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1.
The vertical structure of Planetary boundary layer over Arctic floating ice is presented by using about 50 atmospheric profiles and relevant data sounded at an ice station over Arctic Ocean from 22 August to 3 September,2003.It shows that the height of the convective boundary layer in day is greater than that of the stability boundary layer in night.The boundary layer can be described as vertical structures of stability,instability and multipling The interaction between relative warm and wet down draft air from up level and cool air of surface layer is significant,which causes stronger wind shear,temperature and humidity inversion with typical wind shear of 10 m/s/100 m,intensity of temperature inversion of 8 ℃/100 m.While the larger pack ice is broken by such process,new ice free area in the high latitudes of arctic ocean.The interactions between air/ice/water are enhanced.The fact helps to understanding characteristics of atmospheric boundary layer and its effect in Arctic floating ice region. 相似文献
2.
Mid-latitude air-sea interaction is an important topic that attracts a considerable amount of research interest. The Kuroshio Extension(KE) is one of the main western boundary currents and plays a critical role in the mid-latitude atmospheric circulation. This paper uses the NCEP/NCAR reanalysis and Hadley sea surface temperature datasets to investigate the influence of oceanic fronts in the KE region on surface air temperature in North America over the period 1949–2014. A significant correlation was found between the KE front intensity and the temperatures over North America in autumn and winter. A strong(weak) KE front anomaly in autumn is associated with an increasing(decreasing) surface temperature over western North America but a decreasing(increasing) surface temperature over eastern North America. In winter, central North America warms(cools) when the KE front is strong(weak). The response of the atmospheric circulation, including wind in the high and low troposphere, troughs, and ridges, to the strengthening(weakening) of the KE front is the main cause of these changes in surface temperature. 相似文献
3.
Both low clouds and elevated ducts are common phenomena in the oceanic atmosphere. Low clouds affect elevated ducts by changing the structure of atmospheric temperature and humidity. However, due to the limitation of met-ocean measurements, research on them is still scattered. This paper presents the distribution of elevated ducts and clouds over the central Western Pacific Ocean(WPO) based on Global Position System(GPS) sounding data and Himawari-8 satellite products from November 2015 to January 2016. Results show that the frequency of elevated ducts detected by ship-based GPS soundings was as high as 77% over the central WPO. The height and frequency of elevated ducts are closely related to the low clouds. If there are no clouds, the occurrence probability and mean base height of the elevated ducts are 14% and 730 m, respectively. By comparison, the occurrence probability and mean base height increase up to 24% and 1471 m, respectively, in the presence of cumulus(Cu) clouds, and 22% and 1511 m, respectively, in the presence of stratocumulus(Sc) clouds. Elevated ducts occur near the cloud top. The analysis of geopotential height and wind fields from the European Centre for Medium-Range Weather Forecasts(ECMWF) reanalysis dataset(ERA-interim) shows that the study area is covered by a strong and stable subtropical high, and slowly sinking dry air masses inside the subtropical high are above the moist boundary-layer air mass. The appearance and evolution of low clouds will adjust the temperature and humidity structure of the lower troposphere. If there are no clouds, the marine boundary layer(MBL) is the classic mixed boundary layer. Humidity gradient and subsidence inversion are formed atop the mixed layer. When low clouds are present, long wave radiation and entrainment atop clouds form a strong temperature inversion and humidity gradient, which strengthen elevated ducts. However, when Sc clouds are decoupled, a weaker temperature inversion and humidity gradient may occur between the surface mixed layer and subcloud layer, leading to a weak elevated duct atop the mixed layer. 相似文献
4.
Analysis of COADS data (1958–1987) showed that there is obviously interannual SST oscillation including QBO (Quasi-biennial
oscillation) and quasi-3.5 year oscilation, etc., of the SCS (South China Sea), which is the response of the upper mixed layer
of the sea to the impact of the East Asian Monsoon anomaly. Most SST anomalies appear in the central basin of the SCS. The
phase-locked phenomena linking the SST annual cycle and interannual oscillation is an important characteristic of the SCS
climate. There is not only SST response to atmospheric impact, but also feedback to the air. The authors put forward a scheme
of regional air-sea interaction in winter time in the SCS.
