Download 1. A - Montana State University

In the News: SNOW!!!
• 8 inches ((official)) reported
p
as of 8 am
Bozeman
• Snotel:
– Brackett cr. 9”
– Sacajawea 3”
3
– Lone Mt. 1”
– Lick
Li k cr. 1”
1
http://cateye.msu.montana.edu/
Atmospheric Circulation
a)
b)
c)
d)
e)
f)
Global atmospheric circulation
Semipermanent Pressure Cells
Upper Troposphere Patterns
Oceans
Major Wind Systems
Air-Sea
Air
Sea Interactions
2
Sea surface temperature index during mild 2006 El Nino.
http://earthobservatory.nasa.gov/Newsroom/NewImages/Images/ElNino_JAS_20060905_lrg.jpg
f) Air-Sea Interactions
ENSO is *variable* in space, time, and
intensity,
y thus so are teleconnections!
3
Textbook Figure 8-30
f) Air-Sea Interactions
ENSO-related teleconnections:
4
Textbook Figure 8-33
f) Air-Sea Interactions
El Niño Southern Oscillation Index
(ENSO):
ƒ ENSO = TahitiSLP – DarwinSLP
ƒH – L = +
ƒL – H = -
Darwin
Tahiti
5
f) Air-Sea Interactions
ƒ ENSO = TahitiSLP – DarwinSLP
L–H=* Negative
ENSO =
El Niño
Niño*
H
L
6
f) Air-Sea Interactions
ƒ ENSO = TahitiSLP – DarwinSLP
H–L=+
* Positive
ENSO =
La Niña*
Niña
L
H
7
f) Air-Sea Interactions
El Niño Southern Oscillation Index (ENSO):
http://www.cgd.ucar.edu/cas/catalog/climind/soiAnnual.html
L Niña
La
Niñ
El Niño
8
f) Air-Sea Interactions
El Niño Southern Oscillation Index (ENSO):
http://www.ncdc.noaa.gov/paleo/recons.html#ocean
Cook et al. 2000 NINO3 Reconstruction
2.5
2
La Niña
NINO3 Index
x
1.5
1
0.5
0
-0.5
-1
-1.5
1400
El Niño
Niñ
1500
1600
1700
time (yr AD)
1800
1900
2000
f) Air-Sea Interactions
ENSO Impacts: Fire in the southwest
Dry
Springs
Wet
Springs
Time (year AD)
Swetnam, T. W., and J. L. Betancourt. 1990. Fire-southern
Fire southern oscillation relations in the southwestern United States.
Science 249:1017-1020.
In The US Southwest: La Nina Æ dry springs
El Nino Æ wet springs
10
10
f) Air-Sea Interactions
Pacific Decadal Oscillation (PDO)
ƒ Shift in SST between N/NW Pacific and E tropical
Pacific
ƒ + values Æ warm eastern tropical Pacific (warm phase)
ƒ - values Æ cool eastern tropical Pacific (cool phase)
Warm phase
Cool phase
11
http://jisao.washington.edu/pdo/
f) Air-Sea Interactions
Pacific Decadal Oscillation (PDO)
Warm phase – warm water, eastern tropical Pacific
Cool phase – cool water,
water eastern tropical Pacific
12
http://jisao.washington.edu/pdo/
f) Air-Sea Interactions
Arctic Oscillation (AO) and
North Atlantic Oscillation (NAO):
ƒ Pressure oscillation between Icelandic Low and
Bermuda-Azores High pressure centers
ƒ Warm phase (+): low surface pressure over Arctic,
high surface pressure at lower latitudes (ca 45
45°))
ƒ Cool phase (-): high pressure over Arctic, low
pressure at lower latitudes
13
f) Air-Sea Interactions
Phase relationships: phase of one oscillation
affects the impacts of other oscillations
% of ye
ears
Subalpine Forest Fires in Rocky
Mountain National Park:
Expected
E
t d fire
fi occurrence (1700-1978)
(1700 1978)
Observed fire occurrence (n = 17)
Phase Combination
14
Sibold, J. S., and T. T. Veblen. 2006. Relationships of subalpine forest fires in the Colorado Front Range with interannual and multidecadal-scale climatic
variation. Journal of Biogeography 33:833-842.
Air Masses and Fronts
(ERTH 303 November 12, 2009)
a. Formation and types of air masses
b Fronts
b.
