共查询到19条相似文献，搜索用时 78 毫秒
1.
鄱阳湖夏季水热通量特征及环境要素影响分析 总被引：2，自引：2，他引：0
气候变化加速了全球水文循环过程,然而,气候变化如何影响水体蒸发及其水热通量交换仍然不清楚.基于涡度相关系统观测鄱阳湖水体水热通量过程,在小时和日尺度分析了水热通量的变化规律及其主要影响因子.研究表明,潜热通量日变化波动剧烈,大部分为正值,变化范围在-50~580 W/m2之间.而感热通量数值较小,变化范围在-50~50 W/m2之间.8月份潜热通量和感热通量均呈波动下降趋势,均值分别为167.4和15.9 W/m2.8月份日平均潜热通量和感热通量之和大于净辐射,这是由于这一时段储存在水体中的热量释放并补充潜热通量和感热通量.小时尺度上潜热通量日变化在相位上与净辐射无显著相关性,而与风速显著相关.在日尺度变化趋势上,8月份日平均潜热通量仍主要受到风速和水温的影响,感热通量则主要受到风速和饱和水汽压差的影响. 相似文献
2.
北冰洋夏季开阔洋面和浮冰近地层热量平衡参数的观测估算 总被引：18，自引：3，他引：18
利用中国北极科学考察队在北冰洋浮冰站和“雪龙号”考察船获得的大气边界层观测资料, 采用涡旋相关法和廓线法对1999年8月19~24日北冰洋浮冰和开阔水面近地层的热量平衡参数进行了估算. 结果表明, 冰面的净辐射仅为开阔海面的8%, 主要消耗于感热输送和融化, 冰面损失的热量超过了吸收的净辐射, 并由冰的深层热传导来补偿, 潜热通量对冰面热平衡的贡献较小. 开阔海面吸收的净辐射主要以潜热和感热向大气输送, 分别占52%和25%, 剩余部分向深层水体传导. 观测事实说明北冰洋夏季开阔海面/大气和冰面/大气之间的热量交换过程有显著差异, 开阔洋面有大量的水汽向大气输送, 这对研究北冰洋地区海/冰/气相互作用对气候过程的影响是十分重要的. 相似文献
3.
湖泊模型为数值天气预报模型提供热量通量、水汽通量和动量通量等下边界条件,但是不同时间尺度上湖泊水热通量变化的控制因子不同,因此有必要对湖泊模型进行多时间尺度上的离线评估.本文利用2012-2016年太湖中尺度通量网避风港站的气象资料和辐射数据驱动CLM4-LISSS模型(Community Land Model version 4-Lake,Ice,Snow and Sediment Simulator),并与涡度相关观测(Eddy Covariance,EC)结果进行对比,以年平均潜热通量模拟结果最佳为目标调整了模式中的消光系数、粗糙度长度方案,研究了该模型从半小时到年尺度上对湖表温度和水热通量的模拟性能.结果表明:模型对湖表温度的模拟在各时间尺度上均比较理想,但是模拟的日较差较小;从半小时到年尺度上潜热通量的变化趋势都能被很好地模拟出来,但在季节尺度上,潜热通量的模拟出现了秋冬季偏高、春夏季偏低的情况,季节变化模拟不准确.湖表温度和潜热通量模拟偏差的原因可能是消光系数的参数化方案.相比之下,感热通量尽管年际变化趋势的模拟值与观测值一致,但是从半小时到年尺度均被高估.特别地,冷锋过境期间,模型能较好地模拟出潜热通量和感热通量的变化趋势,但对于高风速条件下的感热通量模拟效果不佳.本文的研究结果能为湖泊模式的应用与发展提供有用信息. 相似文献
4.
