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1.
沙尘气溶胶辐射强迫全球分布的模拟研究 总被引：7，自引：2，他引：5
为了定景了解沙尘气溶胶对气候的影响,文中利用一个改进的辐射传输模式,结合伞球气溶胶数据集(G-ADS),计算了晴空条件下,冬夏两季沙尘气溶胶的直接辐射强迫在对流层顶和地面的全球分布,并讨论了云对沙尘气溶胶辐射强迫的影响.计算结果表明,对北半球冬季和夏季而言,在对流层顶沙尘气溶胶的全球短波辐射强迫的平均值分别为-0.477和-0.501 W/m2;长波辐射强迫分别为0.11和0.085 W/m2;全球平均短波地面辐射强迫冬夏两季分别为-1.362和-1.559 W/m2;长波辐射强迫分别为0.274和0.23 W/m2.沙尘气溶胶在对流层顶和地面的负辐射强迫的绝对值郁随太阳天顶角的余弦和地表反照率的增加而增大;地表反照率对沙尘气溶胶辐射强迫的强度和分布都有重要影响.研究指出:云对沙尘气溶胶的直接辐射强迫的影响不仅取决于云量,而且取决于云的高度和云水路径,以及地面反照率和太阳高度角等综合因素.中云和低云对沙尘气溶胶在对流层顶的短波辐射强迫的影响比高云明显.云的存在都使对流层顶长波辐射强迫减少,其中低云的影响最为明显.因此,在估算沙尘气溶胶总的直接辐射强迫时,云的贡献不可忽视. 相似文献
2.
利用青藏高原拉萨(Lhasa)和珠峰(QOMS_CAS)站点地基CE 318太阳光度计观测数据，研究了2012年4月2日至4月5日一次生物质燃烧输送对青藏高原气溶胶光学和辐射特性的影响；并结合卫星遥感产品以及后向轨迹模式分析了本次生物质燃烧输送的可能来源。结果表明：本次气溶胶污染期间Lhasa和QOMS_CAS站点的主要气溶胶类型变为生物质燃烧气溶胶，气溶胶粒子的消光性增大(气溶胶光学厚度(AOD)增大，Lhasa和QOMS_CAS站点AOD最大值分别为0.4和0.29)，尺度减小(消光波长指数(EAE)>1.5)，吸收性增大(吸收波长指数(AAE)>1.3)，细模态粒子体积浓度增大，而细模态粒子峰值半径减小。气溶胶辐射强迫表明此次输送过程使得Lhasa和QOMS_CAS站点的气溶胶对大气顶和地表的降温作用增强，对大气的增温作用也增强。生物质燃烧输送的可能来源为南亚的印度东北部，尼泊尔与不丹地区。 相似文献
3.
用GMS卫星资料研究我国东南部夏季短波云辐射强迫 总被引：2，自引：0，他引：2
利用中分辨率辐射计算模式（MODTRAN3）、站点的温压湿探空资料和美国标准大气的气溶胶、臭氧和微量气体参数，计算出无云情况下的地面总辐射，再与实测地面总辐射结合得出云对太阳的辐射强迫。同时利用GMS卫星资料反演出云辐射参数——反照率和亮温，分析了短波云辐射强迫和云辐射参数的关系，建立了两者的回归模式，用于估算地面资料缺少地区的短波云辐射强迫。 相似文献
4.
相对湿度对气溶胶辐射特性和辐射强迫的影响 总被引：14，自引：4，他引：14
采用已有的气溶胶折射指数等资料 ,计算了在不同的相对湿度条件下硫酸盐气溶胶的辐射特性。结合两种不同化学输送模式 (CTM )的模拟结果及LASGGOALS/AGCM模式 ,模拟估算了考虑相对湿度影响后全球硫酸盐气溶胶的辐射强迫。结果表明 :(1)随着相对湿度的增加 ,硫酸盐气溶胶的质量消光效率因子在短波波段有所减小 ,单次散射反照率仅在长波波段有所增加 ,不对称因子在整个波段均有所增加 ;(2 )用两个CTM资料模拟辐射强迫的结果相差较大 ,其全球平均辐射强迫分别为 - 0 .2 6 8和 - 0 .816W/m2 ;(3)在考虑相对湿度的影响后 ,硫酸盐气溶胶辐射强迫的分布类型与相应干粒子的强迫分布类型基本相同 ,但全球平均的强迫值减少了 6 %左右。 相似文献
5.
