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921.
922.
923.
利用2003-2012年的地面填图和探空资料,统计常用对流参数满足指定阈值条件时广西6个探空站出现雷暴天气的概率(简称"雷暴概率")。统计结果表明:整层比湿积分(IQ)、K指数(KI)和抬升指数(LI)与雷暴概率有显著的线性关系,当IQ、KI增大,或LI减小时,雷暴概率增大。对流有效位能(CAPE)在0-200J·kg-1之间增长时雷暴概率迅速增大,但超过200J·kg-1后雷暴概率增大不明显。根据统计结果,选取IQ、KI和LI作为预报因子,CAPE作为消空因子,定义了一个适用于广西雷暴天气的经验预报指标。用2013年资料做试报检验,结果表明该指标对6小时内的雷暴天气有较好的预报能力。 相似文献
924.
在中国第28次南极科学考察期间,利用“雪龙号”科考船载SIMRAD EK500(38kHz)科学渔探仪对南极半岛附近海域的南极大磷虾资源量进行了调查。原始声学数据经过信噪比估算和背景噪声剔除数据后处理方法剔除背景噪声以及手动剔除表面混响、海底反射和坏数据之后,在200 m以浅水层中,以1n mile间隔进行积分,并应用Matlab软件编程对积分结果进行后处理,得出调查海域中南极大磷虾的资源分布情况。结果表明:(1)“雪龙号”的平均噪声功率值为-146.47dB re 1W;(2)空白水体的噪声平均剔除百分比为88.3%;(3)调查区域内的南极大磷虾平均密度为27.30 g·m-2(62.95 ind·m-2)。 相似文献
925.
Marine biogenic emission of dimethylsulfide(DMS) has been well recognized as the main natural source of reduced sulfur to the remote marine atmosphere and has the potential to affect climate,especially in the polar regions.We used a global climate model(GCM) to investigate the impact on atmospheric chemistry from a change to the contemporary DMS flux to that which has been projected for the late 21~(st) century.The perturbed simulation corresponded to conditions that pertained to a tripling of equivalent CO_2, which was estimated to occur by year 2090 based on current worst-case greenhouse gas emission scenarios.The changes in zonal mean DMS flux were applied to 50°S-70°′S Antarctic(ANT) and65°N-80°N Arctic(ARC) regions.The re sults indic ate that the re are clearly diffe rent impacts after perturb ation in the southern and northern polar regions.Most quantities related to the sulfur cycle show a higher increase in ANT.However,mo st sulfur compounds have higher peaks in ARC.The perturbation in DMS flux leads to an increase of atmo spheric DMS of about 45% m ANT and 33.6% in ARC.The sulfur dioxide(S02) vertical integral increases around 4 3 % in ANT and 7.5% in ARC.Sulfate(S04) vertical integral increases by 17% in ANT and increases around 6% in ARC.Sulfur emissions increases by 21% in ANT and increases by 9.7%in ARC.However,oxidation of DMS by OH increases by 38.2% in ARC and by 15.17% in ANT.Aerosol optical depth(AOD) increases by 4% in the ARC and by 17.5% in the ANT,and increases by 22.8% in austral summer.The importance of the perturbation of the biogenic source to future aerosol burden in polar regions leads to a cooling in surface temperature of 1 K in the ANT and 0.8 K in the ARC.Generally,polar regions in the Antarctic Ocean will have a higher offsetting effect on warming after DMS flux perturbation. 相似文献
926.
Feng Wang Junling An Ying Li Yujia Tang Jian Lin Yu Qu Yong Chen Bing Zhang Jing Zhai 《大气科学进展》2014,31(6):1331-1342
High levels of uncertainty in non-methane volatile organic compound (NMVOC) emissions in China could lead to significant variation in the budget of the sum of hydroxyl (OH) and peroxy (HO2,RO2) radicals (ROx =OH + HO2 + RO2) and the ozone production rate [P(O3)],but few studies have investigated this possibility,particularly with three-dimensional air quality models.We added diagnostic variables into the WRF-Chem model to assess the impact of the uncertainty in anthropogenic NMVOC (AVOC) emissions on the ROx budget and P(O3) in the Beijing-Tianjin-Hebei region,Yangtze River Delta,and Pearl River Delta of China.The WRF-Chem simulations were compared with satellite and ground observations,and previous observation-based model studies.Results indicated that 68% increases (decreases) in AVOC emissions produced 4%-280% increases (2%-80% decreases) in the concentrations of OH,HO2,and RO2 in the three regions,and resulted in 35%-48% enhancements (26%-39% reductions) in the primary ROx production and ~ 65% decreases (68%-73% increases) of the P(O3) in Beijing,Shanghai,and Guangzhou.For the three cities,the two largest contributors to the ROx production rate were the reaction of O1D + H2O and photolysis of HCHO,ALD2,and others; the reaction of OH + NO2 (71%-85%) was the major ROx sink; and the major contributor to P(O3) was the reaction of HO2 + NO (~ 65%).Our results showed that AVOC emissions in 2006 from Zhang et al.(2009) have been underestimated by ~ 68% in suburban areas and by > 68% in urban areas,implying that daily and hourly concentrations of secondary organic aerosols and inorganic aerosols could be substantially underestimated,and cloud condensation nuclei could be underestimated,whereas local and regional radiation was overestimated. 相似文献
927.
