ANSWERS PAGE
Q1 - The bundle should load showing the height field
pictured in the previous “Loading the IDV Bundle” section. Based on the labeled
contours (geopotential meters), what traditional
isobaric surface do you think this height field represents?
Answer: 500 hPa
Q2 - What is the unit of relative vorticity according to
the contour interval listing?
Answer: The unit for relative vorticity is
1/s or s^-1
Q3 – What is the maximum absolute vorticity at 500-hPa in
the trough for the entire loop? Over what state is this located? At what time
does this occur?
Answer: The highest value of absolute
vorticity shown is 39 s^-1. It is located over eastern
Q4 – Does it appear that the 850-hPa low and the 500-hPa
low are vertically stacked? If they are, what typically will happen to the
reconstituted system? (Hint: Will the system begin to move quicker or slower,
become intense or weaken?)
Answer: Yes, the lows appear to be
vertically stacked. Such systems typically are weakening and are slow-moving,
and are less likely to produce severe weather than tilted systems.
Q5 – Do the geopotential
heights at 500-hPa form a closed low? If so, where?
Answer: Yes the 500-hPa low closes off. It
closes over western
Q6 – Fill in the blanks: If the geostrophic
vorticity is _________ (becoming more cyclonic), then geopotential
heights are _________ (all else being equal).
Answers: increasing, falling
Q7 – Is there PVA or NVA ahead of the low pressure
system? What is this doing the 500-hPa height field ahead of the low?
Answer: There is PVA ahead of the low in
each of the frames. Because of the PVA, there are falling heights ahead of the
low which help to propagate the low eastward.
Q8 - Do you see upward vertical motion downstream or
upstream of the region of maximum absolute vorticity? How about downward
vertical motion? Why is this?
Answer: There is upward motion downstream
of the area of maximum vorticity. This is because of the strong PVA leading to
divergence aloft, which must be compensated for at the surface by horizontal
convergence. There is downward motion behind the area of maximum vorticity.
This is because of strong NVA leading to convergence aloft, subsequent
divergence at the surface leading to the column having net downward motion.
Q9 – What is the sign of Term B, 
, ahead of the low as it progresses eastward? What about
behind the low? (Hint: remember the qualities of a Laplacian).
Answer: The sign of Term B is positive
ahead of the low and negative behind the low.
Q10 – Does vorticity advection act to amplify or
propagate the trough?
Answer: The PVA on the eastern side of the
low pressure system acts to propagate the system to the east.
Q11 – Identify the regions on this map would you expect
to have the best WAA and CAA?
Answer: The area of best WAA would be
through
This may help to visualize this:
Q12 – Do you expect the WAA and CAA to propagate or
amplify the ridge/trough?
Answer: Differential temperature advection
enhances upper level height anomalies in disturbances. Below the 500-hPa ridge
there is strong WAA associated with the warm front. This increases thickness,
thus building the upper level ridge. Below the 500-hPa trough there is strong
CAA, which decreases the thickness, thus deepening the upper level trough.
Q13 – When the sum of Term B and Term C is negative, what
is the sign of ω? Is there upward or downward motion?
Answer: When the sum of terms B and C is
negative, ω is positive. This implies downward motion.
Q14 – When the sum of Term B and Term C is positive, what
is the sign of ω? Is there upward or downward motion?
Answer: When the sum of terms B and C is
positive, ω is negative. This implies upward motion.
Q15– In order for Term A to be positive, what should the
sign of the low-level thermal advection be (in the absence of a vertical
variation in absolute geostrophic vorticity
advection)?
Answer: In order for Term A to be positive
(upward motion), Term C must be positive (in the absence of a vertical
differential of geostrophic absolute vorticity
advection, Term B = 0, or if there is a negative height differential of
absolute vorticity advection, Term B is negative). Term C (+) implies that
there is WAA.
Q16– In order for Term A to be negative, how should the geostrophic advection of geostrophic
absolute vorticity advection vary with height (in the absence of temperature
advection)?
Answer: In order for Term A to be negative
(downward motion), Term B must be negative (in the absence of thermal
advection, Term C = 0, or if there is negative geopotential
thickness advection, Term C is negative). Term B (–) implies that absolute geostrophic vorticity advection decreases with increasing
height (decreasing pressure).
Now try the same concept
as presented in the module with real-time data . Go to
the Lead Portal by clicking here .