准确估算青藏高原的云辐射效应,对分析该地区的近地面感热通量十分重要。本文首先利用加权平均方法,分别将中分辨率成像光谱仪(MODIS)、测云雷达(CPR)和云与地球辐射能量系统(CERES)的像元数据进行融合。利用这些数据,分析了青藏高原上多云个例(2017年5月5日)与少云个例(2017年8月2日)情况下的可见光通道和热红外通道的信号、云参数和大气长短波辐射强迫等的差异。研究表明,少云时高原地区的大气顶大气长波辐射强迫为108.3 W·m-2,多云时为104.5 W·m-2。同时少云个例中塔里木盆地的大气顶大气长波辐射强迫为200.7 W·m-2,表明该辐射强迫受到地表热力状况影响较大。深厚与浅薄云区的云顶高度相差不大,但多云个例中深厚云区的短波辐射强迫是浅薄云区的2倍多,这一比例远大于长波。这表明短波辐射强迫对云厚度较敏感。最后,本文分析了CERES观测的大气顶长短波辐射分别与MODIS热红外和可见光通道之间的关系,结果表明它们存在很好的相关性(相关系数超过0.95),MODIS的可见光通道可以用于估算大气顶的短波辐射量,而MODIS的热红外通道只可用来估算云区的大气顶长波辐射量。 相似文献
6.
《湖北气象》2015,(4)
利用2000年4月—2013年9月搭载于Aqua和Terra卫星上的中分辨率成像光谱仪(moderate-resolution imaging spectroradiometer,MODIS)遥感资料,首先分析上海及周边地区气溶胶光学厚度(AOD)的长期统计特性,而后配合地面自动气象站降水资料,分析气溶胶与不同类型云的特征参数和地面降水之间的关系,研究该地区气溶胶与云和降水的相互作用。结果表明:上海及周边地区AOD年均值从2000—2009年和2011—2013年分别呈现增强、减弱趋势,而2010年出现明显低值。随着气溶胶增多,该地区浅薄水云的发生频率减少15.5%~32.4%,而深厚混合云的发生频率增加2.1%~10.0%。气溶胶增多对水云云滴粒子有效半径变化的影响受环境水汽条件影响很大,当水汽条件充分(不足)时,气溶胶增多会导致水云云滴粒子有效半径增加(减弱)。深厚混合云的云顶温度随AOD增加而显著减少。气溶胶较多时,降雨量小于1.0 mm·h-1的较弱降水发生频率减少,而降雨量大于等于1.0 mm·h-1的较强降水发生频率增加,说明气溶胶增多会抑制弱降水发生而加强强降水发生。 相似文献
7.
黑碳气溶胶直接辐射强迫及其对中国夏季降水影响的模拟研究 总被引：8，自引：1，他引：7
利用NCAR的全球大气模式CAM3分析了黑碳气溶胶在大气顶和地表的直接辐射强迫分布及其季节变化,重点讨论了云对黑碳气溶胶直接辐射强迫的影响,以及黑碳气溶胶对中国夏季降水的影响。结果表明：黑碳气溶胶在大气顶和地表的直接辐射强迫分布范围和强度都具有明显的季节变化。有云条件下,黑碳气溶胶在大气顶产生正的直接辐射强迫,全球年平均强迫值为＋0.33 W·m－2;在地表产生负的直接辐射强迫,全球年平均强迫值为－0.56 W·m－2。晴空条件下,黑碳气溶胶在大气顶和地表的全球年平均辐射强迫值分别为＋0.21 和－0.71 W·m－2。云的存在对黑碳气溶胶的辐射强迫产生了很大的影响,使大气顶的正辐射强迫增加,地表的负辐射强迫减小。黑碳气溶胶导致夏季中国北方30°N～45°N之间区域降水明显增加;而中国长江以南地区除了海南和广西的部分城市外,降水明显减少。模拟结果表明,中国夏季近50年来经常发生的南涝北旱并非由黑碳气溶胶引起。 相似文献
8.
