Chapter 2: SEA SURFACE MICROLAYER
surface roughness is more important than that caused by rain except during
low wind speed conditions.
The application of the cool skin parameterization, including the rain
component, to the field measurements taken during COARE, shows some
additional surface cooling that is still generally less than 0.1
o C. The cooling
and mixing effects of the rainfall on the molecular sublayer partly
compensate each other so that the net effect on the temperature difference
almost vanishes. Nevertheless, the measured bulk versus skin temperature
difference across the cool skin shows a reduction of systematic deviations of
parameterized from measured differences when the rain effects are included.
The errors in the measured parameters and parameterization of the turbulent
surface fluxes that enter the surface renewal and mixed layer models,
however, prevent a statistically significant improvement between the
measured and parameterized cool skin. The salinity changes during rainfall
observed in the upper 2 to 3 cm of the ocean can only be explained when the
salinity difference across the haline molecular diffusion layer is included.
Studies of rain impacts on the sea surface have been limited to a single
rain drop-size distribution, namely the Marshall-Palmer distribution. While
this limitation is due to the fact that it is a distribution based on the rainrate
as the only available rain parameter (which is really not a justification), the
effects induced by a more precise drop-size distribution should be assessed.
Further work is necessary to analyze the effect of high-latitude types of
precipitation on the molecular boundary layers. For example, snowfall
certainly leads to enhanced surface cooling without much volume flux, while
hail falling on the sea surface penetrates deeper into the ocean than rain but
subsequently pops back to the surface. Precipitation in the form of hail
particles results in more complicated surface and volume fluxes because of a
prolonged decay time compared to rain or snow.
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surface roughness is more important than that caused by rain except during
low wind speed conditions.
The application of the cool skin parameterization, including the rain
component, to the field measurements taken during COARE, shows some
additional surface cooling that is still generally less than 0.1
o C. The cooling
and mixing effects of the rainfall on the molecular sublayer partly
compensate each other so that the net effect on the temperature difference
almost vanishes. Nevertheless, the measured bulk versus skin temperature
difference across the cool skin shows a reduction of systematic deviations of
parameterized from measured differences when the rain effects are included.
The errors in the measured parameters and parameterization of the turbulent
surface fluxes that enter the surface renewal and mixed layer models,
however, prevent a statistically significant improvement between the
measured and parameterized cool skin. The salinity changes during rainfall
observed in the upper 2 to 3 cm of the ocean can only be explained when the
salinity difference across the haline molecular diffusion layer is included.
Studies of rain impacts on the sea surface have been limited to a single
rain drop-size distribution, namely the Marshall-Palmer distribution. While
this limitation is due to the fact that it is a distribution based on the rainrate
as the only available rain parameter (which is really not a justification), the
effects induced by a more precise drop-size distribution should be assessed.
Further work is necessary to analyze the effect of high-latitude types of
precipitation on the molecular boundary layers. For example, snowfall
certainly leads to enhanced surface cooling without much volume flux, while
hail falling on the sea surface penetrates deeper into the ocean than rain but
subsequently pops back to the surface. Precipitation in the form of hail
particles results in more complicated surface and volume fluxes because of a
prolonged decay time compared to rain or snow.
141