共查询到20条相似文献，搜索用时 140 毫秒
1.
《干旱气象》2020,(1)
利用耦合了起沙模块的大气化学全耦合WRF/Chem模式,对2014年4月23—25日中国西北一次典型沙尘天气过程进行模拟,分析Shao2004起沙参数化方案(简称“Shao04方案”)垂直沙尘通量公式中权重因子γ对沙尘时空分布特征的影响,并与气象卫星遥感监测沙尘范围以及站点颗粒物质量浓度进行对比分析,确定了较适用于中国西北地区Shao04方案的权重因子γ的取值。结果表明:(1)γ对沙尘质量浓度模拟范围和质量浓度中心值有影响,对垂直沙尘通量中心值的大小有影响;(2)不同γ取值都能很好地模拟出沙尘天气PM10和PM2. 5质量浓度的趋势,但只有当γ=1时,即耦合Shao2011起沙参数化方案(简称“Shao11方案”)的WRF/Chem模式能够较准确地模拟出中国西北沙尘过程中PM10和PM2. 5质量浓度的变化。 相似文献
2.
《高原气象》2017,(5)
沙尘暴是干旱区常见的天气现象,沙尘暴天气过程中,边界层内气象要素发生剧烈的变化。利用WRF/Chem模式结合Shao 2004的参数化方案,模拟了发生在2010年4月24—26日的一次沙尘天气过程,通过控制沙尘气溶胶是否排放到大气中,对比分析沙尘暴过程中沙尘气溶胶对边界层中气象要素的影响。结果发现,在沙尘暴过程中,夜间在沙尘层以下,沙尘气溶胶具有加热大气的作用,使得温度升高,最大值约1.8 K,这种"保温"作用还与地表反照率有关,反照率越大"保温"作用越强;而在沙尘气溶胶层内的中上部具有降温的作用,温度降低,最大值约3 K。夜间沙尘气溶胶能够抬升边界层高度,最大达1000 m;白天则降低,可降低700 m;沙尘气溶胶导致水平风速增大约1.0 m·s-1,使垂直风速在沙尘层下增大,在沙尘层以上减小。 相似文献
3.
2009年4月北方一次强沙尘暴过程的特征分析和数值模拟 总被引：4，自引：0，他引：4
利用观测资料对2009年春季4月22-24日强沙尘暴过程的近地面气象要素(气温、气压、风速)变化和PM10进行分析.结果表明:蒙古气旋和冷锋是这次强沙尘暴的主要影响系统;沙尘暴过程前后温、压和风速有剧烈变化;PM10的强度能较好地反映沙尘暴强度.在观测资料分析基础上,利用沙尘暴数值预报系统对此次过程进行了模拟,采用模拟结果对地面沙尘浓度和起沙进行了分析.结果表明:模式能较好地模拟出这次沙尘天气的时间和空间演变特征,模拟沙尘浓度大值区与强沙尘暴的范围较为一致,比较白天早间和下午的沙尘浓度分布,发现其具有日变化;这次大范围的沙尘天气的起沙中心分别是南疆塔里木盆地、甘肃、内蒙古的西部及蒙古国南部,垂直沙通量超过50 mg·m2·s-1;沙尘浓度垂直输送的高度在550hPa以下,起沙后的沙尘粒子主要靠对流层低层的大风长距离地输送;对不同地区起沙过程贡献最大的沙尘粒子的粒径不尽相同,但是对起沙量贡献最大的是粒径在2μm相似文献
4.
一个适用于我国北方的沙尘暴天气数值预测系统及其应用试验 总被引：32，自引：19，他引：13
将澳大利亚新南威尔士大学(UNSW)邵亚平发展的具有清晰风蚀物理学概念的起沙数值模式、输送模式与PSU/NCAR的中尺度气象预报模式MM5进行耦合,以高精度中国区域的GIS(Geographic Information System)数据为基础,建立了一个较完整的沙尘暴起沙和输送过程的预测系统.该预测系统可以预测地面起沙率和大气中沙尘浓度.在此基础上,采用该系统对2002年3～4月3次影响我国北方大部分地区的沙尘(暴)天气的起沙和输送过程进行了模拟试验.试验结果表明模拟的沙尘浓度与地面天气现象及卫星云图的沙尘天气范围比较一致,预测系统对沙尘天气的起沙和输送过程有较好的模拟能力.北方上述大范围沙尘天气的沙尘源地为蒙古国的南戈壁省、东戈壁省,内蒙古中西部,河北省北部,山西省东北部,甘肃和青海北部等地区.起沙中贡献最大的粒子粒径为2～11μm和11～22 μm,能够长时间、长距离输送的沙尘也是上述大小的粒子,沙尘粒子的垂直输送高度一般在500 hPa以下. 相似文献
5.
