Ocean Atmosphere Circulation

1
Ocean Atmosphere Circulation
2
UNEQUAL HEATING OF EARTH
BUT Outgoing solar radiation is not as uneven
3
Redistribution of heat controlled by

• Atmospheric circulation (including storms)
• Ocean circulation
• Wind driven surface circulation (lt1000 m)
• Density driven deep circulation
• Temperature
• Salinity

4
Sea Surface Temperature
http//www.ldeo.columbia.edu/dees/ees/climate/slid
es/sst_march.gif
5
Ocean Surface Salinity

• http//www.ldeo.columbia.edu/dees/ees/climate/slid
  es/sal_march.gif
• http//ingrid.ldgo.columbia.edu/

6
Temperature-Salinity Diagram used to show Density

• Used to plot density
• Each line is a line of equal density.
• The density range is given as 1.029 to 1.021
  (g/cm3)
• Water with a density of 1.027 g/cm3) could have a
  T of 0 oC and salinity of 33.5 o/oo or a T of 15
  oC and a salinity of 36.3 o/oo.

7
Ocean Salinity at 800 m depth.

• http//www.ldeo.columbia.edu/edu/dees/ees/data/fr_
  index.htm

8
Salinity _at_ 800 m water depth

• http//www.ldeo.columbia.edu/edu/dees/ees/data/fr_
  index.htm

9
Temperature _at_ 800 m water depth

• http//www.ldeo.columbia.edu/edu/dees/ees/data/fr_
  index.htm

10
Temperature-Salinity Diagram used to show Density

• Water Characteristics _at_ 800 m, just N or
  Gibralter
• Temperature 11.5 oC
• Salinity 36.2 o/oo
• Density 1.0276

11
Temperature-Salinity Diagram used to show Density

• Water Characteristics _at_ 800 m water depth, off
  easternmost point in South America
• Temperature 4.4 oC
• Salinity 34.5 o/oo
• Density 1.0275

12
Salinity _at_ 1200 m water depth

• http//www.ldeo.columbia.edu/edu/dees/ees/data/fr_
  index.htm

13
Temperature _at_ 1200 m water depth

• http//www.ldeo.columbia.edu/edu/dees/ees/data/fr_
  index.htm

14
Temperature-Salinity Diagram used to show Density

• Water Characteristics _at_ 1200 m water depth, just
  N or Gibralter
• Temperature 11 oC
• Salinity 36.2 o/oo
• Density 1.0278

15
Temperature-Salinity Diagram used to show Density

• Water Characteristics _at_ 1200 m, off easternmost
  point in South America
• Temperature 4.2 oC
• Salinity 34.5 o/oo
• Density 1.0275

16
Salinity _at_1750 m water depth

• http//www.ldeo.columbia.edu/edu/dees/ees/data/fr_
  index.htm

17
Temperature _at_1750 m water depth

• http//www.ldeo.columbia.edu/edu/dees/ees/data/fr_
  index.htm

18
Temperature-Salinity Diagram used to show Density

• Water Characteristics _at_ 1750 m, just N or
  Gibralter
• Temperature 6.4 oC
• Salinity 35.3 o/oo
• Density 1.0278

19
Temperature-Salinity Diagram used to show Density

• Water Characteristics _at_ 1750 m, off easternmost
  point in South America
• Temperature 3.8 oC
• Salinity 34.7 o/oo
• Density 1.0277

