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 c...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.展开更多
The unmanned semi-submersible vehicle(USSV) developed by the unmanned surface vehicle team of the Institute of Atmospheric Physics is an unmanned, rugged, and high-endurance autonomous navigation vessel designed for t...The unmanned semi-submersible vehicle(USSV) developed by the unmanned surface vehicle team of the Institute of Atmospheric Physics is an unmanned, rugged, and high-endurance autonomous navigation vessel designed for the collection of long-term, continuous and real-time marine meteorological measurements, including atmospheric sounding in the lower troposphere. A series of river and sea trials were conducted from May 2016 to November 2017, and the first rocketsonde was launched from the USSV. Real-time meteorological parameters in the marine atmospheric boundary layer(MABL) were obtained, including sea surface temperature, and vertical profiles of the pressure, temperature, relative humidity, wind speed,and wind direction. These data are extremely useful and important for research on air–sea interactions, sea surface heat and latent heat flux estimations, MABL modeling, and marine satellite product validation.展开更多
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 ...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.展开更多
Evaporation duct is an ubiquitous natural phenomenon over the ocean and can be diagnosed by evaporation duct model.The model proposed by Paulus and Jeske and another model established by the American naval postgraduat...Evaporation duct is an ubiquitous natural phenomenon over the ocean and can be diagnosed by evaporation duct model.The model proposed by Paulus and Jeske and another model established by the American naval postgraduate school are the most widely used.They are called PJ model and NPS model,respectively.Two methods are used to investigate the global sensitivity of PJ model and NPS model in China Seas.The first method is based on meteorological and oceanographic observation data in China Seas.Considering the system random error caused by sensor measurement inaccuracies,the mean relative error and mean absolute error are used as criterion for sensitivity analysis.The second method,called Extended Fourier Amplitude Sensitivity Test(EFAST),takes into account the interaction between input parameters and is used for sensitivity analysis.The results show that NPS model is more sensitive to the random errors of sensors than PJ model.The mean relative errors of PJ model and NPS model are 11.43%and 14.81%,respectively.The results of global sensitivity parameter analysis indicate that wind speed is the key factor of PJ model,while all input parameter of NPS model have relatively large total sensitivity index.In addition,sensitivity analysis results confirm that wind speed is one of main driving factors for the formation of evaporation duct.These results are valuable for the selection of diagnosis models for evaporation duct,the evaluation of radio wave propagation in the marine atmospheric surface layer,and the prediction technique of evaporation duct based on numerical weather prediction(NWP)in China seas.展开更多
A one-dimensional photochemical model with parameterized vertical eddy diffusion is used to simulate the dimethyl sulfide (DMS) in the marine atmospheric boundary layer near the equator. The boundary condition of theD...A one-dimensional photochemical model with parameterized vertical eddy diffusion is used to simulate the dimethyl sulfide (DMS) in the marine atmospheric boundary layer near the equator. The boundary condition of theDMS flux over sea surface is assigned from gas exchange models that deped on sea surface wind speed and DMS concentration in surface water. Photolysis rates at various altitudes are calculated as a function of Solar zenith angle, andthe radiation calculation includes ozone absorption,surface reflection and molecular scattering.The simulated results of the DMS diurnal cycle are in good agreement with the observations. Sensitivity tests ofthe model indicate that the concentration of the DMS in the marine surface layer appears to be affected by a combination of chemical processes and meteorological conditions. In addition, photochemical processes are rather important.The reaction of the DMS with OH radical, the heterogeneous conversion of SO2 and the deposition of NSS-SO andthe methanesulfonic acid (MSA) are critical factors of controlling the DMS, SO2, NSS-SO and the MSA concentrations and distributions in the atmosphere.The DMS concentration in air is directly proportional to surface windspeed, but it is inversely proportional to boundary layer height in the convective boundary layer. The distributions ofthe DMS concentrations in air are strongly influenced by atmospheric stratification in stable conditions.展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 41576013)the National Key Research and Development Program of China (Grant No. 2016YFC1401404)+1 种基金supported by the National Natural Science Foundation of China (Grant No. 41476021 and 41621064)the Indo-Pacific Ocean Environment Variation and Air–Sea Interaction project (GASI-IPOVAI-04)
文摘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.
