Sensitivity of the diurnal warm layer to meteorological fluctuations. Part 2: A new parameterisation for diurnal warming

Abstract

A new diurnal warming parameterisation has been developed which allows the shape of the diurnal sea surface temperature (SST) signal to change in response to meteorological fluctuations during the day based on an extensive examination of over 300 diurnal cycles. The parameterisation estimates the diurnal variation in temperature at the surface and at 1 m over a local day based only on wind and insolation measurements averaged over several different periods of the day. The parameterisation is validated against independent data and is compared against other existing parameterisations. Results show that diurnal warming estimates are more accurate when daily fluctuations in wind and insolation are taken into consideration and the new parameterisation captures some of the variability of the shape of the diurnal SST cycle which other parameterisations are unable to achieve. The parameterisation is currently being trialled in the European Space Agency MEDSPIRATION project (a contribution to the Global Ocean Data Assimilation Experiment High Resolution SST – Pilot Project) as a possible method to account for the diurnal variability in satellite measurements.