Parameterization of Longwave Optical Properties for Water Clouds

Based on relationships between cloud microphysical and optical properties, three different parameterization schemes for narrow and broad band optical properties in longwave region for water clouds have been presented. The effects of different parameterization schemes and different number of broad bands used on cloud radiative properties have been investigated. The effect of scattering role of cloud drops on longwave radiation fluxes and cooling rates in cloudy atmospheres has also been analyzed.

Ecological Significance of Developing Cloud Water Resource in Liaoning Province

The potential evapotranspiration of main ecosystems and its relationship with precipitation during the same period were studied,the results showed that precipitation did not meet the water requirement of main ecosystems influencing ecosystem construction.Based on the data from Liaoning Provincial Department of Water Resources and Liaoning Meteorological Archives,the characteristics of water inflow and each component were analyzed,and it showed that the imbalance between supply and demand of water resource in main ecosystems was improved by means of developing cloud water resource to increase atmospheric precipitation.

Climatic Features of Cloud Water Distribution and Cycle over China

Analyses of cloud water path （CWP） data over China available from the International Satellite Cloud Climatology Project （ISCCP） are performed for the period 1984-2004. Combined with GPCP precipitation data, cloud water cycle index （CWCI） is also calculated. The climatic distributions of CWP are found to be dependent on large-scale circulation, topographical features, water vapor transport and similar distribution features which are found in CWCI except in the Sichuan Basin. Influenced by the Asia monsoon, CWP over China exhibits very large seasonal variations in different regions. The seasonal cycles of CWCI in different regions are consistent and the largest CWCI occurs in July. The long-term trends of CWP and CWCI are investigated, too. Increasing trends of CWP are found during the period with the largest increase found in winter. The decreasing trends of CWCI dominate most regions of China. The differences in long-term trends between CWP and CWCI suggest that CWP only can influence the variation of CWCI to a certain extent and that other factors need to be involved in cloud water cycle researches. This phenomenon reveals the complexity of the hydrological cycle related to cloud water.

Sensitivity of the Grid-point Atmospheric Model of IAP LASG(GAMILI.I.0)Climate Simulations to Cloud Droplet Effective Radius and Liquid Water Path

This paper documents a study to examine the sensitivity to cloud droplet effective radius and liquid water path and the alleviation the energy imbalance at the top of the atmosphere and at the surface in the latest version of the Grid-point Atmospheric Model of the State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics （LASG）, Institute of Atmospheric Physics （IAP） （GAMIL1.1.0）. Considerable negative biases in all flux components, and thus an energy imbalance, are found in GAMIL1.1.0. In order to alleviate the energy imbalance, two modifications, namely an increase in cloud droplet effective radius and a decrease in cloud liquid water path, have been made to the cloud properties used in GAMIL. With the increased cloud droplet effective radius, the single scattering albedo of clouds is reduced, and thus the reflection of solar radiation into space by clouds is reduced and the net solar radiation flux at the top of the atmosphere is increased. With the reduced cloud optical depth, the net surface shortwave radiation flux is increased, causing a net warming over the land surface. This results in an increase in both sensible and latent heat fluxes over the land regions, which is largely balanced by the increased terrestrial radiation fluxes. Consequently, the energy balance at the top of atmosphere and at the surface is achieved with energy flux components consistent with available satellite observations.

Parameterization for narrow band shortwave optical properties of water clouds

Based on the drop size distribution models built from the observational data of microphysical properties of water clouds, the relationships between the optical properties and microphysical characteristics of water clouds have been investigated, and some different parameterization schemes of cloud optical properties have been analyzed. It is found that with the parameterization scheme, in addition to the equivalent radius, also including the mean radius of cloud droplet size distribution, the role of small cloud drops might be able to be considered more properly and better accuracies of parameterization calculation of cloud optical properties can be obtained, compared with that of using only the equivalent radius as parameter.

