THE CLIMATOLOGY OF LAKE EFFECT IN MILWAUKEE,WISCONSIN

Prevailing onshore winds off Lake Michigan in the warm season (April-October) cause cooling along the adjacent coast during the day. Mesoscale lake breeze formation occurs most frequently in August. Synoptic-aided lake breezes, which combine mesoscale inputs with existing large-scale conditions, are most prevalent in May. Lake breezes are favored by high pressure and airmass weather patterns. Synoptic lake effect dominates in April; large-scale onshore flow is often produced by high pressure, post-cold front, and pre-warm front weather conditions. Overall, lake cooling is experienced 60% of the time during the warmer months. The highest frequency of lake effect is found in May. The cooling impact of Lake Michigan across the Milwaukee area is maximized since spring is the season of greatest contrast in land and lake temperatures. Lake-effect conditions in the cool season (November-March) occur less frequently. Onshore flow off the warmer lake reduces cooling at night along the Milwaukee shoreline. Synoptic lake effect is dominant, with a peak in March. Lake snow and mesoscale land breeze developments are most frequent in midwinter, when large land-lake thermal contrasts exist during outbreaks of cold polar air under high pressure patterns. [Key words: lake effect, climatology, mesoscale, onshore winds.]     

干谷和湿谷边界层气候差异的数值模拟研究

本文建立了一个采用地形坐标的、包含大气边界层湍流参数化方案,大气辐射过程的参数化方案、陆-气-水相互作用的地面温湿度预报方案等物理过程的非静力近似中小尺度数值模式,用这个模式试验研究了在气候平均值的背景下谷底水体的有无对山地气候影响的一般情况。模拟结果表明:由于水体的存在,夜间谷底气温较干符情况有较大的升高,山谷逆温受到破坏;白天谷底气温则有降低。湿谷中的地湿一般都较干谷中大,尤其是夜间更为明显。无论白天还是夜间,由于山谷风和湖陆风共同作用的结果,湿谷中的风速都此干谷中大,湿谷中的局地环流比干谷中的更为明显。     

天山天池山谷风的气候研究

本文讨论了天山天池山谷风的风向、风速、转换期、季节变化及对温湿度日变化的影响。     

大型人工湖气候效应观测研究——以密云水库为例

应用近5 a自动气象站观测资料,分析了华北地区最大人工湖——密云水库的局地气候效应。结果表明：① 密云水库库区相比于附近平原地带具有气温偏低、湿度偏高、风速偏弱、降水量偏大等特点。水库对区域气候的影响范围约在10 km内,离水库越近的地方,受影响越大。② 密云水库的气候效应主要体现在夏半年,尤以气温和降水最为明显。③ 水库南、北两侧受到的局地环流的影响具有明显的差异,库区东西方向的年平均局地风速约为0.14 m/s,南北方向约为 0.10 m/s。下垫面属性的热力差异及特殊地形条件使得密云水库附近同时存在山谷风和湖陆风现象,其叠加效应是导致区域内不同位置间气象要素出现季节性及日变化差异的主要原因。     

通过现代观测来检验湖面蒸发对中国干旱、半干旱区湖泊水位变化的影响(英文)

Qinghai Lake and Zhuye Lake, ~400 km apart, are located in the northwest margin of the Asian summer monsoon. Water of these two lakes mostly comes from the middle and eastern parts of the Qilian Mountains. Previous studies show that the Holocene climate changes of the two lakes implied from lake records are different. Whether lake evaporation plays a role in asynchronous Holocene climate changes is important to understand the lake records. In this paper, we used modern observations beside Qinghai Lake and Zhuye Lake to test the impact factors for lake evaporation. Pan evaporation near the two lakes is mainly related to relative humidity, temperature, vapor pressure and sunshine duration. But tem-perature has different impacts to lake evaporation of the two lakes, which can affect Holocene millennial-scale lake level changes. In addition, differences in relative humidity on the millen-nial-scale would be more significant, which also can contribute to asynchronous lake records.     

南极特拉诺瓦湾下降风特征

南极罗斯海特拉诺瓦湾(Terra Nova Bay)是强下降风汇集区之一。采用高分辨率南极中尺度预报系统(Antarctic Mesoscale Prediction System,AMPS)资料和特拉诺瓦湾难言岛Manuela自动气象站实测数据,分析了特拉诺瓦湾及其附近地区的下降风特征。AMPS对难言岛地区风速和气温有较好的模拟能力,但风向比实测值偏西约30°。难言岛地区风速从1月开始迅速增大,4—9月风力平均为8级以上。难言岛夏季1月份的风速变化滞后气温变化约3 h;冬季7月份风向稳定为西至西南。特拉诺瓦湾及其附近地区下降风来自西岸海拔较高的冰盖,其风向的空间分布特征基本几乎不随季节而变化。下降风风速有显著的季节演变特征,11月至次年1月较小,3—9月风速较大。特拉诺瓦湾西岸等几处冰川地带在冬季是强风汇集区,难言岛处于Reeves冰川下降风汇集区中。该汇集区上边界和南北两侧均有清晰的分界线,风速较强区从地面延伸至650—800 m高处,风速最大值距离地面高度约为50—200 m。强下降风气流受难言岛地形阻挡,风速有所减弱,气流越过难言岛之后,风速再次加强。特拉诺瓦湾地区下降风流动过程中近地面气团位势温度变化幅度很小,表明下降风在从内陆高原到沿岸地区的流动是干绝热过程。     

