Abstract:One-month old,rooted semi-hardwood cutting plants of pepino(Solanum muricatum Ait.) cv."Xotus" in sand-potted culture were treated by 200 mL Hoagland nutrient solution with or without additional 25 mg·L^-1 NaCl twice a week for 2 months,and exposed to(350±10),(700±10) or(1 050±10)×10^-6 atmospheric CO₂ in controlled environment chambers during the last month of the experiment,respectively.Dry mass production and water consumption of the plants decreased with NaCl salinity in the root medium,but increased with atmospheric CO₂ enrichment.Salinity raised the leaf transpiration index,root/shoot ratio,and relative distributions of dry mass into stems and roots,while reduced dry mass accumulation in other organs,water-uptake efficiency of the roots,and water consumption of the plants.High CO₂ concentrations,however,accelerated foliage development,increased total leaf area,specific leaf weight,daily increment of dry mass in plant organs and dry mass allocation to both aboveground and underground organs,accompanied by an increased dry mass-production efficiency,total water consumption and water-use efficiency of the plants.Total dry mass increment and water-use efficiency of the plants decreased by 50%—54% and 24%—37% due to salinity in the rhizosphere,but increased by 79%—106% and 61%—88% at 700×10^-6 CO₂,and by 133%—189% and 99%—142% at 1 050×10^-6 CO₂ in comparison with the 350×10^-6 CO₂ treatment,accordingly.Atmospheric CO₂ enrichment tended to improve dry mass productivity of NaCl-stressed plants by improving water-use efficiency of the plants.There were interactive effects of the combined NaCl salinity and CO₂ enrichment treatments on dry mass production and water consumption of the plants.Combined environmental conditions of rhizospheric NaCl salinity and atmospheric CO₂ enrichment promoted daily increment and relative distribution of leaf dry mass,dry mass-production efficiency and water-use efficiency of the plants,reduced total leaf area,shoot and root dry weight,water consumption of the plants,water-uptake efficiency of the roots and leaf transpiration index of the plants,correspondingly.Therefore,the global atmospheric CO₂ enrichment will be of benefit for dry mass production and water utilization of this crop.

Abstract:Based on the ETM+image,the land surface temperature(LST),reduced simple ratio(RSR) and normalized difference vegetation index(NDVI) of Nanjing are retrieved after effective atmospheric correction by ATCOR2 nested in ERDAS IMAGINE 9.1.In comparison of ETM+LST with ASTER LST and observed values,it shows that good consistency exists both at single station and in spatial distribution.Regression and contrastive analysis are conducted for explaining relationships between LST and the two vegetation indexes.Results show that the LST associating with thick vegetation is much lower than that with sparse vegetation or bare lands,when water bodies are without consideration.Fitting models prove a significant negative linear correlation between LST and NDVI,while LST and RSR are more obviously correlated with power function.When RSR is below 3.2,LST decreases rapidly with the vegetation coverage increasing.However,it tends to be unchangeable when RSR exceeds 3.2.Cooling effect of vegetation is at "saturation",and only RSR can reveal the interesting phenomenon.Compared to the ratio vegetation index(RVI),the linear ratio of near infrared and red is suggested as the main reason for different behavior of the two vegetation indexes applied in urban thermal environment.Other factors may include better sensitivity to moisture and canopy closure information detected by near infrared.Urban thermal environment research in six cities of China demonstrates that cooling effect of vegetation is limited by underlying surface patterns.Compared to NDVI,RSR is not only better for indicating the relationship between LST and vegetation coverage,but more effective for indicating thermal environment on city scale.

