我国降水酸度的初步研究

1981年3月至1983年4月,我们在全国不同地区选定了四十几个测点对降水酸度进行了观测。 观测资料表明,酸雨出现的频率,南方城市较北方为高,酸度也较强,酸雨出现频率最高值达到90％。说明酸雨在某些地区已相当严重。pH的最低值是庐山的含鄱口(测值达3.10)。我国北部地区降水多为中性,但局部地区也有酸雨出现。沿海城市青岛也出现酸雨。 作者结合地理环境、污染物的迁移输送以及天气系统等,对降水酸度变化进行了初步分析。     

南京市区降水酸度的初步研究

本文介绍了1979年11月至1980年7月期间南京市区降水酸度的测量结果。结果表明:南京市区降水的pH平均值为5.62,变化范围从4.10—7.93,其中,1980年1月份和7月份出现酸雨,pH的月平均值分别达到5.52和5.26。 测量结果还与日本、英国、美国的观测结果作了比较。     

降水酸度的初步观测

近年来,由于酸雨对动植物和人类生活产生有害的影响[1-6],已经在世界范围引起人们的关注。目前,在降水酸度的观测方面,就采样时段来说,概括起来大致有如下几种:1.收集降水过程中每一时段的样品;2.收集每场降水的样品;3.每天收集一次降水样品;4.每周收取两次样品;5.收取每周干、湿沉降样品;6.收取月样品。     

兰州市降水酸度的初步分析

兰州市降水酸度的初步分析尹宪志，周萍（甘肃省气象局兰州７３００２０）引言大气中经常存在着尘埃等悬浮微粒，这些微粒有些来自自然界，有些却是人类活动所产生的。固态成分的物质微粒，全球天然年排放量大约为７７３—２２００百万ｔ／年，人为排放量目前已达１８５—...     

若尔盖高原草原湿地40年积雪的初步研究

本文利用若尔盖气象站1971～2011年总共40年的积雪和冻土记录,分析了每年冬春季(10月到第二年5月)积雪和冻土的变化,以及它们与温度和降水的关系。积雪的减少是对全球变暖的响应。与积雪渐渐减少的趋势相比,冻土并没有明显的长期变化趋势,而从冻土与温度的相关性看出,冻土深度与当年温度呈负相关。小波分析表明,最大冻土深度的变化周期为8年,而积雪月平均温度的变化周期为4年。     

广州市春季降水酸度的初步气象分析

广州市位于珠江两岸,是我国南方最大的工业和旅游城市.广州市的工业主要分布在西北部的荔湾区和西南部的海珠区,二氧化硫源强中心分别位于市区西北部的火力发电厂和西南部的钢铁厂,喷射粉尘较多的水泥厂等位于市区西北部.为了了解广州市春季的降水污染情况,我们自1983年3月中旬起,在广州市的5个区共布设了7个观测点,(见图1),收集雨水和气象资料.现把3月15日至5月31日的雨水分析结果作一小结.     

南宁市降雨酸度的天气气候初步分析

根据南宁市环保局1981年10月至1982年10月的雨水酸度(pH值)监测记录,舍去处于西郊且受污染少的民族学院监测点记录,从市区内的九个监测点中,取同一天具有三个以上测点记录的pH平均值作为南宁市城区pH的日均值(不足三点的不计)共有92次个例,其中达到酸雨标准(pH<5.6)的有62次个例,占67％。 通过对这92次个例结合气象图表资料,所作的统计分析结果表明,南宁市雨水的酸度(pH值)的大小,与天气条件关系相当密切。其中关系比较明显的有三方面:第一,与近地面低空出现的逆温层、等温层或相对     