应用美国宇航局Goddard地球观测系统四维资料同化系统、计算了我国大陆地区和近海海域1998年各月月平均能量收支各项和10m气温、比湿及风矢量的地理分布特征. 模式计算结果表明,地表短波净辐射最强出现在夏季(7月)新疆和西藏中部地区,高值中心区可达275W/m2,在黄海东海海域春季(4月)最大,其值为250W/m2左右. 地表长波净辐射最强出现在夏季(7月)我国西北地区,中心区值为125W/m2,我国近海海域在冬季(1月)最强,其值为75-100W/m2. 我国近海海面,冬季(1月)潜热通量值高于一般月份,中心区值可达250W/m2,夏季我国大陆西南、华北和东北一带为潜热通量高值区,其值为125W/m2. 月平均能量收支计算结果显示,在黄海、东海海域冬季(1月)净通量为海洋向大气输送,夏季(7月)则反之,新疆和西藏高原中部夏季为净通量正值区. 综合温度、湿度和风矢量场分布发现,夏季从南海向华东地区,孟加拉湾向印度次大陆有明显的水汽平流输送,西藏西南部也有来自西南方向的水汽输送. 相似文献
5.
我国黄土高原地区地处夏季风边缘,分布在气候和生态过渡带,气候环境的空间差异很大,对陆面能量的空间分布格局影响非常显著.然而,由于受该地区陆面过程观测站点较少的局限,对整个黄土高原区域陆面能量的空间分布规律及其影响机制的认识十分有限.在对CLM模式模拟的陆面能量平衡分量资料进行试验验证的基础上,利用CLM模式模拟的近30年黄土高原地区陆面能量平衡分量资料,分析了该地区近30年平均陆面能量平衡分量的空间变化特征以及与最干燥年和最湿润年的差异,研究了陆面能量平衡分量空间分布与经、纬度和海拔高度等地理因素及降水和气温等气候因子之间的关系.发现,黄土高原地区陆面能量平衡分量空间差异非常显著,地表净辐射和感热通量由南至北增加,潜热通量和土壤热通量从东南向西北减少;空间最干格点和最湿格点之间的地表感热、潜热和土壤热通量几乎相差1倍左右,地表能量分配由最干格点的感热通量主导转变为最湿格点的感热和潜热平分秋色;年际干湿波动对地表能量平衡分量的影响也相当显著,对感热和潜热通量的改变幅度最大接近30%.而且,经纬度和海拔高度等地理因素及温度和降水等气候要素均与陆面能量平衡分量空间分布有一定的相关性,但地表净辐射与海拔高度和纬度的关系更密切,感热通量与降水和纬度的关系更密切,而潜热和土壤热通量只与降水的关系比较密切. 相似文献
6.
在2000年6-7月新疆阜康地区野外观测资料和美国宇航局Goddard地球观测系统资料同化系统计算相应时间能量收支基础上分析了夏季我国西部干旱地区辐射特征和能量收支.新疆阜康地区观测的夏季中午平均吸收辐射为664 W/m2左右,反照率为17%,夜间长波净辐射值为60W/m2左右.模式计算的相应地区的辐射特征与观测结果相当接近.模式计算结果表明,夏季新疆、甘肃西部、内蒙一带为感热通量高值区,其最大值在华北、东北地区,其值可达300W/m2.广大西北地区潜热通量都很低,其高值区在华东、华南、西藏东部和四川一带,最大值可达250-300W/m2. 相似文献
7.
西北太平洋海气界面湍流热通量低频振荡强度的特征 总被引：2，自引：0，他引：2
利用美国伍兹霍尔海洋研究所客观分析海气通量项目提供的1985～2006年日平均的湍流热通量及相关基本变量数据,通过小扰动方法和相关分析,详细讨论了西北太平洋湍流热通量低频振荡强度的特征．结果表明：（1）西北太平洋潜热低频振荡强度的空间分布主要受海气比湿差低频振荡强度（△q＇）和海气比湿差平均值（△q^-）的空间分布影响;感热低频振荡强度的空间分布主要受海气温差低频振荡强度（△T）的空间分布影响．（2）湍流热通量低频振荡强度冬季最强,夏季最弱．潜热低频振荡强度的季节变化受△q＇强度季节变化、海表面风速低频振荡强度（U＇）季节变化、△q^-季节变化和风速平均值U^-季节变化共同影响;感热低频振荡强度的季节变化主要受△T强度季节变化和U^-季节变化的影响．（3）20°N以北海域和热带西太平洋,潜热（感热）低频振荡主要受大气变量q＇a（Ta＇）和U＇的影响,表现为海洋对大气强迫的响应;20°N以南的热带中东太平洋,qs＇（Ts＇）的变化对潜热（感热）的低频振荡也有较大影响． 相似文献
8.
