南极瑞穗站辐射平衡及湍流通量特征

本文利用南极瑞穗站１９７９—１９８０年近地面层微气象及辐射平衡等观测资料，分析了春、夏、秋和冬季辐射平衡分量的日、年变化特征，采用空气动力学方法和廓线梯度迭代法计算了不同季节的动量通量、感热通量和由能量平衡方程得到的潜热通量的日变化特征，并对计算结果进行了比较。文中还对湍流热量交换系数、湍流动量交换系数与理查孙数的日变化关系进行了讨论。     

南极瑞穗站雪面热量平衡特征

利用南极瑞穗站(日本)1979年近地面层微气象资料及净辐射、本站气压等资料进行了统计分析。采用鲍文比-能量平衡法求得月平均感热通量和潜热通量,采用热含法计算得出月平均雪面热通量,使用了直接测量的净辐射通量,研究了该站雪面热量平均特征。其中突出的特征是3—12月雪面净辐射值为负值,主要靠感热通量由大气向雪面补充热量。将本文结果与苏联少先队站1956年的结果进行了比较,得出相当一致的年变化规律。最后,得出瑞穗站雪面为一强冷源。     

地面温度与雪面温度对比

通过平行观测,对德州市气象局所辖的陵县(2003～2004年)、武城(2004～2005年)、德州(2006～2007年)3站冬季有积雪时,人工站与自动站的地面温度观测资料进行统计分析,得出有积雪状况下的β值(β=自动观测地面温度/人工观测雪面温度)。自动观测的地面温度更能代表实际地面状况,这种对比关系可为使用地表温度的水文及农业部门提供一个更加准确的地面温度使用参数β,以掌握地面温度的变化规律,为地能、地热、地水的预测与判断提供准确数据。     

敦煌地区荒漠戈壁地表热量和辐射平衡特征的研究

利用2000年5月25日～6月17日"敦煌试验"在戈壁的微气象观测资料,分析了极端干旱地区晴天、阴天和降水等天气条件下的地表辐射平衡、热量平衡和土壤温度等微气象特征的日变化规律.发现在不同天气条件微气象特征有很大变化.但观测期间的平均微气象特征与晴天比较接近,天气过程的影响不是很大,平均的总辐射、净辐射和感热通量与晴天的比值在白天基本大于0.8.观测期间的平均Bowen比全天大于1,在白天都在10以上,最大超过100.     

河西戈壁（化音）小气候和热量平衡特征的初步分析

本文分析了1988年9月在甘肃省临泽县城西南侧戈壁获得的近地面层微气象观测资料。结果表明:白天晴空一般都是超绝热不稳定状态,并存在一种逆湿现象,造成向下输送的水气通量。这可能是由于戈壁地表极其干燥,没有蒸发,上层大气湿度反而比近地面层高,致使水汽从上往下输送。这时在地表面热量平衡过程中,潜热可以忽略不计,感热占绝对优势。     

上海市郊林带附近晴天地表热量平衡特征的分析

林带附近的热量平衡各分量的变化体现了林带对周围近地大气环境的影响.本文根据上海市郊林带附近温、湿、风梯度及净辐射观测资料,分析了林带附近冬夏晴天热量平衡各分量的特征,结果表明:夏季林带附近的净辐射比非林带小,冬季则比非林带大;林带对风速有减弱作用,林带附近的湍流输送较弱,因而林带附近热量和水汽量输送较小;林带附近有植物蒸腾,蒸散耗热量较大,为热量平衡中主要支出项;土壤热通量变化与近地面地温变化有关;林带附近较大的蒸散耗热和较弱的湍流输送有利于有利林带附近土壤水分的储存,并使周围湿润,但高温或低温时,湿度增加会引起人体不适,在林带规划上要充分考虑以上特点.     