卫星遥感检测高原湖泊水面变化及与气候变化分析

对西藏西部的玛旁雍错、中部的纳木错和南部的普莫雍错三大湖泊地区,采用中巴资源卫星自1999年至2007年长时间序列的影像数据,通过最佳波段组合和时相的选取,高精度几何配准和镶嵌以及进行边缘信息提取等处理,绘制湖面变化解译图。并用一景同期ETM 图像作为辅助数据计算湖区地物光谱反射率曲线以辅助分类。为避免个别年份湖面变化出现偶然性,采用几个相邻年份湖面求取平均值的方法统计近年湖面面积。其结果与1984年中国科学院青藏高原综合科学考察队的数字对比表明,西藏南部的普莫雍错和中部的纳木错湖面有明显扩张,分别扩张了大约4.01%和4.55%;而西部的玛旁雍错近年间变化不大,甚至略有萎缩趋势,相比1984年也仅增长了1.31%。为研究西部地区和中东部地区出现不同变化的主要原因,通过对水位数据和气象特征因子的相关性分析,及对三地区近34年的气象资料,包括年均温度、年均降雨量、年均蒸发量等进行距平均值曲线拟合,发现中东部年均温和降雨量均呈显著增加趋势,而西部降雨量则呈微弱减少趋势。这说明近期湖面的扩张与气象资料分析的变化情况具有很好的一致性,反映遥感方法在湖泊水域变化检测方面具有较高的可用性。     

青海湖水量变化模拟及原因分析

为了探讨气候变化和人类活动对流域水文过程的影响,以分布式水文模型SWAT为基础,结合湖泊水量平衡模型,建立了青海湖水位(水量)模型,模拟了青海湖过去几十年水位变化过程。水文因子分析表明,20世纪80~90年代青海湖流域径流和湖泊水位变化的主要原因是气候变化。根据不同气候情景,对未来青海湖水位变化进行了预测。结果表明,未来30年径流增加的可能性比较大,青海湖水位下降速度将会减缓甚至出现上升趋势。这一结果将会缓解青海湖流域水资源日益紧张的局势,并有利于植被的恢复,减少土地沙化面积,对流域生态环境的改善和社会经济的发展将会有极大的帮助。     

南极中山站吹雪雪暴天气分析

本文利用 2 0 0 3年 1月至 2 0 0 3年 1 2月在中国南极中山站考察期间的天气观测记录和气象传真图 ,对东南极中山站地区的吹雪和雪暴天气进行了统计和天气学分析研究。着重分析了吹雪雪暴天气的时间分布和风场 ,温湿场的特点以及相应的天气形势 ,指出了中山站地区预报吹雪雪暴天气的特点     

普里兹湾沿岸下降风特征分析

根据2008年南极中山站的臭氧气球探空观测和塔层自动气象站数据,以及同时期的再分析资料,分析下降风(Katabatic wind)发生时的普里兹湾沿岸和东南极内陆地区的天气形势、中山站的边界层特征、气象要素的日变化规律。并利用对数风速廓线定律模拟中山站下降风,与实测值进行对比。个例研究表明,在晴朗的夜间或多云的白天,内陆地区冰面辐射冷却,导致气温降低,与普里兹湾沿岸地区的温度梯度大。此时内陆地区受高压控制,成为辐散中心,且高压的位置决定普里兹湾东岸和西岸的下降风强度。中山站的下降风出现在边界层低层,地面风速大,风向主要为东、东北东,导致强不稳定层结、气温和位温迅速降低。对数风廓线定律模拟中山站下降风的能力有限。     

基于RS和GIS的库木库勒盆地盐湖面积变化及气候响应

以Landsat卫星1972~2013年间5个时期的遥感影像数据为基础,结合野外实际调查和室内解译分析,运用RS和GIS技术,提取影像中盐湖湖水边界信息,并绘制了5个时期盐湖面积变化的图谱。结合库木库勒盆地气象数据(年降水量、平均气温、相对湿度、平均风速)对盐湖面积变化进行响应分析,探究盐湖变化与气候之间的相关性,并讨论气候变化对库木库勒盆地内盐湖面积变化的影响机制,探讨不同气象因子对盆地内盐湖面积变化的作用。平均气温、降水量、相对湿度对盆地内盐湖的面积扩大均有促进作用,且平均气温的作用占主导性,这为库木库勒盆地盐湖的演化研究以及盐湖资源开发提供了相应参考和借鉴材料。     