Project 49676276 supported by NSFC and also supported by FSEC. 相似文献
5.
INTRODUCTIONTheSouthChinaSea(Srs),nearthewestedgeofthetropicalwestPade,istheoTilyquasi-endotaldeepbasinintheworid,hasa相似文献
6.
In this paper, a heavy sea fog event occurring over the Yellow Sea on 11 April 2004 was investigated based upon observational and modeling analyses. From the observational analyses, this sea fog event is a typical advection cooling case. Sea surface temperature(SST) and specific humidity(SH) show strong gradients from south to north, in which warm water is located in the south and consequently, moisture is larger in the south than in the north due to evaporation processes. After fog formation, evaporation process provides more moisture into the air and further contributes to fog evolution. The sea fog event was reproduced by the Regional Atmospheric Modeling System(RAMS) reasonably. The roles of important physical processes such as radiation, turbulence as well as atmospheric stratification in sea fog’s structure and its formation mechanisms were analyzed using the model results. The roles of long wave radiation cooling, turbulence as well as atmospheric stratification were analyzed based on the modeling results. It is found that the long wave radiative cooling at the fog top plays an important role in cooling down the fog layer through turbulence mixing. The fog top cooling can overpower warming from the surface. Sea fog develops upward with the aid of turbulence. The buoyancy term, i.e., the unstable layer, contributes to the generation of TKE in the fog region. However, the temperature inversion layer prevents fog from growing upward. 相似文献
7.
The nonlinear governing equations and its solutions for the tropical atmospheric planetary boundary layer are derived by means
of scale analysis and vertical coordinate transformation. It is shown that the nonlinear momentum advection may alter the
critical latitude. The restrictive requirement for the solutions to have continuity both in the free atmosphere and in the
planetary boundary layer is derived. The context provides theoretical basis for numerical calculation of the wind field within
the tropic atmospheric planetary boundary layer.
Present affiliation: Shanghai Typhoon Institute, 200030 相似文献
8.
夏季青藏高原低涡结构的动力学研究 总被引：1，自引：0，他引：1
应用卫星云图资料分析了两例夏季青藏高原低涡发展过程及其结构演变,揭示出高原低涡结构特征的若干观测事实。在此基础上借鉴研究类热带气旋低涡的方法,将暖性青藏高原低涡视为受加热和摩擦强迫作用,且满足热成风平衡的轴对称涡旋系统,通过求解柱坐标系中的线性化涡旋模式,得出边界层动力作用下低涡的流函数解,重点讨论了地面热源强迫和边界层动力"抽吸泵"对高原低涡流场结构的作用。研究认为,由于边界层加热和摩擦的共同作用,高原低涡的温度场呈暖心结构。热源强迫的边界层低涡的散度场存在一个动力变性高度,该高度的位置与边界层顶高度有关。通过边界层动力抽吸作用,当边界层顶有气旋性涡度时,能引起边界层低涡的水平辐合运动和随高度增强的上升运动,并可加强低涡的切向流场;如果低涡的中心区域为"内冷外热"型加热分布,则热源强迫的低涡中心区域下层为辐散气流和随时间减弱的切向流场,上层为辐合气流和随时间增强的切向流场,并伴有下沉运动,从而有利于形成涡眼(或空心)结构,在卫星云图上表现为低涡中心为少云(或无云)区,即这类高原低涡具有与台风类似的眼结构,因而可视为类热带气旋涡旋的新例证。最后通过高原低涡的简化模型对低涡所含的波动进行了分析和讨论,结果表明:高原低涡中既含有涡旋Rossby波,又含有惯性重力波,即低涡波动呈现涡旋Rossby-惯性重力混合波特征。 相似文献
9.