东亚地区沙尘气溶胶影响硫酸盐形成的模式评估 总被引：14，自引：0，他引：14
利用STEM-II三维区域大气化学模式,耦合沙尘气溶胶表面相过程,研究了1994年3月1日至14日间东亚地区沙尘气溶胶对硫酸盐形成的影响。结果表明,SO2气体在沙尘气溶胶表面上进行的非均相氧化过程是硫酸盐形成的一条重要途径,由这条途径提供的硫酸盐占其总浓度的20%～50%。 并发现在模拟时段,沙尘暴过程主要影响沙尘源地下游的中国东部地区硫酸盐的分布,使得那里的硫酸盐浓度增加60%以上。 相似文献
6.
Altayeb Raga 王坚红 Abdoul Aziz Saidou Chaibou Muhammad Arsha Mohammed AbdAllah Birhanu Asmerom Habtemicheal 《气象科学》2022,42(6):769-780
基于WRF-chem模式对北非2018年3月下旬的典型强沙尘暴过程进行模拟,分析了此次强沙尘发生季节、持续时间、局地特征以及传输路径的关键动力系统与动力机制。鉴于起沙是沙尘暴发生的关键点之一,并且起沙主要取决于风力和下垫面沙源性质,本文测试了三种起沙参数化方案的影响,并将模拟结果与卫星MODIS监测及其再分析资料MERRA-2进行了对比,又经系列统计方法检验。结果显示,宏观思路的起沙方案GOCART比AFWA和UoC两种起沙方案更适合此次大尺度强沙尘暴数值模拟(锋面跨度接近60个经度)。综合沙尘暴关键系统的动力机制分析和数值模拟结果显示,强沙尘暴关键系统为深厚的西风槽、沙尘冷锋锋面和锋后的地面高压反气旋。北非中部深厚的西风槽为后倾槽,该系统稳定,造成沙尘暴持续时间长。沙尘暴锋后反气旋中的下沉气流抑制了扬沙向高层扩散,造成低层能见度恶劣。沙尘锋区结合了动力、热动力以及湿热动力不稳定,因此锋区风力大,地面沙尘驱动力强。而西风槽和强大反气旋依托环流形势,提供了沙尘传输到三大洲的长途输送力。 相似文献
7.
一次引发华北和北京沙尘(暴)天气起沙机制的数值模拟研究 总被引：45，自引：17，他引：28
在对气象背景场进行诊断分析的基础上,集中对一次沙尘(暴)天气的起沙机制进行了数值模拟.具体做法是先将澳大利亚新南威尔士大学(UNSW)邵亚平博士发展的具有清晰物理概念的起沙数值模式(非参数化方案),与PSU/NCAR的中尺度气象预报模式MM5进行耦合.使用该模式系统,根据陆面状况和大气条件,定量模拟出沙尘(暴)起沙的过程.对2000年4月6～7日发生在华北和北京的一次沙尘暴过程的数值试验结果表明,该模式对沙尘天气的起沙过程有较好的模拟能力. 相似文献
8.
