白洋淀水陆不均匀地区能量平衡特征分析

应用2005年9月在河北白洋淀地区进行的大气边界层综合观测实验资料, 对水陆不均匀地表条件下的白洋淀地区陆地的能量平衡特征进行了分析。结果表明: (1) 该地区存在能量不闭合现象。涡动相关法得到的感热、 潜热之和仅为有效能的75%, 其中涡动相关法得到的潜热通量为Bowen比法得到的潜热通量的70%, 而涡动相关法得到的感热通量为Bowen比法得到的感热通量的77% 。 (2) 地表潜热通量和感热通量随着净辐射的变化而变化。但潜热通量明显比感热通量大, 净辐射主要消耗于地表的水汽蒸发。 (3) 该地区白天的Bowen比平均在-0.4~0.4之间, 总体平均为0.131。受天气条件影响较大, 有明显的日变化, 午后15:00以后近地面层会出现逆温, Bowen比变为负值。 (4) 能量闭合程度有一定的日变化, 随着太阳高度角的增大而增大。     

A cold air outbreak near Spitsbergen in springtime — Boundary-layer modification and cloud development

A moderate cold air outbreak from the Arctic ice over the warm West-Spitsbergen current on 15 and 16 May 1988 during the field experiment ARKTIS '88 is analysed using data from four aircraft and one research vessel.The downstream development of cloud coverage appears to depend sensitively on the moisture content above the inversion. The cloud amount determines the energy balance at the sea surface. Under daytime conditions and little cloud cover, energy is added to the ocean in spite of sensible and latent heat losses.The downstream temperature increase in the boundary layer is controlled by sensible heat flux and by longwave radiation cooling. The entrainment sensible heat flux is the dominating term in the region near the ice edge. The downstream moisture increase is controlled by surface evaporation. Condensation processes play no significant role.On 16 May 1988 cloud streets near the ice edge changed to closed cloud meanders in the downstream direction. The aspect ratio increased from 3 to around 10 over a distance of 200 km. In the cloud street region, the dynamical generation of turbulent kinetic energy due to wind shear at the tilted inversion was larger than the thermal generation.Cloud droplet concentration, mean droplet radius and liquid water content increased linearly with height. The maximum liquid water content was only 0.1 g/kg near the top of a 400 m thick closed cloud and clearly below the adiabatic value. The net longwave radiation flux decreased by 50 W/m² at cloud top and increased by 13 W/m² at cloud base.     

青藏高原五道梁地区湍流输送特征的研究

根据１９９４年６－７月在青藏高原五道梁地区的湍流脉动观测资料，分析了该地区近地层能量平衡、感热和谱热的日变化及湍流强度和端流谱特征。结果表明：晴天该地区近地层能量基本平衡，各能量分量的日变化与常情况相同；白天感热通量的输送占主导地位，潜热通量占次要地位，符合半干旱的一般特征。     

夏季青海湖局地环流及大气边界层特征的数值模拟

使用美国NCAR新版MM5V3.6非静力模式,采用两重嵌套方法,模拟了青海湖区域的局地环流及大气边界层特征,并且与无湖试验进行了比较。结果表明:白天由于青海湖的存在有很好的降温作用,夜晚则有保温效应,表现出明显的冷(暖)湖效应;青海湖对感热和潜热的影响有很强的日变化,白天湖面感热、潜热都小,夜间情况相反,这使得白天青海湖是冷干岛,夜间是暖湿岛;青海湖使得白天湖面边界层顶低,陆面边界层顶高,夜间相反。这样的边界层顶高度和温度、地面能量通量相配合,形成了一个很好的保护机制,对青海湖的水土保持和生态环境的维持有正效应;青海湖使得湖面上空大气下沉,陆面上空大气上升,从而产生了湖面上空大气冷干,陆面上空大气暖湿的边界层特征;青海湖边缘的陆面形成的较大的湿气柱围绕着湖面,起到了保护湖面的作用;青海湖低空白天有明显的湖面向四周的辐散气流,而夜间则为从北偏东方向来的陆风。     