The August 2007 Heat Wave in North Carolina: Meteorological Factors and Local Variability

August 2007 was an exceptionally warm month across North Carolina. Hundreds of daily maximum and daily high minimum temperature records, as well as numerous all-time temperature records, were either tied or broken during the month. At the same time, a drought of historic proportions overspread much of the Southeast United States. A critical aspect of the August 2007 heat wave was the observed variability in heat and humidity across the different geographic regions of North Carolina. The highest maximum temperatures occurred most frequently in the Piedmont and Sandhills regions, while minimum temperatures were exceptionally high along the coast. The broad-scale pattern of heat can be tied to adiabatic warming associated with subsidence downstream of a persistent upper-level ridge centered over the Mississippi River Valley. Regional to local variations in the heat and humidity across North Carolina are linked to upwind sensible heat fluxes associated with major soil moisture deficits, adiabatic warming connected with downsloping winds off the Appalachian Mountains, and the depth of the mixing layer. Along the coast, the pattern of heat and humidity was tied to the positioning of a mesoscale thermal trough and the presence and strength of the sea-breeze circulation.     

Mesoclimatology: Present Themes and Future Prospects

Abstract. Some results of recent research into mesoscale phenomena and climate are reviewed –notably sea breezes, cyclonic eddies, dry lake circulations, urban climates and topoclimates –with particular reference to New Zealand. Extension of this work into modelling and prediction of climate change is likely, and the case for a more integrated geography –one which could fruitfully address questions relating to environmental inputs and societal adjustments which are currently neglected by physical geography –is made.     

WINTER LAND BREEZE IN A HIGH LATITUDE COMPLEX COASTAL AREA

The winter land breeze (WLB) was studied in an area with complex topography on the Swedish West Coast (58°N). Methods used were mapping directions of smoke plumes, temperature soundings by tethered balloon and helicopter, three years of monitoring temperature and wind at three levels on a suspension bridge and on a mast, and meteorological observations from three stations located at different distances from the coast. To initiate the development of the WLB, the necessary temperature difference between sea and land was 5°C, but the magnitude of the difference appeared to have little influence. The direction of the typical WLB was at an oblique angle to the coast. The WLB started with a sudden wind shift as a result of frictional decoupling from the prevailing synoptic wind caused by increased stability. The flow, with a depth of about 100 m, developed within the nocturnal inversion at the level of the plateau-shaped mountains and overrode the cold air in the valleys and followed the uplifted inversion over the city of Göteborg. The different layers in the inversion were tilted toward the sea with an inclination similar to the slope of the terrain. In a layer above the WLB but also within the inversion, there was an onshore wind that might be the return flow to the WLB. [Key words: winter land breeze (WLB), decoupling, overriding, urban heat island circulation (UHIC), high latitude, Sweden.]     

察尔汗盐湖卤水蒸发速度影响因素的量化研究

针对当前气象因素(辐照强度、风速、环境温度和相对湿度)与卤水因素(卤水温度和浓度)综合作用于卤水蒸发速度定量研究的数据缺乏等问题,采用室外蒸发装置及信号采集系统相结合的实验方法,开展了察尔汗盐湖卤水自然蒸发实验。借助多元线性回归分析方法对实验数据进行分析,建立了基于多因素共同作用下的卤水蒸发速度模型。实验结果表明,卤水蒸发速度随辐照强度、风速、环境温度和卤水温度的增加呈线性增加,而随相对湿度和浓度的增加呈线性减小。进一步得出各因素影响卤水蒸发速度的顺序为：辐照强度>风速>环境温度>卤水温度>相对湿度>浓度。     

察尔汗盐湖卤水蒸发速度影响因素的量化研究

针对当前气象因素(辐照强度、风速、环境温度和相对湿度)与卤水因素(卤水温度和浓度)综合作用于卤水蒸发速度定量研究的数据缺乏等问题,采用室外蒸发装置及信号采集系统相结合的实验方法,开展了察尔汗盐湖卤水自然蒸发实验.借助多元线性回归分析方法对实验数据进行分析,建立了基于多因素共同作用下的卤水蒸发速度模型.实验结果表明,卤水...     

