Current Issue

• The A1B Scenario Projection for Climate Change overthe Tibetan Plateau in the Next 30~50 Years
• 2009 Vol. 28 (3): 475-484. 
• Abstract ( ) PDF (3816KB) ( )
• Based on the ensemble average of outputs under the mid-range emission (A1B) scenario from 20 climate models used by the Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC-AR4), and dynamically downscaling results driven by modeling outputs from a global climate model, climate change over the Tibetan Plateau in the next 30~50 years has been studied. The results show that annual-mean surface air temperature would rise by 1.4~2.2℃ averaged for 2030~2049 in most portionsof the Plateau with respect to that for 1980-1999. Climatic warming is more prominent in higher-elevation regions and in colder seasons. For example, the temperature would increase up to 2.4℃or morein Xizang autonomous regionin winter. The change in precipitation would be relatively small and generally below 5%, though the precipitation likely increases in main parts of the Plateau and in most seasons. Considering of various uncertainties in future emission of atmospheric greenhouse gases, skill of multi-model ensemble projection and regional-scale modeling, timing reexamination and correction will be needed when the above projections turn to practical applications.

• Numerical Simulation of Snowfall in Winter of Qilian Mountains.Part (I): Snowfall Process and Orographic Influence
• 2009 Vol. 28 (3): 485-495. 
• Abstract ( ) PDF (8370KB) ( )
• A case of snowfall in Qilian Mountains during 7~8 February 2006 is simulated using the mesoscale model MM5V3. The simulated snow band is basically consistent with observation. The dynamical and thermal conditions and microphysical characteristics of the snowfall are mainly discussed. The orographic influence of Qilian Mountains is also investigated through sensitivity tests. Results show that there is a south\|west cold moist flow in front of the mountainin low levels. The flow is separated into two parts, one is aroundthe mountain, the other flow up along the northern slope of the mountain. During the early stage of the snowfall, the thick saturated layer and strong updraft provide beneficial conditions to snowfall. Afterwards the dry and cold downdraft invades from the high levels which weakened the snowfall. This snowfall process is of cold and stable stratiform characteristics. The maximum hydrometers distributed on the northern slope and mountain top. Ice and snow is below 6 km. There is 0.06 g·kg-1 supercooled water at the cloud top. Qilian Mountains influent directly on formation of the snowfall center at the northern slope of the mountain. If the height of the mountainis lowered down, there are no updraft and cloud particles at mountain top, and cloud at the northern slope is weakened. High mountains increase the snowfall at the northern slope with 3 mm in 24 h.

• Numerical Simulation of Snowfall in Winter of Qilian Mountains.Part (II): Seeding Test
• 2009 Vol. 28 (3): 496-506. 
• Abstract ( ) PDF (8004KB) ( )
• A snowfall process in Qilian mountains during 7~8 February 2006 is simulated using the mesoscale model MM5V3. Seeding tests are made in order to study the effects of adding artificial ice particlesto the snowfall. Tests of different seeding amounts and seeding heights are conducted. The changes of the microphysical processes and thermal and dynamical processes are analyzed. Results show: The seeding area is in the upwind of snowfall center with the supercooled water. After seeding, the precipitation increases at snowfall center and decreases aroundthe center. It is to increase more snowfall if seeding in the levels of more supercooled water and less ice particles. The vapour and supercooled water are depleted to increase ice and snow. The collection of ice by snow, the conversion of ice to snow and the deposition of snow are the main sources of snow. The changes of microphysical phases release more latent heat which results in warming the atmosphere andstrengthening the updraft. At the same time these changes affect the vertical velocity and hydrometers surrounding the snowfall center. The updraft become weaker and snow become less which produces the decrease snowfall area.

• Dry Intrusion Index and Its Physical Interpretation
• 2009 Vol. 28 (3): 507-515. 
• Abstract ( ) PDF (9164KB) ( )
• Based onthe characteristics, mechanisms and impacts of the dry intrusion, a dry intrusion index (DII) is defined to characterize the dry intrusionintensity and its physical interpretation is explored by a case study as well. It is found that DIIis related to the horizontal temperature advection， the potential vorticity and pseudo\|equivalent potential temperature. The positive DII indicates that there exists the dry intrusionprocess. And the greater the positive DIIis, the stronger the dry intrusion exists. Thus, this situation maybe correspond to stronger potential vorticity anomaly, the lower wet\|bulb temperature or stronger cold horizontal temperature advection. There exists agood agreement between the positive DIIarea at the 345K isentropic surface and the dry intrusion illustrated by \!dark zone\" from the water vapor cloud images. The three dimension structure of DII is characterized by a wave disturbance from the upper troposphere to the lower one. The positive DII area originates from the mid\|high latitude to the northwest of the low vortex on a certain isentropic surface. DII contains the horizontal temperature advection effect. The cold temperature advection locates to the west of the low vortex while the warm temperature advection locates to the east of the low vortex. The cold temperature advection led by the northwesterlies descends along the isentropic surface. The formation and enhancement of the heavy rainfall situates the area of the maximum gradient of the horizontal temperature advection while the cold temperature advection meets with the warm temperature advection. DII can be used to identify the area, the process and the intensity of the dry intrusion in the field of weather forecast operationwhich processes the application value in practically.

