THE STUDY ON LATENT AND SENSIBLE HEAT FLUX OVER MIRE IN THE SANJIANG PLAIN

Energy exchange is one of the most importantprocesses in wetland ecosystems,because it has agreat influence on temperature,water transport,plantgrowth,productivityetc.(Dennison and Berry,1989).On small scales,understanding of surface en-ergy exchange is n…     

Radiation balance and the response of albedo to environmental factors above two alpine ecosystems in the eastern Tibetan Plateau

Understanding the energy balance on the Tibetan Plateau is important for better prediction of global climate change. To characterize the energy balance on the Plateau, we examined the radiation balance and the response of albedo to environmental factors above an alpine meadow and an alpine wetland surfaces in the eastern Tibetan Plateau, using 2014 data. Although our two sites belong to the same climatic background, and are close geographically, the annual incident solar radiation at the alpine meadow site(6,447 MJ/(m2·a)) was about 1.1 times that at the alpine wetland site(6,012 MJ/(m2·a)),due to differences in the cloudiness between our two sites. The alpine meadow and the alpine wetland emitted about 38%and 42%, respectively, of annual incident solar radiation back into atmosphere in the form of net longwave radiation; and they reflected about 22% and 18%, respectively, of the annual incident solar radiation back into atmosphere in the form of shortwave radiation. The annual net radiation was 2,648 and 2,544 MJ/(m2·a) for the alpine meadow site and the alpine wetland site, respectively, accounting for only about 40% of the annual incident solar radiation, significantly lower than the global mean. At 30-min scales, surface albedo exponentially decreases with the increase of the solar elevation angle; and it linearly decreases with the increase of soil-water content for our two sites. But those relationships are significantly influenced by cloudiness and are site-specific.     

天山季节性积雪的能量平衡研究和融雪速率模拟

本文采用能量平衡法模拟计算中国西部天山山地季节性积雪的融雪速率。结果表明:在融雪期,净辐射和感热通量分别占融雪能量输入的75.3%和22.6%;用于融雪和雪面蒸发所消耗的能量分别占吸收能量的95.1%和4.9%。用能量平衡法所计算的融雪速率和实测的雪面数据吻合的较好,表明用能量平衡法估算天山山地季节性积雪的融雪速率是可行的。     

The evapotranspiration and environmental controls of typical underlying surfaces on the Qinghai-Tibetan Plateau

To reveal the characteristics of evapotranspiration and environmental control factors of typical underlying surfaces(alpine wetland and alpine meadow)on the Qinghai-Tibetan Plateau,a comprehensive study was performed via in situ observations and remote sensing data in the growing season and non-growing season.Evapotranspiration was positively correlated with precipitation,the decoupling coefficient,and the enhanced vegetation index,but was energy-limited and mainly controlled by the vapor pressure deficit and solar radiation at an annual scale and growing season scale,respectively.Compared with the non-growing season,monthly evapotranspiration,equilibrium evaporation,and decoupling coefficient were greater in the growing season due to lower vegetation resistance and considerable precipitation.However,these factors were restricted in the alpine meadow.The decoupling factor was more sensitive to changes of conductance in the alpine wetland.This study is of great significance for understanding hydro-meteorological processes on the Qinghai-Tibetan Plateau.     

巴丹吉林沙漠典型湖泊湖气界面水一热交换特征

利用2012年8月-2013年7月在巴丹吉林沙漠腹地典型湖泊上用涡动相关系统观测的湍流资料,分析了湍流方差统计特征、微气象特征,计算了湍流热通量和湖泊蒸发量,初步结论为：①湖面上局地环流复杂,湍流三维风速的标准差与稳定度(Z/L)之间满足1/3次律。②湖面辐射分量具有明显季节变化和日变化特征,结冰期和非结冰期能量分配不同,冬季湖泊将储存的能量向大气传递;潜热通量和感热通量季节变化存在差异,但均有明显的昼夜变化特征。③湖气界面的感热通量在不同的月份也存在差异,感热以湖泊向大气传递为主;潜热通量夏半年远大于冬半年,在一天中6:00-8:00时处于最低值,15:00-16:00时达到峰值,在冬季会出现潜热向下输送现象。感热通量和潜热通量日变化呈负相关,湖面有效能量主要分配给潜热,湖泊同周围环境以水汽交换为主。④湖面平均蒸发速率为3.97 mm/d,累计蒸发量为1450±10 mm/a,同期的蒸发量是降水量的20多倍,湖泊主要靠地下水补给。这些结论可为进一步研究巴丹吉林沙漠腹地湖泊群的水循环及补给来源提供参考。     