黄土高原塬区地表辐射和热量平衡观测与分析

利用2005年夏季黄土高原塬区陆面过程野外试验(LOPEX05)的观测资料,初步分析了甘肃平凉黄土高原塬区地表辐射收支和热量平衡特征。结果显示,黄土高原塬区地面长波辐射大于大气长波辐射,典型晴天、阴天和雨天情况下两者平均差值分别为65,25和8 W.m-2;对于地气能量交换各个分量而言,黄土高原塬上和塬下在相同下垫面下的差别不大,但裸地和有植被的下垫面差别很明显;在白天,潜热在净辐射中所占的比重较大,其次是感热,最后是土壤热通量。对能量平衡中的储存项如热通量板上层土壤的热存储和植被冠层存储进行了估算,结果表明,土壤的热储存项在-30~70W.m-2之间,而植被的热能储存项在-10~25 W.m-2之间。在考虑估算的存储项之后,能量平衡散布图斜率由0.68提高到0.79,相关系数R由0.90提高到0.93,两者分别提高了11.0%和3.0%,并对能量不平衡有明显的改进,说明能量储存项在地表能量闭合中必须考虑。     

东亚夏季风边缘摆动区陆面能量时空分布规律及其与气候环境的关系

东亚夏季风边缘摆动区既是气候敏感区,也是生态脆弱区和农牧交错带,其特殊陆面能量空间分布格局和演变特征对理解该区域天气和气候变化有重要意义。然而受限于陆面观测资料缺乏,对这部分陆面特征的认识仍非常有限。通过对34 a陆面模拟集成产品的分析,发现夏季风边缘摆动区内潜热和感热通量在空间上表现出明显的过渡特征,由摆动区外的相对均衡状态进入到摆动区内的“突变转换”;陆面能量平衡具有明显的区域特征,能量平衡各分量在纬向和经向都表现出了“阶梯型”的变化。就演变而言,区域平均感热和潜热没有表现出规律性的递减或递增趋势,波动幅度在±20%以内,但在20世纪末存在一个较为明显的摆动相位转换:1997年之前夏季风边缘摆动区夏季风相对活跃,潜热通量总体高于其气候值而感热通量则低于其气候值,之后出现了相反的现象。此外,区内感热和潜热通量对气候环境干湿性质非常敏感,两者存在明显的线性关系。      

盛夏我国东部地区热量平衡的个例计算

本文选取1959年7月23—26日4天正当高空副热带高压控制我国大陆时,对我国东部地区计算了能量方程中各项数值,以及各边界上的能量输送。计算表明,这个地区为能源区城,向外输送热量和水汽。至于在东、西、南、北四个边界上输送的情况有很大的差异,南界以输入为主;东界低层为输出,高层为输入。这种输送是由这个地区低空为大陆热低压,高空为副热带高压的环流特点所决定的。在热量输送中,扰动输送比平均输送为重要。在能量平衡中,支出项主要为平流输送和辐射冷却,而收入项主要是由下垫面向上输送感热和水汽潜热,大气本身的热量和水汽含量的变化在能量平衡中作用较小。湍流感热输送约为蒸发潜热输送的1.84倍。     

柽柳灌丛热量收支特性与蒸散研究

Bowen能量平衡法是广泛用于测定各种低矮植物蒸散的常用方法。本文将改进的波文比—能量观测系统用于测定灌木柽柳群落的测定，通过6～9月对感热通量、潜热通量、土壤热通量等的测定，计算出额济纳地区柽柳灌丛(6～9月)的蒸散量为335．31mm；在8月潜热通量占能量支出量的62．85％，感热通量占32．85％，土壤热通量占4．44％。在日变化中，潜热在上午大于感热，下午感热交换大于潜热。     