艾比湖地区风沙危害趋势及对欧亚大陆桥的影响

艾比湖是新疆最大的尾闾盐湖,地质历史时期和人类活动时期处于不断干缩状态,所形成的于涸湖盆物质在阿拉山口大风驱动下对区域构成风沙危害。从物质来源和驱动风力两个方面分析了风沙危害的可能性;并在剖析扬尘爆发频率和风力条件变化趋势的基础上,得出近40年风沙危害加剧的主要由于沙尘策源地扩大的结论。重点分析了欧亚大陆桥艾湖段风沙危害现状及趋势,认为由于区域风力条件的稳定性,只有在与艾比湖地区生态环境恢复重建的基础上,进行全线的生物防护措施,改善下界面状况,才能取得可持续的防沙效益。     

Was there ice along the shore of the Sea of Galilee during the last 12,000?—Reply to a comment by Prange et al. (2007) and a comment by Friedman (2007)

Prange et al. (2007) question our reconstruction of the Sea of Galilee (Lake Kinneret) paleoclimate and argue that a “careful” analysis of the paleoclimatic analysis leads to much smaller cooling events than we have considered. By and large, their “careful” analysis is based on correlating the paleotemperatures of the Lake with those of the northern Red-Sea that (geographically) is much closer to the Lake than the two Mediterranean cores that we used. Ironically, their argument contradicts Friedman’s (2007) statements (the second comment on our original paper), which are based on still-closer cores and support our larger cooling choices. This issue alone would be enough to dismiss the uniqueness of PAL argument but there is another issue with their work that we wish to comment on. In support of their own small cooling argument, PAL present winter correlation maps that indeed show a stronger correlation of the northern Red-Sea SST to the lake SST than the correlation of Mediterranean SST with the lake SST. This seemingly correct correlation argument of PAL is totally false (for both daily and millennial time scales) because it has no climatological basis. On the daily time scale, all the storms that reach the Lake originate in the Mediterranean Sea (to the west of the lake), not the Red-Sea (which lies 700 km south of the lake). Also, although the lake and the Red-Sea are only 700 kilometers apart, their climates are very different because they are subject to two totally different air masses. While the climate of the Red-Sea region is desert-like, the climate of the region surrounding the lake is a typical wet Mediterranean climate. Seasonal correlation maps (and even monthly maps) such as those presented by the authors filter out the storms that control the winter climate in the lake region because these storms occur on a daily scale. With this filtering, all that one is left with is the low frequency first baroclinic mode, which merely reflects the Rossby radius scale (measured from the lake). On the millennial time scale, cold events in the lake regions (from an earlier period) have been attributed to Bond cycles and Heinrich events both of which are global and not local processes. As such, they are probably forced by variability in the solar radiation rather than a local process implied by PAL. Overall, all that the PAL correlation shows for both daily and millennial time scales is that changes in the temperature in the Red-Sea occur at the same time as they do in the Lake. But this does not say anything about the dynamics in question and does not imply that it is better to use records from the Red-Sea (which does not lie within the path of the zonal winds reaching the Lake). Neglecting this issue (as proposed by PAL) distorts the physics and reminds us of the classical statistical example for the limitations involved in the interpretation of correlation—the incidence of lung cancer is strongly correlated with the incidence of carrying matches in ones pocket even though the matches do not cause the cancer and the cancer does not force one to carry matches.     

区域气候变化下洞里萨湖表面水温时空变化的归因

基于2001—2019年洞里萨湖白天的湖泊表面水温（LSWT_day）、近地表气温（AT）、太阳辐射（SR）、地表气压（SP）、降水量（TP）、相对湿度（RH）、风速（WS）、总云量（TCC）以及水位（WL）数据,采用趋势分析、稳定性分析、持续性分析和突变分析等方法,研究了LSWT_day及各气候因素的时空分布及变化特征;利用相关性分析、回归分析和Z-Score标准化方法,厘清了各气候因素变化对LSWT_day的影响。结果表明：① 时间尺度上,区域气候以AT、WS、TCC显著升高,WL显著下降为主要特征;LSWT_day的平均升温速率为0.372℃/10a,且具有持续变暖趋势,与气候因素的突变点具有时间一致性。空间尺度上,LSWT_day和各气候因素的空间分布及变化趋势具有明显的空间异质性。其中,LSWT_day除西部湖区有微小降温外,其余湖区表现出明显的升温趋势。气候因素中,AT、SP、TP、TCC和RH的变化率大致呈现为南高值北低值的分布,而SR和WS的变化率分布为南低值北高值。② 不同时间尺度上,驱动洞里萨湖LSWT_day变化的气候因素不同。年均尺度上,LSWT_day主要受到AT、WS和WL的驱动;月均尺度上,AT变化仍是驱动LSWT_day变化的主要因素;季节尺度上,TP、WL和TCC升高为春夏LSWT_day降温的主要原因,RH是秋季LSWT_day波动的主要影响因素,冬季LSWT_day随同AT的升温而变暖。