Climate Change Impacts on Sea Surface Temperature in the Eastern Mediterranean, Levantine Basin

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1 Climate Change Impacts on Sea Surface Temperature in the Eastern Mediterranean, Levantine Basin Yianna Samuel-Rhoads *, George Zodiatis, Daniel Hayes, Gregory Konnaris, Georgios Georgiou, Marios Nikolaides Oceanography Centre, University of Cyprus, P.O.Box , 1678 Nicosia, Cyprus * rhoads.yianna@ucy.ac.cy

IPCC 2007: WG1-AR4 Global SST increases: 0.3ºC -1.0ºC over the last millennium (Salinger, 2005). Most rapid warming occurring over the past 30-40 years (Casey and Cornillon, 2001; Trenberth et al.

2 IPCC 2007: WG1-AR4 Global SST increases: 0.3ºC -1.0ºC over the last millennium (Salinger, 2005). Most rapid warming occurring over the past years (Casey and Cornillon, 2001; Trenberth et al., 2007). Regional temperature increases reported in the Mediterranean Sea for each of its two subbasins(bethoux and Gentili, 1999; Samuel-Rhoads et al., in prep; Skliris et al., 2011;Tsimplis and Rixen, 2002). Regional changes are out of phase, due to different processes affecting the climate of the two sub-basins (Artale et al., 2006; Korres et al., 2000; Reddaway and Bigg, 1996). SSTs across the entire Mediterranean increasing twice as much as the SSTs of the global oceans (Samuel-Rhoads, et al., 2009; in prep; Zodiatis et al., 2010; 2011).

3 Objective Investigate the increase in SSTs due to climatic changes in the Eastern Mediterranean, Levantine basin from 1982 until 2012, with the use of satellite remote sensing data as well as with in-situ data.

4 Data sources (1) SST data collected by the NOAA/NASA AVHRR radiometers and processed by the SST Pathfinder program. Global daily Level-3 (L3), version 5.2, from the night time pass (code numbers 1 and 4), at 4km resolution and equal-angle grid of 8192 pixels/360º from January 1, 1982 through December 31, Daily quality control flag files were obtained from the same source.

Since 2009, the OC-UCY has also been deploying 2 autonomous gliders for missions in the eastern Levantine.

5 From mid 1990s until today, the OC-UCY has been conducting in-situ observations of temperature during more than 24 multi-day oceanographic research cruises. Since 2009, the OC-UCY has also been deploying 2 autonomous gliders for missions in the eastern Levantine. In-situ profiles from both of these types of excursions were used to study seasonal and interannual variability in the Levantine basin from at the surface layer (0-10m).

6 Data sources (2) Ιn-situ SST data collected with CTD (Conductivity-Temperature-Depth) during oceanographic research cruises CYBO, between 1996 until 2012, and with the two autonomous ocean gliders owned by OC-UCY, which were deployed between 2009 and Gliders survey area March July 2009 CYBO survey area OC-UCY gliders

7 Methodology All satellite data for the Eastern Levantine basin were sub-scened from the global sets and bound by the following coordinates: 37 ºN to 30 ºN, and 24 ºE to 37 ºE. Quality control flags were applied to the daily SST Levantine data. Only pixels of highest quality were kept. Annual averages were calculated for 1982 through 2012 across the Eastern Levantine Basin for SST. Annual anomalies for the SST dataset were also obtained by calculating the overall mean for the dataset during , and then subtracting the mean from each year of the corresponding dataset. To investigate the spatial and temporal variability in SSTs, empirical orthogonal function (EOF) analysis was performed on the annual anomalies of SST. Here we present only the first two modes that arise form the EOF analyses. Averages for the in-situ SST data from the CTD from were calculated for the top 10 meters of the water column for each CYBO research cruise. Monthly averages for the SST data from the glider cruises from were calculated for the top 10 meters of the water column, after removal of outliers.

8 23,5 Mediterranean & Levantine Annual mean satellite SST Annual Mean SST (ºC) 23,0 22,5 22,0 21,5 21,0 Lev Med 20,5 20, Mediterranean: general increase: ~ 1.30 C average: C C/year World Oceans: Year Levantine: general increase: ~ 1.33 C average: C C/year : 0.017±0.005 C/year (Good et al., 2007) Since 1950s: C/year (Scott et al., 2010) Since 1970s: C/year(Abraham et al., 2013)

entire Levantine share high positive eigenfunctions. SSTs varied in a spatially coherent manner over time. SST variability is characterized by a broad, basin-wide warming.

10 Mode % Mode % 2,0 1,0 0,0-1,0-2, ,0 1,0 0,0-1,0-2,0-3, Spatial eigenfunctions of mode 1 show that the annual SSTs across the entire Levantine share high positive eigenfunctions. SSTs varied in a spatially coherent manner over time. SST variability is characterized by a broad, basin-wide warming. The principal component (PC) of the same mode (PC1), depicts the time variation of the first mode. PC1 of the annual data supports the fact that higher than average SSTs were observed across the Levantine during the later part of the 31-year time period. An asymmetry in the E-to-W direction is depicted in the spatial eigenfunctions of mode 2, creating a dipole pattern of heating and cooling at interannual time scales.

11 23, Satellite SST ( C) 22, In-situ SST ( C) 19 21, Analyses of annual in-situ SST data (from CYBO cruises) for the first 10m depth from CTD casts : reveal similarities in SSTs to the ones recorded by satellites in the region since The average rate of increase of SSTs is C/year, which is approximately half than the recorded by satellites C/year rate of increase of Levantine SSTs. During 2010, the highest temperatures were recorded up to date, which were much higher than the recorded ones from 2003 (mean values for 2010 for SST=29.54 C)

12 Analyses of monthly in-situ SST data collected during glider expeditions from 2009 until Calculated for the top 10 meters of the water column. Depiction of monthly variability in SSTs in the Eastern Mediterranean Levantine basin. However, the time series in some cases does not represent well the entire region of interest, as the gliders may have been in an area with a local effect, which is then affecting the regional averages. Further examination, processing and analysis of these data is needed.

13 Results We show an SST increase in the Levantine Basin from 1982 to 2012, with higher than average SSTs occurring during the second half of the 30 year period (1998 onward). SST variability is characterized by a broad, basin-wide warming (mode 1) occurring at interannual time scales, and a weaker dipole pattern that fluctuates at similar time scales (mode 2). Satellite SST data are correlated with in-situ CTD SST data. The warming in the Levantine, which is revealed by the satellite SST data, as well as by the recorded increases in in-situ SST, occurred at interannual time scales. The fact that in 2010 the highest insitu SSTs have been recorded so far, which were even higher than the record values of 2003 seen by satellites, indicates that the increasing trend is expected to continue. The driving mechanisms of these changes need to be investigated, as they may be driven by changes in annual latent heat losses and by the variability in regional wind speeds.

14 THANK YOU

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