青藏高原中部季节冻土区地表能量通量的模拟分析

利用“全球协调加强观测计划之亚澳季风青藏高原试验(CAMP/Tibet)”中那曲地区BJ站2002年8月1日\_2003年8月31日的观测资料作为水热耦合模式(Simultaneous Heat and Water, SHAW)的强迫场,对青藏高原中部季节冻土区地表能量通量特征进行了单点模拟研究。通过对实测值与模拟结果的对比分析,发现SHAW模式能较成功地模拟该地区地表能量通量特征, 短波净辐射和长波净辐射的模拟值与观测值吻合较好, 净辐射和土壤热通量在夏半年的模拟值与观测值也吻合,但相对夏\, 秋季而言,它们在冬\, 春季的模拟值较观测值略偏大。模拟的感热和潜热通量的季节变化比较合理,由模拟的感热和潜热通量计算的Bowen比能较好地解释不同季节太阳辐射的能量转化。     

高温和台风影响下的苏州城市粗糙子层湍流通量特征

利用苏州地区2011 年12月20 日-2012年8 月13 日的湍流观测资料对不同季节、高温、台风强天气过程下的湍流特征进行分析.结果表明:城市地区不同季节动量通量、感热通量、潜热通量日变化明显,各通量的夏季平均值、最大值均高于冬春季,夏季感热通量日最大值为160.2 W·m-2,感热在城市地表能量平衡中的作用大于潜...     

Tests of a robust eddy correlation system for sensible heat flux

Summary Sensible heat flux estimates from a simple, one-propeller eddy correlation system (OPEC) were compared with those from a sonic anemometer eddy correlation system (SEC). In accordance with similarity theory, the performance of the OPEC system improved with increasing height of the sensor above the surface. Flux totals from the two systems at sites with adequate fetch were in excellent agreement after frequency response corrections were applied. The propeller system appears suitable for long periods of unattended measurement. The sensible heat flux measurements can be combined with net radiation and soil heat flux measurements to estimate latent heat as a residual in the surface energy balance.With 6 Figures     

广州番禺地区草地陆气相互作用观测研究

介绍了2004年在广州番禺进行的陆气相互作用观测试验。观测研究表明:新型的超声风温仪虽然带有雨滴防护沙网, 但雨滴对超声观测的误差影响显著, 尤其是对u, w方向。雨天情况下与z/L相关系数很低, 湍流强度与稳定度不存在1/3次方关系。涡动相关法和能量平衡法计算的感热通量及潜热通量比较接近, 感热、潜热通量相关系数分别达到0.8699和0.8633, 两种方法带来的误差主要发生在近地层稳定度发生明显变化的时刻, 即在午间热通量的峰值或傍晚或晚间热通量的低值, 其中能量平衡法计算的感热、潜热普遍具有较大的正负峰值。涡动相关法计算的Q_h+Q_e普遍偏小, 与可用能量R_n-Q_g多数情况下存在能量不平衡, 说明了忽略热存储项的地表能量平衡方程的局限性。番禺夏、秋季近地层各能量具有与太阳辐射相似的日变化特征, 但夏季的潜热大于感热, 而秋季则相反。近地面二氧化碳从5—8月是一个减低过程, 尔后上升到12月份浓度最高, 总体浓度值在350×10-6~400×10-6之间变化。     

中国西北干旱区戈壁下垫面夏季的热力输送

以敦煌戈壁站2004年6月和2008年8月的常规观测和超声观测为例,分析了西北干旱区戈壁下垫面夏季热力输送的一般过程及特征。首先评价了湍流通量的观测质量以及仪器观测的地表能量通量闭合问题,结果表明敦煌戈壁站的观测在白天总体较好。夏季地表能量通量的平均日变化显示,潜热通量整天都很小,可以忽略,白天到达地表的短波辐射以及地表向上的长波辐射非常强,地表净辐射主要转化为感热输送（敦煌戈壁站在中午时平均分别达380W·m-2以上和250W·m-2以上）;夜间土壤释放热量以平衡地表的辐射冷却,感热通量略低于0。白天时地表大气经常触发自由对流活动,影响动量通量的观测质量,并有效输送地表热力至上层大气中,有助于形成超厚大气边界层。分析了戈壁下垫面的动量粗糙度特征和热力粗糙度特征（敦煌戈壁站动量粗糙度约为0．6mm）,热力粗糙度基本小于动量粗糙度一个量级,这符合目前对干旱区戈壁下垫面热力输送特征的初步认识。     