基金supported by the Research Equipment Development Project of the Chinese Academy of Sciences and the National Natural Science Foundation of China(Grant No.41627808)
文摘The unmanned semi-submersible vehicle(USSV) developed by the unmanned surface vehicle team of the Institute of Atmospheric Physics is an unmanned, rugged, and high-endurance autonomous navigation vessel designed for the collection of long-term, continuous and real-time marine meteorological measurements, including atmospheric sounding in the lower troposphere. A series of river and sea trials were conducted from May 2016 to November 2017, and the first rocketsonde was launched from the USSV. Real-time meteorological parameters in the marine atmospheric boundary layer(MABL) were obtained, including sea surface temperature, and vertical profiles of the pressure, temperature, relative humidity, wind speed,and wind direction. These data are extremely useful and important for research on air–sea interactions, sea surface heat and latent heat flux estimations, MABL modeling, and marine satellite product validation.
基金Supported by the National Natural Science Foundation of China(40830103 and 91215302)National(Key)Basic Research and Development(973)Program of China(2010CB951804)+1 种基金China Meteorological Administration Special Public Welfare Research Fund(GYHY201306057)Strategy Guide for the Specific Task of the Chinese Academy of Sciences(XDA10010403)
文摘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.
基金supported by the National Natural Science Foundation of China (No. 61471329)
文摘Evaporation duct is an ubiquitous natural phenomenon over the ocean and can be diagnosed by evaporation duct model.The model proposed by Paulus and Jeske and another model established by the American naval postgraduate school are the most widely used.They are called PJ model and NPS model,respectively.Two methods are used to investigate the global sensitivity of PJ model and NPS model in China Seas.The first method is based on meteorological and oceanographic observation data in China Seas.Considering the system random error caused by sensor measurement inaccuracies,the mean relative error and mean absolute error are used as criterion for sensitivity analysis.The second method,called Extended Fourier Amplitude Sensitivity Test(EFAST),takes into account the interaction between input parameters and is used for sensitivity analysis.The results show that NPS model is more sensitive to the random errors of sensors than PJ model.The mean relative errors of PJ model and NPS model are 11.43%and 14.81%,respectively.The results of global sensitivity parameter analysis indicate that wind speed is the key factor of PJ model,while all input parameter of NPS model have relatively large total sensitivity index.In addition,sensitivity analysis results confirm that wind speed is one of main driving factors for the formation of evaporation duct.These results are valuable for the selection of diagnosis models for evaporation duct,the evaluation of radio wave propagation in the marine atmospheric surface layer,and the prediction technique of evaporation duct based on numerical weather prediction(NWP)in China seas.
文摘A one-dimensional photochemical model with parameterized vertical eddy diffusion is used to simulate the dimethyl sulfide (DMS) in the marine atmospheric boundary layer near the equator. The boundary condition of theDMS flux over sea surface is assigned from gas exchange models that deped on sea surface wind speed and DMS concentration in surface water. Photolysis rates at various altitudes are calculated as a function of Solar zenith angle, andthe radiation calculation includes ozone absorption,surface reflection and molecular scattering.The simulated results of the DMS diurnal cycle are in good agreement with the observations. Sensitivity tests ofthe model indicate that the concentration of the DMS in the marine surface layer appears to be affected by a combination of chemical processes and meteorological conditions. In addition, photochemical processes are rather important.The reaction of the DMS with OH radical, the heterogeneous conversion of SO2 and the deposition of NSS-SO andthe methanesulfonic acid (MSA) are critical factors of controlling the DMS, SO2, NSS-SO and the MSA concentrations and distributions in the atmosphere.The DMS concentration in air is directly proportional to surface windspeed, but it is inversely proportional to boundary layer height in the convective boundary layer. The distributions ofthe DMS concentrations in air are strongly influenced by atmospheric stratification in stable conditions.
