Spatial and vertical distribution of phytoplankton community were examined in the coast of the south of the Kerkennah Islands at three different depths 0, 2 and 6 m during the winter 2009 at 6 sampling stations. A tot...Spatial and vertical distribution of phytoplankton community were examined in the coast of the south of the Kerkennah Islands at three different depths 0, 2 and 6 m during the winter 2009 at 6 sampling stations. A total of 49 taxa belonging to five phytoplankton groups were identified （H＇=1.7 to 3.5 bits＇cell^-1）. Dinoflagellates and Diatoms were the most abundant phytoplankton groups which reached 27 and 71% of total abundance, respectively. The spatial distribution of the phytoplankton abundance showed a significant variation between the stations （P 〈 0.001）. While the vertical distribution of total phytoplankton showed a clear pattem, ANOVA test showed only an insignificant variation between the different depths at each station （P 〉 0.01）. On the whole, the maximum abundance of phytoplankton was recorded at the depths of 2 and 6 m （6 ×10^3 ind..Ll）. This might be due to the decrease of the nutrient concentrations in deeper water specially those of phosphate.展开更多
The latitude-altitude distributions of radiative fluxes and heating rates are investigated by utilizing CloudSat satellite data over China during summer. The Tibetan Plateau causes the downward shortwave fluxes of the...The latitude-altitude distributions of radiative fluxes and heating rates are investigated by utilizing CloudSat satellite data over China during summer. The Tibetan Plateau causes the downward shortwave fluxes of the lower atmosphere over central China to be smaller than the fluxes over southern and northern China by generating more clouds. The existence of a larger quantity of clouds over central China reflects a greater amount of solar radiation back into space. The vertical gradients of upward shortwave radiative fluxes in the atmosphere below 8 km are greater than those above 8 km. The latitudinal-altitude distributions of downward longwave radiative fluxes show a slantwise decreasing trend from low latitudes to high latitudes that gradually weaken in the downward direction. The upward longwave radiative fluxes also weaken in the upward direction but with larger gradients. The maximum heating rates by solar radiation and cooling rates by longwave infrared radiation are located over 28 40°N at 7 8 km mean sea level (MSL), and they are larger than the rates in the northern and southern regions. The heating and cooling rates match well both vertically and geographically.展开更多
The spatial distribution and seasonal variations of the hypoxic zone in the eastern equatorial Indian Ocean were investigated using survey data collected from four cruises from 2013 to 2018.Results showed that hypoxic...The spatial distribution and seasonal variations of the hypoxic zone in the eastern equatorial Indian Ocean were investigated using survey data collected from four cruises from 2013 to 2018.Results showed that hypoxic zone occurred all year round in the eastern equatorial Indian Ocean,and it spread southward in the shape of a double tongue at two depths with one at subsurface centered at a depth of 150 m and the other in intermediate water centered at a depth of 800 m.The southward expansion and maximum thickness of the hypoxic zone were greatest in the spring inter-monsoon and least in the summer monsoon.The hypoxic zone originated from the southward expansion of the hypoxic water in the Bay of Bengal and its spatial distribution was driven by southward output flux of mid-deep(100–1000 m)hypoxic water from the Bay of Bengal.The hypoxia southward expansion was blocked near the equator in the subsurface layer,because of mixing with multiple zonal circulations(e.g.,Wyrtki Jets and the equatorial undercurrent),which meant that the hypoxic zone extended over a smaller area than in the intermediate water.These new findings will contribute to an improved understanding of the hypoxic zone and will contribute to circulation research,particularly about intermediate circulation in the eastern equatorial Indian Ocean.展开更多
Variation of haze events occurred in the Yangtze River Delta（YRD） of China, the characteristics of meteorological elements and the vertical distribution of aerosols during haze episodes were analyzed by utilizing da...Variation of haze events occurred in the Yangtze River Delta（YRD） of China, the characteristics of meteorological elements and the vertical distribution of aerosols during haze episodes were analyzed by utilizing data of ground observation, radiosonde and CALIPSO. The results illustrate that the frequency of haze events between 1981 and 2010 peaked in winter but bottomed out in summer and decreased from north to south in the YRD region, reaching at the lowest point in ＂low frequency center＂ - Shanghai. When haze happened, the most seriously affected area was 2-4 km above the ground and the concentrated range of total backscattering coefficient（TBC） that decreased with altitude was 0.8 × 10^（-3）-2.5 × 10^（-3） km^（-1）·sr^（-1）. Particulate depolarization ratio（PDR） was less than 40%in a large part and 93% aerosols over the YRD area were regular particles, while the irregular ones concentrated on 2 km above the surface and the irregularity rose up but the diversity diminished when altitude increased. Color ratio（CR） was lower than 1.2 mostly at all altitudes and distributed asymmetrically above the ground. Nearly 80% aerosols under10 km were fine particles（CR 〈1.0） clustered at 2-4 km. Large particles（CR 〉 1.2） aggregated in lower troposphere massively yet relatively smaller ones gathered in middle and upper troposphere. In the YRD region, aerosols with more powerful capabilities were wider and less regular than the ones of Northwestern China.展开更多
