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Effects of Sea-Surface Waves and Ocean Spray on Air-Sea Momentum Fluxes

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Advances in atmospheric Sciences 2018年第4期35卷 469-478页

作者： Ting ZHANG Jinbao SONG Ocean College Zhejiang University State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyState Oceanic Administration

The effects of sea-surface waves and ocean spray on the marine atmospheric boundary layer （MABL） at different wind speeds and wave ages were investigated. An MABL model was developed that introduces a wave-induced component and spray force to the total surface stress. The theoretical model solution was determined assuming the eddy viscosity coefficient varied linearly with height above the sea surface. The wave-induced component was evaluated using a directional wave spectrum and growth rate. Spray force was described using interactions between ocean-spray droplets and wind-velocity shear. Wind profiles and sea-surface drag coefficients were calculated for low to high wind speeds for wind-generated sea at different wave ages to examine surface-wave and ocean-spray effects on MABL momentum distribution. The theoretical solutions were compared with model solutions neglecting wave-induced stress and/or spray stress. Surface waves strongly affected near-surface wind profiles and sea-surface drag coefficients at low to moderate wind speeds. Drag coefficients and near-surface wind speeds were lower for young than for old waves. At high wind speeds, ocean-spray droplets produced by wind-tearing breaking-wave crests affected the MABL strongly in comparison with surface waves, implying that wave age affects the MABL only negligibly. Low drag coefficients at high wind caused by ocean-spray production increased turbulent stress in the sea-spray generation layer, accelerating near-sea-surface wind. Comparing the analytical drag coefficient values with laboratory measurements and field observations indicated that surface waves and ocean spray significantly affect the MABL at different wind speeds and wave ages.

关键词： drag coefficient marine atmospheric boundary layer ocean spray droplets surface waves

A New Observation Operator for the Assimilation of Satellite-Derived Relative Humidity:Methodology and Experiments with Three Sea Fog Cases over the Yellow Sea

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Journal of Meteorological Research 2021年第6期35卷 1104-1124页

作者： Yue YANG Yongming WANG Shanhong GAO Xiayu YUAN Key Laboratory of Physical Oceanography College of Oceanic and Atmospheric SciencesOcean University of ChinaQingdao 266100China School of Meteorology University of OklahomaNormanOK 73072USA Institute of atmospheric Physics Chinese Academy of SciencesBeijing 100029China

Assimilation of satellite-derived relative humidity(Satellite-RH)is capable of improving sea fog forecasts by saturating the background in the observed foggy areas.Previous studies have achieved saturation by increasing the moisture only(Method-q).However,this method can lead to large wetting and warming biases within the marine atmospheric boundary layer(MABL).A new method using an RH observation operator(Method-RH)is designed to alleviate these biases by simultaneously adjusting the moisture and the temperature.For comparison,saturation is also achieved by decreasing the temperature only(Method-t).The three Satellite-RH assimilation methods are implemented within the Gridpoint Statistical Interpolation-based three-dimensional variational system and examined for three sea fog cases over the Yellow Sea.The three cases on 28 April 2007,9 April 2009,and 29 March 2015 fail to be predicted without the Satellite-RH assimilation as their MABLs have both warming and drying,drying,and warming biases,respectively.Intercomparisons and evaluations show that Method-RH has the best overall performance of the three methods in terms of the forecast of sea fog and MABL structures as only Method-RH can fully or partially address all the bias scenarios in forecasting sea fog.Compared with Method-q,Method-RH produces more well-defined sea fog areas by adding a smaller amount of moisture as well as decreasing the temperature.Compared with Methodt,Method-RH enlarges the sea fog areas by increasing the amount of moisture in addition to the cooling.

关键词： assimilation of satellite-derived relative humidity observation operator for relative humidity sea fog marine atmospheric boundary layer

Tower-based observation of air-sea momentum flux:comparisons between onshore and offshore winds

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Acta Oceanologica Sinica 2020年第7期39卷 61-68页

作者： Maosheng Ye Shuang Li Zhongshui Zou Jinbao Song Hailun He Jian Huang Hongwei Yang Ocean College Zhejiang UniversityZhoushan 316021China State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of OceanographyMinistry of Natural ResourcesHangzhou 310012China Guangzhou Institute of Tropical and marine Meteorology China Meteorological AdministrationGuangzhou 510640China College of Mathematics and System Science Shandong University of Science and TechnologyQingdao 266590China

We investigate the air-sea momentum flux in the marine atmospheric boundary layer using a tower-based direct measurement method.First,we compare the collected data with previous observations,and the results are roughly consistent.Next,in the low-to-moderate winds,the exchange coefficients(or drag coefficients)deviate between onshore and offshore winds,which exhibits the influence of surface wave on the momentum flux.Furthermore,we use a surface-wave-involved parameterization scheme to explain the dependence of momentum flux on surface wave.The results consolidate the influence of surface wave on momentum flux on the one hand,and validate the surface-wave-involved parameterization scheme on the other hand.

关键词： air-sea momentum flux direct measurement method marine atmospheric boundary layer