三江平原季节性积水沼泽湿地能量平衡要素研究

2005年6月1日到8月30日,在中国科学院三江平原沼泽湿地生态试验站沼泽综合试验场季节性积水沼泽湿地,观测了净辐射和土壤热通量;利用Penman-Monteith公式和地表能量平衡方程式计算了潜热通量和感热通量;同时用SHAW模型对以上4个能量平衡要素进行了模拟研究,并用观测值以及模型效率、标准差和平均方差检验和评价了其模拟效果。结果表明,三江平原季节性积水沼泽湿地净辐射在6月末至7月初较大;潜热通量主要受净辐射的影响,与土壤水分关系不密切;沼泽湿地地表在6月初至8月中旬以吸收能量为主,8月末以后则开始释放能量;感热通量在植物生长季的初期和末期较大,在中期则比较小。SHAW模型能较好的模拟出沼泽湿地的净辐射、潜热通量和土壤热通量;该模型虽对感热通量的模拟结果并不理想,但能较好的模拟其变化趋势。这说明SHAW模型基本适用于对季节性浅积水沼泽湿地（水深小于10cm）能量平衡各要素的模拟。     

夏季不同天气条件下沙漠辐射和能量平衡的对比分析

利用2009 年7 月24 日-9 月12 日“巴丹吉林沙漠陆-气相互作用观测试验”资料,对比分析了典型晴天和阴天下巴丹吉林沙漠地表辐射、能量平衡和土壤温度的日变化规律.结果表明：①巴丹吉林沙漠典型晴天条件下总辐射、地表反射辐射、地表长波辐射、有效辐射、净辐射的峰值和日积分值都比典型阴天条件下大,大气长波辐射比阴天条件下小.两种天气条件下净辐射日积分值占太阳总辐射的1/3.②沙漠地区典型晴天地表反射率呈U型,白天均值为0.32;阴天变化较平缓,均值为0.29.③两种天气条件下地表热量平衡都以感热输送为主,波文比分别为4.55 和1.16.晴天不平衡能量达到净辐射的20%,阴天为30%.④晴天条件下有效能量夜间为负值,白天为正值,阴天全天为正值;湍流能量全天均为正值.能量闭合度(EBR)晴天平均为0.68,阴天为0.76.⑤土壤温度5~10 cm日较差逐渐减小,20、40 cm日变化不明显;5 cm土壤热通量日变化较大,20 cm土壤热通量振幅较小.     

西藏当雄高寒草甸碳通量定位观测站小气候的基本特征

分析了西藏当雄高寒草甸碳通量站4 a高密度小气候观测资料的净辐射、光合有效辐射,气温的年变化和日变化的规律,绝对湿度、相对湿度、风、大气压、土壤温度及湿度、土壤热通量的年变化规律.该地区具有明显的高原大陆性气候特征,光照强、日照长,太阳辐射和光合有效辐强;气温年较差小,日较差大;空气湿度小,较干燥,雨季和旱季分明,降水集中强度小;气压低,有常风;土壤温度年变化较小,土壤湿度和降水有明显的对应关系,降水节律是土壤湿度的决定因素.     

