Detecting patterns of climate change in long-term forecasts of marine environmental parameters

ABSTRACT

Forecasting environmental parameters in the distant future requires complex modelling and large computational resources. Due to the sensitivity and complexity of forecast models, long-term parameter forecasts (e.g. up to 2100) are uncommon and only produced by a few organisations, in heterogeneous formats and based on different assumptions of greenhouse gases emissions. However, data mining techniques can be used to coerce the data to a uniform time and spatial representation, which facilitates their use in many applications. In this paper, streams of big data coming from AquaMaps and NASA collections of 126 long-term forecasts of nine types of environmental parameters are processed through a cloud computing platform in order to (i) standardise and harmonise the data representations, (ii) produce intermediate scenarios and new informative parameters, and (iii) align all sets on a common time and spatial resolution. Time series cross-correlation applied to these aligned datasets reveals patterns of climate change and similarities between parameter trends in 10 marine areas. Our results highlight that (i) the Mediterranean Sea may have a standalone ‘response’ to climate change with respect to other areas, (ii) the Poles are most representative of global forecasted change, and (iii) the trends are generally alarming for most oceans.     

副高异常偏西背景下西北一次漏报的雷暴大风中尺度分析*

摘要：利用西安多普勒天气雷达、L波段风廓线雷达和加密自动站探测资料，结合天气实况，对2018年7月26日发生在陕西一次副热带高压影响下的的强风暴过程进行了中尺度分析。结果表明：（1）本次强风暴伴随的阵风锋共维持了4h，其中有3h出现7级以上的大风，且最大风力10级。（2）在副热带高压影响下，陕西处于高温、高湿气团中，大气层结极不稳定。（3）此次强风暴在高的对流有效位能环境下（CAPE）下，抬升触发的关键因子是关中地区中尺度辐合线，当初生的对流云团下山后，中尺度辐合线触发的对流风暴形成小范围冷池出流与环境风场形成新的辐合线，加强对流风暴发展。（4）当阵风锋移动过程中遇到前方的对流云团时，将低层暖湿空气抬升，并随着上升气流输送到主体对流风暴中，迅速补充了主体风暴的能量，使得主体风暴再次强烈发展，延长了阵风锋的生命史。     

Relationships between moment magnitude and fault parameters: theoretical and semi-empirical relationships

Fault parameters are important in earthquake hazard analysis. In this paper, theoretical relationships between moment magnitude and fault parameters including subsurface rupture length, downdip rupture width, rupture area, and average slip over the fault surface are deduced based on seismological theory. These theoretical relationships are further simplified by applying similarity conditions and an unique form is established. Then, combining thc simplified theoretical relationships between moment magnitude and fault parameters with seismic source data selected in this study, a practical semi-empirical relationship is established. The seismic source data selected is also to used to derive empirical relationships between moment magnitude and fault parameters by the ordinary least square regression method. Comparisons between semi-empirical relationships and empirical relationships show that the former depict distribution trends of data better than the latter. It is also observed that downdip rupture widths of strike slip faults are saturated when moment magnitude is more than 7.0, but downdip rupture widths of dip slip faults are not saturated in the moment magnitude ranges of this study.     

测井资料在碳酸盐岩洞—裂缝型储层产能评价中的应用

介绍了一种基于测井资料来预测双孔结构碳酸盐岩储层产能的新方法。首先根据碳酸盐岩剖面中双孔结构储层的地质和测井特征,提取与储层产能密切相关的多个测井和地质参数,考虑到这些参数与产能的非线性相关关系以及产能数据的变化特点,采用BP神经网络技术建立其储层产能的预测模型,由此处理了轮南地区的多口井测井资料。所预测的储层段产能与试油产能较为一致,效果良好。     

Two attempts of study of seismic source from teleseismic data by simulated annealing non-linear inversion