An assessment of Arctic cloud water paths in atmospheric reanalyses

The role of Arctic clouds in the recent rapid Arctic warming has attracted much attention.However,Arctic cloud water paths(CWPs)from reanalysis datasets have not been well evaluated.This study evaluated the CWPs as well as LWPs(cloud liquid water paths)and IWPs(cloud ice water paths)from five reanalysis datasets(MERRA-2,MERRA,ERA-Interim,JRA-55,and ERA5)against the COSP(Cloud Feedback Model Intercomparison Project Observations Simulator Package)output for MODIS from the MERRA-2 CSP(COSP satellite simulator)collection(defined as M2Modis in short).Averaged over 1980-2015 and over the Arctic region(north of 60°N),the mean CWPs of these five datasets range from 49.5 g/m^(2)(MERRA)to 82.7 g/m^(2)(ERA-Interim),much smaller than that from M2Modis(140.0 g/m^(2)).However,the spatial distributions of CWPs,show similar patterns among these reanalyses,with relatively small values over Greenland and large values over the North Atlantic.Consistent with M2Modis,these reanalyses show larger LWPs than IWPs,except for ERA-Interim.However,MERRA-2 and MERRA underestimate the ratio of IWPs to CWPs over the entire Arctic,while ERA-Interim and JRA-55 overestimate this ratio.ERA5 shows the best performance in terms of the ratio of IWPs to CWPs.All datasets exhibit larger CWPs and LWPs in summer than in winter.For M2Modis,IWPs hold seasonal variation similar with LWPs over the land but opposite over the ocean.Following the Arctic warming,the trends in LWPs and IWPs during 1980~2015 show that LWPs increase and IWPs decrease across all datasets,although not statistically significant.Correlation analysis suggests that all datasets have similar interannual variability.The study further found that the inclusion of re-evaporation processes increases the humidity in the atmosphere over the land and that a more realistic liquid/ice phase can be obtained by independently treating the liquid and ice water contents.

EnKF Assimilation of Satellite-retrieved Cloud Water Path to Improve Tropical Cyclone Rainfall Forecast

Tropical cyclone(TC) rainfall forecast has remained a challenge. To create initial conditions with high quality for simulation, the present study implemented a data assimilation scheme based on the EnKF method to ingest the satellite-retrieved cloud water path(C_(w)) and tested it in WRF. The scheme uses the vertical integration of forecasted cloud water content to transform control variables to the observation space, and creates the correlations between C_(w) and control variables in the flow-dependent background error covariance based on all the ensemble members, so that the observed cloud information can affect the background temperature and humidity. For two typhoons in 2018(Yagi and Rumiba), assimilating C_(w) significantly increases the simulated rainfalls and TC intensities. In terms of the average equitable threat score of daily moderate to heavy rainfall(5-120 mm), the improvements are over 130%, and the dry biases are cut by about 30%. Such improvements are traced down to the fact that C_(w) assimilation increases the moisture content, especially that further away from the TC center, which provides more precipitable water for the rainfall,strengthens the TC and broadens the TC size via latent heat release and internal wind field adjustment.

Effects of Doubled Carbon Dioxide on Rainfall Responses to Radiative Processes of Water Clouds

The effects of doubled carbon dioxide on rainfall responses to radiative processes of water clouds are investigated in this study.Two groups of two-dimensional cloud-resolving model sensitivity experiments with regard to pre-summer heavy rainfall around the summer solstice and tropical rainfall around the winter solstice are conducted and their five-day averages over the model domain are analyzed.In the presence of radiative effects of ice clouds,doubled carbon dioxide changes pre-summer rainfall from the decrease associated with the enhanced atmospheric cooling to the increase associated with the enhanced infrared cooling as a result of the exclusion of radiative effects of water clouds.Doubled carbon dioxide leads to the reduction in tropical rainfall,caused by the removal of radiative effects of water clouds through the suppressed infrared cooling.In the absence of radiative effects of ice clouds,doubled carbon dioxide changes pre-summer rainfall from the increase associated with the strengthened atmospheric warming to the decrease associated with the weakened release of latent heat caused by the elimination of radiative effects of water clouds.The exclusion of radiative effects of water clouds increases tropical rainfall through the strengthened infrared cooling,which is insensitive to the change in carbon dioxide.

Analysis of the Relationship between the Cloud Water Path and Precipitation Intensity of Mature Typhoons in the Northwest Pacific Ocean

The relationship between precipitation intensity and cloud water in typhoon systems remains unclear.This study combined time-and space-synchronized precipitation and spectral data obtained by the Precipitation Radar(PR)as well as the Visible and Infrared Scanner(VIRS)onboard the TRMM satellite,to overcome the limitations of precipitation properties and cloud parameters not being synchronized in previous studies.A merged dataset of near-surface rain rate(RR)and corresponding cloud water path(CWP)was established and used to analyze the potential correlation between cloud microphysical properties and precipitation,to deepen our understanding of the evolution of cloud to rain.In addition,25 collocated satellite overpasses of mature typhoon cases in the Northwest Pacific Ocean from 1998 to 2012 were obtained,and the relationships between the CWP and RR of 144515 pixels were analyzed in detail.The results show that the CWP and RR of mature typhoon systems with different precipitation types,precipitation cloud phases,and vertical depths of precipitation can be fitted by a notable sigmoid function,which may be useful for estimating CWP and parameterizing precipitation in models.Furthermore,the relationship was applied and tested with an independent sample to show that RR is a significant indicator of CWP.