Abstract:To detect the dynamic prediction feasibility of tropical cyclone seasonal activities,a 92-d numerical integration of the WRF(Weather Research and Forecasting) mesoscale model is conducted with the National Centers of Environmental Prediction(NCEP) 1°×1° final(FNL) data as the initial and boundary conditions to simulate the tropical cyclone activity in the northern West Pacific basin during July-September 2006.In order to obtain relatively realistic large-scale circulation in the regional model,the nudging technique is used in the coarse domain with 27 km spacing.Compared with the NCEP reanalysis,the model can reasonably reproduce the Madden-Julian oscillation(MJO) and quasi-biweekly oscillation(QBWO).The simulated tropical cyclone activity(including frequency,track and intensity) is fairly comparable to the observation.In the 9 km domain,together with the well-simulated tropical cyclone structure such as the eyewall and warm-core,the simulation well captures the westward prevailing tracks and landfall processes.Further analysis suggests that the model can also simulate the tropical cyclogenesis including a two-step development of the convection,as suggested in previous studies.The initial vortex appears around the monsoon trough,accompanied with cyclonic phase of the QBWO.In the first development process,the initial vortex evolves into an extremely convective core.After a short time decline,associated with the favorable large-scale circulation,the extremely convective area is compassed by the high humidity air,which causes the second development process.

Abstract:Thirty four cases of topical cyclogenesis that occurred in boreal winter(November to February of next year) during 12-yr(1995—2006) have been analyzed by using the composite technique for further understanding of the larger-scale circulation features and the mechanism of the formation of tropical cyclone in the western north Pacific(WNP)during wintertime.It has been found that the easterly waves play a major role in the tropical cyclogenesis.The existence of low-level cross-equatorial tropical cyclone pairs is a remarkable feature in the formation of tropical cyclogenesis.The equatorial mixed Rossby-gravity(MRG) waves in lower troposphere propagated northwestward from the central Pacific.These waves developed into the TD-type disturbances in place where the strong convection overlaps,which provided disturbances for the tropical cyclogenesis.Further analysis in terms of eddy kinetic energy budgets for the TC(tropical cyclone) related with circulations indicates that the available potential energy of disturbances and the energy that converts barotropically from the mean kinetic energy facilitates the TC formation.These two kinds of energy are associated with cumulus convection heating and the asymmetric horizontal flow respectively.The barotropic energy conversion mainly occurs in the low and mid-troposphere while the available energy conversion locates in the mid and upper troposphere.The tropic easterly waves get barotropic instability energy from the mean flow and coupled with the deep convection,inducing the formation of TCs under the interaction of dynamics and thermodynamics.

Abstract:Taking two tropical cyclones that landed southern China and caused great damage in summer of 2001 and 2006 as examples,using the dataset of CMA-STI Tropical Cyclone Optimal Tracks,the NCEP/NCAR reanalysis data and the intensive surface observations,this paper compares the large scale circulation features of maintenance over land and enhanced rainstorm from Durian(0103) in 2001 and Bilis(0604) in 2006.The conclusions are as follows:(1)After landing,Durian interacts with the mid-latitude westerly trough,forming a pattern of "North trough and South vortex".After landing,Bilis is blocked by the western Pacific subtropical high(WPSH),the northern high-pressure dam,and the extending southwest high pressure ridge of WPSH in the south side,allowing its cyclonic circulation to be maintained.(2)During the period of Durian and Bilis over land,the cross-equatorial flow increases significantly.The cross-equatorial flow nearby 100°E is remarkable in 2001,but the cross-equatorial flow nearby 80°E has outstanding performance in 2006.The cross-equatorial flows strengthen the southwest monsoon,which keep providing plentiful water vapor for the declining Durian and Bilis,leading to their long time maintenance over land instead of quick decaying.(3)East Asian monsoon manifest significant low-frequency oscillation,with main periods of 10—20 d in 2001 and 30—60 d in 2006.Low-latitude monsoon surge,characterized by different atmospheric low-frequency oscillations,experience remarkably northward propagation.In an extremely active stage of the low-frequency oscillation of low latitude summer monsoon,the monsoon surge is the strongest and intrudes into the circulations of Durian or Bilis,corresponding to the enhanced rainstorm.In addition,the convergence of low-frequency airflows and transport of low-frequency water vapor aslo play important roles in the enhanced rainstorm from Durian and Bilis.