南海——西太平洋海域热量平衡各发量的年变化特征及其与天气系统的关系

就海表面热量平衡Qι而言，它包括进入海平面的太阳总辐射Qs，海面有效回辐射Qb，蒸发耗热Qe，以及海洋与大气间感热交换Qc，它们之间的关系是：Qι＝Qs－Qb－Qe－Qc。本文对1965－1967年期间南海及西太平洋海域热量平衡各分量的月际变化进行了分析，结果表明：（1）海面热量平衡各人量的年变化中，季节变化是最显著的，各年之间具有共同性。（2）热量平衡各分量的季节变化对该地区的重要天气系统的作用是不一样的：（a）冬季感热加热带（也包括潜热）可能对移出大陆的气旋在海上加强有一定的贡献；（b）全年在低纬度海洋上一直存在的潜热加热带与台风活动有着密切的联系；（c）而进入海面的太阳总辐射可能对西太平洋副热带高压轴线的位移有一定的控制作用。     

陆地下垫面特征对区域能量平衡过程影响的数值试验

陆地下垫面性质的变化将会改变地气系统之间的能量平衡和转换过程，进而影响到区域气候环境。本文主要进行了陆地下垫面特征变化对区域能量平衡过程影响的数值试验，利用三维地气耦合的区域气候模式模拟了我国华北部分地区的地面能量平衡过程。结果表明，不同的陆地下垫面特征其地面能量分配和转换机制存在较大的差异，从而影响区域气候环境的形成和变化。这一结果可为人们通过改变地表特征的方式改善区域气候和生态环境提供一定的气     

半干旱草原下垫面能量平衡特征及土壤热通量对能量闭合率的影响

土壤热通量在半干旱草原下垫面能量平衡研究中极为重要,土壤热通量估计不够准确是导致地表能量不平衡的一个重要原因。利用2008年6—9月锡林郭勒草原主生长期地表辐射、通量和土壤温度梯度观测资料,研究中纬度半干旱草原下垫面地表能量平衡特征。首先,在分析能量平衡各分量月平均日变化特征的基础上,通过对土壤热流量板观测的5 cm深度土壤热通量(G)的相位前移,研究了土壤热通量相位滞后对地表能量平衡产生的影响;其次,利用谐波分析方法,通过计算地表土壤热通量(Gs),分析了地表到热流量板之间的土壤热量储存对地表能量平衡的影响。结果表明:(1)将土壤热通量相位前移30 min,湍流通量与可利用能量(Rn-G)线性回归的斜率从0.835增加到0.842,地表能量闭合率提高了0.7%,但仍有15.8%的能量不闭合;(2)考虑了地表到热流量板之间的土壤热量储存之后,湍流通量与可利用能量之间的回归斜率达到0.979,能量不闭合程度仅为2.1%。     

A study of the structure of low-level katabatic winds at Mizuho Station,East Antarctica

Low-level katabatic wind profiles, which have shapes similar to those of the low-level jet (LLJ) wind profiles, are often observed during strong winds in the summer period at Mizuho Station, which is located at 70°42 S, 44°20 E in East Antarctica. The profiles may be classified according to the height of the maximum wind speed, z _m , found below 30 m height. The behavior of z m and of conditions in the layer above z mare explained well by the normalized frequency, f N = Nz/U at 30 m, whose value can be used to predict the existence of a LLJ wind profile. Subsidence and inertial oscillations above z m are related closely to the height and time variations of z m. Thus, not only effects emanating upward from surface but also momentum and heat transported downward from above are significant for the evolution of z m.     

