In this study the effect of the surface waves over sea surface roughness (z0) and drag coefficient (CD) is investigated by combining an ocean wave model and a simplified algorithm, which estimates z0 and CD with and w...In this study the effect of the surface waves over sea surface roughness (z0) and drag coefficient (CD) is investigated by combining an ocean wave model and a simplified algorithm, which estimates z0 and CD with and without dependence on the sea state. This investigation was possible from several numerical simulations with the Wave-Watch-III (WW3) model for complex wind conditions. The numerical experiments were performed for idealized like-hurricanes with different translation speed (0, 5 and 10 m/s) and maximum wind speed (MWS) at the centre (35, 45 and 55 m/s). It is observed that z0 and CD are strongly dependent on the sea state, via substantial modification in Charnock parameterization (zch). As the hurricane translation speed increases more discrepancies in z0 and CD are observed in opposite quadrants around the region of MWS. As for instance, higher, longer and older (or more developed) waves, located in the front-right quadrant, produce lower values of z0 and CD. In the rear-left quadrant, where the waves are lower, shorter and younger (or less developed), higher values of z0 and CD are observed. In addition the difference between values on opposite quadrants increases as the hurricane intensity increases, showing the hurricane intensification dependence. Interesting aspects are observed in scatter plotting wave age versus Charnock coefficient. It is also observed that zch, which has a constant value of 0.0185, is modified by the sea state, where young waves produce higher values of zch, while old waves are related to lower values of zch when compared with zch without dependence on sea state.展开更多
The passage of tropical cyclones induces ocean surface cooling through vertical mixing,upwelling,and surface heat loss.The dependence of tropical cyclone-induced ocean surface cooling on the intensity and translation ...The passage of tropical cyclones induces ocean surface cooling through vertical mixing,upwelling,and surface heat loss.The dependence of tropical cyclone-induced ocean surface cooling on the intensity and translation speed of tropical cyclones has been documented in previous studies.The present study investigates the latitudinal and seasonal variations in tropical cyclone-induced ocean surface cooling in the tropical western North Pacific based on data for the 2001–2020 period.Our analysis focuses on the open ocean(0°–25°N,130°E–180°)to reduce the interference of coastal topography so that the obtained results better represent the influences of the intensity and translation speed of tropical cyclones.Our analysis confirms the dependence on the intensity and translation speed of tropical cyclone-induced cooling.The new findings are as follows.First,the time to reach the maximum cooling increases with the magnitude of the maximum cooling.Second,the magnitude of ocean surface cooling increases with latitude in the tropical region for tropical cyclones with different intensities and translation speeds.Third,the ocean surface cooling is larger in summer and autumn than in spring for tropical cyclones with different intensities and translation speeds.Fourth,the dependence of ocean surface cooling on the translation speed is more obvious at higher latitudes in the tropics and less apparent in spring.These new findings add to the existing knowledge of the impacts of tropical cyclone intensity and translation speed on ocean surface cooling.展开更多
文摘In this study the effect of the surface waves over sea surface roughness (z0) and drag coefficient (CD) is investigated by combining an ocean wave model and a simplified algorithm, which estimates z0 and CD with and without dependence on the sea state. This investigation was possible from several numerical simulations with the Wave-Watch-III (WW3) model for complex wind conditions. The numerical experiments were performed for idealized like-hurricanes with different translation speed (0, 5 and 10 m/s) and maximum wind speed (MWS) at the centre (35, 45 and 55 m/s). It is observed that z0 and CD are strongly dependent on the sea state, via substantial modification in Charnock parameterization (zch). As the hurricane translation speed increases more discrepancies in z0 and CD are observed in opposite quadrants around the region of MWS. As for instance, higher, longer and older (or more developed) waves, located in the front-right quadrant, produce lower values of z0 and CD. In the rear-left quadrant, where the waves are lower, shorter and younger (or less developed), higher values of z0 and CD are observed. In addition the difference between values on opposite quadrants increases as the hurricane intensity increases, showing the hurricane intensification dependence. Interesting aspects are observed in scatter plotting wave age versus Charnock coefficient. It is also observed that zch, which has a constant value of 0.0185, is modified by the sea state, where young waves produce higher values of zch, while old waves are related to lower values of zch when compared with zch without dependence on sea state.
基金Supported by the National Natural Science Foundation of China(41721004)。
文摘The passage of tropical cyclones induces ocean surface cooling through vertical mixing,upwelling,and surface heat loss.The dependence of tropical cyclone-induced ocean surface cooling on the intensity and translation speed of tropical cyclones has been documented in previous studies.The present study investigates the latitudinal and seasonal variations in tropical cyclone-induced ocean surface cooling in the tropical western North Pacific based on data for the 2001–2020 period.Our analysis focuses on the open ocean(0°–25°N,130°E–180°)to reduce the interference of coastal topography so that the obtained results better represent the influences of the intensity and translation speed of tropical cyclones.Our analysis confirms the dependence on the intensity and translation speed of tropical cyclone-induced cooling.The new findings are as follows.First,the time to reach the maximum cooling increases with the magnitude of the maximum cooling.Second,the magnitude of ocean surface cooling increases with latitude in the tropical region for tropical cyclones with different intensities and translation speeds.Third,the ocean surface cooling is larger in summer and autumn than in spring for tropical cyclones with different intensities and translation speeds.Fourth,the dependence of ocean surface cooling on the translation speed is more obvious at higher latitudes in the tropics and less apparent in spring.These new findings add to the existing knowledge of the impacts of tropical cyclone intensity and translation speed on ocean surface cooling.