• Radiation Character of Mt. Qomolangma Area duringLate Spring to Early Summer in 2007
• 2009 Vol. 28 (3): 516-522. 
• Abstract ( ) PDF (2859KB) ( )
• Based on the observation data and other correlative data during May 23~June 22 2007， the global solar radiation, atmospheric counter radiation, surface upward longwave radiations, net radiation and surface albedo are analyzed. The results are as follows: Global solar radiation exceeded the solar constant are quite frequent, even its hourly average one can also exceeded the solar constant;because of high elevation, thin atmosphere, low temperature and low humidity in Mt. Qomolangma region, atmospheric counter radiation significantly reduced; surface longwave radiation not only lower than the plain areas, but also lower than other parts of the Qinghai\|Tibet Plateau; in the course of surface radiation, surface effective radiation exceeded refected radiation at Mt Qomolangma base camp; as the altitude increases, time of positive net radiation persisting shortened and the maximum reduced accordingly.

• Land Surface Temperature Retrieved from MODISData in Jinta Oasis Area
• 2009 Vol. 28 (3): 523-529. 
• Abstract ( ) PDF (1715KB) ( )
• Land surface temperature (LST) is an important parameter in meteorology, hydrology, ecology and etc.In this paper, the splits window algorithmis recommended to retrieve the important parameter like atmospheric transmittance and surface emissivity using MODIS data, and then the land surface temperature is evaluated using the algorithm. Comparison between the surface measured and retrieved data showed that using the splits window algorithm method can obtain the reasonable land surface temperature, practically according with thesurface status.

• Study on Water Deficit of the Topsoil over theChinese Loess Plateau Mesa Region
• 2009 Vol. 28 (3): 530-538. 
• Abstract ( ) PDF (3046KB) ( )
• Water deficit of the terrestrial topsoil is directly linked to the local climate variation. In this paper, the evapotranspiration and water deficit of the topsoil over different underlying surfaces were evaluated by the data collected during the LOess Plateau land surface process field EXperiment(LOPEX), LOPEX05 and LOPEX06, which were conducted in the Chinese Loess Plateau Mesa Region. The maximal amount of evapotranspiration caused by canopy was about 0.05 mm·h-1 at noon under the moderate soil water condition, whears the evapotranspiration could reach 4.60 mm·d-1 in the first cloud\|free day after a rainfall event over the winter wheat field, and it was 3.70 mm·d-1 over bare soil land. Analyzed results indicate that the local precipitation was the main cause of evapotranspiration variation, whears canopy could enlarge the evapotranspiration. From the last\|ten days of April to middle\|ten days of July in 2006, the water deficit of topsoil were 39.9 mm·m-2 in winter wheat field and 17.9 mm·m-2 and 25.3 mm·m-2 in bare soil land. The most serve soil water deficit period was from the last\|ten days of May to the first\|ten days of June, the maximum of ten days′ could reach 16.50 mm·m-2. Due to the coming of raining season, the soil water began to be surplus in the first and middle\|ten days of July. From the middle\|ten days of July to the last ten\|days of August in 2005, water surplus of topsoil was 17.90 mm·m-2 in underlying surface with corn and 25.30 mm·m-2 over bare soil land. Statistical results at the different time scales indicate that the precipitation were main impact factor to evapotranspiration and determinant factor for water deficit of the terrestrial topsoil in Loess Plateau land mesa region.