南极中山站附近地表大风的统计特征研究

利用近20 a的ERA5再分析资料研究了南极中山站附近的大风和极端大风事件的统计与环流特征。结果表明，春季大风事件的发生频次最高，夏季最少；冬季大风事件的平均持续时间最长，夏季最短；但大风事件的平均强度无明显季节变化。极端大风事件的发生频次具有显著的季节差异，冬季发生频次约为夏季的6倍、春秋的2倍，但平均持续时间和强度无明显季节变化。大风发生期间，南极对流层上层为单一极涡控制。在对流层中层，中低纬暖湿气流的向极入侵使得极涡破碎分裂，在中山站东侧产生高压脊，脊前冷空气下沉在地表堆积形成冷高压反气旋，其偏东气流在地形下坡风的作用下产生大风事件。上述环流特征在冬季最强、夏季最弱，从而导致大风事件的季节变化。     

Influence of snow cover changes on surface radiation and heat balance based on the WRF model

The snow cover extent in mid-high latitude areas of the Northern Hemisphere has significantly declined corresponding to the global warming, especially since the 1970s. Snow-climate feedbacks play a critical role in regulating the global radiation balance and influencing surface heat flux exchange. However, the degree to which snow cover changes affect the radiation budget and energy balance on a regional scale and the difference between snow-climate and land use/cover change (LUCC)-climate feedbacks have been rarely studied. In this paper, we selected Heilongjiang Basin, where the snow cover has changed obviously, as our study area and used the WRF model to simulate the influences of snow cover changes on the surface radiation budget and heat balance. In the scenario simulation, the localized surface parameter data improved the accuracy by 10 % compared with the control group. The spatial and temporal analysis of the surface variables showed that the net surface radiation, sensible heat flux, Bowen ratio, temperature and percentage of snow cover were negatively correlated and that the ground heat flux and latent heat flux were positively correlated with the percentage of snow cover. The spatial analysis also showed that a significant relationship existed between the surface variables and land cover types, which was not obviously as that for snow cover changes. Finally, six typical study areas were selected to quantitatively analyse the influence of land cover types beneath the snow cover on heat absorption and transfer, which showed that when the land was snow covered, the conversion of forest to farmland can dramatically influence the net radiation and other surface variables, whereas the snow-free land showed significantly reduced influence. Furthermore, compared with typical land cover changes, e.g., the conversion of forest into farmland, the influence of snow cover changes on net radiation and sensible heat flux were 60 % higher than that of land cover changes, indicating the importance of snow cover changes in the surface-atmospheric feedback system.     

Evaporation and radiation heat balance at the soil surface

Summary Evaporation from an area covered with short clover-grass has been determined by means of evapotranspirometers (4 m²), open (12 m²) and screened (1/3 m²) evaporimeters, and it has been estimated on the basis ofPenman's andThornthwaite's theories, too. The results of the measurements with the various instruments are compared with each other and with the results derived from the cited theories.Further, radiation heat balances have been made, including evaporation and heating of soil and atmosphere.

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Zusammenfassung Die Verdunstung über einer mit kurzem Kleegras bedeckten Fläche wurde mittels Evapotranspirometern (4 m²), offenen (12 m²) und abgeschirmten (1/3 m²) Evaporimetern gemessen und auch auf Grund vonPenmans undThornthwaites Theorien berechnet. Die Meßergebnisse der verschiedenen Instrumente werden untereinander verglichen und auch den mittels der angeführten Theorien abgeleiteten Resultaten gegenübergestellt.Weiters wurde eine Strahlungs-Wärme-Bilanz aufgestellt, die auch die Verdunstung und die Erwärmung von Boden und Atmosphäre berücksichtigt.

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Résumé On a mesuré l'évaporation sur une surface recouverte de trèfle court à l'aide d'évapotranspiromètres (4 m²) et d'évaporimètres ouverts (12 m²) et protégés (1/3 m²); les résultats de mesures, furent comparés entre eux et avec la théorie dePenman etThornthwaite.Puis on a dressé un bilan radiatif tenant compte, de l'évaporation et du réchauffement du sol et de l'atmosphère.