《干旱气象》2016,(5)
沙尘气溶胶对辐射有显著影响,利用耦合了Shao2004起沙参数化方案的WRF/Chem(大气/化学全耦合模式),模拟分析了沙尘天气过程中沙尘气溶胶对辐射的影响。结果发现沙尘气溶胶可以导致地面向下的短波辐射通量减小42.51%,平均减小-3.30~-49.46 W·m~(-2),最大可达-162.67 W·m~(-2);沙尘气溶胶可以通过自身向外发射长波辐射,导致地面向下的长波辐射通量增大,地面向下的长波辐射通量平均增加为17.49~50.49 W·m~(-2),最大可达99.17 W·m~(-2)。当PM10浓度为10~20 mg·m-3,沙尘气溶胶能够减小地面向下的长波辐射通量,即沙尘气溶胶在该地区对大气具有"保温"作用;白天沙尘气溶胶主要增加大气层顶向上的长波辐射通量,夜间则减少大气层顶向上的长波辐射通量,大气层顶向外的长波辐射通量平均变化为-25.29~28.83 W·m~(-2),最大可达87.22 W·m~(-2)。 相似文献
9.
内蒙古科尔沁沙地起沙近地层动力学阈值的试验研究 总被引：4，自引：0，他引：4
利用内蒙古科尔沁沙地沙尘暴探测与监测试验站2008年和2009年春季沙尘和近地层观测资料,研究了不同沙尘天气条件下沙尘浓度随摩擦速度的变化规律,对比分析了不同天气(晴天、扬沙、沙尘暴和强沙尘暴)入射短波辐射和净辐射的演变,并利用两层高度沙尘浓度差,区分局地起沙和非局地起沙,有效地避免了沙尘水平输送引起的起沙阈值的低估。结果表明,起沙前,摩擦速度和沙尘浓度数值都较低;临近起沙阶段,摩擦速度迅速增大而沙尘浓度基本保持不变;起沙时,摩擦速度数值较高,沙尘浓度迅速增大;沙尘天气减弱阶段,沙尘浓度随摩擦速度近似呈线性减小。科尔沁沙地春季临界起沙摩擦速度u*t和临界起沙风速ut分别为0.62m.s-1和9.5m.s-1,扬沙、沙尘暴和强沙尘暴天气的起沙阈值依次略有增加。与晴天天气相比,沙尘天气到达地面的短波辐射和净辐射明显减少。 相似文献
10.
基于1999—2019年地面气象观测资料,对东亚主要沙尘源地(蒙古国、中国新疆和内蒙古)及中国沙源地下游地区的沙尘天气频数演变特征进行了分析,结果表明：蒙古国是沙尘天气发生最严重的地区,且有明显增加的趋势,扬沙、沙尘暴和强沙尘暴均远高于其他区域。中国整体沙尘天气数量显著减少,新疆快速增多,内蒙古和下游地区明显减少。新疆浮尘发生频次最高,近21 a线性倾向呈明显上升趋势;内蒙古扬沙频次最高,强沙尘暴最少,4类天气均呈逐年减少趋势;我国下游地区多发浮尘和扬沙,沙尘暴和强沙尘暴发生次数很少,全部沙尘天气呈减少趋势。1999—2004年为我国沙尘天气高发期,2005—2019年明显减少,其中2010—2014年减少速度最快。沙尘源地对我国沙尘天气总数的贡献持续增大,从2000年初的39%增长到2015年之后的71%。作为沙尘源地,蒙古国对沙尘天气产生的作用有所增强,而内蒙古则在减弱;国内沙尘源地导致的能够影响并扩展至中国下游地区和下游国家的强沙尘天气显著减少。 相似文献
11.
Fast versus slow response in climate change: implications for the global hydrological cycle 总被引：3，自引：2，他引：1
Recent studies have shown that changes in global mean precipitation are larger for solar forcing than for CO2 forcing of similar magnitude. In this paper, we use an atmospheric general circulation model to show that the differences originate from differing fast responses of the climate system. We estimate the adjusted radiative forcing and fast response using Hansen’s “fixed-SST forcing” method. Total climate system response is calculated using mixed layer simulations using the same model. Our analysis shows that the fast response is almost 40% of the total response for few key variables like precipitation and evaporation. We further demonstrate that the hydrologic sensitivity, defined as the change in global mean precipitation per unit warming, is the same for the two forcings when the fast responses are excluded from the definition of hydrologic sensitivity, suggesting that the slow response (feedback) of the hydrological cycle is independent of the forcing mechanism. Based on our results, we recommend that the fast and slow response be compared separately in multi-model intercomparisons to discover and understand robust responses in hydrologic cycle. The significance of this study to geoengineering is discussed. 相似文献
12.
