Study on Cloud-Radiation Effect on Climate in Eastern Asia

In this paper, the decade data of meteorological satellite and surface meteorological observation of China have been analysed. The relationship between cloud and radiation has been studied. A set of empirical formulae of the ralationships between the albedo and cloud amount, the outgoing longwave radiation and cloud amount in Chinese different districts and different seasons has been deduced. They express simply the response of both planet reflectivity and earth-atmosphere outgoing longwave radiation to the change of cloud amount. So that the sensitivity of net radiation of the earth-atmosphere system to the change of cloud amount and the ratio of cloud reflective effect to greenhouse effect can be estimated. In this paper, the radiative process of the earth-atmosphere system, cloud and radiative balance and its effect on climate have been synthetically studied.     

Man-Computer Interactive Method on Cloud Classification Based on Bispectral Satellite Imagery

Ｍａｎ－ＣｏｍｐｕｔｅｒＩｎｔｅｒａｃｔｉｖｅＭｅｔｈｏｄｏｎＣｌｏｕｄＣｌａｓｉｆｉｃａｔｉｏｎＢａｓｅｄｏｎＢｉｓｐｅｃｔｒａｌＳａｔｅｌｉｔｅＩｍａｇｅｒｙＹｕＦａｎ（郁凡），ＬｉｕＣｈａｎｇｓｈｅｎｇ（刘长盛）ＤｅｐａｒｔｍｅｎｔｏｆＡｔｍｏ...     

Study on the Trace Species in the Stratosphere and Their Impact on Climate

The trace gases （O3, HCl, CH4, H2O, NO, NO2） in the stratosphere play an important role, not only in the photochemical processes in which the ozone layer destroyed, but also in the radiative processes. In this paper, we review the works on the distribution and variation of the trace gases in the stratosphere and their impact on climate, which have been carried out at the University of Science and Technology of China in the recent 20 years. The Halogen Occultation Experiment （HALOE） data were used to analyse the distribution and variation of the mixing ratio of these trace gases and the temperature trends in the stratosphere in the most recent decade. And the reanalyzed National Centers of Environmental Prediction （NCEP）/NCAR data were also used to give the temperature trends and compared with the results from HALOE data. Numerical simulations were also carried out to study the impact of ozone depletion on the global climate. In this review, the distributions of the trace gases, especially those over the Qinghai-Xizang Plateau, are discussed, and the variations and trends for the trace gases in various levels in the stratosphere have been given for the most recent decade. The temperature variation and the cooling trend obtained from HALOE data in the middle and lower stratosphere for the last 13 years are significant, which agree well with the results from NCEP/NCAR data. While the temperature trend in the upper stratosphere in this period do not seem to have much cooling. The numerical simulations show that either the Antarctic ozone hole or the ozone valley over Qinghai-Xizang Plateau affect not only the temperature and circulation in the stratosphere, but also the temperature, pressure and wind fields in the troposphere, then lead to the global climate change.     

Numerical Study on a Severe Downburst-Producing Thunderstorm on 23 August 2001 in Beijing

A thunderstorm that produced severe wind, heavy rain and hail on 23 August 2001 in Beijing was studied by a three-dimensional cloud model including hail-bin microphysics. This model can provide important information for hail size at the surface, which is not available in hail parameterization cloud models. The results shows that the cloud model, using hail-bin microphysics, could reasonably reflect the storm＇s characteristics such as life cycle, rainfall distribution and the diameter of the hailstones and also can reproduce developing processes of downbursts, where they can then be compared with the observed features of the storm. The downburst formation mechanism was investigated based on the cloud microphysics of the simulated storm and it was found that the downburst was primarily produced by hail-loading and enhanced by cooling processes that were due to hail melting and rain evaporation. The loading and melting of hail played crucial roles in the formation of downbursts within the storm.     

A Statistical Analysis on the Effect of Vertical Wind Shear on Tropical Cyclone Development

Using tropical cyclone (TC) best track and intensity of the western North Pacific data from the Joint Typhoon Warning Center (JTWC) of the United States and the NCEP/NCAR reanalysis data for the period of 1992-2002, the effects of vertical wind shear on TC intensity are examined. The samples were limited to the westward or northwestward moving TCs between 5°N and 20°N in order to minimize thermodynamic effects. It is found that the effect of vertical wind shear between 200 and 500 hPa on TC intensity change is larger than that of the shear between 500 and 850 hPa, while similar to that of the shear between 200 and 850 hPa. Vertical wind shear may have a threshold value, which tends to decrease as TC intensifies. As the intensifying rate of TC weakens, the average shear increases. The large shear has the obvious trend of inhibiting TC development. The average shear of TC which can develop into typhoon (tropical depression or tropical storm) is below 7 m s-1 (above 8 m s-1).     

