Warm layer and cool skin corrections for bulk water temperature measurements for air‐sea interaction studies

• Published in: Journal of geophysical research. Oceans 2017-08, Vol.122 (8), p.6470-6481
• Main Authors: Alappattu, Denny P., Wang, Qing, Yamaguchi, Ryan, Lind, Richard J., Reynolds, Mike, Christman, Adam J.
• Format: Article
• Language: English
• Subjects: Air temperature; Air-sea interaction; Buoys; CASPER; Coastal environments; cool skin; Corrections; Flux; Geophysics; Infrared radiometers; Long wave radiation; Mapping; Measurement; Ocean temperature; Radiation; Radiation flux; Radiometers; Rain; Sea spray; Sea surface; Sea surface temperature; Ships; Skin temperature; SST; Surface temperature; Temperature differences; Temperature effects; Temperature measurement; Variability; warm layer; Water depth; Water temperature; Wind effects; Wind speed
• ISSN: 2169-9275; 2169-9291
• DOI: 10.1002/2017JC012688

The sea surface temperature (SST) relevant to air‐sea interaction studies is the temperature immediately adjacent to the air, referred to as skin SST. Generally, SST measurements from ships and buoys are taken at depths varies from several centimeters to 5 m below the surface. These measurements, known as bulk SST, can differ from skin SST up to O(1°C). Shipboard bulk and skin SST measurements were made during the Coupled Air‐Sea Processes and Electromagnetic ducting Research east coast field campaign (CASPER‐East). An Infrared SST Autonomous Radiometer (ISAR) recorded skin SST, while R/V Sharp's Surface Mapping System (SMS) provided bulk SST from 1 m water depth. Since the ISAR is sensitive to sea spray and rain, missing skin SST data occurred in these conditions. However, SMS measurement is less affected by adverse weather and provided continuous bulk SST measurements. It is desirable to correct the bulk SST to obtain a good representation of the skin SST, which is the objective of this research. Bulk‐skin SST difference has been examined with respect to meteorological factors associated with cool skin and diurnal warm layers. Strong influences of wind speed, diurnal effects, and net longwave radiation flux on temperature difference are noticed. A three‐step scheme is established to correct for wind effect, diurnal variability, and then for dependency on net longwave radiation flux. Scheme is tested and compared to existing correction schemes. This method is able to effectively compensate for multiple factors acting to modify bulk SST measurements over the range of conditions experienced during CASPER‐East. Key Points Shipboard bulk and skin SST measurements were made from east coast of USA during CASPER‐East field experiment Strong influence of wind speed, time of the day, and net longwave radiation flux on the bulk‐skin temperature difference is noticed Bulk SST is corrected for cool skin, warm layer effects by quantifying the factors influencing bulk‐skin SST difference