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1.
在中国西部的青藏高原和新疆地区的若干条冰川区域采集雪和冰芯样品,分析了雪冰样品中的黑碳,并模拟了雪冰黑碳产生的辐射强迫。我国西部雪冰黑碳的平均浓度为63 ng/g,高于北半球其他地区的实测结果。影响雪样黑碳浓度空间分布格局的主因是周边的排放源。模拟结果显示,黑碳在中国西部冰川雪表的沉降产生的平均辐射强迫为（+4.0±2.0) W/m2。喜马拉雅山中段的东绒布冰芯记录揭示黑碳主要来源于南亚,经印度夏季风输送;1951年以来黑碳的平均浓度为16 ng/g,产生的月平均辐射强迫在2001年夏季超过了+4.5 W/m2。南亚排放的黑碳可能抵达青藏高原南部腹地,对青藏高原的冰川表面能量平衡有一定影响。 相似文献
2.
Measurements of the stable isotopic ratios of oxygen and simultaneously observed ice crystal structure in freshly fallen snow, have been used to estimate the weighted mean altitudes of ice-phase precipitation formation in winter clouds over the Central Sierra Nevada.Observations of dominant, diffusionally grown ice-crystal habits were used to estimate relatively narrow ranges of temperatures of initial formation of the precipitation particles using the Nakaya (1954) ice-crystal classification techniques. The mean oxygen isotope ratio 18O/16O for each snow sample, together with local upper air soundings, were used to estimate ranges of temperature-altitude within the clouds where the precipitating particles had captured their ice-phase water. For this initial study, snow samples were collected each five (5) to ten (10) minutes during three snowfall periods on 27 January, 26 February and 28 February, 1983.For the 27 January case, the ice formation mechanism was predominantly vapor deposition and hence the narrow range of temperatures determined by the ice-crystal habits was directly relatable to the mean δ18O value.The 26 and 28 February cases were more complicated because the solid-phase precipitation was formed by vapor deposition and by freezing of drops and droplets (which occurs without isotopic fractionation). In these cases, the oxygen isotopic composition of the snow reaching the ground was representative of solid phase precipitation which had formed at warmer temperatures than those corresponding to the primary ice-crystal habits alone. There was no apparent relationship between δ18O values and surface temperature at the sampling site.If relationships between 18O/16O and temperature-altitude are established for this geograpic region for winter snowfall conditions, this crystal habit—isotopic composition technique can provide knowledge about the regions of the clouds in which the ice-phase precipitation is forming over the Central Sierra Nevada. 相似文献
3.
An Overview of the Studies on Black Carbon and Mineral Dust Deposition in Snow and Ice Cores in East Asia 
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下载免费PDF全文 Black carbon （BC） is the most eff ective insoluble light-absorbing particulate （ILAP）, which can strongly absorb solar radiation at visible wavelengths. Once BC is deposited in snow via dry or wet process, even a small amount of BC could signifi cantly decrease snow albedo, enhance absorption of solar radiation, accelerate snow melting, and cause climate feedback. BC is considered the second most important component next to CO2 in terms of global warming. Similarly, mineral dust （MD） is another type of ILAP. So far, little attention has been paid to quantitative measurements of BC and MD deposition on snow surface in the midlatitudes of East Asia, especially over northern China. In this paper, we focus on reviewing several experiments performed for collecting and measuring scavenging BC and MD in the high Asian glaciers over the mountain range （such as the Himalayas） and in seasonal snow over northern China. Results from the surveyed literature indicate that the absorption of ILAP in seasonal snow is dominated by MD in the Qilian Mountains and by local soil dust in the Inner Mongolian region close to dust sources. The detection of BC in snow and ice cores using modern techniques has a large bias and uncertainty when the snow sample is mixed with MD. Evidence also indicates that the reduction of snow albedo by BC and MD perturbations can signifi cantly increase the net surface solar radiation, cause surface air temperature to rise, reduce snow accumulation, and accelerate snow melting. 相似文献
4.