By analyzing airborne observations over North China from 30 flights during spring and autumn of 2005-2007, characteristics of the vertical distributions of aerosol and cloud condensation nuclei （CCN） at 0.3% supersa...By analyzing airborne observations over North China from 30 flights during spring and autumn of 2005-2007, characteristics of the vertical distributions of aerosol and cloud condensation nuclei （CCN） at 0.3% supersaturation in various locations of North China are investigated. The measurement samplings were conducted over different surfaces such as plains, plateau, and sea. The results show that the number concentration of accumulation mode aerosols was greater in autumn than in spring, but the reverse is true for CCN. This means that more aerosols with diameters smaller than 100 nm could be activated as CCN in spring, and this could induce higher aerosol activation efficiency. The aerosol activation efficiency over the plains near the Taihang Mountain was greater in spring than in autumn, and it was greater over sea than over land. The aerosol activation efficiency above the boundary layer over the Bashang Plateau was very low. Based on a fit of the negative exponential vertical distributions of aerosol and CCN, a spatial parameterization model of aerosol and CCN as well as aerosol activation efficiency over North China was proposed. The results show that aerosol activation efficiency was not clearly dependent on altitude because it was mainly affected by regional physical and chemical characteristics of aerosols and the ambient atmospheric conditions. The mean aerosol activation efficiency is 0.66, with values of 0.70 and 0.53 in spring and autumn, respectively.展开更多
通过对滇池底泥118个样品的有机质含量分析统计和利用GIS绘制的底泥0～5cm,5～10cm,10～20 cm 3层有机质空间分布图,得出底泥中有机质含量的一般范围在40.00～90.00g/kg.滇池草海底泥中有机质含量明显大于外海含量;外海有机质垂直分布...通过对滇池底泥118个样品的有机质含量分析统计和利用GIS绘制的底泥0～5cm,5～10cm,10～20 cm 3层有机质空间分布图,得出底泥中有机质含量的一般范围在40.00～90.00g/kg.滇池草海底泥中有机质含量明显大于外海含量;外海有机质垂直分布呈明显规律性-随着深度的增加而递减,而草海的有机质垂直分布没有明显的规律;并分析了滇池底泥中有机质含量的环境意义,为治理滇池提供理论指导.展开更多
文摘Spatial and vertical distribution of phytoplankton community were examined in the coast of the south of the Kerkennah Islands at three different depths 0, 2 and 6 m during the winter 2009 at 6 sampling stations. A total of 49 taxa belonging to five phytoplankton groups were identified （H＇=1.7 to 3.5 bits＇cell^-1）. Dinoflagellates and Diatoms were the most abundant phytoplankton groups which reached 27 and 71% of total abundance, respectively. The spatial distribution of the phytoplankton abundance showed a significant variation between the stations （P 〈 0.001）. While the vertical distribution of total phytoplankton showed a clear pattem, ANOVA test showed only an insignificant variation between the different depths at each station （P 〉 0.01）. On the whole, the maximum abundance of phytoplankton was recorded at the depths of 2 and 6 m （6 ×10^3 ind..Ll）. This might be due to the decrease of the nutrient concentrations in deeper water specially those of phosphate.
基金supported by the National Natural Science Foundation of China(Grant Nos.40875084and40705012)the National Key Technologies R&D Program of China(Grant No.2008BAC40B00)
文摘The latitude-altitude distributions of radiative fluxes and heating rates are investigated by utilizing CloudSat satellite data over China during summer. The Tibetan Plateau causes the downward shortwave fluxes of the lower atmosphere over central China to be smaller than the fluxes over southern and northern China by generating more clouds. The existence of a larger quantity of clouds over central China reflects a greater amount of solar radiation back into space. The vertical gradients of upward shortwave radiative fluxes in the atmosphere below 8 km are greater than those above 8 km. The latitudinal-altitude distributions of downward longwave radiative fluxes show a slantwise decreasing trend from low latitudes to high latitudes that gradually weaken in the downward direction. The upward longwave radiative fluxes also weaken in the upward direction but with larger gradients. The maximum heating rates by solar radiation and cooling rates by longwave infrared radiation are located over 28 40°N at 7 8 km mean sea level (MSL), and they are larger than the rates in the northern and southern regions. The heating and cooling rates match well both vertically and geographically.
基金supported by the National Natural Science Foundation of China(No.41806099)the Global Change and Air-Sea Interaction Project of China(No.GASI-04-HYST-06).