- Create
an account: Step 1
- Log
in: Step 2
- Once
you have logged in, you should see a page similar to the one below
- You
will want to take a tutorial on the experiment builder (#3) as well as the
geographic data search (#4) in order to know how to request real time data
from the Lead Portal.
- Once
you have completed the tutorials, we now can access the data and visualize
it in IDV according to the parameters in the Q-G Omega module.
- In
IDV, you will want to go to the dashboard. Shown Below.
- Go
to the 3D grid heading under the fields section, under that you will want
to click “Geopotential height at isobaric levels.” (#5)
- In the display section Contour Plan View.(#6)
- In the Time section keep it as default or select
the times you want to view.
- In the Level section select 850 hectopascals.
(#7)
- Finally, click the button create display. (#8)
- Do
the same procedure for the rest of the parameters.
- For
Geopotential heights
- 3D Grid
▪
Geopotential height at
isobaric levels
▪
Under Displays : Contour
Plan View
▪
Under level section : 500
hectopascals
▪
Create Display
- For
Temperature
- 3D Grid
▪
Temperature at isobaric
levels
▪
Under Displays : Contour
Plan View
▪
Under level section :
850 hectopascals
▪
Create Display
- For
vertical velocity
- 3D Grid
▪
Pressure vertical
velocity at isobaric levels
▪
Under Displays : 3D
Surface Isosurface
▪
Under level section :
default
▪
Create Display
▪
Repeat vertical velocity
again
- For
Wind
- 3D Grid
▪
Derived
▪
True Wind Vectors
▪
Under Displays : Vector
Plan View
▪
Under level section :
850 hectopascals
▪
Create Display
- For
Vorticity
- 3D Grid
▪
Absolute vorticity at
isobaric levels
▪
Under Displays : Contour
Plan View
▪
Under level section :
500 hectopascals
▪
Create Display
- For
Thickness
- 2D Grid
▪
Derived
▪
1000-500 hPa Thickness
▪
Under Displays : Contour
Plan View
▪
Under level section :
default
▪
Create Display
- Now
that you have all the parameters for the Q-G Omega module, we will have to
adjust them to look similar to the module's parameters.
- Go
into the dashboard and click the displays tab.
- Now for
Geopotential heights for 850 hPa
▪
Under
View 1 select the first: “Z – Contour Plan View”. (#9)
▪
Make
sure Levels is at 850.
▪
Click
the color range and change the range to 1290 – 1650. (#10)
- Now for Geopotetial
heights for 500 hPa
▪
Under
View 1 select the second: “Z – Contour
Plan View”.
▪
Make
sure Levels is at 500 hPa.
▪
Click
the color range and change the range to 5280 – 5880.
- Now for Temperature
▪
Under
View 1 select: “T – Contour Plan View”.
▪
Click
the color range and change the range to -30 – 30.
▪
Click
on the Change button and change interval to 3. (11#)
- Now for upward vertical velocity
▪
Under
View 1 select the first : “omega – isosurface”
▪
Click
default. (#12)
▪
Solid
▪
Green
▪
Change
isosurface value to -.25 (#13)
- Now for downward vertical velocity
▪
Under
View select the second : “omega – isosurface”
▪
Click
default
▪
Solid
▪
Cyan
▪
Change
isosurface value to .35
- Now for Wind
▪
Under
View 1 select: “truewindvectors
▪
Change
Skip Interval to 1. (#14)
- Now for Vorticity
▪
Under
View 1 select: “absvor – Contour Plan View”
▪
Click
the “Change” button and change the Contour Interval to 3
▪
Click
on the color range and change the range to 15 – 42.
▪
Click
the “ – ” sign till you have 6 colors. (#15)
▪
Now
click on the upside down triangle and drag it over the first block. (#16)
▪
Change
the numbers to match the picture below.
▪
Make
sure you hit enter after you put a new number in.
▪
Now
drag the triangle over the second block and match the picture below.
▪
For
the third block match the picture below.
▪
For
the fourth block match the picture below.
▪
For the
fifth block match the picture below.
▪
Lastly,
for the sixth block match the picture below.
- Now for Thickness
▪
Under
View 1 select: “thickness_100_500”
▪
Click
the color range and change the range to 5160 – 6000.
- Now
you should have all the parameters similar to the one in this module.
- You
are able to now go through the worksheet with real-time data.