青海地区常规观测积雪资料对比及积雪变化趋势研究

应用青海44个台站1962—2005年逐月积雪深度和积雪日数资料,对比了这两份常规积雪资料在表征青海地区积雪变化特征上的一致性,并对近十几年来的积雪变化新趋势做了分析。结果表明:积雪深度和积雪日数均能比较一致地反映整个青海地区积雪变化趋势:夏、秋季积雪从20世纪60年代至21世纪初为一致的减少趋势;冬、春季积雪在20世纪60年代至90年代初增加,而从20世纪90年代中期至21世纪初积雪呈显著减少趋势。后期的减少趋势远比前期的增加趋势明显。青海地区不同季节积雪深度和积雪日数趋势变化明显的区域基本一致,但中心位置存在一定的差异。冬季在32.5°~35°N,95°~102°E范围内的唐古拉山、巴颜喀拉山和阿尼玛卿山区,春季在青海东南部阿尼玛卿山区附近,均明显地表现出20世纪90年代中期以后积雪的减少和前期积雪的增加。不同季节积雪深度和积雪日数的相关系数分布存在一定差异:冬季两份资料相关相对较小的区域位于青海中南部巴颜喀拉山西区至阿尼玛卿山西区一线;春季相关系数小于冬季,青海东北边缘以及东南边缘地区,相关系数未能通过95%信度检验;夏、秋季积雪较少,相关较小的区域集中在青海东南部地区。而上述区域大多为各个季节积雪较多的地区,应慎重使用该区域的常规积雪资料。综合分析两份积雪资料,确定青海地区冬季多雪年为1964,1975,1993,1995和1998年,少雪年为1963,1965,1969,1997和2003年;春季多雪年是1977,1982,1987,1989和1990年,少雪年是1969,1979,1985,1999和2001年。     

降水酸度和化学组分垂直监测的初步分析

1986年6—9月,在无锡市近郊的锡惠公园内,在三个不同的高度上进行降水的同步采样,并对雨水的酸度、电导率和各种离子的含量作了测定。结果表明:降水酸度随着高度的增加而增强;电导率和雨水中离子的浓度则随着高度的增加而减小;通常上层减小得慢,下层减小得较快。碱性阳离子的结构在不同的高度上有明显的差异。另外,雨水对大气中污染物的冲刷作用,是一个重要的清除过程,下层比上层的冲刷作用更强。     

秦岭主峰太白山6月积雪考察

太白山是秦岭主峰,历史资料记载太白山冬夏积雪,近34 a太白气象站记录的高山积雪6月平均为0.2 d,眉县气象站为2.6 d。为了了解气象站高山积雪记录是否有很好的代表性,了解气候变暖背景下,太白山高山区6月积雪情况和天气气候特点,2018年6月2-3日对太白山天圆地方至拔仙台较大范围高海拔地区进行了考察。考察发现两处山体阴坡积雪,3日清晨大爷海水面有薄冰,大爷海至大文公庙之间的路边有正在消融的冻土和小冰柱。2-3日太白和眉县气象站都没有观测到高山积雪,但是监测数据说明太白山高山区部分时段气温低于0℃。由此可知太白和眉县气象站6月没有观测到高山积雪时,高山区个别地方有积雪,当气象站观测到高山积雪时,高山区积雪的面积应该比较大,说明气象站高山积雪记录有较好的代表性,也说明太白山山脚盛夏山顶寒,一日历四季,十里不同天名副其实。     

Acid-base characteristics of Russian snow cover

The results of pH measurement results are summarized for 1994–2004. These were obtained from the snow pollution and acidity monitoring network in the Russian Federation. A map of acid-base characteristics is compiled for the Russian territory. The zones of the most frequent cases of snow acidification are singled out. Dependence of pH values on the concentration of acid-forming anions neutralizing cation acids is established based on the ion balance analysis.     

Potential predictability of Eurasian snow cover

Potential predictability and skill of simulated Eurasian snow cover are explored using a suite of seasonal ensemble hindcasts (i.e. retrospective forecasts), an ensemble climate simulation (spanning the years 1982–1998) and observations. Using remotely sensed observations of snow cover, we find significant point-wise correlation over the North Atlantic and North Pacific between winter and spring averaged sea-surface temperatures and Eurasian snow cover area. The observed correlation shows no discernible pattern related to the El Niño-Southern Oscillation (ENSO). The hindcasts show correlation patterns similar to the observations. However, the climate simulation shows an exaggerated ENSO pattern. The results underscore the importance of initialization in seasonal climate forecasts, and that the observed potential predictability of Eurasian snowcover cannot be solely attributed to ENSO.     