《地球物理学进展》2015,(4)
干热风是常发生在中国北方冬小麦产区的高温、低湿、风速较大,并伴随有强热量交换和水分蒸发过程的农业气象灾害.当其发生时如果不能保证作物水分的供给,将严重影响产量.因此,开展干热风发生机理的准确模拟与预报,对指导采取适时的农田管理措施,保障小麦产量至关重要.本文应用中尺度气象模式WRF(Weather Research and Forecasting)输出结果驱动北京大学陆面模式PKULM(Peking University Land Model)的模拟方法,结合气象台站观测与风云3A卫星遥感反演的叶面积指数数据,对关中平原2008-2013六年间干热风过程中农田生态系统温度、湿度、风速、感热通量、潜热通量等陆气交换特征进行了数值模拟.准确模拟出了干热风发生期间的大气温度、相对湿度、风速、土壤温度、土壤含水量及冠层感热通量、总感热通量、冠层潜热通量和总潜热通量等关键要素特征,揭示了本地区干热风的两种形成机制.模拟结果表明:WRF对干热风过程的温度场、湿度场与风场模拟比较准确,PKULM对于植物在干热风过程中、特别是气孔关闭阶段的感热、潜热通量的模拟明显优于WRF-Noah LSM(Noah Land Surface Model)的模拟效果.模拟结果与相应气象要素的观测值数值接近、变化趋势一致,在实际干热风发生时间段内的各要素模拟值均达到干热风指标,因此使用本模式系统模拟预报干热风灾害是可行的. 相似文献
9.
洱海湖气界面水汽和二氧化碳通量交换特征 总被引：2，自引：0，他引：2
基于2012年涡动相关法取得的洱海湖气之间湍流通量资料,计算了湖面反照率、空气动力学粗糙度和整体输送系数等湖气交换过程的基本物理参数;分析高原湖泊表面动量通量、感热通量、潜热通量和二氧化碳通量的变化特征及其主要的控制因子;采用神经网络法对缺失蒸发量数据进行填补,估算了洱海湖面全年蒸发量。2012年全年蒸发量为（1165±15）mm,大于年实际降水量（2012年的年降水量为818mm）。洱海局地环流在全年范围内较显著;全年主导风向为东南（谷风／湖风）和西北风（山风／陆风）。高原湖泊感热通量通常只有每平方米几十瓦,通常午后感热通量为负值;即湖面向大气输送热量。夏季湖泊大气界面感热通量最大值出现在清晨,与湖气温差的出现时间一致;在白天湖面的有效能量主要分配为潜热通量;湖气温差和水汽压差分别是感热通量和潜热通量日变化的主要控制因子。湖气界面二氧化碳通量除夏季存在弱的吸收外,其余季节（冬季）表现为弱的排放。湖面反照率的季节变化规律与太阳高度角的季节变动有关,同时湖面反照率与水的浑浊度等有关。与实际观测得到的湖面反照率相比,CLM4湖泊模式在冬季低估（夏季高估）了湖面反照率。 相似文献
10.
11.
使用2003年7月21日和10月20日云南省大姚县M62、M61地震震后流动数字化地震监测台网所记录的地震走时和波形资料，反演了震中区的Vp、Vs和Qp的三维结构.前人根据余震分布推测该震区存在一条北西西走向右旋走滑断裂带.三维结果表明，Vp和Qp的低值异常可以佐证该断裂带的存在；但除此断裂带，可能还存在一条北北东向断裂带，倾向西，表现为低Vp、Vs以及低Qp异常，并且异常深度达到8～10 km.因此，大姚震中区可能存在两条相互交错的断层，这与整个南北带断层的交错特征非常相似.另外我们推断该北北东向断带在南北方向可能有较长的延伸. 相似文献
12.