Abstract:Based on the Doppler radar data and cloud microphysical data collected by aircraft,the formation and microphysics of a convective-stratiform mixed cloud(CSMC for short) impacted by westerly trough have been analyzed.The results are as follows.CSMC came into being from weakened zonal convective which was merged by small convective clouds.Apparent convection cells with the maximum intensity of 45—50 dBZ and the maximum vertical height of 6 km were embedded in the CSMC.The particle number concentrations measured by CDP,CIP,and PIP were 132.4—220.2 cm^-3,1.54×10^-1—6.28×100 cm^-3and 9.09×10^-4—7.34×10^-3cm^-3,respectively.Two dimensional images show that graupel is the main ice particles in the cold layer,which implies that supercooled water is adequate;columnar aggregates and riming particles found at -7℃ imply that after columnar crystal is formed by sublimation,collision and riming are important mechanisms for graupel’s formation.The average CDP spectra(diameter:2—50 μm) are different with the heights,and the concentration of particles between 2 and 18 μm decreases with height rising,because water vapor condensation is stronger in the low-level,but the concentration of those between 24 and 35 μm increases,because the collision efficiency is lower in the warm cloud and small ice particle number increases with the height rising.The average CIP spectra(diameter:25—1 550μm) follow unimodal distributions except for that at 4 100 m.The average PIP spectra(diameter:100—6 200 μm) are discontinuous at the larger size;the largest concentration and the spectral width occur at 4 450 m and the high number concentration between 3 200 and 4 000 μm implies that convective cells and the surrounding area provide a good environment for the growth of larger solid precipitation particles.

Abstract:In order to investigate the variation characteristics of atmospheric particle pollution in the Olympic Village and evaluate the effect of pollution control measures on particle matter concentrations,the on-line measurements of particle mass concentration(PM₁₀ and PM_2.5) using TEOM were conducted on the rooftop of a six-floor building in the Institute of Remote Sensing Applications,Chinese Academy of Sciences,during both summer of 2007 and 2008.Results show that the average mass concentration of PM₁₀ and PM_2.5 during summer of 2007 are 153.9 and 71.2 μg·m^-3,while the average mass concentration of PM₁₀ and PM_2.5 during summer of 2008 are 85.2 and 52.8 μg·m^-3,respectively.Compared with the same period of one year before,the average mass concentration of PM₁₀ and PM_2.5 decrease by 44.5% and 25.1%,respectively,during the Olympic Games.Two typical particle pollution processes are selected to compare the variation difference of particle mass concentrations before and during the Olympic Games.The result shows that the relative humidity increasing and air masses transportation from south regions both together easily lead to the increasing of atmospheric particles,whereas the rainfall events and air mass transportation from north regions have a great effect on the scavenging of particle matter.In the similar weather conditions,the daily growth rate of fine particles in pollution accumulation process are 25.1 and 13.9 μg·m^-3·d^-1,while the daily growth rate of coarse particles are 20.8 and 2.2 μg·m^-3·d^-1,respectively,before and during Olympic Games.The daily growth rate of coarse and fine particles in pollution process during Olympic Games are significantly and slightly lower than those in pollution process before Olympic Games,which indicates that the implementation of pollution control measures during the Olympic Games has a great effect on the decreasing of particle matter,especially on the reduction of coarse particles.

Abstract:X-band Doppler and dual-polarization radar were used to measure the three thunderstorm processes in 2005 and 2007 in Pingliang area over northwest plateau.Decision tree method was used to classify the hydrometeors types according to polarimetric variables like Z_H,Z_DR,K_DR and ρ_HV and height H,based on which the relationship between microphysical and electrical characteristics,especially the electrical field on the ground,the formation of low positive charge center and the distribution of hydrometeors was analyzed.Then,the polarities charged by different hydrometeors were inferred and the charge structure of thundercloud in the area is further discussed.