Periodic Behavior of Cavitation Cloud Shedding in Submerged Water Jets Issuing from a Sheathed Pipe Nozzle

The behavior of cavitation cloud shedding in submerged water jets issuing from a sheathed pipe nozzle is investigated experimentally by high-speed camera visualization observation. Experiments are carried out under different cavitation numbers decreased to 0.01 with increase of the injection pressure, and the frequency spectrum of cavitation cloud shedding is evaluated by statistical analysis of a sequence of high-speed camera images. Experiments demonstrate that cavitation clouds appear when the cavitation number σ decreases to the level of 0.5-0.7 and developed cavitation clouds shed downstream periodically at multiple frequencies. The low frequency components of cavitation cloud shedding is basically dependent upon the pressure pulsation of plunger pump, which is often employed in various industry application of water jets. However, the high frequency components are closely related to the shedding of vortexes and the collapsing of cavitation clouds, which are dependent on the flow structure of submerged jets and the property of cavitation clouds consisted of numerous bubbles.

Effects of water and ice clouds on cloud microphysical budget:An equilibrium modeling study

The effects of water and ice clouds on the cloud microphysical budget associated with rainfall are investigated through the analysis of grid-scale data from a series of two-dimensional cloud-resolving model equilibrium sensitivity simulations. The model is imposed without large-scale vertical velocity. In the control experiment, the contribution from rainfall （cM） associated with net evaporation and hydrometeor loss/convergence is about 29% of that from the rainfall （Cm） associated with net condensation and hydrometeor gain/divergence and about 39% of that from the rainfall （CM） associated with net condensation and hydrometeor loss/convergence. The exclusion of ice clouds enhances rainfall contribution of CM, whereas it reduces rainfall contributions of Cm and cM. The removal of radiative effects of water clouds increases rainfall contribution of CM, barely changes rainfall contribution of Cm and reduces the rainfall contribution of cM in the presence of the radiative effects of ice clouds. Elimination of the radiative effects of water clouds reduces the rainfall contributions of CM and Cm, whereas it increases the rainfall contribution of cM in the absence of the radiative effects of ice clouds.

Magnitude and Trends of High-elevation Cloud Water Pollutant Concentrations and Modeled Deposition Fluxes

Cloud water samples, LWC （Liquid Water Content） and meteorological data were collected at the Clingmans Dome, Tennessee, high-elevation site in Great Smoky Mountains National Park during the warm season from 1994 through 2011. This paper presents results from 2000 through the conclusion of the study in 2011. Samples were analyzed for SO42＂, NO3, NH4＋ and H＋. These measurements were supplemented by measurements of ambient air and precipitation concentrations to estimate dry and wet deposition. Cloud water concentrations, LWC, cloud frequency, various meteorological measurements and information on nearby forest canopy were used to model cloud water deposition to gauge trends in deposition. Total deposition was calculated as the sum of cloud, dry and wet deposition estimates. Concentrations and deposition fluxes declined over the study period. The decreases in cloud water SO42＂ and NO3 concentrations were 40 percent and 26 percent, respectively. Three-year mean 5042 and NO3 deposition rates decreased by 71 percent and 70 percent, respectively. Trends in concentrations and depositions were comparable with trends in SO2 and NOx emissions from Tennessee Valley Authority power plants and aggregated emission reductions from electric generating units in adjacent states. Back trajectories were simulated with the HYSPLIT model and aggregated over cloud sampling periods from 2000 through 2007 and 2009 through 2011. Trajectories during periods with high H＋ concentrations traveled over local EGU （Electric Generating Unit） emission sources in Tennessee and Kentucky to the Ohio River Valley, Alabama and Georgia with the conclusion that these source regions contributed to acidic cloud water deposition at Clingmans Dome. This work was supported by U.S. Environmental Protection Agency and the Tennessee Valley Authority with infrastructure support provided by the National Park Service.