BCC_AGCM2.1对中国东部地区云辐射特征模拟的偏差分析 总被引：2，自引：0，他引：2
通过与观测及再分析资料的对比,评估了中国国家气候中心大气环流模式BCC_AGCM 2.1对中国东部地区云辐射特征的模拟性能,并着重分析了模拟偏差的原因.在云辐射特征的基本气候态模拟方面,模式能大致再现中国东部中纬度层状云大值带,以及层状云冷季多、暖季少的季节特征,模拟的短波云辐射强迫也具有与观测相对应的季节变化特征.在云辐射强迫和地面温度相互影响过程的模拟方面,模式也能模拟出与观测相近的相互作用过程,即地面温度降低伴随着层状云云量增多以及负的净云辐射强迫加强,升温时层状云云量减少和净云辐射强迫减弱.但模式模拟的大陆层状云云量系统性偏少(尤其在冷季),使得模式在该处的短波云辐射强迫明显偏弱.初步分析表明,造成层状云模拟差异的主要原因是在中国西南地区对流层低层模式模拟的偏南气流明显偏弱以及陆-气潜热通量偏小.偏南气流偏弱导致低层散度和垂直运动条件不利于中层云的形成.同时偏南气流偏弱也不利于向西南地区的水汽输送,再加上模式模拟地表向上潜热通量偏小,这二者都使得模式模拟中国西南区域对流层低层的水汽含量严重偏少,相对湿度偏低,同样不利于层状云生成和发展.水汽偏少进一步导致在冷异常情况下青藏高原下游云辐射-地表温度反馈模拟偏弱,即呈现冷异常时,水汽条件偏弱限制了云量增加,弱化了进一步降低温度的反馈过程. 相似文献
9.
《高原气象》2018,(6)
基于对"全球能量水循环亚洲季风青藏高原试验研究"(GAME/Tibet)和"全球协调加强观测计划(CEOP)之亚澳季风青藏高原试验"(CAMP/Tibet)设在藏北高原的安多站、BJ站、D105站和NPAM站以及中国科学院珠峰站和中国科学院纳木错站10～20年晴天日间的辐射观测资料求年均值,分析了高原草甸(草高为5 cm的高原草甸,10 cm的高原草甸和高原稀疏草甸,15 cm的高原草甸)、戈壁和临湖高原草甸这些典型下垫面观测站多年观测的短波向下辐射、短波向上辐射、长波向上辐射、长波向下辐射、净辐射通量和地表反照率的年际变化,得出了青藏高原地表辐射通量的气候特征,发现高原上大部分站点观测到的短波向下辐射有不同程度的减小的年变化趋势,基本所有站点观测的长波向上辐射有不同程度的逐年增加趋势,且高原上基本所有站点观测的长波向下辐射有不同程度的增加趋势,高原地区大部分站点的净辐射通量的年变化趋势基本与短波向下辐射的年变化相一致,青藏高原大部分站点的地表反照率在不同程度上逐年减小。 相似文献
10.
