云检测在高光谱大气红外探测器 辐射率直接同化中的应用

对于高光谱大气红外探测器AIRS(Atmospheric Infrared Sounder)辐射率的同化,云检测技术是关键的一步.本文借鉴G01dberg的云检测的思想,通过AIRS通道和相应微波通道的经验组合来进行云检测,此云检测方案不需要对通道进行偏差订正,并且除背景场海表温度,不依赖于大气的先验信息,是一个快速简...     

2004年齐河县小麦全生育期气象条件分析

通过对2003-2004年齐河县冬小麦全生育期的气象条件分析,发现有利的气象条件和合理灌溉、科学施肥是小麦高产的主要因素,评价了气象条件对小麦生长和产量的影响.     

丽水凹陷基岩岩性分布预测

东海陆架盆地丽水凹陷基岩潜山十分发育,钻井已证实其含油气性,勘探潜力巨大。综合现有基岩岩芯、铸体薄片、测井、测年、三维地震资料,在构建基岩岩相-地震相模板及岩石物理分析的基础上,对丽水凹陷基岩岩性开展定性和半定量预测,进而预测岩性平面分布特征。丽水凹陷基岩主要由片麻岩、花岗片麻岩、花岗岩组成,片麻岩为古元古界变质岩陆核,花岗岩来自中生代岩浆,沿深大断裂上涌侵入。地震剖面上片麻岩表现为中—高频,中—强振幅,同相轴连续性、成层性好;花岗岩表现为中—低频,弱—中振幅,呈杂乱反射;花岗片麻岩地震相介于前二者之间。岩石物理分析结果显示,密度参数对岩性区分效果最好,叠前密度反演能较好地半定量预测基岩分布特征。研究表明,丽水A洼主体基岩纵向呈片麻岩上覆花岗岩的二元结构特征;平面上不同构造单元的基岩顶面岩性各异,凸起区花岗岩剥蚀程度高,基岩为片麻岩或花岗片麻岩,洼槽区缺乏深大断裂,为原始区域片麻岩基底,其他区域为花岗岩。     

塔克拉玛干沙漠腹地地表辐射与能量平衡

利用2013年塔克拉玛干沙漠塔中流动沙面地表辐射、土壤热通量、土壤温湿度和湍流通量观测资料,分析了沙漠腹地地表辐射和能量收支特征及闭合状况。结果表明：除潜热通量外,其余地表辐射各分量和能量平衡分量的月平均日变化结果整体均表现为标准的单峰型日循环形态,其中R_s↓与R_s↑变化同步,R_l↑、R_l↓滞后R_s↓0.5 ~ 1 h。各分量均表现出夏季高、春秋季次之、冬季低的季节波动性。干旱和极低的植被覆盖造成沙漠腹地全年潜热通量始终较为微弱,约占净辐射的2.8%,感热通量成为能量的主要消耗形式,约占净辐射的49%。偶尔的降水会刺激潜热通量突然增加。地表反照率相对较高且稳定,日变化呈早晚大、正午小的“U”型趋势,并具有明显的冬季高、夏季低的季节波动性,年均值0.28,月均值0.25~0.32。能量残差各月的日变化也均呈单峰曲线,日出后和日落前能量闭合程度最佳,并出现过闭合现象,全年夏季小,春秋季次之,冬季较大,月平均日峰值5.1~99.9 W·m^-2。土壤表层热储存是影响该地区能量平衡的重要因子之一,考虑表层土壤热存储后,地表能量闭合率达75.3%,能量闭合率夏季 > 春季 > 秋季 > 冬季,白天相比夜间有大幅提升。     

汶川地震高速远程滑坡速度研究

汶川地震诱发了大量的高速远程滑坡。在超强的地震动作用下,坡体结构被撕裂并抛射后,受到坡体前缘地形及自身势能的影响,很容易转化为碎屑流作远程运动,这种高位滑坡以其很快的运动速度和超常的运动距离造成了巨大的灾害与损失。本文在对汶川地震大型典型高速远程滑坡大量现场调查的基础上,分析了坡体临空飞行运动初始速度、滑程运动最大速度以及碎屑流运动速度,并且以东河口滑坡为例,对比了不同计算方法下的运动速度和运动性,得到东河口滑坡的运动特征值μ=0.2292,最大运动速度Vm ax=63.40 m/s,平均运动速度超过25 m/s,属于超高速滑坡运动以及强碎屑流性质。     

围岩参数Monte－Carlo有限元反分析

提出了应用隧道施工监测的随机值，采用蒙特一卡罗（Ｍｏｎｔｅ－Ｃａｒｌｏ）有限元随机反分析以反推地层参数和初始地应力分布的方法。反推参数不仅给出其均值，还给出参数的方差及分布类型，为地下结构稳定性和可靠性分析提供必要数据。为检验所提的反分析方法对工程的实用性，文中给出了一个实例。     