Climate change and the regulation of the surface moisture and energy budgets

The increase in the vigor of the hydrological cycle simulated in a 2 × CO₂ experiment with the Canadian Climate Centre general circulation model is smaller than that obtained by other models which have similar increases in mean surface temperature. The surface energy budget, which encompasses also the moisture budget for the oceans, is analyzed. Changes in the net radiative input to and sensible heat flux from the surface act to warm it. This is balanced, at the new equilibrium, by a change in the latent heat flux which acts to cool it. Although this same general behavior is seen in other models, the increase in radiative input to the surface in the CCC GCM is smaller than in other models while the change in the sensible heat flux is of similar size. As a consequence, the latent heat flux required for balance is smaller. The comparatively small increase in the net radiative input at the surface occurs because of a decrease in the solar component. On average the decrease in solar input in the tropical region outweighs the higher latitude increase associated with the snow/ice albedo feedback. The notable tropical decrease in solar input occurs because the albedo of the clouds increase enough in this region to outweigh a small decrease in cloud amount. The increase in cloud albedo in the warmer and moister tropical atmosphere is a consequence of the parameterized cloud optical properties in the model which play an important role in the regulation of the surface energy and moisture budgets. The results demonstrate some of the consequences of the negative feedback mechanism associated with increasing cloud albedo in the model. They also suggest that the simulated change in the vigor of the hydrological cycle is not a simple function of the average increase in surface temperature but is a consequence of all of the processes in the model which control the available energy at the surface as a function of latitude.     

北京郊区草地夏季能量收支平衡的数值模拟

北京郊区地表能量分配可能影响北京地区的天气和气候。为了进一步检验陆面过程模式对北京郊区具有代表性的稀疏草地地表能量分配的模拟能力,利用原版和改进版简化生物圈模式(SiB2,Simple Biosphere Model 2)模拟了2010年7月22日-8月5日期间北京郊区阳坊镇坦克打靶场草地的辐射平衡、能量收支以及地表热通量。并将模拟结果与实际测量的数据进行对比,结果表明:1)原版SiB2低估净辐射11.32%,改进版SiB2则低估净辐射5.81%,主要原因是改进版SiB2更新了土壤热传导率计算方法,从而提高了土壤温度(包括地表温度)模拟结果的精度,进而改善了地表向上的长波辐射模拟结果的准确性;2)改进版SiB2同时改善了感热通量和潜热通量的模拟结果,但是原版SiB2和改进版SiB2均低估了土壤热通量。     

植被冠层截留对地表水分和能量平衡影响的数值模拟

利用NCAR_CLM4.0模式,通过有无植被冠层截留的试验对比分析,讨论了植被冠层截留对全球陆面水分和能量平衡产生的潜在影响.结果表明:就全球水分平衡而言,不考虑植被冠层截留时,全球平均土壤总含水量、表面径流和次表面径流增加,蒸散发减少.空间分布特征表明,低纬地区各水分平衡分量全年维持较高的差值分布,并随季节变化沿赤道南北振荡;北半球中高纬高值区有春季扩张、夏季极盛、秋冬季撤退的趋势.冠层截留消失后冠层蒸发的消失是蒸散发减弱的主要原因.对于能量平衡而言,不考虑冠层截留时,全球感热通量增加,冠层感热的增加明显大于地面感热的减少;潜热减少.此外,不同植被类型对不考虑冠层截留后产生的响应存在明显差异.     

Suburban-rural energy balance comparisons in summer for Vancouver,B.C.