利用NCC/IAP T63海气耦合模式进行了20 a积分,详细分析了模式对云量及其辐射影响的模拟能力。结果表明,模式能够模拟出云量分布的基本特征,但同ISCCP卫星观测资料及ERA再分析资料相比还存在较大的差距,总体表现为模拟的云量偏小,尤其是海洋上部分地区出现了异常的低值区。通过对云量方案的改进,明显改善了两大洋东岸、夏半球副热带到中纬度海洋上空低云的模拟。但模式对热带印度洋到西太平洋地区云量的模拟仍然存在明显的偏差,这主要是由于模式对该地区强对流云模拟能力差,造成该地区高云模拟存在较大的误差。对辐射及其云辐射强迫的分析表明,模式对长波及其云辐射强迫的模拟要明显好于短波。短波辐射模拟的偏差主要是由于短波云辐射强迫模拟过小、耦合模式对积雪和海冰模拟较差、以及未考虑气溶胶的影响等原因共同引起的;而长波辐射模拟的差距主要是云量以及下垫面温度模拟不足造成的。相应于云量方案的改进,两大洋东岸、夏半球副热带到中纬度海洋上辐射(尤其是短波辐射)的模拟有了明显的改善,这也明显改进了这些地区的净辐射模拟。 相似文献
11.
Anthropogenic aerosols play an important role in the atmospheric energy balance. Anthropogenic aerosol optical depth (AOD) and its accompanying shortwave radiative forcing (RF) are usually simulated by nu- merical models. Recently, with the development of space-borne instruments and sophisticated retrieval algorithms, it has become possible to estimate aerosol radiative forcing based on satellite observations. In this study, we have estimated shortwave direct radiative forcing due to anthropogenic aerosols over oceans in all-sky conditions by combining clouds and the Single Scanner Footprint data of the Clouds and Earth’s Radiant Energy System (CERES/SSF) experiment, which provide measurements of upward shortwave fluxes at the top of atmosphere, with Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol and cloud products. We found that globally averaged aerosol radiative forcing over oceans in the clear-sky conditions and all-sky conditions were -1.03±0.48 W m-2 and -0.34 ±0.16 W m-2, respectively. Direct radiative forcing by anthropogenic aerosols shows large regional and seasonal variations. In some regions and in particular seasons, the magnitude of direct forcing by anthropogenic aerosols can be comparable to the forcing of greenhouse gases. However, it shows that aerosols caused the cooling effect, rather than warming effect from global scale, which is different from greenhouse gases. 相似文献
12.
气候模式分辨率作为影响模式模拟结果的重要因素,其对气溶胶与云相互作用的影响尚未全面认识。利用公共大气模型CAM5.3在3种分辨率（2°、1°、0.5°）下,分别采用2000年和1850年气溶胶排放情景进行试验,检验提高分辨率是否能改进气候模式的模拟能力,分析不同分辨率下气溶胶气候效应的异同,探索模式分辨率对气溶胶气候效应数值模拟结果的影响。通过观测资料与模式结果对比发现,提高分辨率可以明显改进模式对总云量、云短波辐射强迫的模拟能力,0.5°分辨率下模拟结果与观测更接近,其他变量并无明显改善。在不同分辨率下,全球平均的气溶胶气候效应较为一致,总云量、云水路径均增加,云短波和长波辐射强迫均加强,而云顶的云滴有效半径和降水均减小,地面气温降低。不同分辨率下,气溶胶增加引起的气溶胶光学厚度、云水路径、地面温度、云短波和长波辐射强迫变化的纬向平均分布相似但大小存在差异;而降水和云量变化的纬向分布与大小均存在较大差异,在区域尺度上还存在较大的不确定性。全球平均而言, 0.5°分辨率下气溶胶的间接辐射强迫相比1°分辨率下的结果降低了2.5%,相比2°分辨率下的结果降低了6.4%。提高模式分辨率可以部分改进模式模拟能力,同时,气溶胶的间接效应随着模式分辨率的提高而减弱。但气溶胶引起的云量、降水的变化在不同分辨率下差异较大,存在较大的不确定性。 相似文献
13.