• Study on the Relationship between South Asia High andRainfall of Sichuan-Chongqing Regions in Summer
• 2009 Vol. 28 (3): 539-548. 
• Abstract ( ) PDF (8018KB) ( )
• Using the rainfall data of Sichuan\|Chongqing regions at 160 stations of China and NCEP/NCAR data, the relationships between South Asia High and rainfall of Sichuan\|Chongqing regions in July and August have been analysed. The results show that both had coincident periods, such as approximate 5\|year time scales, approximate 10\|year time scales. At approximate 5\|year time scales, both the moving eastward of ridge line of SAHand variations of east basin of Sichuan\|Chongqing had opposite phases, SAH and rainfall of west basin had coincident phases before the middle of 1990, after lately 1990, theirphases werecoincident. However, both SAH and rainfall of plateau of Sichuan had inconspicuous phases, at inter\|decadal time scales, three regions of Sichuan\|Chongqing andmoving eastward of ridge line of SAHhad coincident phases, it was meaning that while SAH displayed East deviations, the trend about rainfall of Sichuan\|Chongqing regions became increasing. Meanwhile, rainfall variations of Sichuan\|Chongqing regions had dramatic relationshipswith wind fields of SAH on 100 hPa, wind fields of Sichuan\|Chongqing regions on 500 hPa and 700 hPa. In flood of east basin and drought of westbasinyear, the 16800 gpm line of SAH appeared the boundary position nearly of Sichuan and Chongqing. In flood of westbasin and drought of east basinyear, the 16800 gpm line of SAH appeared west region nearly of Hubei province. Therefore, the 16800 gpm line had well indicative meanings for rainfall of Sichuan\|Chongqingregions when it librated in Sichuan province and Chongqing.

• The Observational Analysis of Shear Line and Low Vortexover the Tibetan Plateau in Summer from 2000 to 2007
• 2009 Vol. 28 (3): 549-555. 
• Abstract ( ) PDF (1953KB) ( )
• Using the radiosonde data on500 hPa level at 08:00 and 20:00 in2000\_2007, the ground station observed rainfall data and TRMM satellite data, the shear line and low vortex over the Tibetan Plateau are investigated and analyzed. Some new understandings of the shear line and Plateau vortex activities were obtained. (1) The shear line is more active than the Plateau vortex over the Tibetan Plateau. (2) The most often appearance month of shear line and Plateau vortex are in June; the least, in September in the 8 years. And 2002 years is the more active year; 2006 years, less active year with two low weather systems only. Furthermore, the persistent high temperature and drought in Sichuan\|Chongqing in 2006 maybe has something with the less active low weather systems over the Plateau. (3) The shear line and Plateau vortex generation region indicates they are mainly appeared in high altitude and steep areas, which means the steep topography and Plateau heating are possibly one of the causes of the generation of the shear line and Plateau vortex. (4) The shear line and Plateau vortex are not easily moved out of the Plateau. When the Plateau vortex moved out of the Plateau, it is often moving eastward along the shear line. (5) The Plateau vortex and the Plateau shear line often appears concurrently or one after another, they have largely weather influence on the Plateau and on the east of the Plateau.

• Low Frequency Oscillation Characteristics of the SurfaceHeat Fluxes in Western Tibetan Plateau
• 2009 Vol. 28 (3): 556-563. 
• Abstract ( ) PDF (4904KB) ( )
• Based on the continuous observational gradient data of the surface layer obtained from automatic weather station (AWS) in Gaize of the western Tibetan Plateau from September 1997 to October 1998, the surface sensible heat flux, the latent heat flux of evaporation and the heat source intensity are calculated. The stress of this paper focuses on analyzing the periodic oscillation characteristic of the surface heat fluxes, precipitation, soil moisture and soil heat fluxby Marr wavelet transform. The result shows that the surface sensible heat flux have taken on the feature of 30~60 d low frequency oscillations obviously, and quasi\|8 d medium frequency oscillations exist in summer; the latent heat flux of evaporation and the precipitation is based on the principle of bi\|week oscillation. The remarkable feature of the soil heat flux is 30~50 d low frequency oscillations, and quasi\|8 d medium frequency oscillations exist in summer. The soil moisture shows 30~50 d low frequency oscillations in winter and 20~30 d low frequency oscillations in summer.

