The diurnal cycle of sea-surface temperature and estimation of the heat budget of the Mediterranean Sea

Abstract

The diurnal cycle in sea‐surface temperature (SST) is reconstructed for the year 2013 by combining numerical model analyses and satellite measurements using Optimal Interpolation (OI). The method is applied to derive hourly Mediterranean SST fields using Spinning Enhanced Visible and Infrared Imager (SEVIRI) data and Mediterranean Forecasting System analyses (Copernicus Marine Environment Monitoring Service ‐ Analysis and Forecast product). The evaluation of the Diurnal OI SST (DOISST) values against drifter measurements results in a mean bias of −0.1°C and a RMS of 0.4°C. The DOISST fields reproduce well the diurnal cycle in SST including extreme Diurnal Warming events as measured by drifting buoys. We evaluate the impact of resolving the SST diurnal cycle, including extreme events, on estimates of the heat budget of the Mediterranean Sea over an entire annual cycle. It results in the mean annual difference in the heat loss derived using SSTs with and without diurnal variations of 4 Wm−2 with a peak of 9 Wm−2 in July. This value is comparable to several other sources of uncertainty in the calculation of the heat and water budgets of the Mediterranean Sea. The results are an important step toward reducing uncertainties in the “Mediterranean Sea Heat Budget Closure Problem”.

Annual and Semiannual Cycles of Diurnal Warming of Sea Surface Temperature in the South China Sea

“…Diurnal warming of the upper ocean is caused by the daytime absorption of solar radiation. It has a significant influence on both air‐sea heat and gas fluxes (e.g., Clayson & Bogdanoff, ; Kettle et al, ; Marullo et al, ; Ward, ; Weihs & Bourassa, ) and sea surface temperature (SST) at longer time scales (e.g., Bernie et al, , ; Guemas et al, ; Shinoda et al, ). While the typical magnitude of diurnal warming of SST (dSST) is O(0.1 °C; e.g., Kennedy et al, ; Stuart‐Menteth et al, ), it may reach 5–7 °C on days with low wind speed and strong insolation (e.g., Gentemann et al, ; Gentemann & Minnett, ).…”

Comparison of SST Diurnal Variation Models Over the Tropical Warm Pool Region

“…The importance of incorporating sea surface temperature (SST) diurnal variations (DVs) into numerical weather prediction (NWP) or climate models is becoming more recognized (e.g., Masson et al, 2012;Stuart-Menteth et al, 2003;Takaya et al, 2010). Including SST DV effects has been demonstrated to more accurately represent the air-sea interaction and therefore is expected to enhance air-sea coupled, NWP, and climate model performance (e.g., Brunke et al, 2008;Clayson & Bogdanoff, 2013;Halpern & Reed, 1976;Li et al, 2001;Marullo et al, 2016). For instance, Clayson and Bogdanoff (2013) have shown that including SST DV effects results in up to 10 W m 22 yearly average heat flux difference over significant portions of the tropical oceans.…”

Effects of Australian Summer Monsoon on Sea Surface Temperature Diurnal Variation Over the Australian North‐Western Shelf

“…A diurnal warm layer typically has a temperature difference relative to the water body below on the order of 0-3 K; but in some cases, it can reach values up to 5-8 K (e.g., Gentemann et al, 2008;Karagali & Høyer, 2014). Past studies on SST DV ranged from the determination and characterization of DV events (e.g., Clayson & Weitlich, 2005;Eastwood et al, 2011;Gentemann et al, 2008;Karagali & Høyer, 2014;Kawai & Wada, 2007;Soloviev & Lukas, 1997;Sverdrup et al, 1942;Zhang, Beggs, Majewski, et al, 2016) to the roles of DV events in air-sea interaction (e.g., Clayson & Bogdanoff, 2013, Halpern & Reed, 1976Li et al, 2001;Marullo et al, 2016) and to their impacts on long-term climate patterns (e.g., Masson et al, 2012).…”