Characteristics of Anthropogenic Sulfate and Carbonaceous Aerosols over East Asia： Regional Modeling and Observation 总被引：3，自引：0，他引：3
The authors present spatial and temporal characteristics of anthropogenic sulfate and carbonaceous aerosols over East Asia using a 3-D coupled regional climate-chemistry-aerosol model, and compare the simulation with the limited aerosol observations over the region. The aerosol module consists of SO2, SO4^2-, hydrophobic and hydrophilic black carbon （BC） and organic carbon compounds （OC）, including emission, advections, dry and wet deposition, and chemical production and conversion. The simulated patterns of SO2 are closely tied to its emission rate, with sharp gradients between the highly polluted regions and more rural areas. Chemical conversion （especially in the aqueous phase） and dry deposition remove 60% and 30% of the total SO2 emission, respectively. The SO4^2- shows less horizontal gradient and seasonality than SO2, with wet deposition （60%） and export （27%） being two major sinks. Carbonaceous aerosols are spatially smoother than sulfur species. The aging process transforms more than 80% of hydrophobic BC and OC to hydrophilic components, which are removed by wet deposition （60%） and export （30%）. The simulated spatial and seasonal SO4^2-, BC and OC aerosol concentrations and total aerosol optical depth are generally consistent with the observations in rural areas over East Asia, with lower bias in simulated OC aerosols, likely due to the underestimation of anthropogenic OC emissions and missing treatment of secondary organic carbon. The results suggest that our model is a useful tool for characterizing the anthropogenic aerosol cycle and for assessing its potential climatic and environmental effects in future studies. 相似文献
5.
降雪是北京冬季的重要降水天气过程,但目前对实例降雪形成的微物理机制的观测-模拟研究较少。本文利用中尺度WRF模式结合外场观测资料,对北京2015年1月24日和11月5~6日两次不同天气条件下的山区降雪云系的微物理结构特征及降雪形成的微物理转化机制进行了分析研究,定量比较了云中水凝物含量的比例和降雪形成机制的差异。研究结果表明:(1)由于两次降雪过程的天气形势和水汽输送有较大差异,导致降雪形成的微物理转化机制也出现较大差异。11月5日降雪第一阶段水汽输送较强,云中过冷水含量较高,降雪形成以凝华增长和凇附增长为主,地面表现为雨夹雪天气,而1月24日和11月5~6日第二阶段水汽输送弱,降雪形成以凝华增长和聚并增长为主,地面表现为纯降雪天气;(2)11月5日的雨夹雪天气过程中,云中不仅有冰晶(9%)、雪晶(72%),还有云水(6%)和雨水(12%)的存在,高层生成的雪胚在下落过程中主要通过凝华(78%)和凇附(20%)过程增长。而1月24日与11月5~6日第二阶段的纯降雪过程中,云中水凝物分布相似,以冰晶和雪晶为主,1月24日冰晶含量占28%,雪晶含量占72%;11月5~6日冰晶含量占11%,雪晶含量占88%,冰粒子主要分布在高层。首先高层6~12 km通过云冰转换生成的雪胚下落到低层水汽充足区,然后通过凝华和聚并过程增长,1月24日凝华增长过程占92%,聚并增长过程仅占5%;11月5~6日凝华占88%,聚并仅占3%。(3)垂直上升气流速度与冰晶、雪晶生成和增长过程呈正相关,上升气流带来充足的水汽,配合垂直运动使得雪胚增加,凝华、凇附凇附和聚并过程增强,导致雪晶含量增加。 相似文献
6.
A unified chemistry-aerosol-climate model is applied in this work to compare climate responses to chang- ing concentrations of long-lived greenhouse gases(GHGs,CO2,CH4,N2O),tropospheric O3,and aerosols during the years 1951–2000.Concentrations of sulfate,nitrate,primary organic carbon(POA),secondary organic carbon(SOA),black carbon(BC)aerosols,and tropospheric O3 for the years 1950 and 2000 are obtained a priori by coupled chemistry-aerosol-GCM simulations,and then monthly concentrations are in- terpolated ... 相似文献
7.