Temporal and spatial distribution characteristics of water resources in Guangdong Province based on a cloud model

With a focus on the difficulty of quantitatively describing the degree of nonuniformity of temporal and spatial distributions of water resources, quantitative research was carried out on the temporal and spatial distribution characteristics of water resources in Guangdong Province from 1956 to 2000 based on a cloud model. The spatial variation of the temporal distribution characteristics and the temporal variation of the spatial distribution characteristics were both analyzed. In addition, the relationships between the numerical characteristics of the cloud model of temporal and spatial distributions of water resources and precipitation were also studied. The results show that, using a cloud model, it is possible to intuitively describe the temporal and spatial distribution characteristics of water resources in cloud images. Water resources in Guangdong Province and their temporal and spatial distribution characteristics are differentiated by their geographic locations. Downstream and coastal areas have a larger amount of water resources with greater uniformity and stronger stability in terms of temporal distribution. Regions with more precipitation possess larger amounts of water resources, and years with more precipitation show greater nonuniformity in the spatial distribution of water resources. The correlation between the nonuniformity of the temporal distribution and local precipitation is small, and no correlation is found between the stability of the nonuniformity of the temporal and spatial distributions of water resources and precipitation. The amount of water resources in Guangdong Province shows an increasing trend from 1956 to 2000, the nonuniformity of the spatial distribution of water resources declines, and the stability of the nonuniformity of the spatial distribution of water resources is enhanced.

A Comparative Study of Cloud Liquid Water Content from Radiosonde Data at a Tropical Location

In this paper, some features of cloud liquid water content with respect to rain and water vapor are presented. Cloud liquid water density profile is obtained from radiosonde observation with Salonen's model and Karsten's model at Kolkata, a tropical location in the Indian region. Cloud liquid water contents (LWC) are obtained from these profiles which show a prominent seasonal variation. The monsoon months exhibit much higher values of LWC than in other months. However Salonen's model yields higher LWC values than that obtained with Karsten's model. The variation of daily total rainfall with LWC shows a positive relationship indicating the role of LWC in controlling the rainfall. Also the variation pattern of LWC with integrated water vapor (IWV) content of the atmosphere indicates that a threshold value of water vapor is required for cloud to form and once cloud is formed LWC increases with IWV.

基于Sentinel-1/2改进极化指数和纹理特征的土壤含盐量反演模型

目前Sentinel-1/2协同反演植被土壤含盐量的研究大多是基于Sentinel-2光谱信息和Sentinel-1后向散射系数,没有考虑Sentinel-2光谱信息容易受土壤亮度等信息影响,Sentinel-1后向散射系数容易受土壤粗糙度和水分影响。为进一步提高Sentinel-1/2协同反演植被土壤含盐量的精度,用水云模型对雷达卫星后向散射系数进行校正,消除植被影响;然后协同Sentinel-2纹理特征,基于VIP、OOB、PCA 3种变量筛选和RF、ELM、Cubist 3种机器学习回归模型构建植被土壤含盐量反演模型。研究结果表明:经过水云模型去除植被影响后的雷达后向散射系数及其极化组合指数与土壤含盐量的相关性有一定程度的提高。不同变量选择方法与不同机器学习方法耦合模型在反演土壤含盐量中,OOB变量筛选方法与RF、ELM和Cubist 3种机器学习方法的耦合模型精度最佳,建模集和验证集的R2都在0.750以上,且验证集的RMSE和MAE均最小;其中OOB-Cubist耦合模型精度最高,且R_(v)^(2)/R_(c)^(2)为0.955,具有良好的鲁棒性。研究可为机器学习协同物理模型、光学卫星协同雷达卫星在土壤含盐量反演中的进一步应用提供思路。

基于多源遥感数据与模型对比的冬小麦土壤含水量区域监测研究

实时、精准的土壤水分含量监测是农业用水管理的基础,探究冬小麦土壤水分反演的最优模型对于提高农业用水效率和可持续发展均具有重要的意义。本研究以河南省鹤壁市浚县冬小麦种植区域的土壤水分含量为研究对象,采用无人机遥感数据、卫星遥感数据、田间采样数据,分别运用温度植被干旱指数模型、水云模型和改进的水云模型3种方法,进行土壤含水量反演对比分析与最优模型选择。结果表明,3种方法中10 cm深度的反演精度均高于20 cm,且R^(2)均大于0.4。其中采用改进的水云模型方法在10 cm深度的R^(2)为0.7055、RMSE为0.0209,20 cm深度的R^(2)为0.5069、RMSE为0.0271,优于水云模型和温度植被干旱指数的反演效果。因此,改进的水云模型是一种适合用于麦田土壤水分反演的方法,它能够提供较高的反演精度。