利用甘肃地震台网16个台站记录的远震资料，采用最大熵谱反褶积方法，得到了各个台站的接收函数. 采用接收函数扫描法和线性反演方法对研究区的壳幔结构进行了研究，这两种接收函数方法得出的结果具有很好的一致性. 青藏高原东北缘地壳厚度变化剧烈，祁连块体为50～55 km、柴达木块体和河西走廊为45 km左右（合作台除外），由北向南，Moho界面呈中央下凹的准对称状. 研究区地壳VP/VS介于166～185（σ=0215～0294，均值0254），其均值接近或略低于全球平均值；S波速度结构可见壳幔过渡带具有明显的突跳，结合其他地球物理学证据，推断该区可能不存在岩浆底侵作用和地壳部分熔融现象. 该区地壳VP/VS值与地壳厚度呈反相关关系，推断该区地壳的主要组成成分以中酸性岩石为主，其45～55 km厚的地壳可能主要是通过上地壳的叠置形成的. 相似文献
13.
基于大气边界层动量、感热和水汽通量的基本方程,定量地计算了波动海面的动量、感热和水汽通量。首先,应用Prandtl的混合长概念,推导出贴海面大气层中风速、位温和比湿的涡动交换率及其贴海面层厚度,并且证明了波面上位温或比湿贴海面层厚度与速度贴海面层厚度的比值,和平面上的相应比值完全相等。随后,利用空气动力学理论讨论了贴海面动量、感热和水汽输送的参数化问题。最后,对现有五种理论模式进行了比较说明。 相似文献
14.
15.
Naresh Krishna Vissa A. N. V. Satyanarayana B. Prasad Kumar 《Pure and Applied Geophysics》2013,170(12):2369-2381
In the present study, an attempt was made to understand the role of South China Sea (SCS) convection associated with northerly cold surges and Typhoon Peipah in initiating Cyclone Sidr in the Bay of Bengal (BoB). The variation of air sea fluxes during the entire history of Cyclone Sidr tracking before its landfall over Bangladesh was also studied. The presence of cold surges in the north SCS associated with heavy rainfall episodes has been noticed at the southern Gulf of Tonkin coast prior to the formation of Typhoon Peipah. Subsequently, these surges migrated south, which resulted in intensification of a deep convection on reaching the Vietnamese coast. During the same period in the western Pacific, Typhoon Peipah developed, propagating in the westward direction and entering the SCS. Analysis of geostationary water vapour images, mean sea level pressure, and surface wind maps clearly depicted the transport of convective cloud clusters, moisture, and westward momentum from Typhoon Peipah to the deep convection cells over the SCS. Consequently, the existing deep convection over the Vietnamese coast resulted in a westward direction and entered the Gulf of Thailand and Andaman Sea. The availability of higher latent heat fluxes, warmer sea surface temperatures, and suitable atmospheric conditions over this region favoured the formation of a tropical depression in the Andaman Sea. This depression further intensified in the southeast BoB, resulting in the formation of Cyclone Sidr. NCEP/NCAR wind fields and air-sea fluxes revealed left asymmetry surface winds and higher latent heat flux on the left side of the track during the intensification phase of Sidr. 相似文献
16.
XiaoHang Wen XiaoHan Liao WenPing Yuan XiaoDong Yan ZhiGang Wei HuiZhi Liu JinMing Feng ShiHua Lu WenJie Dong 《中国科学:地球科学(英文版)》2014,57(10):2340-2356
The default fractional vegetation cover and terrain height were replaced by the estimated fractional vegetation cover, which was calculated by the Normalized Difference Vegetation Index(NDVI) of Earth Observing System Moderate-Resolution Imaging Spectroradiometer(EOS-MODIS) and the Digital Elevation Model of the Shuttle Radar Topography Mission(SRTM) system. The near-surface meteorological elements over northeastern China were assimilated into the three-dimensional variational data assimilation system(3DVar) module in the Weather Research and Forecasting(WRF) model. The structure and daily variations of air temperature, humidity, wind and energy fields over northeastern China were simulated using the WRF model. Four groups of numerical experiments were performed, and the simulation results were analyzed of latent heat flux, sensible heat flux, and their relationships with changes in the surface energy flux due to soil moisture and precipitation over different surfaces. The simulations were compared with observations of the stations Tongyu, Naiman, Jinzhou, and Miyun from June to August, 2009. The results showed that the WRF model achieves high-quality simulations of the diurnal characteristics of the surface layer temperature, wind direction, net radiation, sensible heat flux, and latent heat flux over semiarid northeastern China in the summer. The simulated near-surface temperature, relative humidity, and wind speed were improved in the data assimilation case(Case 2) compared with control case(Case 1). The simulated sensible heat fluxes and surface heat fluxes were improved by the land surface parameterization case(Case 3) and the combined case(Case 4). The simulated temporal variations in soil moisture over the northeastern arid areas agree well with observations in Case 4, but the simulated precipitation should be improved in the WRF model. This study could improve the land surface parameters by utilizing remote sensing data and could further improve atmospheric elements with a data assimilation system. This work provides an effective attempt at combining multi-source data with different spatial and temporal scales into numerical simulations. The assimilation datasets generated by this work can be applied to research on climate change and environmental monitoring of arid lands, as well as research on the formation and stability of climate over semiarid areas. 相似文献
17.
