| Energy and water cycle is an important process in the global climate system. Cloud plays a very important role Cloud plays a very important role in climate change, weather analysis and weather modification which is the main process in the global climate system as an important process of atmospheric water cycle.There are few research on cloud water, which includes three dimension cloud field diagnosis, cloud water balance and transformation. Based on the cloudsat observation and reanalysis data, three-dimensional cloud fields and cloud water field diagnostic methods is proposed. Water budget including hydrometeors, cloud water resource and precipitation efficiency are calculated, The main work and preliminary results of this paper are as follows.(1) Atmospheric moisture budget equations including hydrometeors are proposed. water budget three-dimensional cloud fields and cloud water field diagnostic methods is proposed. The concepts and formulas of various water material amount, precipitation efficiency and update cycle in a certain time and space scale are proposed. The concepts of cloud water resource and atmospheric remanding cloud water are given.(2) In order to get the three-dimension cloud distribution, based on cloud mask and relative humidity (RH) provided by Cloudsat products from2007to2008. The cloud determining RH threshold and its vertical variation over china is statistical analyzed and the monitoring and diagnosis method on three-dimensional cloud fields distribution is proposed, based on reanalysis data. Cloud region where cloud mask, which is bigger than20,has a good space and time corresponding to the high value relative humidity region.Distribution of RH in cloud at different height range shows single peak type, and the peak is near a RH value of100%. Local atmospheric environment affects the RH distribution outside cloud, which leads to RH distribution vary in different region or different height. RH threshold used for cloud diagnostic statist through the cross of cumulative RH frequency within and outside cloud, is less than the RH threshold get from Threat score(TS) method by10%. The two threshold both increased with the height first, and then reduced.(3)The method is applied to a three dimension cloud diagnosis case study which based on NCEP reanalysis data, and the diagnostic cloud field is compared to satellite, radar and cloud precipitation observation on ground. It is found that, RH gradient is very high around cloud region and the cloud area which diagnosed by RH threshold method is relatively stable. Diagnostic cloud area highly corresponds to updraft region and the cloud and clear sky distribution corresponds to satellite the Tbb observations overall. Diagnostic cloud depth, or sum cloud layers distribution greatly consists with optical thickness and precipitation on ground. The cloud vertical profile reveals the relation between cloud vertical structure and weather system clearly. Diagnostic of cloud distribution corresponds to cloud observations on ground very well. Precipitation on ground usually can be observed at deep-developed cloud area. The time series of cloud vertical structure evolution at single point is well consistent with local radar and surface cloud and precipitation observations.(4) In order to get the three-dimension cloud water distribution, based on Cloudsat cloud classification and cloud water content products from2007to2008, cloud water content and typical value and distribution characteristics of particle effective radius over China are statistical analyzed and different cloud systems. Results showed that, as the national average, the liquid water content (LWC) is most plentiful at lower layer and decreases with altitude, The average of LWC is less than0.35g/m3, and average effective radius of the liquid phase particles is about10μ m at all layers. The average ice water content (IWC) is less than0.1g/m3.The IWC in stratiform clouds increases with altitude, while which in convective cloud is first increases with altitude. The largest IWC in stratiform and convective clouds is at high level and near7km respectively. The average effective radius of the ice phase particles is between60-90u m. In different climatic zones of china, water content of convective cloud is always greater than stratiform cloud. LWC decreases from south to north, from the east to the west, while IWC reduces from west to east under6km height and reduces from south to north over6km height.(5) According to technology program of monitoring and evaluation of cloud and water resources, using the reanalysis data of NCEP, combining the observations of satellite and radar and ground precipitation data, we can calculate and assess the cloud and water resources of different cloud system, different times and range, and the main conclusion can be listed as follows:The daily calculated results of cloud and water resources over the year of China in2011show that, the total annual precipitation is about658trillion tons, the total inputting water vapor content is22.6trillion tons, the annual net inputting water vapor content is2.1trillion tons, the total inputting hydrometeors content is2trillion tons, and the annual net inputting hydrometeors content is200billion tons. The annual average value of update cycle of water vapor and hydrometeors were11days and15hours, and the annual average value of precipitation efficiency of water vapor and hydrometeors were18%and77%. Atmospheric water cycle has a significant seasonal and annual variation feature, owing to development and coverage’s diversity of cloud system in different season, the water vapor, hydrometeors and total ground precipitation are most abundant in summer and least in winter, the update cycle of water vapor and hydrometeors are shortest in summer and longest in winter, the precipitation efficiency of water vapor and hydrometeors are highest in summer and lowest in winter. The efficiency of water material recycling and conversion in spring and autumn is between summer and winter. The evaluation result varies in different precipitation days. The assessment result of cloud water resources is closely related to research area and period, when research period is very short, the initial stock of water material take up a larger proportion in total content of water material; when research period is very long just like the whole year, the advection of water material is particularly important and instantaneous stock has little effect on the results. With regard to local convective precipitation process, it has fast updating velocity of water material and high precipitation efficiency. The spatial and temporal scale has great impact on the accessing of atmospheric water balance and cloud water resource. The water substances initial and final value is small relative to the flux evaporation, condensation net amount and precipitation and can be ignored in long time assessing. The shorter research period, the greater the impact of the initial and final values of the water substance. The importance of hydrometeors flux compared with the net amount of condensation varies with different scales, meanwhile closely related to precipitation in research period.(6) WRF model simulation study of the precipitation process on April18,2009shows that, water vapor, hydrometeors and precipitation of this event are well simulated overall by the CAMS program. The simulated results are in good consistent to NCEP water vapor field, satellite retrieval optical thickness,the diagnostic field of cloud and surface precipitation observations, which reflect the development and evolution of the real cloud and precipitation. Diagnosis cloud and simulated cloud field always form nearby the weather system and develop and move with the weather systems. There’s more abundant of big particles like snowflake and graupel in cloud than little cloud particles and ice crystals. The atmospheric water balance, moisture budget and cloud water resource of this event can be analyzed later. |
PDF Full Text Request