Vertical Atmospheric Structure of the Late Summer Clear Days over the East Gansu Loess Plateau in China

In this paper, by using the sounding data collected in LOPEX05, we have analyzed the vertical atmospheric structure and boundary layer characteristics of temperature and humidity in the late summer over the east Gansu loess plateau. The results show that the bottom of the stratosphere is at about 16 500 m and varies between 14 000 m and 18 000 m above the ground. The center of the westerly jet is located between 8300 m and 14 300 m above the ground and its direction moves between 260~ and 305~. There is an inverse humidity layer at about 3000 m height above the ground. The maximum of the air temperature occurs at 1700 LST in the layer below 800 m above the ground. The inversion layer is relatively thick. The time that the maximum of the vapor occurs is not the same for different layers. The depth of the atmospheric boundary layer can reach about 1000 m and the depth of the stable boundary layer can be 650 m.

Profile and Character of Atmospheric Structure Constant of Refractive Index C_n^2

Random fluctuations of turbulence bring random fluctuations of the refractive index, making the atmosphere a random fluctuation medium that destroys the coherence of light-waves. Research in atmospheric turbulence is actually the investigation of the atmospheric refractive index. The atmospheric structure constant of refractive index, C n 2 , is an important parameter denoting atmospheric turbulence. In this paper, C n 2 is measured during the day and at night and in all four seasons using a high sensitivity micro-thermal meter QHTP-2. The vertical profile of C n 2 in Hefei (0-30 km) is investigated by the analysis of experimental data. The average profile of C n 2 in Hefei exhibits conspicuous day and night differences with increased altitude. The distribution of log(C n 2 ) is nearly normal and has conspicuous seasonal differences.

Atmospheric Structure Observed over the Antarctic Plateau and Its Response to a Prominent Blocking High Event

Studies on the atmospheric structure over the Antarctic Plateau are important for better understanding the weather and climate systems of polar regions.In the summer of 2017,an observational experiment was conducted at Dome-A,the highest station in Antarctica,with a total of 32 profiles obtained from global positioning system(GPS)radiosondes.Based on observational data,the atmospheric temperature,humidity,and wind structures and their variations are investigated,and compared with those from four other stations inside the Antarctic circle.Distinguished thermal and dynamic structures were revealed over Dome-A,characterized by the lowest temperature,the highest tropopause,the largest lapse rate,and the most frequent temperature and humidity inversion.During the experiment,a prominent blocking event was identified,with great influence on the atmospheric structure over Dome-A.The blocking high produced a strong anticyclone that brought warm and moist air to the hinterland of the Antarctic Plateau,causing a much warmer,wetter,and windier troposphere over the Dome-A station.Meanwhile,a polar air mass was forced out of the Antarctic,formed a cold surge extending as far as southern New Zealand and affected the weather there.Our results proved that there would be a direct interaction between the atmosphere over the hinterland of the Antarctic Plateau and mid latitudes with the action of a blocking high.Further studies are needed to explore the interaction between the atmospheric systems over the Antarctic and mid latitudes under intense synoptic disturbance,with longterm data and numerical modeling.

Structure and seasonal changes in atmospheric boundary layer on coast of the east Antarctic continent

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.

Application of wind profiler data to rainfall analyses in Tazhong Oilfield region,Xinjiang,China

To improve the level of meteorological service for the Oilfield region in the Taklimakan Desert, the Urumqi Institute of Desert Meteorology of the China Meteorological Administration （CMA） conducted a detection experiment by means of wind profiling radar （WPR） in Tazhong Oilfield region of Xinjiang, China in July 2010. By using the wind profiler data obtained during the rainfall process on 27 July, this paper analyzed the wind field fea- tures and some related scientific issues of this weather event. The results indicated that： （1） wind profiler data had high temporal resolution and vertical spatial resolution, and could be used to analyze detailed vertical structures of rainfall processes and the characteristics of meso-scale systems. Before and after the rain event on 27 July, the wind field showed multi-layer vertical structures, having an obvious meso-scale wind shear line and three airflows from different directions, speeding up the motion of updraft convergence in the lower atmosphere. Besides, the wind directions before and after the rainfall changed inversely with increasing height. Before the rain, the winds blew clockwise, but after the onset of the rain, the wind directions became counterclockwise mainly; （2） the temperature advection derived from wind profiler data can reproduce the characteristics of low-level thermodynamic evolution in the process of rainfall, which is capable to reflect the variation trend of hydrostatic stability in the atmosphere. In the early stage of the precipitation on 27 July, the lower atmosphere was mainly affected by warm advection which had accumulated unstable energy for the rainfall event and was beneficial for the occurrence of updraft motion and precipitation; （3） the ＂large-value zone＂ of the radar reflectivity factor Z was virtually consistent with the onset and end of the rainfall, the height for the formation of rain cloud particles, and precipitation intensity. The reflectivity factor Z during this event varied approximately in the range of 18-38 dBZ and the rain droplets formed mainly at the layer of 3,800-4,500 m.