利用SBDART（Santa Barbara DISORT Atmospheric Radiative Transfer）辐射传输模式,结合AERONET（Aerosol Robotic Network）北京站观测的气溶胶光学特性数据,评估北京地区近十年气溶胶以及黑碳气溶胶的辐射强迫,主要研究结果如下:北京近十年气溶胶平均光学厚度（aerosol optical depth, AOD440nm）为0.61±0.56,?ngstr?m波长指数均值为1.09,单次散射反照率（single scattering albedo, SSA440nm）的均值为0.888±0.045;AOD呈现下降趋势,SSA呈上升趋势,表明该区域气溶胶污染有所改善。晴空条件下,大气层顶、地面和大气的气溶胶直接辐射强迫多年均值分别为?24.91±19.80 W m?2、?65.52±43.78 W m?2、40.61±28.62 W m?2,即气溶胶对大气层顶和地表为冷却效应,对大气产生加热作用。气溶胶和黑碳气溶胶的直接辐射强迫绝对值的年际变化表现为微弱的下降趋势,季节变化特征为春夏季高,冬季低,这与AOD的变化规律一致。并且黑碳气溶胶的直接辐射强迫下降趋势与SSA的上升趋势呈现较好的反位相关系。 相似文献
14.
The direct and semi-direct radiative effects of anthropogenic aerosols on the radiative transfer and cloud fields in the Western United States (WUS) according to seasonal aerosol optical depth (AOD) and regional climate are examined using a regional climate model (RCM) in conjunction with the aerosol fields from a GEOS-Chem chemical-transport model (CTM) simulation. The two radiative effects cannot be separated within the experimental design in this study, thus the combined direct- and semi-direct effects are called radiative effects hereafter. The CTM shows that the AOD associated with the anthropogenic aerosols is chiefly due to sulfates with minor contributions from black carbon (BC) and that the AOD of the anthropogenic aerosol varies according to local emissions and the seasonal low-level winds. The RCM-simulated anthropogenic aerosol radiative effects vary according to the characteristics of regional climate, in addition to the AOD. The effects on the top of the atmosphere (TOA) outgoing shortwave radiation (OSRT) range from ?0.2?Wm?2 to ?1?Wm?2. In Northwestern US (NWUS), the maximum and minimum impact of anthropogenic aerosols on OSRT occurs in summer and winter, respectively, following the seasonal AOD. In Arizona-New Mexico (AZNM), the effect of anthropogenic sulfates on OSRT shows a bimodal distribution with winter/summer minima and spring/fall maxima, while the effect of anthropogenic BC shows a single peak in summer. The anthropogenic aerosols affect surface insolation range from ?0.6?Wm?2 to ?2.4?Wm?2, with similar variations found for the effects on OSRT except that the radiative effects of anthropogenic BC over AZNM show a bimodal distribution with spring/fall maxima and summer/winter minima. The radiative effects of anthropogenic sulfates on TOA outgoing longwave radiation (OLR) and the surface downward longwave radiation (DLRS) are notable only in summer and are characterized by strong geographical contrasts; the summer OLR in NWUS (AZNM) is reduced (enhanced) by 0.52?Wm?2 (1.14?Wm?2). The anthropogenic sulfates enhance (reduce) summer DLRS by 0.2?Wm?2 (0.65?Wm?2) in NWUS (AZNM). The anthropogenic BC affect DLRS noticeably only in AZNM during summer. The anthropogenic aerosols affect the cloud water path (CWP) and the radiative transfer noticeably only in summer when convective clouds are dominant. Primarily shortwave-reflecting anthropogenic sulfates decrease and increase CWP in AZNM and NWUS, respectively, however, the shortwave-absorbing anthropogenic BC reduces CWP in both regions. Due to strong feedback via convective clouds, the radiative effects of anthropogenic aerosols on the summer radiation field are more closely correlated with the changes in CWP than the AOD. The radiative effect of the total anthropogenic aerosols is dominated by the anthropogenic sulfates that contribute more than 80% of the total AOD associated with the anthropogenic aerosols. 相似文献
15.