Wind and waves are key components of the climate system as they drive air-sea interactions and influence weather systems and atmospheric circulation. In marine environments, understanding surface wind and wave fields and their evolution over time is important for conducting safe and efficient human activities, such as navigation and engineering. This study considers long-term trends in the sea surface wind speed(WS) and significant wave height(SWH) in the China Seas over the period 1988–2011 using the Cross-Calibrated Multi-Platform(CCMP) ocean surface wind product and a 24-year hindcast wave dataset obtained from the WAVEWATCH-III(WW3) wave model forced with CCMP winds. The long-term trends in WS and SWH in the China Seas are analyzed over the past 24 years to provide a reference point from which to assess future climate change and offshore wind and wave energy resource development in the region. Results demonstrate that over the period 1988–2011 in the China Seas: 1) WS and SWH showed a significant increasing trend of 3.38 cm s~(-1)yr~(-1) and 1.52 cm yr~(-1), respectively; 2) there were notable regional differences in the long-term trends of WS and SWH; 3) areas with strong increasing trends were located mainly in the middle of the Tsushima Strait, the northern and southern areas of the Taiwan Strait, and in nearshore regions of the northern South China Sea; and 4) the long-term trend in WS was closely associated with El Ni?o and a significant increase in the occurrence of gale force winds in the region. 相似文献
10.
The South China Sea (SCS) is significantly influenced by El Niño and the Southern Oscillation (ENSO) through ENSO-driven atmospheric and oceanic changes. We analyzed measurements made from 1960 to 2004 to investigate the interannual variability of the latent and sensible heat fluxes over the SCS. Both the interannual variations of latent and sensible heat fluxes are closely related to ENSO events. The low-pass mean heat flux anomalies vary in a coherent manner with the low-pass mean Southern Oscillation Index (SOI). Time lags between the heat flux anomalies and the SST anomalies were also studied. We found that latent heat flux anomalies have a minimum value around January of the year following El Niño events. During and after the mature phase of El Niño, a change of atmospheric circulation alters the local SCS near-surface humidity and the monsoon winds. During the mature phase of El Niño, the wind speed decreases over the entire sea, and the air-sea specific humidity difference anomalies decreases in the northern SCS and increases in the southern SCS. Thus, a combined effect of wind speed anomalies and air-sea specific humidity difference anomalies results in the latent heat flux anomalies attaining minimum levels around January of the year following an El Niño year. 相似文献
11.
A THEORETICAL SOLUTION FOR THE THERMOHALINE CIRCULATION IN THE SOUTHERN YELLOW SEA 总被引：10，自引：2，他引：10
Application of the thermocline equations in the thermocline areas and the boundary layer and the asymptotic matching techniques in each boundary in order to satisfy the surface and bottom conditions yielded a theoretical 2- D solution of the vertical thermohaline circulation of the Southern Yellow Sea in summer when the quasi-statically varying seasonal thermocline (density layer) is the background density structure , the deviations from which cause the secondary vertical circulation . The results show that the thermocline can be considered as an internal boundary or a barrier to the vertical heat advection so that in the central areas of the Southern Yellow Sea or the center of the Yellow Sea Cold Water Mass(YCWM)> the downwelling in the upper layer and upwelling in the lower or bottom layer form a double cell vertical circulation . The solution is similar to Hu's conceptual model ( 1986) in the central areas of the YCWM and is consistent with observed temperature . salinity and dissolved oxygen distri 相似文献
12.
The temperature, humidity, and vertical distribution of ozone in the Antarctic atmospheric boundary layer（ABL） and their seasonal changes are analyzed, by using the high-resolution profile data obtained during the International Polar Year 2008 to 2009 at Zhongshan Station, to further the understanding of the structure and processes of the ABL. The results show that the fre- quency of the convective boundary layer in the warm season accounts for 84% of its annual occurrence frequency. The frequency of the stable boundary layer in the cold season accounts for 71% of its annual occurrence frequency. A neutral boundary layer ap- pears rarely. The average altitude of the convective boundary layer determined by the parcel method is 600 m; this is 200 to 300 m higher than that over inland Antarctica. The average altitude of the top of the boundary layer determined by the potential tempera- ture gradient and humidity gradient is 1 200 m in the warm season and 1 500 m in the cold season. The vertical structures of ozone and specific humidity in the ABL exhibit obvious seasonal changes. The specific humidity is very high with greater vertical gradi- ent in the warm season and very low with a lesser gradient in the cold season under 2 000 m. The atmospheric ozone in the ABL is consumed by photochemical processes in the warm season, which results in a slight difference in altitude. The sub-highest ozone center is located in the boundary layer, indicating that the ozone transferred from the stratosphere to the troposphere reaches the low boundary layer during October and November in Antarctica. 相似文献
13.
