THE EFFECT OF DIURNAL SEA SURFACE TEMPERATURE WARMING ON THE MEDITERRANEAN SEA HEAT AND WATER BUDGET S. Marulloa,P. Minne/b, R. Santoleric , V. Artalea a Italian Na)onal Agency for New Technologies, Energy and Sustainable Economic Development (ENEA), Frasca) Research Center, Italy bRosenstiel School of Marine & Atmospheric Science, Miami, USA cItalian Na)onal Research Council (CNR)-­‐ Ins)tute of Atmospheric Sciences and Climate (ISAC), Roma, Italy) ABSTRACT Diurnal Warming and Mediterranean Heat Budget Data and Methods ValidaDon The diurnal cycle in sea-­‐surface temperature is reconstructed by combining numerical model analyses and satellite measurements in the context of the Op)mal Interpola)on theory. The method (Marullo et al., 2014) is applied to reconstruct hourly Mediterranean SST ﬁelds during 2013 using data from the Spinning Enhanced Visible and Infrared Imager (SEVIRI) and Mediterranean Forecas)ng System analyses provided by the Copernicus Marine environment monitoring service. The Diurnal OI SST (DOISST) ﬁelds reproduce well the diurnal cycles including extreme diurnal warming events as measured by driQing buoys. The evalua)on of DOISST products against driQer measurements results in a mean bias of −0.1°C and a RMS of 0.4°C. We evaluate the impact of resolving the SST diurnal cycle on the heat budget of the Mediterranean Sea over an en)re annual cycle. The mean annual diﬀerence in the heat budget derived using SST’s with and without diurnal varia)ons being -­‐4 Wm-­‐2 with a peak monthly diﬀerence of -­‐9 Wm-­‐2 in July-­‐August. Input data: ü Satellite data: hourly SEVIRI SST ﬁelds, distributed by OSI-­‐SAF (Ocean and Sea Ice -­‐ Satellite ApplicaCon Facility) ü CMEMS (Copernicus Marine Environmental Monitoring Service) Mediterranean ForecasCng SST Analysis Method: Diurnal OpCmal InterpolaCon SST method which combines numerical model analyses and geostaConary satellite data (Marullo et al. RSE, 2014). Output: L4 Hourly reconstructed SST maps Monthly Bias (Sat – In Situ) DriSers PosiCon (2013 Data) SEVIRI (Measured) SST ReconstrucDon (sat-­‐buoy) -­‐0.03 °C -­‐0.13 °C STD 0.47 °C 0.39 °C Corr. Coef. 0.9957 0.9953 N. of matchups 26149 13846 Diurnal Warming in the Mediterranean Sea A Diurnal Warming (DW) Event in The Mediterranean Sea on June 18° 2013. Figure (a) shows the maximum day – night temperature excursion during this day. DW events require sustained low winds under favorable insolaCon condiCons. The DW pa/ern in ﬁg (a) highlights this eﬀect downwind of the Crete Island and on its east and west side. Diurnal Warming Event are very frequent in The Mediterranean Sea. Figures below (a), (b) and (c) show the number of occurrence of Diurnal Warming Event with day-­‐night diﬀerence above 1, 2 and 3 K respecCvely during 2013 (a) ba ) (c) Spa$al distribu$on of the number of DW events with amplitude greater than 1°C for each month of the year 2013. The impact of the SST Diurnal Warming on air-­‐sea Heat Fluxes. Diﬀerence between ocean heat loss es$mated using founda$on SST or hourly DOISST Radia$ve and Turbulent Heat Flux formulae: monthly spa$al distribu$on (to the right) and monthly mean (below) April 9 2015: Sea Surface Temperature The COSIMO 2015 Experiment 1. CTD Casts 2. Near surface Thermistor Measurements 3. Meteo data 4. M-­‐AERI conCnuous skin SST Measurements (SST retrieval uncertainty <<0.1 K) Hourly CTD Casts During the COSIMO Experiment ( from 2015/04/08 22:14:00 to 2015/04/10 07:59:00) GOTM Run (25 cm verCcal resoluCon) using in situ iniCal condiCon and Meteo data acquired on board (no SST assimilaCon) The COSIMO Diurnal Experiment was conducted in the north AdriaCc Sea from 2015/04/08 22:14:00 to 2015/04/10 07:59:00 The M-­‐AERI Mounted on Italian R/V Minerva Uno CTD Casts Acknowledgments This research was supported by the Italian Ministry of Foreign Aﬀairs and InternaConal CooperaCon in the framework of the DeclaraCon Italia – United States 2014-­‐2015. The research was also supported by MyOcean 2 a