不同形状冰晶权重假定对冰云光学和辐射特性的影响 总被引：1，自引：0，他引：1
在BCC_RAD辐射传输模式和包含多形状冰晶粒子的冰云光学性质参数化方案的基础上,详细分析了不同冰晶粒子权重选取对冰云光学和辐射特性的影响。结果显示,不同形状冰晶粒子权重的选取对长波带平均消光系数、单次散射比、不对称因子和短波带平均不对称因子均有较大的影响。冰晶粒子权重选取对长波辐射通量有很大影响:对长波向下辐射通量,权重选择不同可在云底处造成高达10.50 W/m2的差别;对长波向上辐射通量,权重选择不同可在云顶处造成高达15.05 W/m2的差别。冰晶粒子权重选择对短波辐射通量也存在较大影响:对短波向下辐射通量,权重选择不同可在云底处造成高达12.48 W/m2的差别;对短波向上辐射通量,权重选择不同可在云顶处造成高达10.23 W/m2的差别。冰晶粒子权重选择对长波加热率影响较大,在云顶处和云底处分别可达1.31和-2.06 K/d。研究表明,不同形状冰晶粒子权重的选取对冰云光学性质和辐射计算均有较大的影响,在长波区间尤其明显。 相似文献
16.
Quantifying the radiative forcing due to aerosol–cloud interactions especially through cirrus clouds remains challenging because of our limited understanding of aerosol and cloud processes. In this study, we investigate the anthropogenic aerosol indirect forcing (AIF) through cirrus clouds using the Community Atmosphere Model version 5 (CAM5) with a state-of-the-art treatment of ice nucleation. We adopt a new approach to isolate anthropogenic AIF through cirrus clouds in which ice nucleation parameterization is driven by prescribed pre-industrial (PI) and presentday (PD) aerosols, respectively. Sensitivities of anthropogenic ice AIF (i.e., anthropogenic AIF through cirrus clouds) to different ice nucleation parameterizations, homogeneous freezing occurrence, and uncertainties in the cloud microphysics scheme are investigated. Results of sensitivity experiments show that the change (PD minus PI) in global annual mean longwave cloud forcing (i.e., longwave anthropogenic ice AIF) ranges from 0.14 to 0.35 W m–2, the change in global annual mean shortwave cloud forcing (i.e., shortwave anthropogenic ice AIF) from–0.47 to–0.20 W m–2, and the change in net cloud forcing from–0.12 to 0.05 W m–2. Our results suggest that different ice nucleation parameterizations are an important factor for the large uncertainty of anthropogenic ice AIF. Furthermore, improved understanding of the spatial and temporal occurrence characteristics of homogeneous freezing events and the mean states of cirrus cloud properties are also important for constraining anthropogenic ice AIF. 相似文献
17.
Yuan WANG Jonathan M.VOGEL Yun LIN Bowen PAN Jiaxi HU Yangang LIU Xiquan DONG Jonathan H.JIANG Yuk L.YUNG Renyi ZHANG 《大气科学进展》2018,35(2):234-247
Aerosol–cloud–radiation interactions represent one of the largest uncertainties in the current climate assessment. Much of the complexity arises from the non-monotonic responses of clouds, precipitation and radiative fluxes to aerosol perturbations under various meteorological conditions. In this study, an aerosol-aware WRF model is used to investigate the microphysical and radiative effects of aerosols in three weather systems during the March 2000 Cloud Intensive Observational Period campaign at the US Southern Great Plains. Three simulated cloud ensembles include a low-pressure deep convective cloud system, a collection of less-precipitating stratus and shallow cumulus, and a cold frontal passage. The WRF simulations are evaluated by several ground-based measurements. The microphysical properties of cloud hydrometeors, such as their mass and number concentrations, generally show monotonic trends as a function of cloud condensation nuclei concentrations.Aerosol radiative effects do not influence the trends of cloud microphysics, except for the stratus and shallow cumulus cases where aerosol semi-direct effects are identified. The precipitation changes by aerosols vary with the cloud types and their evolving stages, with a prominent aerosol invigoration effect and associated enhanced precipitation from the convective sources. The simulated aerosol direct effect suppresses precipitation in all three cases but does not overturn the aerosol indirect effect. Cloud fraction exhibits much smaller sensitivity(typically less than 2%) to aerosol perturbations, and the responses vary with aerosol concentrations and cloud regimes. The surface shortwave radiation shows a monotonic decrease by increasing aerosols, while the magnitude of the decrease depends on the cloud type. 相似文献
18.