分析大气气溶胶空间分布的影响因素有助于理解其变化机制与规律,从而为大气环境质量的调控提供科学依据。本文以厦门市为例,利用MODIS-Aqua卫星遥感影像,反演了大气气溶胶光学厚度。同时,选取Landsat8 OLI卫星数据,进行土地覆被分类。在此基础上,利用相关分析、一元线性回归模型和方差分解,对比研究了城市林地和建设用地对大气气溶胶空间分布的影响作用,得出以下结论：① 暗像元与插值法的结合适合厦门地区春季气溶胶光学厚度的反演;② 建设用地上空气溶胶光学厚度值明显高于林地;③ 林地对气溶胶空间分布的影响作用强于建设用地。本研究对缓解城市大气污染和改善城市生态环境具有重要参考价值和意义。 相似文献
14.
15.
Various satellite data, JRA-25 (Japan reanalysis of 25 years) reanalyzed data and WRF (Weather Research Forecast) model are used to investigate the in situ effect of the ESKF (East China Sea Kuroshio Front) on the MABL (marine atmospheric boundary layer). The intensity of the ESKF is most robust from January to April in its annual cycle. The local strong surface northerly/northeasterly winds are observed right over the ESKF in January and in April and the wind speeds decrease upward in the MABL. The thermal wind effect that is derived from the baroclinic MABL forced by the strong SST gradient contributes to the strong surface winds to a large degree. The convergence zone existing along the warm flank of the ESKF is stronger in April than in January corresponding to the steeper SST (sea surface temperature) gradient. The collocations of the cloud cover maximum and precipitation maximum are basically consistent with the convergence zone of the wind field. The clouds develop higher (lower) in the warm (cold) flank of the ESKF due to the less (more) stable stratification in the MABL. The lowest clouds are observed in April on the cold flank of the ESKF and over the Yellow Sea due to the existence of the pronounced temperature inversion. The numerical experiments with smoothed SST are consistent with the results from the ovservations. 相似文献
16.
Recent observations and modeling study about sea fog over the Yellow Sea and East China Sea 总被引：1，自引：0，他引：1
ZHANG Suping 《中国海洋大学学报(英文版)》2012,11(4):465-472
This review presents some of the latest achievements in sea fog research,including fog climatology,fog structure in the marine atmospheric boundary layer,and numerical simulations and forecasting of fog.With the development of atmospheric observational techniques and equipments,new facts about sea fog are revealed.The mechanisms involved in the formation,development and dissipation of sea fog are further explored with the help of advanced atmospheric models. 相似文献
17.
As an important physical process at the air-sea interface, wave movement and breaking have a significant effect on the ocean surface mixed layer （OSML）. When breaking waves occur at the ocean surface, turbulent kinetic energy （TKE） is input downwards, and a sublayer is formed near the surface and turbulence vertical mixing is intensively enhanced. A one-dimensional ocean model including the Mellor-Yamada level 2.5 turbulence closure equations was employed in our research on variations in turbulent energy budget within OSML. The influence of wave breaking could be introduced into the model by modifying an existing surface boundary condition of the TKE equation and specifying its input. The vertical diffusion and dissipation of TKE were effectively enhanced in the sublayer when wave breaking was considered. Turbulent energy dissipated in the sublayer was about 92.0% of the total depth-integrated dissipated TKE, which is twice higher than that of non-wave breaking. The shear production of TKE decreased by 3.5% because the mean flow fields tended to be uniform due to wave-enhanced turbulent mixing. As a result, a new local equilibrium between diffusion and dissipation of TKE was reached in the wave-enhanced layer. Below the sublayer, the local equilibrium between shear production and dissipation of TKE agreed with the conclusion drawn from the classical law-of-the-wall （Craig and Banner, 1994）. 相似文献
18.