沙漠腹地人工绿地地表能量交换特征

运用涡度相关法开路系统对塔克拉玛干沙漠腹地人工灌溉绿地生长季地表能量交换特征以及与环境因子的关系进行测定分析。结果表明：在典型晴天条件下,无论是沙漠区还是沙漠腹地灌溉绿地,白天感热通量在净辐射通量的分配中所占的份额最大,潜热交换仅占很小的比例,人工绿地感热通量和潜热通量的峰值为230.54 W/m²和88.5 W/m²,沙漠区为220 W/m²和17.55 W/m²,沙漠腹地人工灌溉造林后潜热交换明显增加。沙漠腹地造林后,绿地波文比日变幅和日均波文比均减小,绿地日均波文比为沙漠区的15%,人工绿地的营建促使了局地气候的改变。绿地地表能量交换受气象因子和下垫面条件的影响和制约,按相关系数的高低,环境因子对感热、潜热通量的影响依次为：Rn>△Ta>△TS>v>TS,沙漠区人工造林后地表能量交换与多个环境因子有着密切的关系。这些研究结果将加深我们对沙漠地区人工灌溉造林地近地层能量交换的认识。     

内蒙古半干旱草原沙尘天气对近地层微气象学特征影响分析

利用锡林浩特国家气候观象台2011年4-5月近地层微气象、地表辐射和湍流通量观测数据,对比分析了内蒙古典型半干旱草原下垫面在晴天、扬沙和沙尘暴天气下各气象要素、地表辐射分量和能量平衡的变化特征。对于半干旱草原区,地面风速越大沙尘天气越强;沙尘过程开始前地面空气较暖,开始后地面空气转为相对较冷的状态;沙尘气溶胶含量越高,5 cm地温日变化趋势越弱,在沙尘过程中5 cm地温值越小。沙尘气溶胶含量越高,太阳总辐射越弱,大气长波辐射越强;地表反射辐射与总辐射有相同的日变化特征;沙尘气溶胶白天使净辐射值减小,夜间使净辐射值增大。沙尘天气直接辐射衰减非常明显,而且散射辐射在总辐射中占很大的比重。沙尘气溶胶对紫外辐射的削弱很强,并且沙尘含量越高,对紫外辐射的削弱越强。沙尘气溶胶的辐射强迫作用对地表能量平衡产生影响,使向上的感热和潜热输送减弱,使向上的土壤热通量增强或向下的土壤热通量减弱。     

三江平原典型沼泽湿地生态系统水分通量研究

利用野外定位观测数据 ,对三江平原典型沼泽湿地主要界面水分通量进行计算和分析。结果表明 ,2 0 0 3年生长季沼泽湿地系统与大气水分交换量 (蒸散发 )总量为 4 2 4 .7mm ,沼泽湿地水面 -大气水分通量 (水面蒸发 )总量为 2 6 0mm ,沼泽湿地植被 -大气界面水分通量 (蒸腾量 )总量约为 16 4 .7mm ;对沼泽湿地生长季水平衡的计算表明 ,生长季水分亏缺量达 14 0 .5mm ;非生长季大气降水是沼泽湿地生长季生态用水的重要来源。     

沙漠人工植被和流动沙丘的小气候特征观测研究

本文利用１９９２年８月在中国科学院沙坡头治沙试验研究站沙漠人工植被防护体系和流动沙丘下垫面近地面层的微气象观测资料，分析了其小气候特征，效应的物理机制及实际和理论意义。     

北冰洋浮冰和开阔海面上的能量平衡特征

利用中国首次北极考察队于 1 999年 8月 1 9日～ 2 4日在北冰洋浮冰区获得的大气近地层垂直廓线和辐射等资料 ,依据相似理论方法 ,对比分析了北冰洋无冰海面和冰面上热平衡参数的变化特征。结果表明 ,海面与大气和冰面与大气之间相互作用的边界层物理过程差异十分明显。冰面吸收的净辐射仅为海面的 6%左右 ,主要消耗于感热输送和冰面融化过程 ,不足部分由水汽在冰面上凝结释放的潜热和冰中的热通量来补充。海面吸收的净辐射主要消耗于潜热输送过程 ,占净辐射的 50 % ,其余热量传向水体深层和用于感热输送 ,分别占净辐射的 2 6%和 2 4 %。由此可见 ,在北冰洋夏季 ,无冰海面有大量的水汽向大气输送 ,这对研究北冰洋地区大气边界层的季节变化过程是至关重要的     

荒漠下垫面陆面过程和大气边界层相互作用敏感性实验

建立了一个研究荒漠下垫面陆面物理过程与大气边界层相互作用的模式. 模拟了荒漠下垫面的土壤环境物理、地面热量通量、蒸发、蒸散及大气边界层结构特征.并对主要的环境物理参数进行了敏感性实验.结果表明,本模式能合理地模拟荒漠下垫面地表热量平衡、土壤体积含水量、地表植被蒸发散阻抗、地表水汽通量日变化和湍流交换系数、湍流动能、位温和比湿廓线等.该模式还可进一步应用于研究区域陆面物理过程与大气边界层相互作用机制,及与中尺度大气模式耦合用于区域环境生态和气候的研究.     

