The Ocean's Skin Layer in the Tropics

Area of Science:

• Oceanography
• Atmospheric Science
• Geophysics

Background:

• The ocean's skin layer, the uppermost microlayer, plays a critical role in air-sea interactions.
• Understanding salinity and temperature anomalies in this layer is vital for climate modeling.

Purpose of the Study:

• To present a large dataset on ocean skin layer salinity and temperature anomalies.
• To investigate the impact of meteorological forcing (rain, wind) on these anomalies.
• To explore the implications of skin layer properties on buoyancy fluxes.

Main Methods:

• Collection of a large dataset on ocean skin layer salinity and temperature anomalies.
• Utilizing infrared thermography for temperature anomaly measurements.
• Analysis of meteorological data including rain rates and wind speed.

Main Results:

• Observed average salinity anomaly of 0.40 PSU, with 83% of observations showing a saltier skin layer.
• Confirmed a cooler skin layer in 75% of observations, with temperature anomalies between -0.23 and -0.19 °C.
• Documented immediate freshening under light rain and masking of freshening by strong winds during heavy rain.

Conclusions:

• Skin layer salinization by evaporation influences buoyancy fluxes.
• Denser skin layers can remain afloat due to interfacial tension.
• These processes are key for regulating climate-relevant gas and heat exchange between the ocean and atmosphere.