Flux measurements in the surface marine Atmospheric Boundary Layer over the Aegean Sea, Greece

Abstract

Micro-meteorological measurements within the surface Marine Atmospheric Boundary Layer took place at the shoreline of two islands at northern and south-eastern Aegean Sea of Greece. The primary goal of these experimental campaigns was to study the momentum, heat and humidity fluxes over this part of the north-eastern Mediterranean Sea, characterized by limited spatial and temporal scales which could affect these exchanges at the air-sea interface. The great majority of the obtained records from both sites gave higher values up to factor of two, compared with the estimations from the most widely used parametric formulas that came mostly from measurements over open seas and oceans. Friction velocity values from both campaigns varied within the same range and presented strong correlation with the wind speed at 10 m height while the calculated drag coefficient values at the same height for both sites were found to be constant in relation with the wind speed. Using eddy correlation analysis, the heat flux values were calculated (virtual heat fluxes varied from -60 to 40 W/m(2)) and it was found that they are affected by the limited spatial and temporal scales of the responding air-sea interaction mechanism. Similarly, the humidity fluxes appeared to be strongly influenced by the observed intense spatial heterogeneity of the sea surface temperature.

The planetary boundary layer physical processes, the secondary thermal baroclinic circulation and inertial oscillation contribution to diurnal variation of the Etesian winds over the Aegean Sea

“…Since 1990, many attempts have been made by Greek scientists to explore the PBL mainly in rural and coastal places in conjunction with atmospheric pollution and the contribution of local and regional sea-land breezes. All of these papers, which appeared in the international literature deal with the PBL structure and their findings are mostly derived from experimental real observational data (Asimakopoulos et al, 1993;Soilemes et al, 1993;Asimakopoulos and Helmis, 1994;Founda et al, 1997;Helmis et al, 2002;Tombrou et al, 2007;Kostopoulos and Helmis, 2014;Helmis et al, 2015;Dandou et al, 2017;Agathangelidis et al, 2020;Mithimaki et al, 2020). The distinguished observational campaign held over the Aegean Sea (GAME) during late August and early September in 2011 (Tombrou et al, 2007;Dandou et al, 2017) provided many scientists with the necessary measurements to elaborate extensive research work relevant to Aegean sea PBL.…”

Παραμετροποίηση Των Συντελεστών Μεταφοράς Ορμής, Θερμότητας Και Υγρασίας Του Θαλάσσιου Ατμοσφαιρικού Οριακού Στρώματος Και Εφαρμογή Σε Ατμοσφαιρικό Ή Και Σε Ωκεανογραφικό Μοντέλο

“…Αξίζει τέλος να σημειωθεί η μεγαλύτερη τριβή που εμφανίζεται πάνω από κύματα σε ρηχά ύδατα (Busch 1977, Geemaert et al 1986). Αυξημένες τιμές μεταφοράς ορμής κατεγράφησαν πάνω από τα νερά του Αιγαίου, οι οποίες σχετίζονται πιθανότατα με την κυρίαρχη ανεμογενή φύση των κυμάτων λόγω της περιορισμένης έκτασης της αλληλεπίδρασης αέρα-θάλασσας στην περιοχή (Kostopoulos and Helmis, 2014). Ο περιοχικός χαρακτήρας των τιμών της ροής ορμής αντικατοπτρίστηκε και στις προκύπτουσες παραμετροποιήσεις της ταχύτητας τριβής με την ένταση του ανέμου στα 10m ύψος από τα δεδομένα και των δύο πειραματικών περιοχών, συγκρινόμενες με αντίστοιχες εξισώσεις στην διεθνή βιβλιογραφία.…”