20

• http//www.ldeo.columbia.edu/edu/dees/ees/data/fr_
  index.htm

21
During an El Nino there are changes in
Wind Strength Sea Surface Temperature Atmospheric
Pressure Cause global changes in gt
precipitation productivity What starts the
process?
22
Sea Surface Temperature
http//www.ldeo.columbia.edu/edu/dees/ees/data/fr_
index.htm
23
Sea Surface Temperature
Sea Surface Temperature Shortened Scale
http//www.ldeo.columbia.edu/edu/dees/ees/data/fr_
index.htm
24
Wind Strength - Normal and El Nino Conditions,
Cross-Section View
Normal Year
El Nino Year
25
El Nino winds - map view
November, 1988 - Normal
November, 1982 -El Nino
View of how El Nino rearranges the distribution
of rainfall over the tropical Pacific. The colors
indicate the distribution of sea-surface
temperature. Red indicates warmer water, and blue
indicates colder water.
26
LaNina, Normal El Nino SST Conditions
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Normal Conditions
Normal Conditions
SST water T profile, Equatorial Pacific Ocean,
January, 1997
28
El Nino conditions
El Nino Conditions
29
Developing La Nina
Developing La Nina
30
Precipitation
El Nino Conditions
Northern Hemisphere Summer
31
El Nino Summary Websites
http//www.pmel.noaa.gov/ toga-tao/el-nino/nino-ho
me.htm http//earthobservatory.nasa.gov/ Observato
ry/Datasets/sst.avhrr.htmll
El Nino is a disruption of the ocean-atmosphere
system in the tropical Pacific having important
consequences for weather around the globe.
32
1982-1983 El Nino Impact
33
Class ended here

• You are not responsible for the material that
  follows, but incase you want to know more about
  monsoons read on.

34
El Nino websites

• Start here http//topex-www.jpl.nasa.gov/science/
  el-nino.html
•  
• http//earthobservatory.nasa.gov/Study/ElNinoColo
  r/
•  
• http//earthobservatory.nasa.gov/Study/ElNinoColor
  /el_nino_color_2.html
•  
• http//earthobservatory.nasa.gov/Study/ElNinoColor
  /el_nino_color_3.html
•  
• http//earthobservatory.nasa.gov/Library/ElNino/
•  
• http//earthobservatory.nasa.gov/Library/ElNino/el
  nino2.html

35
North Atlantic Oscillation Other Primarily
Atmospheric Teleconnections

• Primarily atmospheric
• Positive high pressure (CCW) around Iceland,
  low pressure (CW) in Azores
• Seems fairly steady

36
Southern Oscillation (SO)

• Monsoon connection 1877, 1899 no Indian monsoon
• 1904 Gilbert Walker
• High pressure (western Pacific) at Darwin and low
  pressure in Tahiti (central Pacific) heavy rain
  in central equatorial Pacific, drought in India,
  warmer winter in SW Canada, colder winter in SE US

37
EN SO

• 1957-1958
• Jacob Bjerknes (UCLA) atmospheric measurements
  and Pacific Ocean measurements
• El Nino extended 1000s of miles into Pacific
• Same atmospheric changes as Walkers SO

38
NAO Positive Mode

• Strong northern winter winds
• On average colder winters (winds brought down
  from Canada)
• European winters warmer and wetter (Gulf Stream
  influence) (e.g. more rain in Scandinavia

39
Monsoon Areas

• http//www.usda.gov/oce/waob/jawf/profiles/special
  s/monsoon/mon1.gif

40

• Unequal heat capacities of land and water
• The flow of air in sea breezes and land breezes
  (a) Afternoon onshore sea breeze. (b) Nighttime
  offshore land breeze.

41

• Valley breezes blow uphill during the day
  mountain breezes blow downhill at night. (The Ls
  and Hs represent pressure, while the purple lines
  represent surfaces of constant pressure.)

42

• Development of a sea breeze and a land breeze.
  (a) At the surface, a sea breeze blows from the
  water onto the land, while (b) the land breeze
  blows from the land out over the water.

43
Winter
http//www.usda.gov/oce/waob/jawf/profiles/special
s/monsoon/mon3b.gif
44
Onset of Indian Monsoon

• Indian Meteorological Department (IMD) predicts
  the onset date and rainfall potential of the
  monsoon using a statistical model that evaluates
  16 "precursor" conditions. Of the 16 parameters
  used,
• 6 regard temperature conditions,
• 3 wind or pressure field values,
• 5 pressure anomalies, and
• 2 snowcover.
• The most important of these appear to be
• 1) the position of the 500mb ridge centered over
  75 E longitude averaged over the month of April
• 2) monthly average temperatures over the Indian
  sub-continent (March and May monthly averages at
  different locations) and
• 3) El Niño/Southern Oscillation conditions.

45

• http//www.usda.gov/oce/waob/jawf/profiles/special
  s/monsoon/mon3a.gif

46

• http//www.usda.gov/oce/waob/jawf/profiles/special
  s/monsoon/mon5.gif

47
Monsoon Areas

• http//www.usda.gov/oce/waob/jawf/profiles/special
  s/monsoon/mon1.gif