Air Flow.
Part 2 - Current Weather
a.) Answers to Station Observation questions (both Surface and Upper)
b.) Paragraph on GFS Forecast over Boston
Part 3 - Case Study
c.) Estimate of Rossby number for a 500 mb air
particle circumnavigating the globe.
d.) Geostrophic wind estimates at upper level.
e.) Geostrophic wind estimates at surface and
cross-isobaric angle.
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