Impact of the snow cover scheme on snow distribution and energy budget modeling over the Tibetan Plateau

This paper presents the impact of two snow cover schemes (NY07 and SL12) in the Community Land Model version 4.5 (CLM4.5) on the snow distribution and surface energy budget over the Tibetan Plateau. The simulated snow cover fraction (SCF), snow depth, and snow cover days were evaluated against in situ snow depth observations and a satellite-based snow cover product and snow depth dataset. The results show that the SL12 scheme, which considers snow accumulation and snowmelt processes separately, has a higher overall accuracy (81.8%) than the NY07 (75.8%). The newer scheme performs better in the prediction of overall accuracy compared with the NY07; however, SL12 yields a 15.1% underestimation rate while NY07 overestimated the SCF with a 15.2% overestimation rate. Both two schemes capture the distribution of the maximum snow depth well but show large positive biases in the average value through all periods (3.37, 3.15, and 1.48 cm for NY07; 3.91, 3.52, and 1.17 cm for SL12) and overestimate snow cover days compared with the satellite-based product and in situ observations. Higher altitudes show larger root-mean-square errors (RMSEs) in the simulations of snow depth and snow cover days during the snow-free period. Moreover, the surface energy flux estimations from the SL12 scheme are generally superior to the simulation from NY07 when evaluated against ground-based observations, in particular for net radiation and sensible heat flux. This study has great implications for further improvement of the subgrid-scale snow variations over the Tibetan Plateau.     

Effect of snow cover on pan-Arctic permafrost thermal regimes

This study quantitatively evaluated how insulation by snow depth (SND) affected the soil thermal regime and permafrost degradation in the pan-Arctic area, and more generally defined the characteristics of soil temperature (T_SOIL) and SND from 1901 to 2009. This was achieved through experiments performed with the land surface model CHANGE to assess sensitivity to winter precipitation as well as air temperature. Simulated T_SOIL, active layer thickness (ALT), SND, and snow density were generally comparable with in situ or satellite observations at large scales and over long periods. Northernmost regions had snow that remained relatively stable and in a thicker state during the past four decades, generating greater increases in T_SOIL. Changes in snow cover have led to changes in the thermal state of the underlying soil, which is strongly dependent on both the magnitude and the timing of changes in snowfall. Simulations of the period 2001–2009 revealed significant differences in the extent of near-surface permafrost, reflecting differences in the model’s treatment of meteorology and the soil bottom boundary. Permafrost loss was greater when SND increased in autumn rather than in winter, due to insulation of the soil resulting from early cooling. Simulations revealed that T_SOIL tended to increase over most of the pan-Arctic from 1901 to 2009, and that this increase was significant in northern regions, especially in northeastern Siberia where SND is responsible for 50 % or more of the changes in T_SOIL at a depth of 3.6 m. In the same region, ALT also increased at a rate of approximately 2.3 cm per decade. The most sensitive response of ALT to changes in SND appeared in the southern boundary regions of permafrost, in contrast to permafrost temperatures within the 60°N–80°N region, which were more sensitive to changes in snow cover. Finally, our model suggests that snow cover contributes to the warming of permafrost in northern regions and could play a more important role under conditions of future Arctic warming.     

中国西部积雪类型划分

利用中国105°E以西地区189个地面气象台站1960-2004年积雪日资料和1981-2004年SMMR、SSM/Ⅰ反演的逐日雪深资料,使用积雪年际变率方法划分中国西部积雪类型,并与积雪日数方法的划分结果进行比较.在此基础上,尝试建立了结合以上两种要素的综合分类指标.利用积雪年际变率方法和台站资料,将中国西部积雪划分为3类.其中,稳定积雪区主要包括北疆、天山和青藏高原东部高海拔山区;年周期性不稳定积雪区包括南疆和东疆盆地周边、河西走廊、青海北部、青藏高原中西部、藏南谷地以及青藏高原东南缘;其他积雪区均为非年周期性不稳定积雪区.气候突变后,积雪日数方法划分的积雪类型变化反映出沙漠和低纬度地区积雪变幅增大,在积雪年际变率方法的结果中体现出青藏高原东部地区趋于稳定的积雪面积在增加.在没有台站记录地区,卫星遥感资料很大程度上弥补了台站观测的缺陷,使用这种资料划分积雪类型时,积雪年际变率方法比积雪日数方法的结果更符合西部积雪的分布特点,反映出积雪分布与地形的密切关系.利用综合分类指标划分西部积雪类型的结果表明,台站资料的划分结果很大程度上受积雪持续时间的影响,而在卫星遥感结果中,积雪年际变率则是影响类型划分的主要因素.     