Jianguo LIU Zong-Liang YANG Binghao JIA Longhuan WANG Ping WANG Zhenghui XIE Chunxiang SHI 《大气科学进展》2023,40(2):235-250
In order to compare the impacts of the choice of land surface model(LSM) parameterization schemes, meteorological forcing, and land surface parameters on land surface hydrological simulations, and explore to what extent the quality can be improved, a series of experiments with different LSMs, forcing datasets, and parameter datasets concerning soil texture and land cover were conducted. Six simulations are run for the Chinese mainland on 0.1° × 0.1° grids from 1979 to 2008, and the simulated mon... 相似文献
13.
Impact of Horizontal Resolution and Cumulus Parameterization Scheme on the Simulation of Heavy Rainfall Events over the Korean Peninsula 总被引：1，自引：0，他引：1
In this paper, we present the results from high-resolution numerical simulations of three heavy rainfall events over the Korean Peninsula. The numerical results show that the prediction accuracy for heavy rainfall events improved as horizontal resolution increased. The fine-grid precipitation fields were much closer to the real precipitation fields in the case of large synoptic forcing over the Korean Peninsula. In the case of large convective available potential energy and weak synoptic forcing, it seems that even when using a high resolution, the models still showed poor performance in reproducing the observed high precipitation amounts. However, activation of the cumulus parameterization scheme in the intermediate resolution of 9 km, even at a grid spacing of 3 km, had a positive impact on the simulation of the heavy rainfall event. 相似文献
14.
Changes of the summer evapotranspiration regime under increased levels of atmospheric greenhouse gases are discussed for three Alpine river basins on the basis of a new set of simulations carried out with a high-resolution hydrological model. The climate change signal was inferred from the output of two simulations with a state-of-the-art global climate model (GCM), a reference run valid for 1961–1990 and a time-slice simulation valid for 2071–2100 under forcing from the A2 IPCC emission scenario. In this particular GCM experiment and with respect to the Alpine region summer temperature was found to increase by 3 to 4 ∘C, whereas precipitation was found to decrease by 10 to 20%. Global radiation and water vapor pressure deficit were found to increase by about 5% and 2 hPa, respectively. On this background, an overall increase of potential evapotranspiration of about 20% relative to the baseline was predicted by the hydrological model, with important variations between but also within individual basins. The results of the hydrological simulations also revealed a reduction in the evapotranspiration efficiency that depends on altitude. Accordingly, actual evapotranspiration was found to increase at high altitudes and to the south of the Alps, but to decrease in low elevation areas of the northern forelands and in the inner-Alpine domain. Such a differentiation does not appear in the GCM scenario, which predicts an overall increase in evapotranspiration over the Alps. This underlines the importance of detailed simulations for the quantitative assessment of the regional impact of climate change on the hydrological cycle. 相似文献
15.
Hydroclimatological response to dynamically downscaled climate change simulations for Korean basins 总被引：1，自引：1，他引：0
Eun-Soon Im Il-Won Jung Heejun Chang Deg-Hyo Bae Won-Tae Kwon 《Climatic change》2010,100(3-4):485-508
We investigated the hydrological response to climate change simulations for three basins in South Korea. To provide fine-scale climate information to the PRMS hydrological model, an ECHO-G B2 simulation was dynamically downscaled using the RegCM3 double-nested system implementing two different convection schemes, namely, the Grell and the MIT-Emanuel (EMU) schemes. The daily minimum and maximum temperatures and precipitation from the nested domain for a grid spacing of 20 km are used as the input for the PRMS run. Two sets of multi-decadal simulations are performed over a reference period (1971–2000) and a future period (2021–2050). We focus on the differences of hydrological impacts in response to both simulations with different performances. Based on the validation of the reference simulations, the EMU simulation shows considerable improvement compared to the Grell simulation, indicating a reduction in the cold and dry biases during summer. This improvement is directly reflected in the hydrological simulation of evapotranspiration and runoff. However, using the RCM simulations without bias-correction showed the limitations of hydrologic simulation, especially snowmelt. Despite large differences in both reference simulations, the change signals of temperature and precipitation derived from the differences between the reference and future simulations show a similar pattern and sign. However, the differences in monthly change in precipitation and temperature between Grell and EMU caused the relatively large differences in runoff changes in the study areas. 相似文献
16.