• Relationships between Rainfall Anomalies in XinjiangSummer and Indian Rainfall
• 2009 Vol. 28 (3): 564-572. 
• Abstract ( ) PDF (5515KB) ( )
• The relationships between the summer rainfall in Xinjiang and Indian rainfall as well as and possible physics mechanism of their relationships are investigated using the monthly rainfall data of India monsoon areas and 75 stations in Xinjiang and NCEP/NCAR reanalysis datasetfrom June to August 1960\_2003. It is found that there is remarkably negative correlation between summer rainfallin Xinjiang and Indian rainfall which the linear correlation coefficient is -0.39.There is prominent positive correlation between Indian rainfall andtroposphere temperatureover west Asia\|middle Asia area which is to the northwest of coagulatelatent heat released by India rainfall, as a result, the center of South Asia high (SAH) is favorablefor moving westward (eastward) to Iran Plateau (Tibetan Plateau), the west SAH and west Asia westerly jet stream (WAWJS) strengthens (weakens). At the same time, heating atmosphere inducing by strong coagulatelatent heat brings about Iran high northward and eastward at 500 hPa to extend over Xinjiang, so that it is favorable for less rainfall in Xinjiang. By contrast, cooling atmosphere causing by weakcoagulatelatent heat induces Iran high southward and westward resulting in the middle Asia low system activity to impress Xinjiang; consequentlythere is prominent positive correlation between Indian rainfall and summer rainfall in Xinjiang. Further, Eliasson\|Palm flux diagnoses confirmthat waves activity flux propagation entering into WAWJS along west side of SAH from low latitude to middle latitude is stronger (weaker) than normal while Indian rainfall is more (less) than climatic average resulting in strengthened (weakened) WAWJS.

• Extreme Precipitation Experimentation over EasternChina Based on Generalized Pareto Distribution
• 2009 Vol. 28 (3): 573-580. 
• Abstract ( ) PDF (3822KB) ( )
• The Generalized Pareto Distribution (GPD) is introduced to simulate the daily extreme precipitation at 78 stations over Eastern China from May to September. The results indicate that the probability distribution of the daily extreme precipitation is subjected to GPD under the different threshold, and GPD is superior to other extreme value distributions such as Generalized Extreme Value Distribution (GEV). According to the observed climatic conditions from 1951\_2000, the 50\|year and 100\|year return values of annual extreme precipitation are calculated, respectively and the space distribution features are analyzed. They are in substantial agreement which in general present downtrend from southeast to northwest, while there are obvious differences between south and north and the return valuesin the former area may reach more than twice compared to the latter one. In addition, the larger size of observed time series is, the better of the fitting is.

• A Projecting Test of Lanzhou Ground Temperature(GT) andPrecipitation Data to "Rule of More Rain in Positive GTand Less Rain in Negative GT"
• 2009 Vol. 28 (3): 581-585. 
• Abstract ( ) PDF (823KB) ( )
• For the seasonally and monthly precipitation prediction test of \!rule of more rain in positive GT and less rain in negative GT\" ground temperature and rainfall data of Lanzhou in 1954\_2006, we discuss about the impact degree of earthquake and surface ground temperature on the seasonal and monthly rainfall projecting. The same symbol ratio of the rainfall prediction of summer and autumn using spring and summer data reach to 62.5%, this result can preliminarily be applied to prediction operation, but for monthly prediction had no such performence moreover, the result is not good after correction by ground temperature. The ratio of 3.2 m inter\|monthly variable temperature corresponding less rainfall in next month is 72% without the strong earthquake quiet month, this can be used to less rainfall climate prediction. Strong earthquakes of Ms≥6 are intensive stimulating facters of pluvial period in Lanzhou. Spatial representative of monthly precipitation data in Lanzhou is not very high, an average of the relative radius of 0.01 reliability is only about 170 km.

• Study on Statistical Power of Artificial PrecipitationExperimental Area in Liaoning
• 2009 Vol. 28 (3): 586-593. 
• Abstract ( ) PDF (2067KB) ( )
• This paper analyses the statistical power of Liaoning artificial precipitation experimental area by re\|randomization method, and finds most suitable evaluation method and sample size through comparison between Cluster\|Analysis\|based Floating Control historical regression evaluation method (CA\|FCM) and the other evaluation methods. The result indicates that the target control randomized evaluation method and historical regression randomized evaluation method need 400 experimental samples in order to detect 10% cloud seeding effect with 80% statistical power at 0.05 significant level, however cross\|over randomized evaluation method, multi\|area double radio regression evaluation method and CA\|FCM only need 250 experimental samples. To the same cloud seeding effects and sample size, CA\|FCM has greatest statistical power and best evaluation effect.

• Applicability Evaluation of Surface Air Temperaturefrom Several Reanalysis Datasets in China
• 2009 Vol. 28 (3): 594-606. 
• Abstract ( ) PDF (11592KB) ( )

• Applicability of2 m temperature from the ERA\|40, NCEP/NCAR, NCEP/DOE and JRA\|25 reanalysis areevaluated according to climate mean, interannual variation and variability, and climate trends, respectively in different regions, different periods and seasons using the stationobservations in China.The results indicate that these reanalyzed products all can be employed to study the climate change in most of regions of China to a certain extent, but they display a better applicability after 1979. The quality displayed by them is usuallyis better in winter than in summer， and more reliable in east area  of China than in west area. The ERA\|40 and the JRA\|25 reanalyzed productscomparativelyshow betterapplicabilitythan the NCEP/NCAR and the NCEP/DOE counterparts. The JRA\|25 can better to represent the observed climate mean, interannual variation and variabilitythan other reanalyzed products, but the ERA\|40 is more superior tothe NCEP/NCAR to represent the long\|term trends of climate change.