Simultaneous energy balance observations at a rural and a suburban site in Vancouver, B.C. during the summer of 1983 are presented. The study is a follow-up to that conducted in 1980. Many of the 1980 results were unexpected and the present study seeks to assess their representativeness. The net radiant, turbulent sensible, and rural soil heat flux densities were measured directly. The suburban heat storage was parameterized and the turbulent latent heat flux densities were resolved as residuals in the energy balances. The 1983 average diurnal energy partitioning for both sites was typical of those quoted in the literature, suggesting that the 1980 results represent an extreme case. Suburban-rural differences showed the suburban area to have a 4% increase in net radiation, a 51% increase in turbulent sensible heat, and a 46% decrease in turbulent latent heat flux density. The values of the average daytime Bowen ratio were 0.46 and 1.28 for the rural and suburban areas, respectively. The sensible heat flux density exhibited relatively large values in the late afternoon and remained directed upward on many summer evenings. Large day-to-day variability in the relative magnitude of the suburban turbulent fluxes may have been due to synoptic influences. In this environment, the turbulent surface and mixed layers are closely coupled because of the low aerodynamic resistance over the rough surface.     

淮河流域典型地面水热通量的观测分析

根据1998年淮河流域能量和水循环试验加密观测(HUBEX-IOP)获得的资料,用三种微气象方法计算该地区的感热通量和潜热通量状况,比较了不同方法所估算结果的异同,并以梯度法的资料为主分析了其变化特征.结果表明:(1)梯度法估算的潜热通量与用波文比-能量平衡方法的估算值比较接近,与涡度相关方法估算的值之间有一定的差异.(2)感热通量和波文比在梅雨(6月28日～7月4日)前较大,在后期较小.大部分辐射能用于地面蒸发.     

Simulation of the Bare Soil Surface Energy Balance at the Tongyu Reference Site in Semiarid Area of North China

The performance of a 1-D soil model in a semiarid area of North China was investigated using observational data from a cropland station at the Tongyu reference site of the Coordinated Enhanced Observing Period (CEOP) during the non-growing period, when the ground surface was covered with bare soil. Comparisons between simulated and observed soil surface energy balance components as well as soil temperatures and water contents were conducted to validate the soil model. Results show that the soil model could produce good simulations of soil surface temperature, net radiation flux and sensible heat flux against observed values with the RMSE of 1.54oC, 7.71 W m-2 and 27.79 W m-2, respectively. The simulated volumetric soil water content is close to the observed values at various depths with the maximal difference between them being 0.03. Simulated latent heat and ground heat fluxes have relatively lower errors in relative to net radiation and sensible heat flux. In conclusion, the soil model has good capacity to simulate the bare soil surface energy balance at the Tongyu cropland station and needs to be further tested in longer period and at more sites in semiarid areas.     

上海秋冬季地表能量平衡及CO2通量特征分析

利用2012年11月11日至2013年1月20日上海秋冬季涡动相关通量观测资料,对比分析地表能量平衡和CO₂通量在不同天气条件下的日变化特征。结果表明：2012-2013年上海晴天和多云天气条件下,最大能量通量为储热项,其次为感热项;用于蒸发的潜热通量项最小,低于50 w·m^-2。储热项日峰值出现在11时,出现时间早于净辐射通量,而在日落前转为负值。感热项日变化曲线并不以12时为中心呈对称分布,日落后感热项仍为明显正值。中午至日落时波文比值为3以上。感热通量受风向影响最大,在主导风向为西北风时,感热通量日峰值从其他风向的175 w·m^-2左右减小至120 w·m^-2左右。霾和云对短波辐射均表现为衰减作用,云的衰减作用明显大于霾。云使地表向上长波辐射和净长波辐射明显减少,而使大气逆辐射增加。晴天条件下,全天表现为CO₂排放源,且日变化呈双峰型,两个峰值出现时间正好对应上下班高峰时段,傍晚峰值大于早上峰值。