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With 8 Figures     

Chemical composition of falling snow at Dumont d'Urville,Antarctica

Fourteen samples of fresh falling snow were collected at Antarctic coastal base Dumont d'Urville in 1984. The samples have been analysed for major ions (including MSA) by ion chromatography and acid titration. The results are relevant to the chemical composition of background precipitation in polar marine conditions. The seasalt aerosol contribution is dominant. All samples are found to be acidic in the range 3–16 eq/l. The calculated non-seasalt sulfate (nssSO₄ ^2-) concentration is significantly negative for 3 of the 14 samples. NssSO₄ ^2- is found to be relatively high in summer and fall. MSA also exhibits the same pattern probably linked to local marine biogenic activity and/or atmospheric photochemical processes. The MSA to nssSO₄ ^2- ratio is in good agreement with values reported for coastal Antarctic ice cores and subantarctic acrosol. The background mean value for nitrate concentration is 1.1 eq/l but two very strong spikes (up to 16 eq/l) are observed. The first seems to be linked with long range transport of continental air masses while the second (in winter) is clearly due to a sudden input of nitric acid, possibly from the stratosphere.This paper represents a preliminary approach to a larger air and snow monitoring to be developped at this site.     

New estimations of precipitation and surface sublimation in East Antarctica from snow accumulation measurements

Surface mass balance (SMB) distribution and its temporal and spatial variability is an essential input parameter in mass balance studies. Different methods were used, compared and integrated (stake farms, ice cores, snow radar, surface morphology, remote sensing) at eight sites along a transect from Terra Nova Bay (TNB) to Dome C (DC) (East Antarctica), to provide detailed information on the SMB. Spatial variability measurements show that the measured maximum snow accumulation (SA) in a 15 km area is well correlated to firn temperature. Wind-driven sublimation processes, controlled by the surface slope in the wind direction, have a huge impact (up to 85% of snow precipitation) on SMB and are significant in terms of past, present and future SMB evaluations. The snow redistribution process is local and has a strong impact on the annual variability of accumulation. The spatial variability of SMB at the kilometre scale is one order of magnitude higher than its temporal variability (20–30%) at the centennial time scale. This high spatial variability is due to wind-driven sublimation. Compared with our SMB calculations, previous compilations generally over-estimate SMB, up to 65% in some areas.     

东亚地区的地表面辐射平衡、热量平衡及冷热源问题的研究

本文是<我国辐射平衡、热量平衡及水分平衡的研究>工作中的一部份。根据我国七十多个日射台站1974年前的全部实测资料,推求出适合于我国实际情况的计算方法。计算了我国300多个台站的太阳辐射各分量(直达辐射、散射、辐射、总辐射)数值。同时设计了计算理论公式的计算图,求得了这些台站的有效辐射量,从而得到我国辐射平衡及其各分量。又根据我国六个台站热量平衡观测资料,得到土壤热交换量与气温变化的关系,确定了土壤热交换量。并采用和计算了与我国邻近的国外几十个台站辐射平衡各分量及研究成果。最后分析了东亚地区的辐射平衡、热量平衡及冷热源的时空分布。     

The surface energy balance of a snow cover: comparing measurements to two differentsimulation models

Summary  We compared two one-dimensional simulation models for heat and water fluxes in the soil-snow-atmosphere system with respect to their mathematical formulations of the surface heat exchange and the snow pack evolution. They were chosen as examples of a simple one-layer snow model and a more detailed multiple-layer snow model (SNTHERM). The snow models were combined with the same one-dimensional model for the heat and water balance of the underlying soil (CoupModel). Data from an arable field in central Sweden (Marsta), covering two years (1997–1999) of soil temperature, snow depth and eddy-correlation measurements were successfully compared with the models. Conditions with a snow pack deeper or shallower than 10 cm and bare soil resulted in similar discrepancies. The simulated net radiation and sensible heat flux were in good agreement with that measured during snow-covered periods, except for situations with snowmelt when the downward sensible heat flux was overestimated by 10–20 Wm⁻². The results showed that the uncertainties in parameter values were more important than the model formulation and that both models were useful in evaluating the limitations and uncertainties of the measurements. Received November 1, 1999 Revised April 20, 2000