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991.
最近在辽宁本溪牛毛岭剖面上的上石炭统(宾夕法尼亚亚系)本溪组新洞沟段(本溪组中段)的煤系地层中发现了大量鳞木化石。现有资料证明,在牛毛岭剖面本溪组复洲湾段(本溪组上段)灰岩中发现了属于晚石炭世莫斯科期的牙形石,而在牛毛岭剖面邻近地区本溪组湖田段(本溪组下段)中则发现了属于早石炭世(密西西比亚纪)的亚鳞木、大脉羊齿和贝叶。由此认为,新发现的牛毛岭剖面本溪组新洞沟段(本溪组中段)的鳞木化石,应晚于早石炭世,早于晚石炭世莫斯科期,即应属巴什基尔期。鳞木是辽宁东部第一次成煤期滨海沼泽相成煤植物群中的代表性植物。 相似文献
992.
993.
对黄土高原中部朝那剖面末次冰期-间冰期旋回黄土-古土壤序列色度指标与磁化率对比研究后发现,亮度L*值与Hm(赤铁矿)和Gt(针铁矿)的比值相关性较好,在S0和L1阶段其与Hm和Gt的比值呈正相关,在S1阶段为负相关。红度a*与Hm和Gt的比值有较强的正相关关系,反映土壤发育时期的水热条件。而黄度b*与针铁矿的相关性较好,与低频磁化率χlf使用可以更好地反映土壤的发育程度。色度指标在变化频率和幅度上较磁化率大,能很好地识别S1阶段弱黄土-古土壤层。 相似文献
994.
In the present reported study, the vertical distributions of local atmospheric refractivity were retrieved from ground- based GPS observations at low elevation angles. An improved optimization method was implemented at altitudes of 0-10 km to search for a best-fit refractivity profile that resulted in atmospheric delays most similar to the delays calculated from the observations. A ray-tracing model was used to simulate neutral atmospheric delays corresponding to a given refractivity profile. We initially performed a "theoretical retrieval", in which no observation data were involved, to verify the optimization method. A statistical relative error of this "theoretical retrieval" (-2% to 2%) indicated that such a retrieval is effective. In a practical retrieval, observations were obtained using a dual-frequency GPS receiver, and its initial value was provided by CIRA86aQ_UoG data. The statistical relative errors of the practical retrieval range from -3% to 5% were compared with co-located radiosonde measurements, Results clearly revealed diurnal variations in local refractivity prc,files, The results also suggest that the general vertical distribution of refractivity can be derived with a high temporal resolution. However, further study is needed to describe the vertical refractivity gradient clearly. 相似文献
995.
996.
The velocity structure of the residual current across an entire section of the Qiongzhou Strait(QS) in summer is presented for the fi rst time. Shipboard Acoustic Doppler Current Profi le measurements, from the mid-region of the QS(110.18°E), were collected on 1–4 August 2010. The diurnal tidal currents had their maximum amplitudes between 4.24 and 20.24 m. Their amplitude along the major axis ranged from approximately 0.55 m/s in the middle part of the strait(20.15°N) to 0.84 m/s in the north part of the strait(20.20°N). Both anticlockwise and clockwise tidal current rotations exist in the QS. During the observation period(neap tide), a signifi cant westward residual current occupied almost the entire study section. Two velocity cores of westward current were observed at the northern part and near the deepest trough, although an eastward current appeared in the middle part of the transect. The deepest core was located near 62 m at 20.13°N, with a maximum velocity of-0.34 m/s. The shallower core was located at approximately 16 m at 20.20°N, with a maximum velocity of-0.33 m/s. The estimated total volume of water transported through the QS was-0.16 Sv. This value is an important boundary condition, applicable to numerical models studying coastal ocean circulation in the northwestern South China Sea. 相似文献
997.
Sungkyun SHIN Young Min NOH Kwonho LEE Hanlim LEE Detlef MLLER Y.J.KIM Kwanchul KIM Dongho SHIN 《大气科学进展》2014,31(6):1417-1426
The vertical distribution of single scattering albedos (SSAs) of Asian dust mixed with pollutants was derived using the multi-wavelength Raman lidar observation system at Gwangju (35.10°N,126.53°E).Vertical profiles of both backscatter and extinction coefficients for dust and non-dust aerosols were extracted from a mixed Asian dust plume using the depolarization ratio from lidar observations.Vertical profiles of backscatter and extinction coefficients of non-dust particles were input into an inversion algorithm to retrieve the SSAs of non-dust aerosols.Atmospheric aerosol layers at different heights had different light-absorbing characteristics.The SSAs of non-dust particles at each height varied with aerosol type,which was either urban/industrial pollutants from China transported over long distances at high altitude,or regional/local pollutants from the Korean peninsula.Taking advantage of independent profiles of SSAs of non-dust particles,vertical profiles of SSAs of Asian dust mixed with pollutants were estimated for the first time,with a new approach suggested in this study using an empirical determination of the SSA of pure dust.The SSAs of the Asian dust-pollutants mixture within the planetary boundary layer (PBL) were in the range 0.88-0.91,while the values above the PBL were in the range 0.76-0.87,with a very low mean value of 0.76 ± 0.05.The total mixed dust plume SSAs in each aerosol layer were integrated over height for comparison with results from the Aerosol Robotics Network (AERONET) measurements.Values of SSA retrieved from lidar observations of 0.92 ± 0.01 were in good agreement with the results from AERONET measurements. 相似文献
998.
短时强降水特征统计及临近预警 总被引:9,自引:3,他引:6
利用多普勒天气雷达、探空和逐小时降水量资料,对2010 2012年,滇西南普洱、西双版纳537次短时强降水天气过程进行统计分析,建立三种短时强降水概念模型,分别是:低质心弱辐合型短时强降水、低质心辐合型短时强降水、高质心短时强降水。对比分析了不同类型短时强降水的强度特征、移速特征、生命期特征、垂直风切变特征等,探讨了辐合作用与强降水维持时间的关系、辐合切变量与雨强的关系、D_(VIL)与降水量的关系。并得出预警方法:满足如下条件时,出现短时强降水的可能较大:(1)低质心强降水中,回波无倾斜特征,强度以40~45 dBz为主,强度从低层到高层维持或缓慢减弱,大部分回波的H_((40dBz))≥H_0,且0℃层高度上40 dBz的回波的累计长度/回波移速≥0.67 h(辐合切变量≥2.2 m·s~(-1)时,累计长度/回波移速≥0.50 h),预报提前时间30~40 min。(2)高质心强降水中,强回波边缘存在宽≥3 km、强度为40~45 dBz的回波,且0℃层高度上40 dBz的回波的累计长度/回波移速≥0.47 h,预报提前时间28 min左右。此外,对短时强降水成因进行了探讨。 相似文献
999.
正一、高考地理试题中的比较情境笔者查阅近五年的浙江高考地理试题,能力型的试题始终占据很大的比重,在考查地理解题能力的高考地理试题中,采用比较性情境的题型随处可见,现列举如下。1.浙江卷选择题中的比较性情境分析浙江省在2009年第一次独立高考命题,这一年试题中很大的亮点就是比较性情境的大量运用。比如第1题,三类土壤的不同剖面深度处土壤有机质含量的比 相似文献
1000.