欧亚大陆积雪两种物理效应对2010年春末夏初华南降水的影响 总被引：8，自引：6，他引：2
本文基于欧亚大陆积雪深度资料和中国台站降水资料的奇异值分析 (SVD) 结果, 使用大气环流模式 (CAM3.1) 分别进行三组集合试验来研究欧亚大陆积雪的反照率效应和水文效应对2010年5～6月华南降水的影响: 第一组试验综合考虑积雪的两种物理效应, 既有反照率效应又有水文效应; 第二组试验仅考虑积雪反照率效应, 忽略水文效应; 第三组试验只考虑积雪水文效应, 忽略反照率效应。试验结果表明, 积雪的两种物理效应都会对后期华南降水产生影响, 但是三组试验中积雪不同物理效应所导致的异常幅度和范围存在较大差异, 其中积雪水文效应比反照率效应引起的变化幅度大。当两种效应共同作用时产生的异常与统计分析结果最为接近, 变化幅度也最大, 但是并不等于单纯反照率效应和单纯水文效应作用之和。 相似文献
17.
本文基于气候系统模式CESM4.0长期积分试验,分析评估了工业革命前（1850年）及当前（2000年）两种辐射强迫作用（分别为太阳活动和温室气体）对中国北方干旱半干旱区降水的影响。结果表明,模拟结果与观测之间尽管存在一定的偏差,但仍能再现降水气候态的空间分布以及季节变化特征;两种辐射强迫下的降水长期变化均无明显趋势,但二者的差异却呈现出70~100年的准周期振荡;由人类活动引起的当前辐射强迫作用对降水的多年际变率幅度有一定影响,造成极端强降水事件出现的概率增多,而由太阳活动引起的辐射强迫作用主要对降水多年代际周期具有一定的调制作用。进一步分析表明,两种辐射强迫下中国北方干旱半干旱区降水年多年代际变率的主要模态基本一致,但人类活动引起的辐射强迫作用会影响降水多年代际变率与热带海温异常的相互作用的强度,从而改变降水多年代际变率的幅度。 相似文献
18.
The Canadian Centre for Climate Modelling and Analysis (CCCma) global coupled model is used to investigate the potential
climate effects of increasing greenhouse gas (GHG) concentrations and changes in sulfate aerosol loadings. The forcing scenario
adopted closely resembles that of Mitchell et al. for both the greenhouse gas and aerosol components. Its implementation in
the model and the resulting changes in forcing are described. Five simulations of 200 years in length, nominally for the years
1900 to 2100, are available for analysis. They consist of a control simulation without change in forcing, three independent
simulations with the same greenhouse gas and aerosol changes, and a single simulation with greenhouse gas only forcing. Simulations
of the evolution of temperature and precipitation from 1900 to the present are compared with available observations. Temperature
and precipitation are primary climate variables with reasonable temporal and spatial coverage in the observational record
for the period. The simulation of potential climate change from the present to the end of the twenty-first century, based
on projected GHG and aerosol forcing changes, is discussed in a companion paper. For the historical period dealt with here,
the GHG and aerosol forcing has changed relatively little compared to the forcing changes projected to the end of the twenty-first
century. Nevertheless, the forced climate signal for temperature in the model is reasonably consistent with the observed global
mean temperature from the instrumental record. This is true also for the trend in zonally averaged temperature as a function
of latitude and for some aspects of the geographical and regional distributions of temperature. Despite the modest change
in overall forcing, the difference between GHG+aerosol and GHG-only forcing is discernible in the temperature response for
this period. Changes in precipitation, on the other hand, are much less evident in both the instrumental and simulated record.
There is an apparent increasing trend in average precipitation in both the observations and the model results over that part
of the land for which observations are available. Regional and geographical changes and trends (which are less affected by
sampling considerations), if they exist, are masked by the large natural variability of precipitation in both model and observations.
Received: 24 September 1998 / Accepted: 8 October 1999 相似文献
19.