Boru MAI Xuejiao DENG Zhanqing LI Jianjun LIU Xiang'ao XIA Huizheng CHE Xia LIU Fei LI Yu ZOU Maureen CRIBB 《大气科学进展》2018,35(2):195-208
Aerosol optical properties and direct radiative effects on surface irradiance were examined using seven years(2006–2012)of Cimel sunphotometer data collected at Panyu—the main atmospheric composition monitoring station in the Pearl River Delta(PRD) region of China. During the dry season(October to February), mean values of the aerosol optical depth(AOD)at 550 nm, the ?ngstr?m exponent, and the single scattering albedo at 440 nm(SSA) were 0.54, 1.33 and 0.87, respectively.About 90% of aerosols were dominated by fine-mode strongly absorbing particles. The size distribution was bimodal, with fine-mode particles dominating. The fine mode showed a peak at a radius of 0.12 μm in February and October(~0.10μm~3μm~(-2)). The mean diurnal shortwave direct radiative forcing at the surface, inside the atmosphere(FATM), and at the top of the atmosphere, was-33.4 ± 7.0, 26.1 ± 5.6 and-7.3 ± 2.7 W m~(-2), respectively. The corresponding mean values of aerosol direct shortwave radiative forcing per AOD were-60.0 ± 7.8, 47.3 ± 8.3 and-12.8 ± 3.1 W m~(-2), respectively. Moreover,during the study period, FATMshowed a significant decreasing trend(p 0.01) and SSA increased from 0.87 in 2006 to 0.91 in 2012, suggesting a decreasing trend of absorbing particles being released into the atmosphere. Optical properties and radiative impacts of the absorbing particles can be used to improve the accuracy of inversion algorithms for satellite-based aerosol retrievals in the PRD region and to better constrain the climate effect of aerosols in climate models. 相似文献
19.
The Southern Ocean is covered by a large amount of clouds with high cloud albedo. However, as reported by previous climate model intercomparison projects, underestimated cloudiness and overestimated absorption of solar radiation (ASR) over the Southern Ocean lead to substantial biases in climate sensitivity. The present study revisits this long-standing issue and explores the uncertainty sources in the latest CMIP6 models. We employ 10-year satellite observations to evaluate cloud radiative effect (CRE) and cloud physical properties in five CMIP6 models that provide comprehensive output of cloud, radiation, and aerosol. The simulated longwave, shortwave, and net CRE at the top of atmosphere in CMIP6 are comparable with the CERES satellite observations. Total cloud fraction (CF) is also reasonably simulated in CMIP6, but the comparison of liquid cloud fraction (LCF) reveals marked biases in spatial pattern and seasonal variations. The discrepancies between the CMIP6 models and the MODIS satellite observations become even larger in other cloud macro- and micro-physical properties, including liquid water path (LWP), cloud optical depth (COD), and cloud effective radius, as well as aerosol optical depth (AOD). However, the large underestimation of both LWP and cloud effective radius (regional means ~20% and 11%, respectively) results in relatively smaller bias in COD, and the impacts of the biases in COD and LCF also cancel out with each other, leaving CRE and ASR reasonably predicted in CMIP6. An error estimation framework is employed, and the different signs of the sensitivity errors and biases from CF and LWP corroborate the notions that there are compensating errors in the modeled shortwave CRE. Further correlation analyses of the geospatial patterns reveal that CF is the most relevant factor in determining CRE in observations, while the modeled CRE is too sensitive to LWP and COD. The relationships between cloud effective radius, LWP, and COD are also analyzed to explore the possible uncertainty sources in different models. Our study calls for more rigorous calibration of detailed cloud physical properties for future climate model development and climate projection. 相似文献