F
t
15
http://www.srh.weather.gov/srh/jetstream/synoptic/airmass.htm
http://www.opc.ncep.noaa.gov/UA.shtml
a) Formation of air masses
Air masses:
ƒ
ƒ
Large volumes
ol mes of air (subcontinental)
( b
ti
t l) with
ith ≈
uniform characteristics (temp., humidity)
Source regions:
ƒ
ƒ
Area of uniform topography and surface
conditions
diti
Only occur in mid to high latitudes
Identified by moisture content and temperature
ƒ
Continental (c) or Maritime (Marine) (m)
ƒ
A ti (A)
Arctic
(A), Polar
P l (P),
(P) Tropical
T
i l (T)
16
a) Types of air masses
17
Textbook Figure 9-1
a) Types of air masses
18
Textbook Table 9-1
a) Types of air masses
Continental polar (cP) and Continental
Arctic :
19
http://ww2010.atmos.uiuc.edu/(Gl)/guides/mtr/af/arms/artc.rxml
a) Types of air masses
Continental polar (cP) vs. Continental
arctic (cA):
ƒ cA shallow relative to cP
ƒ cA rarely reaches CAN – US border
Textbook Figure 9-2
Latitude
20
a) Types of air masses
Maritime polar (mP):
ƒ Originate in high-latitude
high latitude oceans
ƒ Cool and moist
ƒ
ƒ
Commonly affect PNW in winter
Affect East Coast via northeasters (aka:
nor’ easters)
21
a) Types of air masses
M ii
Maritime
polar
l (mP):
( P) nor’’ easters
22
Textbook Figure 9-2
a) Types of air masses
Continental tropical (cT):
ƒ Originate over desert regions (e.g.
southwestern US)
ƒ Hot and dry
ƒ Inherently unstable (but still dry)
Maritime tropical (mT):
ƒ Originate over tropical oceans (e.g. Gulf
of Mexico)
ƒ Warm and moist
23
ƒ Inherently unstable
a) Types of air masses
(equatorial)
Textbook Table 9-1
http://rst.gsfc.nasa.gov/Sect14/air_masses_2.jpg
(antarctic)
24
b) Fronts
Four fronts:
ƒ Cold
ƒ Warm
ƒ Stationary
ƒ Occluded
25
Textbook Figure 9-4
b) Fronts
Cold Fronts:
ƒ
ƒ
Cold air displaces warm air
Steep uplift causes cumulonimbus clouds
and
d heavy
h
precipitation
i it ti
26
Textbook Figure 9-5
b) Fronts
Cold Fronts:
ƒ
ƒ
surface slope 1:100
Moves in different direction from
warm air ahead of front
27
Textbook Figure 9-6
b) Fronts
Warm Fronts:
ƒ
ƒ
ƒ
Warm air displaces cold air
Warmer air flow upward along boundary
(
(overrunning)
i )
Shallow lifting produces stratus clouds
and light precipitation
28
b) Fronts
Warm Fronts:
29
Textbook Figure 9-8
b) Fronts
Stationary Fronts:
ƒ
Nonmoving
boundary between
cold and warm
front
ƒ
Frontal boundary
y
slopes towards
cold air
30
b) Fronts
Occluded Fronts:
ƒ
Formed with a cold front overtakes a warm
front
ƒ
Creates complex weather
ƒ
Precipitation associated with warm air being
forced aloft
31
Textbook Figure 9-10
b) Fronts
Occluded Fronts:
ƒ
Cold type occlusion: air behind front colder
Cold-type
than air it is overtaking; mostly occurs east of
the Rockies
ƒ
Warm-type occlusion: air behind front warmer
than air it is overtaking;
g mostly
y occurs on west
coast (e.g. mP overtakes cP)
32
b) Fronts
Occluded Fronts:
33
Textbook Figure 9-10
b) Fronts
Occluded Fronts:
Other sources:
Intersection of
cold
ld and
d
warm fronts
moves along
warm front
34
Textbook Figure 9-11
b) Fronts
Fronts: defined
subjectively
based on
ƒ
Temperature changes
ƒ
Dew point changes
ƒ
Bands of clouds
ƒ
Wind direction changes
((NW in cold sector,, SW
in warm sector)
ƒ
Pressure changes
35
Textbook Figure 9-7
09.01
Which air mass has a source region at “A”?
A?
1. continental Tropical
p
2. maritime Tropical
3. continental Polar
4. none of these
A
Courtesy, CIA
09.01
Which air mass has a source region at “A”?
A?
1. continental Tropical
p
2. maritime Tropical
3. continental Polar
4. none of these
A
Courtesy, CIA
09.02
Which of the following describes continental
Tropical air masses?
1. A
A
B
2. B
3. C
4. D
C
D
09.02
Which of the following describes continental
Tropical air masses?
1. A
A
B
C
D
2. B
3. C
4. D
09.03
This figure shows a(n) _______.