A Study of the Atmospheric Boundary Layer Structure During a Clear Day in the Arid Region of Northwest China

The local climate and atmospheric circulation pattern exert a clear influence on the atmospheric boundary layer （ABL） formation and development in Northwest China. In this paper, we use field observational data to analyze the distribution and characteristics of the ABL in the extremely arid desert in Dunhuang, Northwest China. These data show that the daytime convective boundary layer and night time stable boundary layer in this area extend to higher altitudes than in other areas. In the night time, the stable boundary layer exceeds 900 m in altitude and can sometimes peak at 1750 m, above which the residual layer may reach up to about 4000 m. The daytime convective boundary layer develops rapidly after entering the residual layer, and exceeds 4000 m in thickness. The results show that the deep convective boundary layer in the daytime is a pre-requisite for maintaining the deep residual mixed layer in the night time. Meanwhile, the deep residual mixed layer in the night time provides favorable thermal conditions for the development of the convective boundary layer in the daytime. The prolonged periods of clear weather that often occurs in this area allow the cumulative effect of the atmospheric residual layer to develop fully, which creates thermal conditions beneficial for the growth of the daytime convective boundary layer. At the same time, the land surface process and atmospheric motion within the surface layer in this area also provide helpful support for forming the particular structure of the thermal ABL. High surface temperature is clearly the powerful external thermal forcing for the deep convective boundary layer. Strong sensible heat flux in the surface layer provides the required energy. Highly convective atmosphere and strong turbulence provide the necessary dynamic conditions, and the accumulative effect of the residual layer provides a favorable thermal environment.

A Case Study of Typical Regional Pollution Transport in Fuzhou City

Based on data of PM2.5 hourly concentration and HYSPLIT model backward trajectory in coastal cities of Fujian Province during January 25 -26, 2014, a typical regional pollution process affecting Fujian from the north to the south and the east to the west on January 26 was investiga- ted. Taking Fuzhou as an example, based on weather situation on the ground and at high altitudes as well as corresponding meteorological data such as wind direction, wind velocity, and visibility, the changes of meteorological elements before, during and after the pollution were compared. Based on the V-3θ atmospheric vertical structure diagrams, the weather reasons for the generation, maintaining and dissipation of the pollution were discussed. The results indicated that the regional pollution was transported from the northeast to the southwest. The northeasterly air flow in front of the cold ridge strengthened and moved toward the east, so that the pollutant from the north affected Fujian form the north to the south and from the east to the west. As a result, there was a dramatic increase of pollutant concentration, rapid drop of visibility, and deterioration of air quality in the affected areas. The heavy pollution process featured high-speed transport and short-time generation. The air quality changed from good state to heavy pollution in just 3 -4 hours. The maximum of IAQIpM2.5 reached 280. The whole pollution process lasted for 14 hours. Solar radiation had been deeply affected by aerosol clouds, so that atmospheric stratification was extremely stable. Along with the eastward movement of cold high pressure into the sea, the dominant wind direction near the ground changed from the northeast to the east, so that the source of the pollutant was cut off , and air quality quickly turned well. The changes of atmospheric vertical structure indicated that the high inversion layer and clouds near 700 hPa kept lower air clean and blocked upper pollution transport. The later sudden increase of wind speed and strengthening of atmospheric mechanical turbu- lent destroyed inversion layer, so that the upper pollutants invaded air near the ground rapidly. During the period of high pollution, the isothermal layer （aerosol clouds） leaded to decrease of wind speed, and the atmosphere became more stable. The pollution ended until the wind field changed.

THE EFFECT OF THE NEGATIVE ENTROPY FLOW ON THE ORGANIZATION OF ATMOSPHERIC DISSIPATIVE STRUCTURES IN NON-EQUILIBRIUM CONDITIONS

The entropy balance equation that describes the entropy budget of atmospheric systems is derived from the Gibbs relation.The distribution of the entropy flows of a west-Pacific typhoon and a Bengal-Bay cyclone is calculated and thus the dissipativity of the atmospheric systems is revealed.

SENSITIVITY TESTS OF INTERACTION BETWEEN LAND SURFACE PHYSICAL PROCESS AND ATMOSPHERIC BOUNDARY LAYER

In this paper,an interactive model between land surface physical process and atmosphere boundary layer is established,and is used to simulate the features of soil environmental physics, surface heat fluxes,evaporation from soil and evapotranspiration from vegetation and structures of atmosphere boundary layer over grassland underlying.The sensitivity experiments are engaged in primary physics parameters.The results show that this model can obtain reasonable simulation for diurnal variations of heat balance,soil volumetric water content,resistance of vegetation evaporation,flux of surface moisture,and profiles of turbulent exchange coefficient,turbulent momentum,potential temperature,and specific humidity.The model developed can be used to study the interaction between land surface processes and atmospheric boundary layer in city regions,and can also be used in the simulation of regional climate incorporating a mesoscale model.

Hydrographic field investigations in the Northern South China Sea by open cruises during 2004-2013

In the past 10 years （2004-2013）, annual open cruise during late summer provided new opportunities for comprehensive studies in the Northern South China Sea （NSCS）. The 10-year field investigation program was carried out by the South China Sea Institute of Oceanology, Chinese Academy of Sciences （SCSIO, CAS）. Measurements inclu- ded water mass property, ocean circulation, atmospheric structure, and chemical and biological elements. The observation data collected during these open cruises have been intensively used in the studies of marine oceanographic, meteorological, chemical, and biological processes in the NSCS. In this study, comprehensive assessment of data application in oceanographic and meteorological studies is provided： （1） the property and variability of water masses in different layers; （2） the distribution of main currents and three-dimensional structure of mesoscale eddies; and （3） atmospheric structure and its feedback to the ocean. With the continuance of open cruises, it is feasible to construct high- quality, gridded climatological marine meteorological datasets in the NSCS in the near future.