Two seismic source studies usingteleseismic data are performed by Simulated Annealing(SA), a non-linear inversion method. The Very FastSimulated Annealing (VFSA) algorithm is used and onlyteleseismic data are inverted. We have designed a fastand efficient way of multiple direct problemevaluation, which is based on pre-calculating theelementary Green's function. During the process we setthe values of the inversion control parameters(temperature, number of iterations) and modified thecooling schedule. In the current version, theinversion seeks for the point source mechanism, thedepth of the source, the scalar moment and the sourcetime function (STF). The method is applied to twoearthquakes: 18 Nov. 1992 in Greece, M 5.9 and 14 Sep.1995 in Mexico, M7.3. The calculation is performed ona simple 1D model of the structure. For the firstearthquake the inversion recovered the solution fairlywell; for the second the solution was less acceptable.However, we do not consider this fact to be a failureof the method, but a consequence of an inadequatemodel of the source and of the medium structure. Acasual attempt of reliability determination was alsoperformed; the obtained values of errors arereasonable, except for a few cases when the methodfailed.     

A modified ISBA surface scheme for modeling the hydrology of Athabasca River Basin with GCM-scale data

A soil–vegetation–atmosphere transfer model (SVAT), interactions between the soil–biosphere–atmosphere (ISBA) of Météo France, is modified and applied to the Athabasca River Basin (ARB) to model its water and energy fluxes. Two meteorological datasets are used: the archived forecasts from the Meteorological Survey of Canada’s Global Environmental Multiscale Model (GEM) and the European Centre for Mid-range Weather Forecasts global re-analysis (ERA-40), representing spatial scales typical of a weather forecasting model and a global circulation model (GCM), respectively. The original treatment of soil moisture and rainfall in ISBA (OISBA) is modified to statistically account for sub-grid heterogeneity of soil moisture and rainfall to produce new, highly non-linear formulations for surface and sub-surface runoff (MISBA). These new formulations can be readily applied to most existing SVATs. Stand alone mode simulations using the GEM data demonstrate that MISBA significantly improves streamflow predictions despite requiring two fewer parameters than OISBA. Simulations using the ERA-40 data show that it is possible to reproduce the annual variation in monthly, mean annual, and annual minimum flows at GCM scales without using downscaling techniques. Finally, simulations using a simple downscaling scheme show that the better performance of higher resolution datasets can be primarily attributed to improved representation of local variation of land cover, topography, and climate.     

利用抽水试验资料确定水文地质参数

本文根据抽水试验取得的数据,分别采用稳定流公式法、降深-距离配线法、漏斗疏干法和直线解析法四种方法,计算了黄河侧渗补给浅层地下水的各项水文地质参数,最后对试验成果的合理性进行了分析评价并确定了各项水文地质参数.     

土在高压力段的压缩性参数外推方法探讨

根据土高压固结试验的压缩曲线几何特征,提出了基于一定较高压力水平的固结试验结果外推更大压力段的压缩性参数和压缩曲线的方法。实际验证结果表明,该方法简便易行,且精确度较高。     

进化策略算法在地面沉降量计算参数反演中的应用

多数情况下,评估的研究区缺乏多年积累的地下水位及开采量资料。因此,通常采用土力学模型,根据太沙基固结理论,进行地面沉降量预测。在地面沉降量计算中,土层变形参数值的选取直接影响计算结果的精确性。深层含水层埋深通常大于100m。通过现场勘探,采取土样进行岩土物理力学性质试验获取参数值,成本过于昂贵。通过参考区域土层物理力学性质资料,结合工程经验获取参数值,预测结果的精度得不到保证。针对上述情况,作者提出用非线性优化算法-进化策略算法,根据实测地面沉降量反演土层变形参数值。通过这种方法确定参数值,既节约成本,又保证了计算结果的可靠性。进化策略算法通过模拟生物遗传及进化过程,利用转移概率来帮助指导搜索。搜索结果不依赖于初始点的选择,对于求解全局最优解有很强的鲁棒性。作者将进化策略算法用于某一工程实例土层变形参数的反演,结果表明了该算法的可行性及稳健性,值得在工程实践中推广应用。