Implementation of the Semi-Lagrangian Advection Scheme on a Quasi-Uniform Overset Grid on a Sphere

The semi-Lagrangian advection scheme is implemented on a new quasi-uniform overset （Yin-Yang） grid on the sphere. The Yin-Yang grid is a newly developed grid system in spherical geometry with two perpendicularly-oriented latitude-longitude grid components （called Yin and Yang respectively） that overlapp each other, and this effectively avoids the coordinate singularity and the grid convergence near the poles. In this overset grid, the way of transferring data between the Yin and Yang components is the key to maintaining the accuracy and robustness in numerical solutions. A numerical interpolation for boundary data exchange, which maintains the accuracy of the original advection scheme and is computationally efficient, is given in this paper. A standard test of the solid-body advection proposed by Williamson is carried out on the Yin-Yang grid. Numerical results show that the quasi-uniform Yin-Yang grid can get around the problems near the poles, and the numerical accuracy in the original semi-Lagrangian scheme is effectively maintained in the Yin-Yang grid.     

A Diagnostic Study of the Impact of El Nion on the Precipitation in China

1.IntroductionEINifioisthemostoutstandinginterannualvariabilityintheocean.Itiswellknownthattheheatsourcedrivingtheatmosphericgeneralcirculationismainlywithinthetropics.EINinooccursinthetropicalPacificandthewarmingoftheoceanduringtheEINinocancoveralar...     

Analysis on Formation Mechanism of Rare ＇Thundersnow＇ Phenomenon in Shandong on 28 February 2010

利用各种常规观测资料、探空资料、T639模式资料和卫星云图,分析了2010年2月28日山东境内的一次罕见“雷打雪”过程。结果表明,此次过程是在有利的大尺度环流背景下产生的。西南暖湿气流强盛,对流层低层的低空急流不断向山东输送水汽和能量;同时,近低层冷空气的侵入,迫使暖湿空气沿冷空气爬升,触发不稳定能量释放,导致强对流天气发生。850hPa低涡及地面气旋的产生,使得气旋性辐合上升增强,加强了上升运动。随着近地层温度降到零度以下,雨转雪。降水过程后期,气旋向东北方向移动,造成鲁中和山东半岛的暴雪天气。卫星云图显示,MCC是造成此次强降水的直接原因。     

Numerical Study on the Impacts of Heterogeneous Reactions on Ozone Formation in the Beijing Urban Area

The air quality model CMAQ-MADRID （Community Multiscale Air Quality-Model of Aerosol Dynamics, Reaction, Ionization and Dissolution） was employed to simulate summer O3 formation in Beijing China, in order to explore the impacts of four heterogeneous reactions on O3 formation in an urban area. The results showed that the impacts were obvious and exhibited the characteristics of a typical response of a VOC-limited regime in the urban area. For the four heterogeneous reactions considered, the NO2 and HO2 heterogeneous reactions have the most severe impacts on O3 formation. During the O3 formation period, the NO2 heterogeneous reaction increased new radical creation by 30%, raising the atmospheric activity as more NO→NO2 conversion occurred, thus causing the O3 to rise. The increase of O3 peak concentration reached a maximum value of 67 ppb in the urban area. In the morning hours, high NO titration reduced the effect of the photolysis of HONO, which was produced heterogeneously at night in the surface layer. The NO2 heterogeneous reaction in the daytime is likely one of the major reasons causing the O3 increase in the Beijing urban area. The HO2 heterogeneous reaction accelerated radical termination, resulting in a decrease of the radical concentration by 44% at the most. O3 peak concentration decreased by a maximum amount of 24 ppb in the urban area. The simulation results were improved when the heterogeneous reactions were included, with the O3 and HONO model results close to the observations.     