青藏高原冬春季积雪异常对中国春夏季降水的影响 总被引：27，自引：3，他引：27
利用1956年12月～1998年12月共42a，青藏高原及其附近地区78个积雪观测站的雪深和我国160站月降水的距平资料，分析了其气候特征，并用SVD方法分析了冬春季积雪异常与春夏季我国降水异常的关系。用区域气候模式RegCM2模拟了青藏高原积雪异常的气候效应并检验了诊断分析的结果。分析表明，雪深异常，尤其是冬季雪深异常是影响中国降水的一个因子。研究证明，高原冬季雪深异常对后期中国区域降水的影响比春季雪深异常的影响更为重要。数值模拟的结果表明，高原雪深和雪盖的正异常推迟了东亚夏季风的爆发日期，减弱了季风强度，造成华南和华北降水减少，而长江和淮河流域降水增加。冬季雪深异常比冬季雪盖异常和春季雪深异常对降水的影响更为显著。机理分析指出，高原及其邻近地区的积雪异常首先通过融雪改变土壤湿度和地表温度，从而改变了地面到大气的热量、水汽和辐射通量。由此所引起的大气环流变化又反过来影响下垫面的特征和通量输送。在湿土壤和大气之间，这样一种长时间的相互作用是造成后期气候变化的关键过程。与干土壤和大气的相互作用过程有本质差别。 相似文献
8.
The Weather Research and Forecasting model with Chemistry (WRF-Chem) is utilized to examine the radiative effects of black carbon (BC) aerosols on the Indian monsoon, for the year 2010. Five ensemble simulations with different initial conditions (1st to 5th December, 2009) were performed and simulation results between 1st January, 2010 to 31st December, 2010 were used for analysis. Most of the BC which stays near the surface during the pre-monsoon season gets transported to higher altitudes with the northward migration of the Inter Tropical Convergence Zone (ITCZ) during the monsoon season. In both the seasons, strong negative SW anomalies are present at the surface along with positive anomalies in the atmosphere, which results in the surface cooling and lower tropospheric heating, respectively. During the pre-monsoon season, lower troposphere heating causes increased convection and enhanced meridional wind circulation, bringing moist air from Indian Ocean and Bay of Bengal to the North-East India, leading to increased rainfall there. However, during the monsoon season, along with cooling over the land regions, a warming over the Bay of Bengal is simulated. This differential heating results in an increased westerly moisture flux anomaly over central India, leading to increased rainfall over northern parts of India but decreased rainfall over southern parts. Decreased rainfall over southern India is also substantiated by the presence of increased evaporation over Bay of Bengal and decrease over land regions. 相似文献
9.
夏季硫酸盐和黑碳气溶胶对中国云特性的影响 总被引：1，自引：2，他引：1
利用WRF-Chem（Weather Research and Forecasting model coupled with Chemistry）模式研究2006年8月1日—9月1日中国区域硫酸盐和黑碳气溶胶对云特性的影响。模式验证利用了卫星和地面观测的气象要素、化学物质浓度、气溶胶光学特性和云微物理特性。模式性能评估表明该模式能较好地抓住气象要素（温度、降水、相对湿度和风速）的量级和空间分布特征。通过与地面观测和MODIS卫星数据对比发现,尽管模式模拟还存在偏差,但还是能较好模拟出气溶胶物种的地表浓度、气溶胶光学厚度（AOD）、云光学厚度（COD）、云量（CLDF）、云顶云滴有效半径（CER）和云水路径（LWP）。通过两个敏感性试验（分别增加二氧化硫和黑碳排放量至控制试验排放的3倍）与控制试验的对比发现硫酸盐比黑碳更易成为云凝结核,在中国东部云顶云滴数浓度和其它云特性参数对二氧化硫排放增加的响应均从北向南呈递增,这与地面湿度分布有关。云滴有效半径对硫酸盐气溶胶的响应符合气溶胶第一间接效应的定义,即硫酸盐气溶胶增多,云滴数浓度增加,云滴有效半径减少,但是对黑碳气溶胶的响应在各区域不尽相同。还发现黑碳对云量的影响远大于硫酸盐,主要原因是由于黑碳气溶胶直接辐射效应（对太阳光的吸收）导致的云的“燃烧”作用。 相似文献
10.
