SAN FRANCISCO STATE UNIVERSITY          NAME _______________________

DEPARTMENT OF GEOSCIENCES                                                               Spring 2006

 

METR 490/790:  MONTEVERDI QUIZ 1 -- Key

Open Book and Open Notes

200 points, 80 minutes

 

1.  Compute the altitude of a geostationary orbit for Mars.  (radius = 3,397 km; mass=6.4219 X 1023 kg; orbital period=~24 h). (50 points)

 

Show all work.  Label all equations sequentially with numbers.

 

Problem 1:

 

Equations Needed

 

                                 (1)

                          (2)

                                                       (3)

 

Relations or Constants Needed

 

(4)

 

 

Solution

 

For a geosynchronous orbit,

 

Fc = Fg                                                                (5)

Insert (1), (2), (3) and (4 b, d and e) into (5) and solve for R3

 

R3=8.056 X 1021  m3                     (6)

 

R=2.005 X 107  m                         (7)

 

Substitute (4a and b) into (7) and solve for h

 

h=1.66 X 107  m = 16,600 km            (8)

 

2.  Examine the satellite images below (55 points):

 

 

Satellite Image A

 

 

Satellite Image B

 

A.  State whether the satellite images were from the imagers of a geostationary satellite or a polar orbiter, and why. (15 points)

 

The images are from the GOES-12 satellite.  The images are labeled as such at the bottom of the image.  Also, the imagery has a much wider east-west extent than imagery from the POES.

 

B.  State the size of a cloud element for the two images, and why.  (15 points)

 

The images have a resolution of 4 km.  The images are so labeled on the bottom.  Since a cloud element is the smallest resolvable feature on the imagery, a cloud element would have a diamter of 4 km on these images.

 

C.  What is the cloud top temperature at the border of Louisiana and Mississippi? (10 points)

 

The color temperature on the infrared image in the area of the Louisiana/Mississippi border is a return black to white.  This corresponds to a temperature between -60 and -70 C.

 

D.  Although the Satellite Image B uses a color enhancement curve, that enhancement most closely resembles which of the following grey scale enhancement curves:  (a) Standard; (b) ZA; (c) MB.  (5 points)

 

E.  The color enhancement probably is designed to highlight what features of meteorological significance.  Explain. (10 points)

 

It appears that the color enhancement is designed to capture the coldest cloud tops associated with convection, possibly severe thunderstorms.  In the case of this image, the return black/grey clearly is the anvil top of a thunderstorm, possibly severe.

 

3.  Examine the enhancement curve given below.  (20 points)

 

A.  What is the designation (name) of this enhancement curve? (10 points)

 

This is the MB enhancement curve, designed to highlight convective storms.

 

B.  At what two temperatures is the ZA enhancement designed to produce a marked grey-scale change obvious to the human eye. (10 points) 

 

ZA Enhancement

There is a color shift from black to gray scale or gray scale to white at around 30 C and -78 to -80C, respectively.  There are also marked gray scale shifts at around 12C and -55 to -60C.

 

4.  The following image is a GOES-10 Visible 4 km image processed by the US Navy. (30 points)

FEDCBA

 

Locate the following by putting the appropriate letter right on the image:  (a)  Cloud line;

(b)  Cloud band;  (c)  Cloud shield;  (d)  Cloud street;  (e)  Open cell cumulus field; and, (f)  Closed cell cumulus field

 


5.  Examine the figure below.  (15 points)

 

 

(a)  Which instrument on the GOES platform senses the data used to create this plot? (5 points)

 

The GOES sounding instrument senses the data used to create this sounding.

 

(b)  Although the plots of this sort are quite accurate, there is a danger in overrelying on them to infer potential for convection, for example.  Briefly state what that danger is. (10 points)

 

The GOES-sounder only detects information for around 22 levels.  Actual soundings may  have much more structure/detail than suggested by the GOES sounding, and stable layers/inversions/unstable layers may be misdiagnosed or misdescribed by the GOES soundings.


6.  Examine the MOSDIS image below: (30 points)

 

 

A.  State how you would know that this image was produced from data sensed by a polar orbiting satellite, even without legend information on the image. (5 points)

 

The image shows part of the polar regions.

 

B.  The Aqua satellite has an orbit designed to pass different points on the earth’s surface at two times (12 hours apart) during the day and at night each 24 hour period.  What are those times?   __1:30____ PM and  ____1:30____ AM. (10 points)

 

C.  The thermal infrared sensors for both the POES and GOES series detects infrared energy emitted by the earth and clouds passing through the so-called INFRARED or ATMOSPHERIC WINDOW.  Define the “infrared window” and give the approximate range of wavelengths to which it corresponds. (15 points)

 

The infrared or atmospheric window is the transparent portion of the water vapor spectrum through which emitted long wave radiation is allowed free passage to space.  It corresponds generally to the range of wavelengths 7 to 11 microns.