Future impacts of environmental factors on achieving the SDG target on child mortality—A synergistic assessment

An estimated 26% of current global child deaths can be attributed to various and modifiable environmental factors, which are addressed under multiple Sustainable Development Goals (SDGs). This study assesses future reductions in child mortality in relation to the achievement of environment-related SDG targets. It uses projections of health risk factors from the IMAGE 3.0 Integrated Assessment Model, based on the Shared Socioeconomic Pathways (SSPs), linked to a standard multi-state health model (GISMO), distinguishing risk factors, disease occurrence and cause-specific death. The study concludes that, on a global level, the SDG target on child mortality will not be achieved in any of the three SSP scenarios analysed, mainly due to persistent high mortality rates in Sub-Saharan Africa and South Asia. By 2030, environmental health risk factors – including childhood undernutrition, no access to improved drinking water and sanitation, no access to modern fuels and exposure to malaria – will still be responsible for 14% to 16% of total global child deaths (8% to 10% when excluding nutrition-related mortality). Under the middle-of-the-road SSP2 baseline scenario, achievement of the SDG targets on hunger, drinking water and sanitation and modern energy services, would avoid 433 thousand child deaths by 2030. If, in addition, also higher standards would be achieved for access to water and energy, as well as universal secondary female education and advanced malaria control, a total of 733 thousand child deaths is projected to be avoided by 2030 (444 thousand child deaths, when excluding nutrition-related mortality), which would reduce projected global child mortality by 13%. Overall, more than 25% of the child mortality reduction that is needed to achieve the SDG target in Sub-Saharan Africa can be achieved through SDG-related policies on food, water and energy. This requires integrated and intersectoral approaches to environmental health.     

The Effect of Topography on Quasi-Geostrophic Frontogenesis

This paper improves Bannon's work on the quasi-geostrophic frontogenesis in a horizontal deformation field. By setting the lower boundary condition for the equation of potential temperature on the realistic topography instead of on z = 0, a general solution for the temperature field is derived after applying conformal mapping to the equation for the potential temperature, the vertical velocity and divergence field are also calculated. The general characteristics for the frontogenetic process still are frontolytic for warm front and frontogenetic for cold front in downstream of a mountain and the reverse is true upstream of a mountain, but more fine spatial structure of the temperature field and frontogenetic characteristics than Bannon's are obtained near surface because of the treatment of lower boundary condition. It is concluded that the frontogenetic characteristics are related to the translating speed of the deformation field with respect to the topography.     

A Study on Frontal Motion over Orography

肖庆农，伍荣生ＡＳｔｕｄｙｏｎＦｒｏｎｔａｌＭｏｔｉｏｎｏｖｅｒＯｒｏｇｒａｐｈｙ￥ＸｉａｏＱｉｎｇｎｏｎｓａｎｄＷｕＲｏｎｇｓｈｅｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＡｔｍｏｓｐｈｅｒｉｃＳｃｉｅｎｃｅｓ，ＮａｎｊｉｎｇＵｎｉｖｅｒｓｉｔｙ，Ｎａｍｉｎｇ...     

Effect of Initial Vortex Intensity Correction on Tropical Cyclone Intensity Prediction:A Study Based on GRAPES_TYM

Predicting the intensity of tropical cyclones(TCs)is challenging in operational weather prediction systems,partly due to the difficulty in defining the initial vortex.In an attempt to solve this problem,this study investigated the effect of initial vortex intensity correction on the prediction of the intensity of TCs by the operational numerical prediction system GRAPES_TYM(Global and Regional Assimilation and Prediction System_Typhoon Model)of the National Meteorological Center of the China Meteorological Administration.The statistical results based on experiments using data for major TCs in 2018 show that initial vortex intensity correction can reduce the errors in mean intensity for up to 120-h integration,with a noticeable decrease in the negative bias of intensity and a slight increase in the mean track error.The correction leads to an increase in the correlation coefficient of Vmax(maximum wind speed at 10-m height)for the severe typhoon and super typhoon stages.Analyses of the errors in intensity at different stages of intensity(including tropical storms,severe tropical storms,typhoons,severe typhoons,and super typhoons)show that vortex intensity correction has a remarkable positive influence on the prediction of super typhoons from 0 to 120h.Analyses of the errors in intensity for TCs with different initial intensities indicate that initial vortex correction can significantly improve the prediction of intensity from 24 to 96 h for weak TCs(including tropical storms and severe tropical storms at the initial time)and up to 24 h for strong TCs(including severe typhoons and super typhoons at the initial time).The effect of the initial vortex intensity correction is more important for developing TCs than for weakening TCs.     

Influence of Advection on Marine PBL Development

Based on the DRS model (one coupled dynamical-radiational model of stratocumulus), though extended to take advection into account, several calculations have been made to estimate its contributions to the thermodynamical structure of the PBL (planetary boundary layer). Advection various calculations show does affect the development of :he PBL, particularly in cloud forming and evolving. One of the intriguing findings which accords well with observations demonstrates that cold currents create strong convective weather, while warm currents bring about stable weather: produce prolonged low clouds or fogs.     

