Marine-Atmospheric Boundary Layer Characteristics over the South China Sea During the Passage of Strong Typhoon Hagupit

The structures and characteristics of the marine-atmospheric boundary layer over the South China Sea during the passage of strong Typhoon Hagupit are analyzed in detail in this paper. The typhoon was generated in the western Pacific Ocean, and it passed across the South China Sea, finally landfalling in the west of Guangdong Province. The shortest distance between the typhoon center and the observation station on Zhizi Island （10 m in height） is 8.5 km. The observation data capture the whole of processes that occurred in the regions of the typhoon eye, two squall regions of the eye wall, and weak wind regions, before and after the typhoon’s passage. The results show that： （a） during the strong wind （average velocityˉu≧10 m s？1） period, in the atmospheric boundary layer below 110 m, ˉu is almost independent of height, and vertical velocity ˉw is greater than 0, increasing with ˉu and reaching 2–4 m s？1 in the squall regions;（b） the turbulent fl uctuations （frequency＆gt;1/60 Hz） and gusty disturbances （frequency between 1/600 and 1/60 Hz） are both strong and anisotropic, but the anisotropy of the turbulent fl uctuations is less strong;（c） ˉu can be used as the basic parameter to parameterize all the characteristics of fl uctuations;and （d） the vertical fl ux of horizontal momentum contributed by the average fl ow （ˉu＆#183; ˉw） is one order of magnitude larger than those contributed by fl uctuation fl uxes （u＆#39;w＆#39; and v＆#39;w＆#39;）, implying that strong wind may have seriously disturbed the sea surface through drag force and downward transport of eddy momentum and generated large breaking waves, leading to formation of a strongly coupled marine-atmospheric boundary layer. This results in ˉw ＆gt; 0 in the atmosphere, and some portion of the momentum in the sea may be fed back again to the atmosphere due to ˉu ＆#183; ˉw＆gt;0.

Is atmospheric pathway a significant contributor to microplastics in the marine environment?

Transmission of microplastics(MPs)through aerosolization has been recently realized as an important route.Inspite of the reports of the ubiquitous MP presence in aerosols,the spatio-temporal information is inadequate and has very limited practicality in assessing if aerosol can be a significant source of MPs to the marine environment.Data on marine contribution to atmospheric MPs is exceptionally scarce,and the ocean-air exchange is considered an emerging research area.Evidence of MPs entering the oceans via atmospheric deposition has been recently produced.The idea of ocean-air exchange emanates from the fact that beach sediments can get suspended under sand and dust storms,bubble bursts and sea sprays due to wind and waves in surf zones can lead to the ejection of particles into aerosols.In this succinct review,we have tried compiling the data on atmospheric MPs that can shed some light on the flux from and to the aquatic environment.While the information is too limited never the less its incorporation into the marine MP cycle cannot be neglected.