Analysis And Evaluation Of Atmospheric Water Cycle Variables Based On Multi-type Data

The water cycle is the link between the earth and all kinds of water bodies.The atmospheric water cycle is the most important branch of it.The atmospheric water cycle are important modulators of climate and are involved in feedbacks that strongly affect global circulation and energy balance.And,it also significantly affect the radiation budget through their shortwave albedo and longwave greenhouse effects.The study of the atmospheric water cycle related variables could help us to know more about the weather changes and earth-atmosphere system,and predict the future climate.We will study the atmospheric water cycle related variables on multiple space-time scales.The main variables of atmospheric water cycle include water vapor and hydrometeors.For the water vapor,the atmospheric reanalysis datasets will be used to understand the variability of atmospheric water vapor on various temporal and spatial scales for climate change research.These results would help better understand the climatology difference among various reanalysis datasets better,and more properly choose water vapor datasets for different research requirements.For hydrometeors,we will focus on the study of typhoon hydrometeors in a relatively small space-time scales.The hydrometeors in storms are related with adiabatic heating and vertical velocity structure,and regarded as effective indicators of storm intensity.In numerical models,the variations of hydrometeors in storms are mainly modulated by some microphysics schemes.The evaluation of these microphysics schemes derived from different design ideas is important to improve cloud microphysics parameterizations,in turn is helpful to better understand thermodynamics process of tropical cyclones.Meanwhile,the verification whether the simulated cloud hydrometeors can realistically represent observed radiances,is important for the direct assimilation of satellite data(e.g.,radiances).In addition,proper microphysics schemes is beneficial to retrieving rainfall and latent heating profiles correctly from remote sensing observations.(1)A climatological comparison of column-integrated water vaporWater vapor is an important link in the study of climate change.The difference among a variety of reanalysis datasets,however,causes the uncertainty of climate change research.In this study,the climatology of atmospheric column-integrated water vapor was compared among three latest third-generation atmospheric reanalyses including European Centre for Medium-range Weather Forecasts Interim Reanalysis(ERA-Interim),Modern-Era Retrospective Analysis for Research and Applications(MERRA),and Climate Forecast System Reanalysis(CFSR),while possible explanation on the difference between them was given.The results show that there are significant differences among three datasets in the multi-year global distribution,variation of interannual cycle,long-term trend and so on,though high similarity for principal mode describing the variability of water vapor.Over oceans,the characteristics of long-term CWV variability are similar,whereas the main discrepancy among three datasets is located around the equatorial regions of the Intertropical Convergence Zone,theSouth Pacific Convergence Zone and warm cloud area,which is related with the difference between reanalysis models for the scheme of convective parameterization,the treatment of warm clouds,and the assimilation of satellite-based observations-Moreover,these CWV products are fairly consistent with observations(satellite-based retrievals)for oceans.On the other hand,there are systematic underestimations about 2.5 kg/m2 over lands for all three CWV datasets,compared with radiosonde observations.The difference between models to solve land-atmosphere interaction in complex environment,as well as the paucity in radiosonde observations,leads to significant water vapor gaps in the Amazon Basin of South America,central parts of Africa and some mountainous regions.(2)Evaluation of microphysics schemes to simulations of hydrometeors in typhoonThe impact of five cloud microphysics schemes(GSFC,WSM6,THOM,MORR and NSSL)in the ARW-WRF V3.6.1 model for a typhoon case of Neoguri(2014)over the North Western Pacific is analyzed and evaluated on hydrometeor distributions and on the structure and evolution of Neoguri.Statistical comparisons of modeled fields with observations collected from the MWRI and MWHS onboard the FY-3B satellite and JTWC are used to assess the importance of microphysical processes acting within the typhoon case of Neoguri.Firstly,the simulated track is not very sensitive to the microphysics schemes.Moreover,the comparison of modeling surface precipitation distributions with MRR exposes that simulations exhibit systematically wetter over the strong convective activity areas of inner rainband,whereas noticeably drier for the stratiform cloud rainband.The results also indicate that the peak intensity and surface precipitation extension of NSSL generally more closely matches observations.Simulated liquid hydrometer(cloud water and rain)show general similarities.However,frozen hydrometeor species(snow,graupel,cloud ice)demonstrate considerably larger variability amongst microphysics schemes.Then,hydrometeor simulations are used to calculate "modeling observations of microwave brightness temperature" based on a microwave radiative transfer model,in turn obtain two corresponding radiance indices of emission index(EI)and scattering index(SI)as the indicator of liquid and frozen hydrometeors,respectively.The horizontal distributions of these modeling radiance indices are statistically verified using the nonlinear LK-OF approach.The results show that both of simulated El and SI have significant intensity bias,especially in strong convective areas.And the simulated El are generally lower in the outer spiral rain bands and of greater magnitude in the near-core region,compared with the observed.For another,simulated SI errors are obviously negative over the eastern part of the typhoon,with a slightly positive bias in the outer cloud edge of western typhoon.In addition,similar displacement and angular errors(a systematic west-southwest bias of approximately about 10?20 km)of El or SI among five microphysical schemes might indicate a serious model systematic issue.Five microphysics schemes are evaluated in terms of the joint histogram of SI and El,to combine the information from frozen precipitation hydrometeors and liquid hydrometeors.Compared with radiance indices from MWRI observations,the NSSL results closer to the observations than the other schemes at the SI extension,for the entire typhoon life cycle,consistent with the less graupel.Moreover,the corresponding El of the large value areas(that is,the average EI)in all five schemes is appreciably lower than the observations of MWRI.Generally speaking,in the stronger stage of the typhoon life cycle(developing and mature stage),the joint histograms are more significant differences between the simulated and observed,while in the weaker stage of the typhoon life cycle(decaying and formation period),the simulated results are closer to the observed.The SI-EI joint histograms shows that NSSL reproduces a more realistic distribution compared to the observations than does the other four schemes.Moreover,Sensitivity tests are used to better interpret the differences and contributions shown in the relationship between SI and El for various hydrometeors among the five microphysical schemes.It shows that NSSL and TOMP have the graupe1 closer to the realistic value,while the graupel derived from the other three schemes are greatly exaggerated;there are exaggerated snow amount,in all five schemes;NSSL have the supercooled cloud water closer to the realistic value,while that from the other four schemes is understated.Furthermore,the distribution trends of simulated joint histograms incline to SI-axis,while the trends of observation results is inclined to EI-axis,probably because of the discrepancy in the spatial distribution,vertical distribution and matching proportion of frozen and liquid hydrometeors between the simulated and observed.Overall,the fully two-moment 4ICE scheme microphysics schemes,NSSL,offer more faithful representations of the complex microphysical processes in the ARW-WRF,for simulation of hydrometeors and evolution of Neoguri.