Advances in Studies on Nonlinear Atmospheric Waves

A review on the progress in the research of nonlinear atmospheric waves, especially the nonlinear Rossby waves is made in this paper. Many results reported here have been obtained in Peking University.     

Preliminary Study on Vertical Velocity Caused by Katabatic Wind in Antarctica and Its Influence on Atmospheric Circulation

The vertical velocity at the top of Ekman layer caused by katabatic winds is proposed and deduced. By computing actual data we get a distribution of the velocities over Antarctica. The distribution plays a positive role in maintaining the cyclone and anticyclone over Antarctica.     

A Numerical Research on the Influences of the Diurnal Variation of Solar Radiation on the Medium-Range Weather Processes

In this paper, we use a spectral model for the medium-range numerical weather forecast to discuss the impact of the diurnal variation of solar radiation on the medium-range weather processes. Under the tests of two typical winter and summer cases, we find that the influences of the diurnal variation of solar radiation on summer weather are really important, especially on its rainfall, surface heat transport and 500 hPa height field. On winter weather, however, the influences are very weak.     

Comparative Experiments on the Effect of Radar Data Assimilation and Increasing Horizontal Resolution on Short-term Numerical Weather Prediction

To examine the effect of radar data assimilation and increasing horizontal resolution on the short-term numerical weather prediction, comparative numerical experiments are conducted for a Huabei (North China) torrential rainfall event by using the Advanced Regional Prediction System (ARPS) and ARPS Data Analysis System (ADAS). The experiments use five different horizontal grid spacings, i.e., 18, 15, 9, 6, and 3 km,respectively, under the two different types of analyses: one with radar data, the other without. Results show that, when radar data are not used in the analysis (i.e., only using the conventional observation data), increasing horizontal resolution can improve the short-term prediction of 6 h with better representation of the frontal structure and higher scores of the rainfall prediction, particularly for heavy rain situations. When radar data are assimilated, it significantly improves the rainfall prediction for the first 6 h, especially the locality and intensity of precipitation. Moreover, using radar data in the analysis is more effective in improving the short-term prediction than increasing horizontal resolution of the model alone, which is demonstrated by the fact that by using radar data in the analysis and a coarser resolution of the 18-km grid spacing, the predicted results are as good as that by using a higher resolution of the 3-km grid spacing without radar data. Further study of the results under the radar data assimilation with grid spacing of 18-3 km reveals that the rainfall prediction is more sensitive to the grid spacing in heavy rain situations (more than 40 mm) than in ordinary rain situations (less than 40 mm). When the horizontal grid spacing reduces from 6 to 3 km, there is no obvious improvement to the prediction results. This suggests that there is a limit to how far increasing horizontal resolution can do for the improvement of the prediction. Therefore, an effective approach to improve the short-term numerical prediction is to combine the radar data assimilation with an optimal horizontal resolution.     

Effect of The Atmosphere on UVB Radiation Reaching The Earth’s Surface:Dependence on Solar Zenith Angle

The atmosphere protects humans,plants,animals,and microorganisms from damaging doses of ultraviolet-B(UVB) solar radiation(280-320 nm) because it modifies the UVB reaching the Earth’s surface.This modification is a function of the solar radiation’s path length through the atmosphere and the amount of each attenuator along the path length.The path length is determined by solar zenith angle(SZA).The present work explains the dependence of hemispherical transmittance of UVB on SZA.The database used consists of five years of hourly UVB and global solar radiation measurements.From 2001 to 2005,the South Valley University(SVU) meteorological research station(26.20°N,32.75°E) carried out these measurements on a horizontal surface.In addition,the corresponding extraterrestrial UVB(UVBext) and broadband solar radiation(Gext) were estimated.Consequently,the hemispherical transmittance of UVB(KtUVB) and the hemispherical transmittance of global solar radiation(Kt) were estimated.Furthermore,the UVB redaction due to the atmosphere was evaluated.An analysis of the dependence between KtUVB and SZA at different ranges of Kt was performed.A functional dependence between KtUVB and SZA(KtUVB=-a(SZA)+b) for very narrow Kt-ranges(width of ranges was 0.01) was developed.The results are discussed,and the sensitivity of △KtUVB to △SZA for very narrow Kt-ranges was studied.It was found that the sensitivity of △KtUVB to △SZA slightly increases with increased Kt,which means KtUVB is sensitive to SZA as Kt increases.The maximum correlation(R) between KtUVB and SZA was equal to-0.83 for Kt= 0.76.