11.
Both observational and numerical studies suggest that the Eurasian winter snow cover has a strong influence on the subsequent
summer monsoon in Asia. An updated version of the ARPEGE climate model of Météo-France, including a simple but physically-based
snow parameterization, is used to test the impact of an increased snow mass prescribed at the beginning of March on the simulated
summer monsoon circulation and rainfall. The large-scale features of the Asian monsoon are reproduced in a realistic way in
the control integration, which is a necessary premise of such a sensitivity test. In the heavy snow cover experiment, the
anomalous persistence of the winter snow pack delays the springtime continental heating. This weakens the thermal low over
northern India and Persia as well as the southwesterly winds over the monsoon area. There is also a significant decrease in
the rainfall over western India and Bengal-Burma, which usually represent the centers of maximum precipitation. Radiative,
turbulence transfer and hydrological processes seem to be involved in the snow-monsoon relationship. The changes in the monsoon
precipitation are strongly related to changes in the atmospheric circulation and are not reinforced by a local evaporation/convection
feedback in our experiment.
Received: 17 May 1995 / Accepted: 27 November 1995 相似文献
12.
A Modeling Study of the Climate Effects of Sulfate and Carbonaceous Aerosols over China 总被引：4，自引：0，他引：4
In this paper, the RIEMS 2.0 model is used to simulate the distribution of sulfate, black carbon, and organic carbon aerosols over China (16.2°-44.1°N, 93.4°-132.4°E) in 1998. The climate effects of these three anthropogenic aerosols are also simulated. The results are summarized as follows: (1) The regional average column burdens of sulfate, BC, OC, and SOC were 5.9, 0.24, 2.4, and 0.49 mg m-2, with maxima of 33.9, 1.48, 7.3, and 1.1 mg m-2, respectively. The column burden and surface concentration of seco... 相似文献
13.
Assessing the Impacts of Initial Snow Conditions over the Tibetan Plateau on China Precipitation Prediction Using a Global Climate Model 下载免费PDF全文
下载免费PDF全文 CHEN Hong 《大气和海洋科学快报》2014,(2):81-86
Two ensemble experiments were conducted using a general atmospheric circulation model. These experiments were used to investigate the impacts of initial snow anomalies over the Tibetan Plateau（TP） on China precipitation prediction. In one of the experiments, the initial snow conditions over the TP were climatological values; while in the other experiment, the initial snow anomalies were snow depth estimates derived from the passive microwave remote-sensing data. In the current study, the difference between these two experiments was assessed to evaluate the impact of initial snow anomalies over the TP on simulated precipitation. The results indicated that the model simulation for precipitation over eastern China had certain improvements while applying a more realistic initial snow anomaly, especially for spring precipitation over Northeast China and North China and for summer precipitation over North China and Southeast China. The results suggest that seasonal prediction could be enhanced by using more realistic initial snow conditions over TP, and microwave remote-sensing snow data could be used to initialize climate models and improve the simulation of eastern China precipitation during spring and summer. Further analyses showed that higher snow anomalies over TP cooled the surface, resulting in lower near- surface air temperature over the TP in spring and summer. The surface cooling over TP weakened the Asian summer monsoon and brought more precipitation in South China in spring and more precipitation to Southeast China during summer. 相似文献
14.