• Attenuation Correction of Radar Differential Reflectivityfor X\|Band Dual Polarization Radar
• 2009 Vol. 28 (3): 607-616. 
• Abstract ( ) PDF (9169KB) ( )
• Two channels reflectivity and phase can be acquired by dual polarization radar which can transmithorizontal and vertical polarized electromagnetic waves simultaneously. The physical basis of using polarization radar is that the precipitation particles always exhibit oblate ellipse shape duringfalling. The ratio of major and minor axis of precipitation particle is related with the volume at balance. Differential reflectivity is the measurement of physical essenceof ellipticity of the particle. Unfortunately, differences between horizontal and vertical lead to attenuation difference along the two directions, resulting in the attenuated differential reflectivity can not reflect particle ellipticity any more, so it is absolutely necessary to do attenuation correction. On the basis of actual radar reflectivity data, the paper uses the relationship between reflectivity and differential reflectivity, by statistical fitting method and taking into account the detecting elevation angle effects on differentialreflectivity, the relationship between differential attenuation and propagationphase is determined. Thus the difference between before and after correction of two relatively homogeneous rain areas in stratiformprecipitation is compared. Results show that Radar RHI and PPI images are significantly changed after correction, and the relationship between corrected differential reflectivity and reflectivity is improved, which indicates the feasibilityand practicability of this method. The method can statistically determine correction parameters, and can be used flexibly according to different radar, location and weather, since it is based on the constraint relationship of its own actual radar data, thus it can avoid that changing quantities such as temperature exert an influence oncorrection parameters.

• Characteristic Analysis and Early\|Warning of Tornado Supercell Storm
• 2009 Vol. 28 (3): 617-625. 
• Abstract ( ) PDF (7805KB) ( )
• Usingthe Doppler radar data, three severe tornado processes occurred inAnhui were analyzed.The characteristics of Doppler base reflectivity in these F2~F3 tornados caused by supercell stormand the difference between tornado and hail supercellstormswere mainly studied. In addition, the meteorologicdata of 80 observations in Anhuiand the disaster dataof climate evaluation in past years, partlyfrom the disaster reportsof civil administration, were used. Based on these data, not only the space\|time distributions and its variation trendof tornado processes, but alsothe circulation situationforming tornados from1960 up to nowwere researched. Theresults show that: (1) Tornados mainly occurred in plain places from east of Huaibei to east of Jianghuai region. The highest probabilityof tornados taking place were in July. (2) The supercell tornado occurred under the conditionof middleCAPE and severe vertical wind shear. Atthe same time its lifting condensation levelwas lower. (3) The three F2~F3 tornados all detected evere meso\|cyclone and TVS（Tornadic Vortex Signature）at radar before and during occurrence.Comparing with non\|tornado supercellstorm, the bottom height of meso\|cyclonecausing severe tornados were obvious lower, mostly lower than 1 km. Atthe same timethe storm structure also had difference. The maximum reflectivityof supercell storm causing tornado is near to storm centroidat height, basicallyat 3 km or so, and the reflectivity was within 50~60 dBz. But for severe hail supercell storm, themaximum reflectivitywas higher than the storm centroidat heightbefore the storm disaster. When hailing, the height of maximum reflectivity became lower, but the height of storm centroidhad no change which was higher than the maximum reflectivity, keeping at 5 km or so and the reflectivity within60~70 dBz.

