Climatology of dust deposition in the Adriatic Sea and biological response of Rogoznica Lake (central Adriatic)

Boris Mifka,Maja Telišman Prtenjak,Irena Ciglenečki

doi:10.5194/egusphere-egu21-5793

Abstract

&lt;p&gt;Airborne desert dust is one of the most abundant aerosols and an important factor in climate&lt;br&gt;change. After deposition in the sea, mineral dust acts as the nutrient. In this study, the climatology&lt;br&gt;of desert dust deposition in the Adriatic Sea was investigated with special reference to the possible&lt;br&gt;source and mineralogical characteristics of transported dust from North Africa. The effect is&lt;br&gt;particularly examined in unique, isolated marine system, Rogoznica Lake (RL; 43&amp;#176; 32 &amp;#8217;N, 15&amp;#176; 58&amp;#8217;&lt;br&gt;E) through its biological response.&lt;br&gt;For that purpose, the MERRA-2 reanalysis data for dust deposition in the period 1989-&lt;br&gt;2019 were used. Annual dust deposition cycle in the Adriatic Sea has maximum in spring and fall&lt;br&gt;with stronger deposition in central and south. Wet deposition accounts for 63-92% of total&lt;br&gt;deposition and 75% of data contains less than 1.5% of the mass. Intensity classes are defined for&lt;br&gt;the remaining 25% and each refers to about 30% of the mass. On average, over 73 days per year&lt;br&gt;is of weak, 14.6 of moderate, and 3.65 of extreme intensity, which varies spatially. In order to&lt;br&gt;detect the specific synoptic patterns for the dust transport in relation to the dust sources activity&lt;br&gt;and deposition in the Adriatic Sea, the EOF analysis on 850 hPa was utilized. Positive or negative&lt;br&gt;mode phases correspond to deposition anomalies in the Adriatic Sea and can be related to particular&lt;br&gt;dust sources in North Africa.&lt;br&gt;Given the seasonal strong physicochemical stratification, relatively small volume, and only&lt;br&gt;source of freshwater and nutrients through precipitation during stratification, the Rogoznica Lake&lt;br&gt;proved ideal for monitoring desert dust deposition events, by monitoring nutrient concentration in&lt;br&gt;the surface layer (0&amp;#8211;2 m). For the 2000-2012 period no correlation with MERRA-2 deposition&lt;br&gt;time series were found, but biological activity as a direct consequence of nutrient increase was&lt;br&gt;observed during deposition events. Since the Adriatic Sea was proved to be phosphate (P) and iron&lt;br&gt;(Fe) limited, the mineralogical database was used to estimate the amount of deposited P and Fe&lt;br&gt;during intense deposition events.&lt;/p&gt;

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