桂西岩溶区云水分布和移动特征

利用欧洲中期天气预报中心(ECMWF)发布的第五代全球大气再分析资料(ERA5)和中国气象局人工影响天气中心发布的云水资源监测评估方法,研究广西西部岩溶地貌区2002—2021年云水资源总量、时空分布及移动特征。结果表明:桂西年均水凝物总量约22.5×10^(13)kg,水凝物降水效率约为65.5%,年均云水资源总量约7.8×10^(13)kg。水平分布上,云水在冬、春和夏季主要呈东北和西南高、西北和南部低的鞍形场分布特征,秋季呈自西北向东南逐步降低的阶梯型分布特征;垂直分布上,秋、冬和春季主要是分布在925~600 hPa低层的暖云云水,夏季主要是分布在600~400 hPa中层的冷云云水。中层云水主要以向东移动为主,低层云水有2个主要移动方向,分别为向北到东北方向移动和向西到南偏西方向移动。云水的水平输送通量呈冬春季较大、夏秋季较小的特点。

楼宇热水供应循环系统综合应用研究

随着城市化进程的加速,楼宇热水供应系统在人们的生活和工作中扮演着越来越重要的角色。对楼宇热水供应循环系统进行了综合研究,为了方便监控与管理搭建了云平台进行实时远程在线监控。

基于三维点云计算的CO_(2)-水-岩反应程度量化表征方法

CO_(2)地质封存是减少大气中CO_(2)排放,降低温室效应的重要途径,CO_(2)注入含水地层中时,CO_(2)-水-岩反应可能引起岩石矿物的侵蚀,对CO_(2)地质封存安全性产生显著影响。在室内实验中,通过表征岩石表面的形貌特征可以有效地评估CO_(2)-水-岩反应程度,为CO_(2)地质封存的安全性评估提供科学依据。通过三维点云计算可以精确量化地表征CO_(2)-水-岩反应程度,这种方法首先运用三维激光扫描技术,构建岩石表面的三维模型,确定CO_(2)-水处理前岩石表面三维模型的基准面,并基于处理前的均方根粗糙度确定处理后岩石表面三维模型的基准面。基于三维模型点云信息,提出了两种不同的体积计算新方法,并通过对规则模型体积的计算比较了两种计算方法的准确性与适用性,可根据实际情况选择两种计算方法量化表征CO_(2)-水处理前后岩石表面的侵蚀体积。最后,以陕西省咸阳市某煤矿煤样为例,开展了CO_(2)-水-岩反应模拟试验,验证了计算的可行性。试验结果表明:该文提出的侵蚀体积计算方法可有效地量化表征CO_(2)-水-岩反应程度,CO_(2)-水处理后岩石表面不同区域的侵蚀差异性明显,岩石表面的侵蚀体积与均方根粗糙度之间存在显著的正比关系,随着均方根粗糙度的增大,侵蚀体积也相应上升。

青藏高原东侧九龙夏季非降水云的观测特征

青藏高原东侧九龙地区是西南涡多发区,利用该地区新型探测设备开展云探测,有助于增强对西南涡多发区云特征的认识。利用2018—2019年6—8月九龙站地基微波辐射计资料,分析了该地区夏季非降水云的出现率、液态水路径及过冷水路径的观测特征。结果表明:九龙夏季非降水云出现率月均值在67%~82%之间,以低云和中云为主,高云较少;低云出现率表现为白天低、夜间高,而中云和高云则相反;云出现率的垂直分布表现为单峰形态,在约2km高度存在云出现率峰值8.1%;受大气热力层结日变化影响,云出现率的单峰垂直分布呈现日夜差异。另外,九龙夏季非降水云的液态水路径均值为0.433kg·m^(-2),其中低云、中云、高云的液态水路径均值分别为0.665、0.240、0.102kg·m^(-2);低云的液态水路径日变化特征与其出现率相似,而中云和高云的液态水路径日变化特征不明显。此外,九龙夏季非降水云中冷云的过冷水路径均值为0.154kg·m^(-2),其中低云、中云、高云的过冷水路径均值分别为0.065、0.166、0.102kg·m^(-2);总体上过冷水路径在液态水路径中的占比约为34.3%~38.8%,过冷水路径占比随云的高度而增大,这使得中云和高云的过冷水路径日变化与其液态水路径相似。与同纬度华中地区相比,九龙夏季非降水云具有明显不同的特征,这与两地之间的大气水汽特征差异密切相关。