1 ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅＡｒｃｔｉｃａｒｅａ ,ａｓｔｈｅｂａｃｋｇｒｏｕｎｄｏｆｇｌｏｂａｌｃｌｉｍａｔｅａｎｄｅｎｖｉｒｏｎｍｅｎｔ,ｄｒａｗｓｐｅｏ ｐｌｅ’ｓａｔｔｅｎｔｉｏｎｗｉｔｈｉｔｓｉｍｐａｃｔｏｎｇｌｏｂａｌｃｈａｎｇｅ (ＩＰＣＣ 1 990 ) .Ｇｒｅａｔａｍｏｕｎｔｏｆｅｎｅｒｇｙａｎｄｍａｓｓａｒｅｅｘｃｈａｎｇｅｄｂｅｔｗｅｅｎｔｈｅｓｅａａｎｄａｉｒｗｉｔｈｓｐｅｃｉａｌｉｎｔｅｒｆａｃｅ,ａｉｒ ｉｃｅ ｓｅａｓｕｒｆａｃｅ ,ｉｎｔｈｉｓａｒｅａ .Ｔｈｅｒｅｆｏｒｅｉｔｉ… 相似文献
19.
结合气象观测和大气边界层探测资料，分析了１９９０年１月２日重庆雾的声雷达回波特征，并与１９８９年１２月３０日雾的回波作了比较。结果表明，雾顶回波高度与逆温和相对湿度的转折高度一致；雾顶回波在雾的成熟期呈现波动，在消散期有一下降过程。上午大气污染物地面浓度的变化与逆温混合层状况有密切关系，混合层较薄且持续时间较长时，地面浓度较大 相似文献
20.
ENSO cycle and climate anomaly in China 总被引：2，自引：0，他引：2
The inter-annual variability of the tropical Pacific Subsurface Ocean Temperature Anomaly (SOTA) and the associated anomalous atmospheric circulation over the Asian North Pacific during the El Ni o-Southern Oscillation (ENSO) were investigated using National Centers for Environmental Prediction/ National Center for Atmospheric Research (NCEP/NCAR) atmospheric reanalysis data and simple ocean data simulation (SODA). The relationship between the ENSO and the climate of China was revealed. The main results indicated the following: 1) there are two ENSO modes acting on the subsurface tropical Pacific. The first mode is related to the mature phase of ENSO, which mainly appears during winter. The second mode is associated with a transition stage of the ENSO developing or decaying, which mainly occurs during summer; 2) during the mature phase of El Ni o, the meridionality of the atmosphere in the mid-high latitude increases, the Aleutian low and high pressure ridge over Lake Baikal strengthens, northerly winds prevail in northern China, and precipitation in northern China decreases significantly. The ridge of the Ural High strengthens during the decaying phase of El Ni o, as atmospheric circulation is sustained during winter, and the northerly wind anomaly appears in northern China during summer. Due to the ascending branch of the Walker circulation over the western Pacific, the western Pacific Subtropical High becomes weaker, and south-southeasterly winds prevail over southern China. As a result, less rainfall occurs over northern China and more rainfall over the Changjiang River basin and the southwestern and eastern region of Inner Mongolia. The flood disaster that occurred south of Changjiang River can be attributed to this. The La Ni a event causes an opposite, but weaker effect; 3) the ENSO cycle can influence climate anomalies within China via zonal and meridional heat transport. This is known as the "atmospheric-bridge", where the energy anomaly within the tropical Pacific transfers to the mid-high latitude in the northern Pacific through Hadley cells and Rossby waves, and to the western Pacific-eastern Indian Ocean through Walker circulation. This research also discusses the special air-sea boundary processes during the ENSO events in the tropical Pacific, and indicates that the influence of the subsurface water of the tropical Pacific on the atmospheric circulation may be realized through the sea surface temperature anomalies of the mixed water, which contact the atmosphere and transfer the anomalous heat and moisture to the atmosphere directly. Moreover, the reason for the heavy flood within the Changjiang River during the summer of 1998 is reviewed in this paper. 相似文献