文摘The spatial distribution and seasonal variations of the hypoxic zone in the eastern equatorial Indian Ocean were investigated using survey data collected from four cruises from 2013 to 2018.Results showed that hypoxic zone occurred all year round in the eastern equatorial Indian Ocean,and it spread southward in the shape of a double tongue at two depths with one at subsurface centered at a depth of 150 m and the other in intermediate water centered at a depth of 800 m.The southward expansion and maximum thickness of the hypoxic zone were greatest in the spring inter-monsoon and least in the summer monsoon.The hypoxic zone originated from the southward expansion of the hypoxic water in the Bay of Bengal and its spatial distribution was driven by southward output flux of mid-deep(100–1000 m)hypoxic water from the Bay of Bengal.The hypoxia southward expansion was blocked near the equator in the subsurface layer,because of mixing with multiple zonal circulations(e.g.,Wyrtki Jets and the equatorial undercurrent),which meant that the hypoxic zone extended over a smaller area than in the intermediate water.These new findings will contribute to an improved understanding of the hypoxic zone and will contribute to circulation research,particularly about intermediate circulation in the eastern equatorial Indian Ocean.
基金supported by the National Natural Science Foundation of China (No. 41430425)
文摘Variation of haze events occurred in the Yangtze River Delta（YRD） of China, the characteristics of meteorological elements and the vertical distribution of aerosols during haze episodes were analyzed by utilizing data of ground observation, radiosonde and CALIPSO. The results illustrate that the frequency of haze events between 1981 and 2010 peaked in winter but bottomed out in summer and decreased from north to south in the YRD region, reaching at the lowest point in ＂low frequency center＂ - Shanghai. When haze happened, the most seriously affected area was 2-4 km above the ground and the concentrated range of total backscattering coefficient（TBC） that decreased with altitude was 0.8 × 10^（-3）-2.5 × 10^（-3） km^（-1）·sr^（-1）. Particulate depolarization ratio（PDR） was less than 40%in a large part and 93% aerosols over the YRD area were regular particles, while the irregular ones concentrated on 2 km above the surface and the irregularity rose up but the diversity diminished when altitude increased. Color ratio（CR） was lower than 1.2 mostly at all altitudes and distributed asymmetrically above the ground. Nearly 80% aerosols under10 km were fine particles（CR 〈1.0） clustered at 2-4 km. Large particles（CR 〉 1.2） aggregated in lower troposphere massively yet relatively smaller ones gathered in middle and upper troposphere. In the YRD region, aerosols with more powerful capabilities were wider and less regular than the ones of Northwestern China.
基金Supported by the National Natural Science Foundation of China (40905058 and 40475003)Chinese Academy of Meteorological Sciences Basic Research and Operation Fund (2009Z003 and 2011Z005)China Meteorological Administration Special Public Welfare Research Fund (GYHY200806001)
文摘By analyzing airborne observations over North China from 30 flights during spring and autumn of 2005-2007, characteristics of the vertical distributions of aerosol and cloud condensation nuclei （CCN） at 0.3% supersaturation in various locations of North China are investigated. The measurement samplings were conducted over different surfaces such as plains, plateau, and sea. The results show that the number concentration of accumulation mode aerosols was greater in autumn than in spring, but the reverse is true for CCN. This means that more aerosols with diameters smaller than 100 nm could be activated as CCN in spring, and this could induce higher aerosol activation efficiency. The aerosol activation efficiency over the plains near the Taihang Mountain was greater in spring than in autumn, and it was greater over sea than over land. The aerosol activation efficiency above the boundary layer over the Bashang Plateau was very low. Based on a fit of the negative exponential vertical distributions of aerosol and CCN, a spatial parameterization model of aerosol and CCN as well as aerosol activation efficiency over North China was proposed. The results show that aerosol activation efficiency was not clearly dependent on altitude because it was mainly affected by regional physical and chemical characteristics of aerosols and the ambient atmospheric conditions. The mean aerosol activation efficiency is 0.66, with values of 0.70 and 0.53 in spring and autumn, respectively.
文摘为探究封育保护后具有人工经营背景森林的群落结构和物种多样性在自然更替过程中的变化规律,以鄂西南地区的百户湾林场内0.01 km^(2)针阔混交林固定监测样地为研究对象,对木本植物的物种组成、群落结构和物种多样性进行调查与分析。结果表明,样地内胸径(diameter at breast height,DBH)≥1 cm的木本植物有8702株,隶属于39科66属111种;重要值排名前10位的物种中,常绿阔叶树种占明显优势;林冠层优势种为杉木(Cunninghamia lanceolata)和枹栎(Quercus serrata),灌木层优势种为翅柃(Eurya alata);样地内个体数量随DBH值增加而逐渐减少,小径级个体较多,平均DBH为5.2 cm;样地内物种较为丰富,各层级中亚乔木层的物种多样性最高。该研究为进一步探究森林群落结构和物种多样性的动态变化提供了科学依据。
文摘通过对滇池底泥118个样品的有机质含量分析统计和利用GIS绘制的底泥0～5cm,5～10cm,10～20 cm 3层有机质空间分布图,得出底泥中有机质含量的一般范围在40.00～90.00g/kg.滇池草海底泥中有机质含量明显大于外海含量;外海有机质垂直分布呈明显规律性-随着深度的增加而递减,而草海的有机质垂直分布没有明显的规律;并分析了滇池底泥中有机质含量的环境意义,为治理滇池提供理论指导.