黑龙江省自侏罗纪以来,受太平洋板块及欧亚大陆板块的相互作用,形成了具有一定规模的盆岭构造系统,呈现出北北东向展布的三隆三坳。受此构造控制,在黑龙江省发育着大小不一的凹陷含煤盆地,并共生或伴生着大量的油页岩等矿产资源。通过对全省东、中、西部盆地群14含油页岩盆地的分析,预测全省油页岩资源储量可达1612亿t,折合页岩油资源量约161亿t,相当于4个大庆的油气资源储量。为了全面掌握黑龙江省油页岩资源状况,计划利用三年时间在全省区域内按西部、中部及东部13个区块(14个主要盆地)开展油页岩调查工作,总面积达137192.93km2。 相似文献
928.
Qingjie Han Jianjun Qu Kongtai Liao Shujuan Zhu Kecun Zhang Ruiping Zu Qinghe Niu 《Environmental Earth Sciences》2011,64(5):1375-1385
This article reported a wind tunnel test of sediment transport related to surface moisture content and wind velocity using
sands from tropical humid coastal area. A 1 mm-thick portion of surface sand was scraped using a self-made sediment sampler,
and the gravimetric moisture content was determined. Sand transport was measured via a standard vertical sand trap with a
60 cm height. The result shows that the sand transport profile above the wet surface can be expressed with an exponential
equation. In general, the influence of moisture content on sand transport profile mainly focuses on the bottom of the blowing
sand cloud. Meanwhile, with moisture content increased, total sand transport dropped, and a relatively larger proportion is
transported at greater heights. The vertical movement of particles on higher moisture surface (0.587% < M < 1.448%) is more sensitive to moisture content variation as compared to those on low wet surface (M < 0.587%), total sand transport rate tends to be rather low (0.99 g cm−1 s−1) when M > 1.448%. The total sand transport rate varying with moisture content is divided into three regions of differing gradient
at the moisture contents of 0.587 and 1.448%. The gradient of the curve reflected the different influences of the various
water forms in surface sediments. The higher moisture surface (M > 1.448%) merely functions as a transport plain for the saltation material. Surface moisture content was the dominant control
factor for saltation activity between the moisture contents of 0.587 and 1.448%, wind velocity could resume control saltation
after the surface dried to the extent (M < 0.587%). 相似文献
929.
930.
Huaiwei Ni Hans Keppler Nicolas Walte Federica Schiavi Yang Chen Matteo Masotta Zhenjiang Li 《Contributions to Mineralogy and Petrology》2014,167(5):1-13
The speciation of CO2 in dacite, phonolite, basaltic andesite, and alkali silicate melt was studied by synchrotron infrared spectroscopy in diamond anvil cells to 1,000 °C and more than 200 kbar. Upon compression to 110 kbar at room temperature, a conversion of molecular CO2 into a metastable carbonate species was observed for dacite and phonolite glass. Upon heating under high pressure, molecular CO2 re-appeared. Infrared extinction coefficients of both carbonate and molecular CO2 decrease with temperature. This effect can be quantitatively modeled as the result of a reduced occupancy of the vibrational ground state. In alkali silicate (NBO/t = 0.98) and basaltic andesite (NBO/t = 0.42) melt, only carbonate was detected up to the highest temperatures studied. For dacite (NBO/t = 0.09) and phonolite melts (NBO/t = 0.14), the equilibrium CO2 + O2? = CO3 2? in the melt shifts toward CO2 with increasing temperature, with ln K = ?4.57 (±1.68) + 5.05 (±1.44) 103 T ?1 for dacite melt (ΔH = ?42 kJ mol?1) and ln K = ?6.13 (±2.41) + 7.82 (±2.41) 103 T ?1 for phonolite melt (ΔH = ?65 kJ mol?1), where K is the molar ratio of carbonate over molecular CO2 and T is temperature in Kelvin. Together with published data from annealing experiments, these results suggest that ΔS and ΔH are linear functions of NBO/t. Based on this relationship, a general model for CO2 speciation in silicate melts is developed, with ln K = a + b/T, where T is temperature in Kelvin and a = ?2.69 ? 21.38 (NBO/t), b = 1,480 + 38,810 (NBO/t). The model shows that at temperatures around 1,500 °C, even depolymerized melts such as basalt contain appreciable amounts of molecular CO2, and therefore, the diffusion coefficient of CO2 is only slightly dependent on composition at such high temperatures. However, at temperatures close to 1,000 °C, the model predicts a much stronger dependence of CO2 solubility and speciation on melt composition, in accordance with available solubility data. 相似文献