塔克拉玛干沙漠近地层湍流热通量计算方法比较研究

利用2007年8月3日至10月31日在塔克拉玛干沙漠大气环境观测试验站取得的大气边界层观测资料,比较了涡动相关法、波文比法和空气动力学法计算得到的湍流热通量,分析了塔克拉玛干沙漠腹地能量平衡各分量的日变化特征。结果表明：波文比法、空气动力学和涡动相关法计算得到的塔克拉玛干沙漠腹地湍流热通量日变化特征是一致的,整个观测期间,空气动力学方法和波文比法计算得出的湍流通量大于涡动相关法。它们的顺序分别为,波文比法计算得出的湍流热通量最大,空气动力学方法次之,涡动相关法最小;塔克拉玛干沙漠腹地能量平衡各分量基本上以12:00时为中心,呈对称分布。净辐射、土壤热通量、感热通量具有非常明显的日变化特征。净辐射日最高值324 W·m-2出现在当地时间11:30,最小值-85 W·m-2出现在当地时间18:30;土壤热通量在12:00左右达到日最高值143 W·m-2,而20:00时出现最小值-69 W·m-2;感热通量在13:30时左右达到最高值178 W·m-2,19:00时左右出现最小值-7 W·m-2;相对于上述3个能量平衡分量,潜热通量的日变化特征不太明显。每日12:30左右出现潜热通量的最大值43 W·m-2,06:00时出现日最低值－1 W·m-2。     

Analysis about the influence on the thermal regime in permafrost regions with different underlying surfaces

In the last several decades, the underlying surface conditions on the Qinghai-Tibet Plateau have changed dramatically, causing permafrost degradation due to climate change and human activities. This change severely influenced the cold regions environment and engineering infrastructure built above permafrost. Permafrost is a product of the interaction between the atmosphere and the ground. The formation and change of permafrost are determined by the energy exchange between earth and atmosphere system. Fieldwork was performed in order to learn how land surface change influenced the thermal regime in permafrost regions. In this article, the field data observed in the Fenghuo Mountain regions was used to analyze the thermal conditions under different underlying surfaces on the Qinghai-Tibet Plateau. Results show that underlying surface change may alter the primary energy balance and the thermal conditions of permafrost. The thermal flux in the permafrost regions is also changed, resulting in rising upper soil temperature and thickening active layer. Vegetation could prevent solar radiation from entering the ground, cooling the ground in the warm season. Also, vegetation has heat insulation and heat preservation functions related to the ground surface and may keep the permafrost stable. Plots covered with black plastic film have higher temperatures compared with plots covered by natural vegetation. The reason is that black plastic film has a low albedo, which could increase the absorbed solar radiation, and also decrease evapotranspiration. The ＂greenhouse effect＂ of transparent plastic film might effectively reduce the emission of long-wave radiation from the surface, decreasing heat loss from the earth＇s surface, and prominently increasing ground surface temperature.     