A transient climate change simulation with greenhouse gas and aerosol forcing: projected climate to the twenty-first century 总被引：3，自引：0，他引：3
The potential climatic consequences of increasing atmospheric greenhouse gas (GHG) concentration and sulfate aerosol loading
are investigated for the years 1900 to 2100 based on five simulations with the CCCma coupled climate model. The five simulations
comprise a control experiment without change in GHG or aerosol amount, three independent simulations with increasing GHG and
aerosol forcing, and a simulation with increasing GHG forcing only. Climate warming accelerates from the present with global
mean temperatures simulated to increase by 1.7 °C to the year 2050 and by a further 2.7 °C by the year 2100. The warming is
non-uniform as to hemisphere, season, and underlying surface. Changes in interannual variability of temperature show considerable
structure and seasonal dependence. The effect of the comparatively localized negative radiative forcing associated with the
aerosol is to retard and reduce the warming by about 0.9 °C at 2050 and 1.2 °C at 2100. Its primary effect on temperature
is to counteract the global pattern of GHG-induced warming and only secondarily to affect local temperatures suggesting that
the first order transient climate response of the system is determined by feedback processes and only secondarily by the local
pattern of radiative forcing. The warming is accompanied by a more active hydrological cycle with increases in precipitation
and evaporation rates that are delayed by comparison with temperature increases. There is an “El Nino-like” shift in precipitation
and an overall increase in the interannual variability of precipitation. The effect of the aerosol forcing is again primarily
to delay and counteract the GHG-induced increase. Decreases in soil moisture are common but regionally dependent and interannual
variability changes show considerable structure. Snow cover and sea-ice retreat. A PNA-like anomaly in mean sea-level pressure
with an enhanced Aleutian low in northern winter is associated with the tropical shift in precipitation regime. The interannual
variability of mean sea-level pressure generally decreases with largest decreases in the tropical Indian ocean region. Changes
to the ocean thermal structure are associated with a spin-down of the Atlantic thermohaline circulation together with a decrease
in its variability. The effect of aerosol forcing, although modest, differs from that for most other quantities in that it
does not act primarily to counteract the GHG forcing effect. The barotropic stream function in the ocean exhibits modest change
in the north Pacific but accelerating changes in much of the Southern Ocean and particularly in the north Atlantic where the
gyre spins down in conjunction with the decrease in the thermohaline circulation. The results differ in non-trivial ways from
earlier equilibrium 2 × CO2 results with the CCCma model as a consequence of the coupling to a fully three-dimensional ocean model and the evolving nature
of the forcing.
Received: 24 September 1998 / Accepted: 8 October 1999 相似文献
20.
The Global Soil Wetness Project (GSWP) is an international initiative aimed at producing global data sets of soil wetness and energy and water fluxes by driving land surface models with state-of-the-art 1° by 1° atmospheric forcing and land surface parameters. It also provides a unique opportunity to develop and test land surface parameterizations at the global scale, using multi-year off-line simulations that are not affected by the systematic errors found in atmospheric models. Nevertheless, the accuracy and reliability of the 10?year GSWP-2 atmospheric forcing remain questionable. A first comparison using the high-resolution Rhône-AGGregation (Rhône-AGG) database reveals that the baseline GSWP-2 precipitation forcing is drastically overestimated over the Rhône river basin. Hydrological simulations driven with each dataset and using the ISBA land surface model and the MODCOU river routing model are also compared. The simulated river discharges are validated against a dense network of river gauges and are generally less realistic when using the GSWP-2 instead of the Rhône-AGG precipitation forcing. Secondly, the GSWP-2 precipitation forcing is compared with three alternative data sets (GPCP-2, CRU-2, CMAP) at the global scale. Moreover, the results of a global sensitivity study to the precipitation forcing conducted with six land surface models are shown. The TRIP river routing model is used to convert daily runoff from all models into river discharges, which are compared at 80 gauging stations distributed over the globe. In agreement with the regional evaluation, the results reveal that the baseline GSWP-2 precipitation forcing is generally overestimated over the mid and high latitudes, which implies systematic errors in the simulated discharges. This study reveals that the empirical wind corrections applied to the GSWP-2 precipitation forcing are exaggerated, whereas the GPCP satellite adjustments seem to be useful for simulating realistic annual mean river discharges over the East Siberian river basins. 相似文献