Landscape pattern evolution processes of alpine wetlands and their driving factors in the Zoige Plateau of China

Zoige Plateau wetlands are located in the northeastern corner of the Qinghai-Tibet Plateau.The landscape pattern evolution processes in the Zoige Plateau and their driving factors were identified by analyzing the dynamic changes in landscape modification and conversion and their dynamic rates of alpine wetlands over the past four decades.The results showed that the landscape conversion between wetlands and non-wetlands mainly occurred during the period from 1966 to 1986.The marsh wetland area converted from lake and river wetlands was larger because of swamping compared to other wetland landscapes.Meanwhile,the larger area of marsh wetlands was also converted to lake wetlands more than other types of wetlands.The modification processes mainly occurred among natural wetland landscapes in the first three periods.Obvious conversions were observed between wetland and nonwetland landscapes(i.e.,forestland,grassland,and other landscapes) in the Zoige Plateau.These natural wetland landscapes such as river,lake and marsh wetlands showed a net loss over the past four decades,whereas artificial wetland landscapes(i.e.,paddy field and reservoir and pond wetlands) showed a net decrease.The annual dynamic rate of the whole wetland landscape was 0.72%,in which the annual dynamic rate of river wetlands was the highest,followed by lake wetlands,while marsh wetlands had the lowest dynamic rate.The integrated landscape dynamic rate showed a decreasing trend in the first three periods.The changes in wetland landscape patterns were comprehensively controlled by natural factors and human activities,especially human activities play an important role in changing wetland landscape patterns.     

长江河口拦门沙河床淤积和泥沙再悬浮过程

利用近２０年来长江河口所观测的地形、水文、悬沙和河床沉积物资料,着重对１９８８、１９８９、１９９６和１９９７年最新观测资料进行计算分析。结果表明,长江河口航道拦门沙河段来水沙量大,潮流作用强,潮波变形明显,水流挟沙力强。该河段潮流速随时间和空间变化,又处在盐淡水交换地带,流域和海域来沙在此河率时淤时冲,悬沙与床沙交换频繁,表现在涨急、落急时可床淤积层泥沙再次起动悬浮,憩流时只河床,在一个潮周期中含     

EH-4系统观测资料的非远区场校正研究

EH－4系统实测的卡尼亚视电阻率在非远区场时应作必要的校正。基于导出的EH－4系统的卡尼亚电阻率ρxy和ρyx的表达式，采用多项式分段逼近的方法，建立EH－4系统测深数据的全频域的视电阻率算法。根据建立的算法对均匀大地、二层大地和三层大地模型的EH－4系统测深数据进行非远区场校正的结果表明：均匀大地时，全频域的视电阻率与真电阻率吻合很好，D型、K型和Q型断面的视电阻率曲线与MT法的接近，G型、H型和A型的视电阻率曲线得到很大改善。     

A comparative analysis of the NDVIg and NDVI3g in monitoring vegetation phenology changes in the Northern Hemisphere

Phenology is a sensitive and critical feature of vegetation and is a good indicator for climate change studies. The global inventory modelling and mapping studies (GIMMS) normalized difference vegetation index (NDVI) has been the most widely used data source for monitoring of the vegetation dynamics over large geographical areas in the past two decades. With the release of the third version of the NDVI (GIMMS NDVI3g) recently, it is important to compare the NDVI3g data with those of the previous version (NDVIg) to link existing studies with future applications of the NDVI3g in monitoring vegetation phenology. In this study, the three most popular satellite start of vegetation growing season (SOS) extraction methods were used, and the differences between SOSg and SOS3g arising from the methods were explored. The amplitude and the peak values of the NDVI3g are higher than those of the NDVIg curve, which indicated that the SOS derived from the NDVIg (SOSg) was significantly later than that derived from the NDVI3g (SOS3g) based on all the methods, for the whole northern hemisphere. In addition, SOSg and SOS3g both showed an advancing trend during 1982–2006, but that trend was more significant with SOSg than with SOS3g in the results from all three methods. In summary, the difference between SOSg and SOS3g (in the multi-year mean SOS, SOS change slope and the turning point in the time series) varied among the methods and was partly related to latitude. For the multi-year mean SOS, the difference increased with latitude intervals in the low latitudes (0–30°N) and decreased in the mid- and high-latitude intervals. The GIMMS NDVI3g data-sets seemed more sensitive than the GIMMS NDVIg in detecting information about the ground, and the SOS3g data were better correlated both with the in situ observations and the SOS derived from the Moderate Resolution Imaging Spectroradiometer NDVI. For the northern hemisphere, previous satellite measures (SOS derived from GIMMS NDVIg) may have overestimated the advancing trend of the SOS by an average of 0.032 d yr^–1.