Abstract:This paper proposes a method of reflectivity quality control for CINRAD Doppler weather radar in China on the basis on FCM(fuzzy C-means) algorithm.A statistical analysis was done on the reflectivity data from the radar in Bengbu and Fuyang during June 3 and 5,2009.The results showed that the precipitation and non-precipitation radar reflectivity echoes presented different features in horizontal reflectivity texture(T) and vertical difference of reflectivity(V),which can be clearly identified.The method is able to identify the echo type automatically by using the two feature parameters in FCM.Then,the method is applied to the above data.The Quality control results showed that the appropriate characteristic parameters can be used as the feature vectors in the FCM algorithm to identify the non-precipitation echoes from the precipitation ones and the performance of the quality control can thus be improved.

Abstract:For the actual demand of analyzing intraseasonal oscillation of atmospheric heat source over the Tibetan Plateau,this paper devises Lanczos filter suitable for filtering quasi-two-week(10—20 d) and quasi-one-month(20—40 d) oscillations.By using the quantitative analysis and comparing with the filtering effect of Butterworth filter,the critical values l₀ of window width parameter l of quasi-two week and quasi-one month Lanczos filter are determined as 24 and 46,respectively.The filtering capability of Lanczos filter is better than that of Butterworth filter when l is greater than or equal to l₀.The whole atmospheric heat source data of the grid point(30°N,90°E) near Lhasa from 1950 to 2006 are used for test.Results indicate that,filtered by Lanczos filter with its parameter l being equal to 121,the quasi-two week and the quasi-one month components are dependable and can be used to analyze interannual difference and intraseasonal process of intraseasonal oscillation intensity of atmospheric heat source over the Tibetan Plateau.

Abstract:From autumn 2009 to early summer 2010,Yunnan has suffered a most serious drought disaster.In this drought process,autumn rainfall is the least since the data record and its anomalous precipitation percentage exceeds-50%.Based on diagnostic analysis,the anomalous characteristics of autumn rainfall and atmospheric circulation are investigated.Results show that the autumn rainfall accounts for more than 20% of annual rainfall.The continuously less water vapor from low to high levels,the convergence at lower level companied with divergence at higher level over Yunnan region directly result in the drought.Otherwise,the continuously strong subtropical high over the western Pacific,the weak cold air and the weak warm and wet flow as well as their out-phase effects,the early retreat of summer monsoon circulation also play significant role on this drought.

Abstract:Based on the NCEP/NCAR reanalysis data from 1948 to 2009,this paper studies the spatial and temporal characteristics of vertically integrated water vapor content of annual average,January,April,July and October over the Yellow River basin.Results show that the annual average water vapor content is 5—27 mm.The water vapor content reaches the minimum in winter(January) and the maximum in summer(July),and it is the lowest over the Tibetan Plateau and the highest over the lower Yellow River,while it is in the middle over the westerly belt.By means of REOF(rotated empirical orthogonal function) method,the atmospheric precipitable water of annual average,January,April,July and October can be divided into two,four,four,four and four sub-regions over the Yellow River basin,respectively.The water vapor content over the whole basin and the middle and lower Yellow River basin tends to decrease,while the trends are different over other subareas.

Abstract:To understand the regional heat and water vapor exchange and the flow motion law in Chaohu Lake basin,it is important to study the wind characteristics.The wind and temperature characteristics are analyzed based on the data from automatic weather stations at Hefei,Feidong,Chaohu,Lujiang and Laoshan Island in 2006.Results show that the annual average wind speed of Chaohu Lake basin is 2.17 m/s on land and 2.41 m/s over the lake.Wind speed in spring and summer is larger than that in autumn and winter both on land and over the lake.Wind speed in the daytime is larger than that at night on land,but the diurnal variation of wind speed over the lake is less noticeable.The wind direction on land is from the south in spring and summer,and from the north in autumn and winter,showing a significant seasonal variation.Diurnal variation of wind direction on land in spring and summer is more noticeable than that in autumn and winter.Seasonal variation over the lake was not pronounced.The longer the distance between the lake and the station is,the less the lake-land breeze affects the station.Anomaly of wind direction differences between stations on land and Laoshan Island station and anomaly of temperature differences have consistent diurnal variation,which indicates that the temperature difference is the key factor to influence the lake-land breeze over Chaohu Lake basin.