• Analysis on Torrential Rain Caused by "Bilis" and "Sepat"in South-East of Hunan Using Doppler Radar Data
• 2009 Vol. 28 (3): 626-633. 
• Abstract ( ) PDF (7741KB) ( )
• Using the Doppler radar data in Shaoguan, Guangdong Province and other conventional meteorological data, the mesoscale system features of torrential rain in southeast of Hunan Province caused by strong tropical cyclone \!Bilis\" and super\|typhoon \!Sepat\" were analyzed. Results show that, there are easterly system events with significant topography effect; the helix band echoes and merging echoes are the main stages of heavy rainfall with the warm and low centroid and high efficiency of precipitation features. The \!train effect\" is the key of the events, but the ways of formation are different: that of \!Bilis\" is caused by the band echo while for \!Sepat\" mainly by the locally intensified echo. The echo intensity and echo top of \!Bilis\" are higher than those of \!Sepat\". The echo of \!Bilis\" is similar to that of westerly cold shear rainstorm with strong convection, small scope but great intensity of precipitation. The echo of \!Sepat\" is homogeneous, long lasting, which is similar to that of westerly warm shear rainstorm with slow speed and high accumulated precipitation. Warm advection superposed on convergence wind fields led the favorable environment for heavy precipitation in two cases. The well organized secondary circulation caused by discontinuous mesoscale jet\|core at the medium level of troposphere may be the main reason to form and sustain the train effect. At the low level, the spectral width is quite high and at the medium level it is very homogeneous. This indicates that violent turbulence at low altitude because of the surface friction, which helps the low pressure center weaken from the low level. The stable and strong jet at medium altitude sustained the cyclone and caused the lasting precipitation.

• Temporal and Spatial Distributions of Storms over the Bayof Bengal and Its Activity Characteristic
• 2009 Vol. 28 (3): 634-641. 
• Abstract ( ) PDF (3467KB) ( )
• By statistically analyzingthe storm data from JTWC over the Bay of Bengal during the period 1945\_2006, it is found that theyearly averaged TC numbers over the Bay of Bengal is 8.12, which takes place in each month of the whole year, and TC numbers in February and March are the lease. The TC numbers begin to increase from April and arrive at peak value in October. Differing from TC over the Bay of Bengal, the TS over the area has two peak values. They respectively appear in May and in September or October. In the aspect of TS intensity, the super severe storm of H4 criterion appeared only one time during the period 1971\_1986, but appeared eight times during the period 1987\_2006. The monthly change of the original position, the averaged maintaining time and the longest maintaining time of the TS also have two peak values. The two peak values respectively appear in April or May and in October or November. The peak value of the original positionin October or November is bigger than in April or May. The peak value of the averaged maintaining time and the longest maintaining time of the TSin April or May is bigger than in October or November.TC landfalling path is mostly the northwest\|or west\|toward and accounts for 56.7%. The landfalling path of the TS differs from TC in some aspect. The main difference is that the numbers of the northwest path and un\|landfalling of TS are less than TC and the numbers of the west path and northeast path of TS are more than TC. Because of the landfalling TS in the north\|east has a peak, itand the beginning of the rainy season in Yunnan Provinceare closely related, and it on Yunnan Province early summer precipitationhas a greater impact.

• Characteristic of Long Wave Radiation over theTaklimakan Desert Hinterland
• 2009 Vol. 28 (3): 642-646. 
• Abstract ( ) PDF (1527KB) ( )
• Based on the long wave radiation data of Tazhong measured by atmosphere environment observation station， the characteristics of long wave radiation are analyzed in drift desert. The result shows that long wave radiation could concretely reflect the condition of heat energy loss of the surface. In desert， because of the strong turbulent flow and high temperature difference between underling and air temperature， it makes the heat flux is stronger transferring from surface to atmosphere， so the value of long wave radiation is larger, sometimes it is close to global radiation， which minimum value appears before sunrise， maximum appears at 15:00. In desert， it is due to the less water vapor in air， less cloud amount, but with more aerosol， the atmospheric long wave radiation is large too. Therefore， the effective radiation is larger， that which makes Taklimakan desert become one of the most larger regions of annual total of the effective in our country. The rate of net long wave radiation in total radiation is less than the surface reflective radiation， they are closed only in the summer， conversely the surface reflection radiation is greater. In the regional climate change process， the intensity of desert heating is one of the local desert climate change.

• Effect of the Cloud-Top Height on Back-Scattered UltravioletRadiation Measuring Total Ozone
• 2009 Vol. 28 (3): 647-651. 
• Abstract ( ) PDF (1425KB) ( )
• Cloud\|top height is one of the most importantparameters in the retrieval algorithm by back\|scattered ultraviolet radiation measuring total ozone. On the basis of model simulating calculation the paper studies and discusses retrieval errors of total ozone due to cloud\|top\|height\|induced errors. The errors are radiation interpolation error, retrieval error above and below cloud, respectively. Comparing with radiation interpolation error, the later two errors are larger and they couldn′t cancel each other, which will induce larger errors. When the assumed cloud\|top\|height is lower than the actual one, the retrieval value of total ozone is lower than the true one, when the assumed cloud\|top\|height is higher than the actual one, the retrieval value of total ozone is higher than the true one. On the basis of the assumed conditions in the paper, the error of total ozone retrieved is distributed between 10%～-20％. Furthermore, EPTOMS(Earth Probe Total Ozone Mapping Spectrometer)measurement data in low latitude field on 30thJuly 2003 is retrieved and the results obtained are consistent to the results of model simulating calculation.