青藏高原地区积雪及其变化的不确定性:3种积雪观测资料的对比分析

为了探究青藏高原积雪不同观测资料间的差异,本文通过定义积雪覆盖率(Snow Cover Percentage,SCP)对比了NOAA-CDR卫星可见光遥感积雪资料、卫星被动微波遥感积雪资料和我国146个台站观测的积雪资料在高原地区的气候态及年际变动特征。从年平均气候态看,微波与可见光资料的SCP分布较为接近,高值区均位于念青唐古拉山与喜马拉雅山南缘之间的山区。而台站资料SCP的高值区范围则相对较小,在高原东部的巴颜喀拉山及南部的念青唐古拉山。3种资料的积雪低值区均位于高原中南部沿雅鲁藏布江一带、阿尔金山北侧以及东边界的内陆省份。从季节平均场看,不同资料的积雪分布在冬季及秋季,无论是气候态还是年际变动均较为类似。在春季时,微波和台站资料间较为一致。而在夏季,资料间差异很大,不同资料间的两两相关接近于零,甚至为负数。本文同时选取了青藏高原地区4个典型台站(索县、清水河、康定、甘孜),将卫星资料插值于台站上,对比3种资料间的异同,以及与地表气温异常间的关系。结果表明,在这4个典型站上,台站SCP在过去36 a中为线性减少的趋势,而卫星SCP主要为线性增加的趋势,且台站年平均SCP与地表气温异常的协同性最好。     

The role of terrestrial snow cover in the climate system

Snow cover is known to exert a strong influence on climate, but quantifying its impact is difficult. This study investigates the global impact of terrestrial snow cover through a pair of GCM simulations run with prognostic snow cover and with all snow cover on land eliminated (NOSNOWCOVER). In this experiment all snowfall over land was converted into its liquid–water equivalent upon reaching the surface. Compared with the control run, NOSNOWCOVER produces mean-annual surface air temperatures up to 5 K higher over northern North America and Eurasia and 8–10 K greater during winter. The globally averaged warming of 0.8 K is one-third as large as the model’s response to 2 × CO₂ forcing. The pronounced surface heating propagates throughout the troposphere, causing changes in surface and upper-air circulation patterns. Despite the large atmospheric warming, the absence of an insulating snow pack causes soil temperatures in NOSNOWCOVER to fall throughout northern Asia and Canada, including extreme wintertime cooling of over 20 K in Siberia and a 70% increase in permafrost area. The absence of snow melt water also affects extratropical surface hydrology, causing significantly drier upper-layer soils and dramatic changes in the annual cycle of runoff. Removing snow cover also drastically affects extreme weather. Extreme cold-air outbreaks (CAOs)—defined relative to the control climatology—essentially disappear in NOSNOWCOVER. The loss of CAOs appears to stem from both the local effects of eliminating snow cover in mid-latitudes and a remote effect over source regions in the Arctic, where −40°C air masses are no longer able to form.     

Influence of horizontal inhomogeneity on albedo and absorptivity of snow cover

The variations of albedo and absorptivity of the snow cover are considered caused by the presence of the snow roughness in the form of sastrugi. The numerical modeling is carried out within the framework of statistical approach based on the analytic averaging of the radiative transfer equation and statistically homogeneous model on the basis of Poisson flows of points at the straight lines. The estimates of the influence of 3D-effects of the rough surface are represented depending on optical and geometrical characteristics of sastrugi and on the illumination conditions. It is demonstrated that if the absorption by the snow particles is weak (the single scattering albedo w = 0.9999) the reflection of radiation by snow decreases by ∼ 2–3% when the sastrugi appear. This effect is more significant in near infrared spectral region where w is below 0.99.     

青藏高原积雪异常对高原地面加热的影响

On the basis of snow data and AWS (Automatic Weather Station) data obtained from the Tibetan Plateau in recent years (1993 to 1999), the features of sensible heat, latent heat and net long-wave radiations are estimated, and their variations in more-snow year (1997/1998) and less-snow year (1996/1997) are analyzed comparatively. The relationships between snow cover of the Tibetan Plateau and plateau＇s surface heating to the atmospheric heating are also discussed. The difference between more-snow and less-snow year in spring is remarkably larger than that in winter. Therefore, the effect of anomalous snow cover of the Tibetan Plateau in winter on the plateau heating appears more clearly in the following spring of anomalous snow cover.