1. upper
pp air disturbance
2. middle latitude cyclone
3. anticyclone
y
4. occluded front
09.03
This figure shows a(n) _______.
1. upper
pp air disturbance
2. middle latitude
cyclone
3. anticyclone
4. occluded front
09.04
Which frontal symbol is used for a stationary
front?
A
1. A
2. B
3. C
B
C
D
4. D
09.04
Which frontal symbol is used for a stationary
front?
A
1. A
2. B
3. C
B
C
D
4. D
09.05
Which frontal symbol is used for a warm front?
A
1. A
2. B
3. C
B
C
D
4. D
09.05
Which frontal symbol is used for a warm front?
A
1. A
2. B
3. C
B
C
D
4. D
09.06
This diagram shows _______.
1. a cold front
2. an arctic front
3. a middle latitude
cyclone
4. overrunning
09.06
This diagram shows _______.
1. a cold front
2. an arctic front
3. a middle latitude
cyclone
4. overrunning
09.07
Over the next few days this warm front will
probably _______.
1. stayy the same
2. become less steep
3. become more steep
p
4. become a cold front
09.07
Over the next few days this warm front will
probably _______.
1. stayy the same
2. become less steep
3. become more steep
p
4. become a cold front
09.08
An occluded front will first form at _______.
1. C
2. D
3. E
4. F
D
C
E
F
09.08
An occluded front will first form at _______.
1. C
2. D
3. E
4. F
D
C
E
F
09.09
This cross section shows a(n) _______ front at
the surface.
1. cold
2. warm
3. stationaryy
4. occluded
?
09.09
This cross section shows a(n) _______ front at
the surface.
1. cold
2. warm
3. stationaryy
4. occluded
?
09.10
This map shows a(n) _______.
1. set up
p for tornadoes
2. northeaster
3. huge
g continental
Tropical air mass
4. anticyclone
09.10
This map shows a(n) _______.
1. set up
p for tornadoes
2. northeaster
3. huge
g continental
Tropical air mass
4. anticyclone
09.11
At “A
A,” _______ is the name of the air mass
mass.
1. continental Polar
A
2. Great Lakes
3. maritime Polar
4. maritime Tropical
09.11
At “A
A,” _______ is the name of the air mass
mass.
1. continental Polar
A
2. Great Lakes
3. maritime Polar
4. maritime Tropical
09.15
Maritime Tropical air has a source region at ___.
1. A
2. B
3. C
C
D
4. D
B
A
Courtesy, CIA
09.15
Maritime Tropical air has a source region at ___.
1. A
2. B
3. C
C
D
4. D
B
A
Courtesy, CIA
Midlatitude Cyclones
a. Why do we care
about
midlatitude
cyclones?
l
?
b. Polar front
theory
c Life cycle of a
c.
midlatitude
cyclone
l
60
http://upload.wikimedia.org/wikipedia/commons/2/2c/Feb242007_blizzard.gif
a. Why midlatitude cyclones?
Midlatitude cyclones:
Low pressure center characterized by the presence of
frontal boundaries; travel great distances and affect
large areas
61
http://upload.wikimedia.org/wikipedia/commons/3/35/Extratropical_formation_areas.jpg
a. Why midlatitude cyclones?
Midlatitude cyclones:
62
Textbook Figure 10-1.
a. Why midlatitude cyclones?
Midlatitude cyclones:
Look at latest:
http://www.hpc.ncep.noaa.gov/basicwx/day07loop html
7loop.html
63
http://upload.wikimedia.org/wikipedia/commons/3/35/Extratropical_formation_areas.jpg
b. Polar Front theory
Polar Front Theory:
ƒ Vilhem Bjerknes, Bergen Norway,
early 20th century
ƒ Described formation, growth, and
dissipation of midlatitude cyclones
Vilhemn Bjerknes, 1862-1951.
Norwegian Geophysicist who
developed Polar Front Theory
Theory.
http://media-2.web.britannica.com/eb-media/95/65195-004-2ED1EBA5.jpg
http://upload.wikimedia.org/wikipedia/en/0/01/Vilhelmbjerknes.jpg
64
b. Polar Front theory
65
c. Life cycle of a midlatitude cyclone
Cyclogenesis
ƒ Begins
B i along
l
the
th polar
l front
f
t
ƒ Low p
pressure forms
ƒ Fronts develop
66
c. Life cycle of a midlatitude cyclone
Cyclogenesis
67
Life cycle of a midlatitude cyclone
Cyclogenesis:
68
c. Life cycle of a midlatitude cyclone
Cyclogenesis
ƒ Begins
B i along
l
the
th polar
l front
f
t
ƒ Low p
pressure forms
ƒ Fronts develop
69