• Characteristics of Meteorological Elements in the Surface Layerbefore and after a Severe Sandstorm in the TaklimakanDesert Hinterland, Southern Xinjiang, China
• 2009 Vol. 28 (3): 652-662. 
• Abstract ( ) PDF (3424KB) ( )
• Utilizing the observed data from the surface station and the 80 m high tower of the Tazhong Meteorological Observatory in the center of the Taklimakan Desert, we analyzed the characteristics of meteorological elements of the near surface layer over a five\|day periods before and after a severe sandstorm. The powerful sandstorm started at around the midnight of April 10, 2006, and nearly lasted for over 24 hours. The data show that this sandstorm was a consequence of a rigorous thermal depression, a continuous increase in air temperature, and an eastward cold air mass invasion in the southern Xinjiang. On the storm day, the temperature and humidity profiles of the near surface layer were basically static; the specific humidity was inversely correlated with wind speed. Over the life\|span of the sandstorm, temperature decreased and humidity increased across the surface layer. The sandstorm\|day atmospheric stratification and the temperature and humidity inversion structures of the surface layer were substantially different from that before and after the storm. The wind velocity increased with the logarithm of altitude on the sandstorm day, but not in the days before or after the storm. The regularity is poor when the wind velocity is low. The ground temperatures at the depths of 0 cm and 5 cm tracked the air temperature 1.5 m above the surface very well during the sandstorm passing time. However, there is a substantial time lag between the 1.5 m air temperature and 5 cm ground temperature in a non storm day. Before the storm, the arrival time of 1.5 m air temperature reached the peak value is about 1～2 hours earlier than that of 5 cm ground temperature, but after the storm, it is 1～2 hours later on the contrary.

• Relationship between the Characteristics of Lightning Activityand Precipitation during Midsummer in the Leizhou Peninsula
• 2009 Vol. 28 (3): 663-668. 
• Abstract ( ) PDF (3330KB) ( )
• The rainfall and lightning activity produced by rain events in the Leizhou Peninsula from July to August 2007 are studied. The data consist of 24 h accumulated precipitation and rainfall intensity reported by the surface network and the lightning strokes detected by LD lightning positioning systems. It is found that most of the lightning activity occurs over the eastern maritime area and distributesfrom northto south near the coastline. There is an obvious change in diurnal distribution of the cloud\|to\|ground (CG) flash,and occurs most frequentlyfrom 13:00 to 18:00. It is found that for almost 41.3% and 61.5% of the cases in which rain happens without lightning, 24 h and 1 h accumulated precipitation is smaller than or equal to 1 mm, respectively. These two percentages drop to about 25.9% and 37.7% for the cases with lightning. The rainfall events in which 24 h accumulated precipitation is over 30 mm mostly occur with lightning activity. Although lighting activity broadensthe amplitude of the average of rainfall intensity, there is no obvious diurnalvariation of probability distribution of rainfall intensity.

• Characteristics of Cloud-to-Ground Flashesin Zhejiang and Gansu Areas
• 2009 Vol. 28 (3): 669-674. 
• Abstract ( ) PDF (1986KB) ( )
• Based on the cloud\|to\|groundflashes data obtained by lightning location system from Zhejiang and Gansu, the regularities of lightning factors have been analysed respectively. The results indicate that there are great differences in monthly and diurnal variations and intensity spectra in different areas. Thisgap makes us pay attention to correlations between the convective available potential energy(CAPE) and the lightning activities.Itshows that the CAPE is higher in south\|east than in north\|west, but the sensitivity of lightning to CAPE is lower than north\|west.

• Calculation of Electron Density for Lightning DischargePlasma by NI 493.5 nm Line Stark Broadening
• 2009 Vol. 28 (3): 675-679. 
• Abstract ( ) PDF (1385KB) ( )
• According to one spectrum of lightning return stroke in Qinghai Province, it is show that the Stark broadening are about 1.5～2.5 nm and the NI 493.5 nm lines at different positions within the channel present slight asymmetry after analyzing the Stark broadening effect of NI 493.5 nm line. The electron densities at different positions of the channel have been calculated combining with semi\|empirical parameters of NI 493.5 nm lines Stark broadening, and the average electron density at 1.657×1017 cm-3 is further obtained. After comparing the electron densities obtained from NI 493.5 nm and Hα lines at different positions within channel, we confirm that the electron densities obtained from NI 493.5 nm and Hα lines are approximately same, and it is a creditable and practical way for calculation of eletron density by NI 493.5 nm lines Stark broadening. The result reveals that the electron densities show a tiny trend of becoming low with increasing of height along the channel. Besides, the electron densities exhibit a nearly linear dependence on the half\|widths of NI 493.5 nm lines.