LAPS是中国气象局武汉暴雨研究所引进的中尺度分析系统,能融合区域内多种非常规观测资料,提供高分辨率中尺度分析场。该文对探空资料和LAPS分析场两种初始场的大气层结和环境风场信息进行了比较,并应用探空资料和不同时次的降雹点的LAPS分析场作为三维对流云模式的初始场对2008年7月27日、28日湖北西部山区冰雹天气过程进行数值模拟,并将模拟结果与观测实况进行了对比分析,最后对27日降雹过程应用临近降雹时次的LAPS分析场作为云模式初始场模拟的回波、风场和垂直速度等特征进行了分析,以探讨LAPS用于云数值模式的适用性、优越性以及冰雹云发生发展特点。结果表明: LAPS输出场用于云模式初始场进行冰雹云数值模拟具有时空上的优势,能更好地模拟出午后局地降雹,可以弥补探空资料作为云模式初始场的不足,应用临近时次的LAPS分析场作为云模式初始场的数值模拟能体现出冰雹云发展过程中多次增强等细节,有利于人工防雹作业预警和催化方案的确定。 相似文献
15.
Wintertime climatic trends in the western Himalayas 总被引：2，自引：0，他引：2
Northern Indian rivers are primarily fed by wintertime (December, January, February—DJF) precipitation, in the form of snow—yielded by eastward moving synoptic weather systems called Western Disturbances (WDs), over the western Himalayas (WH). This accumulated snow melts during ablation period. In the context of today’s warming atmosphere, it is imperative to study the changes in the temperature and precipitation patterns over the WH to assess the impact of global warming on climatic conditions of the region. Keeping that in mind, observational analysis of temperature and precipitation fields is planned. In the present study various climatic indices are analyzed based on wintertime (DJF) data of 30?years (1975–2006) obtained from the Snow and Avalanche Study Establishment (SASE), India. Results indicate enhancement in the surface air temperature across the WH. Percent number of warm (cold) days have increased (decreased) during 1975–2006 over the WH. Further analysis of precipitation reveals slightly decreasing but inconsistent trends. 相似文献
16.
Ice-free glacial northern Asia due to dust deposition on snow 总被引：3，自引：0，他引：3
During the Last Glacial Maximum (LGM, 21 kyr BP), no large ice sheets were present in northern Asia, while northern Europe and North America (except Alaska) were heavily glaciated. We use a general circulation model with high regional resolution and a new parameterization of snow albedo to show that the ice-free conditions in northern Asia during the LGM are favoured by strong glacial dust deposition on the seasonal snow cover. Our climate model simulations indicate that mineral dust deposition on the snow surface leads to low snow albedo during the melt season. This, in turn, caused enhanced snow melt and therefore favoured snow-free peak summer conditions over almost the entire Asian continent during the LGM, whereas perennial snow cover is simulated over a large part of eastern Siberia when glacial dust deposition is not taken into account. 相似文献
17.
将区域气候模式（RegCM3）与对流层大气化学模式（TACM）耦合, 建立区域气候化学模拟系统（RegCCMS）, 用以模拟研究中国地区黑碳气溶胶的空间分布、 第一间接辐射强迫及其气候效应。利用RegCCMS模式对2003年1月和7月进行模拟, 结果表明, 我国黑碳气溶胶主要集中在四川、 河北、 山东等地, 1月份浓度最高值中心在四川, 达到4 μg·m-3; 而在7月则出现在华中地区, 高值中心值为3.5 μg·m-3。地面浓度的季节差异不是很明显。1月和7月由黑碳气溶胶所造成的第一间接辐射强迫全国平均值分别为-0.389 W·m-2和-1.18 W·m-2, 局部地区达到-4～-4.5 W·m-2。敏感性试验结果表明, 考虑黑碳气溶胶的第一间接气候效应后, 使得近地面气温下降, 降水减少, 1月变化的平均值分别为-0.025K和-0.0027 mm·d-1, 7月变化的平均值分别为-0.16K和-0.095 mm·d-1, 在不同季节和地区, 气温和降水的变化存在明显差异。 相似文献
18.