Stream temperature and riparian microclimate were characterized for a 1·5 km wildfire‐disturbed reach of Fishtrap Creek, located north of Kamloops, British Columbia. A deterministic net radiation model was developed using hemispherical canopy images coupled with on‐site microclimate measurements. Modelled net radiation agreed reasonably with measured net radiation. Air temperature and humidity measured at two locations above the stream, separated by 900 m, were generally similar, whereas wind speed was poorly correlated between the two sites. Modelled net radiation varied considerably along the reach, and measurements at a single location did not provide a reliable estimate of the modelled reach average. During summer, net radiation dominated the surface heat exchanges, particularly because the sensible and latent heat fluxes were normally of opposite sign and thus tended to cancel each other. All surface heat fluxes shifted to negative values in autumn and were of similar magnitude through winter. In March, net radiation became positive, but heat gains were cancelled by sensible and latent heat fluxes, which remained negative. A modelling exercise using three canopy cover scenarios (current, simulated pre‐wildfire and simulated complete vegetation removal) showed that net radiation under the standing dead trees was double that modelled for the pre‐fire canopy cover. However, post‐disturbance standing dead trees reduce daytime net radiation reaching the stream surface by one‐third compared with complete vegetation removal. The results of this study have highlighted the need to account for reach‐scale spatial variability of energy exchange processes, especially net radiation, when modelling stream energy budgets. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
18.
Observational estimation of heat budgets on drifting ice and open water over the Arctic Ocean 总被引：9，自引：0，他引：9
It is of major scientific interests to determine the parameters of momentum, heat and vapor exchange in the planetary boundary layer in order to study the effects of ocean-ice-atmosphere interactions and their feedback mechanisms on global climate[1]. Lin… 相似文献
19.
Response of water and energy exchange to the environmental variable in a desert‐oasis wetland of Northwest China 
下载免费PDF全文
下载免费PDF全文 A case study on a desert‐oasis wetland ecosystem in the arid region of Northwest China measured the seasonal and interannual variation in energy partitioning and evapotranspiration to analyse the response of water and energy exchange on soil moisture, groundwater, and environmental variables. Energy partitioning showed a clear seasonal and interannual variability, and the process of water and energy exchange differed significantly in the monthly and interannual scales. The net radiation was 7.31 MJ m?2· day?1, and sensible heat flux accounted for 50.42% of net radiation in energy fluxes, 40.56% for latent heat flux, and 9.02% for ground heat flux. The parameters in energy fluxes were best described by a unimodal curve, whereas sensible heat flux followed a bimodal curve. Variations in the daily evapotranspiration and crop evapotranspiration also exhibited a single peak curve with annual values of 569.84 and 644.47 mm, respectively. Canopy conductance averaged 20.77 ± 13.75 mm s?1 and varied from 0.16 to 83.96 mm s?1 during the two hydrological years. The variation in water and energy exchange reflected environmental conditions and depended primarily on vapour pressure deficit, net radiation, soil moisture, and water depth. Although the effects of precipitation on evapotranspiration showed that the response of this ecosystem to climate changes was not obvious, the variation of air temperatures had a strong influence on evapotranspiration, resulting in a significant increase in evapotranspiration (R = 0.730; P < 0.01). Copyright © 2013 John Wiley & Sons, Ltd. 相似文献