海洋鋒海表風(fēng)速最小值及其成因
發(fā)布時(shí)間:2018-08-29 10:53
【摘要】:利用2000—2008年AVHRR、QuickSCAT等高分辨率衛(wèi)星觀測資料和CFSR再分析資料,分析了墨西哥灣流區(qū)、東海黑潮鋒區(qū)、巴西-馬爾維納斯合流區(qū)和厄加勒斯回流區(qū)等全球主要海洋鋒區(qū)的大氣響應(yīng)特征,發(fā)現(xiàn)在上述海洋鋒區(qū)普遍存在海表矢量風(fēng)速的最小值分布,并對這一現(xiàn)象的產(chǎn)生原因進(jìn)行探討。研究指出:夏季(6—8月)墨西哥灣流區(qū)、6月東海黑潮鋒區(qū)附近有明顯的矢量風(fēng)速最小值分布,而巴西-馬爾維納斯合流區(qū)及厄加勒斯回流區(qū)海洋鋒附近則終年存在矢量風(fēng)速最小值。產(chǎn)生這一現(xiàn)象的條件是大尺度氣壓背景場梯度方向與海洋鋒附近海表溫度梯度方向接近一致,其物理過程為:海洋鋒暖(冷)水區(qū)一側(cè)上空對應(yīng)有低(高)氣壓,由此產(chǎn)生的局地氣壓梯度與大尺度背景氣壓梯度方向接近相反,導(dǎo)致鋒區(qū)附近疊加后的氣壓梯度最小,海表風(fēng)速因此也最小。同時(shí),摩擦作用使海表風(fēng)偏向低壓一側(cè),于是沿鋒區(qū)走向(跨鋒區(qū)走向)的風(fēng)速分量差在暖水區(qū)一側(cè)產(chǎn)生氣旋性切變渦度(風(fēng)速輻合),進(jìn)而造成上升運(yùn)動和強(qiáng)降水,而該分量差在冷水區(qū)一側(cè)則產(chǎn)生相反的大氣響應(yīng)特征。
[Abstract]:Based on the high resolution satellite observations such as AVHRR,QuickSCAT and CFSR reanalysis data from 2000 to 2008, the Gulf Stream and the Kuroshio front in the East China Sea are analyzed. The atmospheric response characteristics of the major global ocean fronts, such as the Brazilian-Malvinas confluence zone and the return zone of Ogharest, show that the minimum distribution of sea surface vector wind speed exists generally in these sea fronts. The causes of this phenomenon are also discussed. It is pointed out that in the summer (June-August) Gulf Stream, there is an obvious minimum distribution of vector wind speed near the Kuroshio front in the East China Sea in June. However, the minimum vector wind speed exists all year round near the oceanic front in the Brazilian-Malvinas confluence area and in the reflux area of Ogharest. The condition for this phenomenon is that the gradient direction of large-scale atmospheric pressure background field is close to the direction of sea surface temperature gradient near the ocean front, and the physical process is that there is a low (high) pressure over the warm (cold) water area of the ocean front. The resulting local pressure gradient is close to the reverse direction of the large-scale background pressure gradient, resulting in the minimum pressure gradient near the frontal area and the minimum sea surface wind speed. At the same time, the friction makes the sea surface wind incline to the low pressure side, so the difference of the wind velocity component along the front area (across the front zone) produces the cyclonic shear vorticity (convergence of the wind speed) on the warm water area, and then causes the rising motion and the heavy precipitation. On the other side of the cold water zone, this component difference produces the opposite atmospheric response.
【作者單位】: 南京信息工程大學(xué)氣象災(zāi)害預(yù)報(bào)預(yù)警與評估協(xié)同創(chuàng)新中心和氣象災(zāi)害教育部重點(diǎn)實(shí)驗(yàn)室;
【基金】:江蘇高校優(yōu)勢學(xué)科建設(shè)工程資助項(xiàng)目(PAPD)資助
【分類號】:P732
本文編號:2210983
[Abstract]:Based on the high resolution satellite observations such as AVHRR,QuickSCAT and CFSR reanalysis data from 2000 to 2008, the Gulf Stream and the Kuroshio front in the East China Sea are analyzed. The atmospheric response characteristics of the major global ocean fronts, such as the Brazilian-Malvinas confluence zone and the return zone of Ogharest, show that the minimum distribution of sea surface vector wind speed exists generally in these sea fronts. The causes of this phenomenon are also discussed. It is pointed out that in the summer (June-August) Gulf Stream, there is an obvious minimum distribution of vector wind speed near the Kuroshio front in the East China Sea in June. However, the minimum vector wind speed exists all year round near the oceanic front in the Brazilian-Malvinas confluence area and in the reflux area of Ogharest. The condition for this phenomenon is that the gradient direction of large-scale atmospheric pressure background field is close to the direction of sea surface temperature gradient near the ocean front, and the physical process is that there is a low (high) pressure over the warm (cold) water area of the ocean front. The resulting local pressure gradient is close to the reverse direction of the large-scale background pressure gradient, resulting in the minimum pressure gradient near the frontal area and the minimum sea surface wind speed. At the same time, the friction makes the sea surface wind incline to the low pressure side, so the difference of the wind velocity component along the front area (across the front zone) produces the cyclonic shear vorticity (convergence of the wind speed) on the warm water area, and then causes the rising motion and the heavy precipitation. On the other side of the cold water zone, this component difference produces the opposite atmospheric response.
【作者單位】: 南京信息工程大學(xué)氣象災(zāi)害預(yù)報(bào)預(yù)警與評估協(xié)同創(chuàng)新中心和氣象災(zāi)害教育部重點(diǎn)實(shí)驗(yàn)室;
【基金】:江蘇高校優(yōu)勢學(xué)科建設(shè)工程資助項(xiàng)目(PAPD)資助
【分類號】:P732
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