敦煌戈壁冬夏季地表辐射与能量平衡特征对比研究

利用敦煌戈壁夏（2006年7月）、冬（2007年1月1—10日）季观测得到的微气象资料,比较了夏、冬季敦煌戈壁的地表辐射平衡、能量平衡特征。分析了地表反照率（Albedo）与土壤特性的关系,发现地表反照率和表层土壤温度日变化呈反相关;冬季地表反照率和土壤湿度的线性相关差,夏季地表反照率和土壤湿度的线性相关性好;地表反照率和土壤热通量呈反相关,并且冬季二者的拟合性好于夏季。分析了降水前后各能量通量的变化,发现阵雨时感热H是变小的,降雨过后H和净辐射Rn有明显的增大,土壤热通量Gn在降雨过后也有增大,潜热LE变化微弱,对阵性降水强迫后的非平衡态的张弛时间大约为3 d。     

塔克拉玛干沙漠塔中与巴丹吉林沙漠拐子湖地表辐射特征对比

利用塔克拉玛干沙漠腹地塔中和巴丹吉林沙漠北缘拐子湖两个陆气通量监测站2013年2月-2014年1月地面辐射观测数据及相应气象资料,对比分析塔中和拐子湖两地的太阳辐射通量和地表反照率差异特征,同时也探究了两地太阳辐射通量和地表反照率与太阳高度角之间的关系。结果表明：（1）塔中和拐子湖两地各辐射通量均呈较为同步的季节变化特征;具有太阳辐射优势的塔中地区因沙尘天气的影响在部分月份地表总辐射小于拐子湖地区;拐子湖由于地表沙粒相对较粗且包含大量透明度较高的石英颗粒,地表反照率和反射辐射均大于塔中地区;两地各辐射通量月平均日变化均呈现出标准倒"U"型结构;（2）拐子湖较粗的地表沙粒导致沙尘天气过后不易形成浮尘,沙尘天气过后各辐射通量恢复至发生之前的状态较塔中地区迅速;（3）两地太阳高度角夏季最大,冬季最小,最大值均可达75°左右,最小值塔中和拐子湖地区分别为45°和40°;各辐射通量随着太阳高度角的升高而增加,地表反照率随之减小,但受多种因素影响各辐射通量最大值并未出现在太阳高度角最大的时候。     

土地覆被变化过程中叶面积指数与降水量对地表能量平衡的贡献——基于SiB2的模拟结果

土地覆被变化过程中,叶面积指数（LAI）是地表能量平衡重要的影响因素,且与降水等多种因素存在交互作用。以2003 年中国东北地区农田、森林和草地三种覆被类型和三种LAI月变化过程为研究对象,着重分离出土地覆被变化过程中LAI对地表能量平衡的作用,认清覆被和LAI 变化对地表能量平衡的相对作用。利用SiB2 模型研究不同降水条件下土地覆被和LAI 变化对地表能量平衡的影响。结果表明：① 覆被变化对净辐射的影响最大,年均14.5W·m^-2左右。② LAI 主要改变净辐射对潜热和显热的分配,对农田和草地而言,LAI 增加明显提高（减小）潜热（显热）分配比例;对森林而言,LAI对潜热和显热分配的影响较弱。③ 降水对净辐射的分配起重要作用,降水增加,潜热增加。④ 表层土壤水分受降水和LAI 调控,与潜热有相反的变化趋势。     

Role of sea ice in air-sea exchange and its relation to sea fog

Synchronous or quasi-synchronous stereoscopic sea-ice-air comprehensive observation was conducted during the First China Arctic Expedition in summer of 1999. Based on these data, the role of sea ice in sea-air exchange was studied. The study shows that the kinds, distribution and thickness of sea ice and their variation significantly influence the air-sea heat exchange. In floating ice area, the heat momentum transferred from ocean to atmosphere is in form of latent heat; latent heat flux is closely related to floating ice concentration; if floating ice is less, the heat flux would be larger. Latent heat flux is about 21 23 6 W·m -2, which is greater than sensible heat flux. On ice field or giant floating ice, heat momentum transferred from atmosphere to sea ice or snow surface is in form of sensible heat. In the floating ice area or polynya, sea-air exchange is the most active, and also the most sensible for climate. Also this area is the most important condition for the creation of Arctic vapor fog. The heat exchange of a large-scale vapor fog process of about 500000 km 2 on Aug. 21 22,1999 was calculated; the heat momentum transferred from ocean to air was about 14 8×10 9 kW. There are various kinds of sea fog, radiation fog, vapor fog and advection fog, forming in the Arctic Ocean in summer. One important cause is the existence of sea ice and its resultant complexity of both underlying surface and sea-air exchange.