M. Rebetez 《Theoretical and Applied Climatology》1996,54(3-4):99-106
Summary An analysis of correlation coefficients for climatological data covering the period 1901–1994 or 1931–1994 for six locations in Switzerland has been made in order to highlight the relationships between temperature, precipitation (rain and snow) and snow in summer and in winter. The results show that colder summers tend to be associated with more precipitation, mainly in terms of the frequency of occurrence of precipitation, but also in terms of its abundancy. In winter, sites located at lower altitudes behave differently from those at higher elevations. At lower altitudes, warmer winters tend to be rainier and to have less snow (only a small part of winter precipitation falls in the form of snow). Above 1000–1500 m, correlations between temperature on the one hand, and precipitation or snow on the other, tend to be weaker than at lower elevations; warmer winters are associated with less snow but also with less precipitation in general, while the relationship between precipitation and snow is stronger.These results confirm that during cold periods of the past, such as Löbben Phase (1400 BC — 1230 BC) cold summers were probably linked to frequent and abundant precipitation. These conditions led to increased mortality as well as to population migrations. In terms of potential future global warming, if the current temperature/precipitation relationships remain unchanged, then warmer summers will likely be linked to a decrease in precipitation. Higher winter temperatures can be expected to lead to a general decrease of snow and to a decrease in precipitation, but only at higher elevations; warmer winters would conversely be associated with an increase in precipitation at lower altitudes.With 4 Figures 相似文献
19.
利用NCEP FNL再分析资料为初始场,通过WRF中尺度数值模式(V3.9.1版本)对2015年8月26~27日青藏高原那曲地区一次对流云降水过程进行了模拟,分析了不同积云对流参数化方案和云微物理参数化方案组合对本次降水过程中降水量、环流场、雷达反射率以及云微物理特征模拟效果的影响。结果表明:WRF模式能较好地模拟出本次降水的时空变化特征,但不同参数化方案组合各有优势,总体而言,Grell-Devenyi+SUBYLIN和Grell-Freitas+SUBYLIN组合模拟性能最优。本次对流云降水以冰相过程为主,雪粒子贡献最大,暖云粒子对降水的影响并不明显。从云微物理过程的时间演变可看出,性能最好的SUBYLIN方案能合理模拟降水过程中雪粒子与冰晶粒子间的转换过程,雪粒子可在凝结过程中释放潜热促使对流运动发展,也可通过融化过程促进降水发生,对流层高层冰晶粒子凝华产生的潜热释放亦为深对流的发展创造了有利条件。 相似文献
20.
Snow depth over sea ice is an essential variable for understanding the Arctic energy budget.In this study,we evaluate snow depth over Arctic sea ice during 1993-2014 simulated by 31 models from phase 6 of the Coupled Model Intercomparison Project(CMIP6)against recent satellite retrievals.The CMIP6 models capture some aspects of the observed snow depth climatology and variability.The observed variability lies in the middle of the models’simulations.All the models show negative trends of snow depth during 1993-2014.However,substantial spatiotemporal discrepancies are identified.Compared to the observation,most models have late seasonal maximum snow depth(by two months),remarkably thinner snow for the seasonal minimum,an incorrect transition from the growth to decay period,and a greatly underestimated interannual variability and thinning trend of snow depth over areas with frequent occurrence of multi-year sea ice.Most models are unable to reproduce the observed snow depth gradient from the Canadian Arctic to the outer areas and the largest thinning rate in the central Arctic.Future projections suggest that snow depth in the Arctic will continue to decrease from 2015 to 2099.Under the SSP5-8.5 scenario,the Arctic will be almost snow-free during the summer and fall and the accumulation of snow starts from January.Further investigation into the possible causes of the issues for the simulated snow depth by some models based on the same family of models suggests that resolution,the inclusion of a hightop atmospheric model,and biogeochemistry processes are important factors for snow depth simulation. 相似文献