• Change Trend Analyses on Upper\|Air Wind Speedover China in Past 30 Years
• 2009 Vol. 28 (3): 680-687. 
• Abstract ( ) PDF (2261KB) ( )
• Based on the monthly mean upper\|air wind speed data from 1980 to 2006 at 119 radiosonde stations in China， the long\|term change trends in upper\|air wind speed are analyzed， and a comparison of the change with surface wind speed change in the same time period is made as well． Results show that both in the mid\| and lower\|and upper troposphere the annual mean wind speed decreases during the period analyzed，with change rates of -0．10 m·s-1·(10a)-1 and -0．17 m·s-1·(10a)-1， and has′nt passed the significant level at 0．05， respectively． The stratospheric wind speed， however， increases in the same period， with the rate of 0．24 m·s-1·(10a)-1， which has passed the significant level at 0．05． Contrast to the upper atmosphere， the surface wind speed significantly decreases in the same time period， with the rate of -0．16 m·s-1·(10a)-1， which has passed the significant level at 0．05． The results indicate that the decrease of surface wind speed widely reported is not only associated with the large\|scale circulation change， but also with the urbanization\|induced change in observational settings around the meteorological stations．

• An Extension Forecast Expreiment for Regional RainstormProcess of Guangxi in June
• 2009 Vol. 28 (3): 688-693. 
• Abstract ( ) PDF (2009KB) ( )
• Based on the NCEP/NCAR reanalysis data from March to June of 1958\_2008 and the 16 grids covering Guangxi, the leading influencing systems of the regional rainstorm in Guangxi were found out using the Lamb circulation sub\|type method and EOF. The rainstorm processes were forecasted in the extension climate prediction using the method of dynamic similarity and integrated forecast during the June 2003\_2008, the results of these experiments shown that it have a good performance. This paper presents a new method for the short\|term climate prediction and provides a valuable objective basis for the severe wheather prediction and has an important practical value for the effectice policy\|making for local goverment. Meanwhile it also has a better reference and early warning function under the situation of great difficalty for the middle and short term regional rainstorm prediction.

• Analyses on the Space-Time Distribution Characteristics andTheir Influence Factors of Freezing Rain in Guizhou Province
• 2009 Vol. 28 (3): 694-701. 
• Abstract ( ) PDF (4866KB) ( )
• Using the data of the freezing rain days at 84 stations in Guizhou and the NCEP/NCAR reanalysis data, the space\|time distribution characteristics and time change discipline and the influence factors are firstlystudied with EOF and wavelet analysis, and other ways. It is found that the characteristic of freezing rain distribution is that it happened more in the west of Guizhou and middle than the east, northand south. The big gradient changeof freezing rain day′s area is middle\|west of Guizhou, especially northwest. Theresults of the GIS refutationsare similar as the real distributions, namely the freezing is severe in common height, but themost of stations locate nearby low height cities and towns lead to the observation results weaker than the real freezing intensity. There is big change of interannual timescale of Guizhou freezing rain. It has obviously 12\|year and 32\|year oscillation periods. In the four year timescales, the oscillation period is alsoobviously. The influence factors of the winter freezing rain distribution and space\|time change are the height above sea level, relative height, windward sideand lee slope, stationary frontarea, cold air thickness and activities in different heights.

• Relationship and Difference between Droughtand High Temperature Heat Waves
• 2009 Vol. 28 (3): 702-709. 
• Abstract ( ) PDF (937KB) ( )
• The difference and distinction between drought and high temperature heat wave invarious aspects are summarized. This includes in the definition, standard and types; in characteristics of geologicaldistribution, time and intensity variation; inthe nature and magnitudeof its damageand effect; in the mechanism and causes for its formation; in the formsand degree of its responsesto global warming; in the techniques of detecting andforecasting; and in the countermeasures and strategy of disaster recovery andreducing disaster. The results showed a close relationship between high temperature andprecipitation, which often interfere with each other. Increasedprecipitation often causes decreased temperature, and vise versa. High temperatureaccelerates water evaporation rate and causes rapid water loss fromsoil and plants. This is particularly severe in summer. Consequently, the loss imitates the onset of drought or increases the severity of a pre\|existing drought condition.