Sergey Gulev, gulsail'msk'ru, sgulevifmgeomar'de

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AIR-SEA INTERACTION
Sergey Gulev, gul_at_sail.msk.ru,
sgulev_at_ifm-geomar.de

• Air-sea interaction is the redistribution of the
  solar energy through the exchange of properties
  between the ocean and the atmosphere and
  associated processes of the energy transformation
  in the ocean and the atmosphere.
• Hard core of the ocean-atmosphere coupling
• Boundary conditions for ocean and atmospheric
  GCMs
• Global and regional energy budgets of the
  ocean and
• atmosphere

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General assessment of energy sources in the
climate system
?1024 J/year
Incoming solar radiation
?2?1023 J/year
Evaporation
Advection of heat by ocean currents
?5?1022 J/year
Anthropogenic energy production
?5?1019 J/year
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Sea water and atmospheric air
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Major sea-air interaction processes
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Major sea-air interaction processes our outline

• Solar radiation (SW) absorption, reflection and
  scattering
• Infrared radiation emission, reflection and
  absorbtion
• Turbulent heat transfer
• Evaporation
• Precipitation
• Buoyancy flux at sea surface
• Turbulent transfer of kinetic energy by
  tangential components (stress)
• Turbulent transfer of kinetic energy by normal
  components (normal pressure)
• Ocean surface wave generation and decay
• Mixing in the atmosphere and generation of
  atmospheric vorticity in ABL
• Mixing (mechanical and convective) in the ocean
  and
• generation of water masses
• Gas transfer

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Major consequences of sea-air interaction
processes (will not be discussed, but very
important)

• Advection of heat by ocean currents and
  atmospheric flows
• 2. Instabilities in the ocean and atmosphere
• 3. Generation of temperature anomalies in the
  ocean
• 4. Generation of circulation anomalies in the
  atmosphere

Annual range of air tempe-rature (Monin 1968)
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SHORT-WAVE RADIATION AT SEA SURFACE
H SW? - LW? - Qh? - Qe?
100 65 8 27
Definition of sign is arbitrary, but important to
be set
Temperature of the Sun Tsun ? 5800K
Esun?Tsun4 99 of energy is within 0.2-3
? Solar constant (S0) annual mean amount of
solar radiation at the top of the atmosphere S0
1378 W/m2 (1359 1384 W/m2)
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The Earths orbit is not a perfect circumference,
but an ellipse Solar constant may vary while
the Earth is rotating
Solar radiation on the top of the atmosphere
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Sun brigthness How much brighter is the Sun as
viewed from the planet Mercury as compared to
Earth? How much fainter is it at Jupiter? These
questions can be answered through the inverse
square law. The equation relates the relative
distances of two objects as compared to a third.
Typically one of the objects is Earth, the second
is a space craft and the third is the Sun. There
is a certain amount of sunlight reaching Earth at
any given moment. This is not an absolute
quantity because Earth is closer to the Sun at
some times of the year verses others and the
number of sunspots effects the Sun's energy
output. Overall, however, the Sun is remarkably
constant in its behavior. The amount of the
Sun's energy reaching Earth is 1 solar constant.
The average distance from the Sun to Earth is
149,597,870.66 kilometers, (1 Astronomical Unit
or 1 AU). So Earth is 1 AU from the Sun and
receives 1 solar constant. The relationship can
be expressed most simply as 1/d2 where d
distance as compared to Earth's distance from the
Sun. At 1 AU, Earth receives 1 unit of sunlight
what we generally might associate with a bright
sunny day at noon. How much sunlight would a
spacecraft receive if it were twice as far from
the Sun as Earth? The distance from the Sun to
the spacecraft would be 2 AUs so... d 2. If we
plug that into the equation 1/d2 1/22 1/4
25. The spacecraft is getting only one quarter
of the amount of sunlight that would reach it if
it were near Earth. This is because the light is
being radiated from the Sun in a sphere. As the
distance from the Sun increases the surface area
of the sphere grows by the square of the
distance. That means that there is only 1/d2
energy falling on any similar area on the
expanding sphere. Mercury is at 0.387 AUs. 1/d2
1/0.3872 1/.15 666.67, almost seven times
brighter! We can use this method to compare any
spot in the Universe if we describe its distance
as compared to Earth relative to the Sun. Mars
is at a distance of 1.5 AUs from the Sun. 1/d2
1/1.52 1/2.25 44. Jupiter is at 5.2 AUs so
1/d2 1/5.22 1/27 3.7
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To know how much of solar radiation comes to the
surface, you should know what happens with the
solar energy in the atmosphere Spectral view
What this range is about?
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Radiation on the top of the atmosphere
Radiation on the Earths surface
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• SW radiation at
• sea surface is
• determined by
• Solar altitude
• Molecular
• diffusion
• Gas absorption
• Water vapor
• absorption
• Aerosols
• diffusion

Measurements
Modelling
Parameterization
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Measurements of SW radiation
Downwelling shortwave (SW) radiation can be
measured with the pyranometer, facing skyward.
Modern pyranometers are still based on the
Moll-Gorczynski design (Moll 1923) in which
radiation falls on a blackened horizontal
receiving surface bonded to a thermopile and
protected by two concentric precision
hemispheric glass domes.

• The most important factors affecting the accuracy
  of these instruments
• reliability and stability of calibration,
• dome temperature effects,
• cosine response,
• detector temperature stability.
• Another source of error, particular to
  pyranometers used at sea, is caused by the
  platform motion. For correct measurement the
  receiving surface must be horizontal, but both
  ships and buoys can roll through several degrees.
  Uncertainty of daily average can be as large as
  10-20. At sea pyranometers must be set in
  gimbals.

Moll-Gorczynski pyranometer
Multi-Filter Rotating Shadowband Radiometer
(MFRSR)
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Where to find/buy/order a perfect package?
http//www.arm.gov/instruments/instclass.php?idra
dio
http//www.kippzonen.com/pages/1250/3/HowcanIkeepb
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Solar altitude
Compute solar altitude for 0700 GMT
05.04.2006 35 N, 55 W Derive the dependence
of solar altitude on latitude for 1200,
04.04.2006 hour for 45 N /home/gulev/problems
/solar.f
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