基于颗粒类型的冻土分类

Based on the log-normal distribution of the grain size density function derived earlier for the entire zone of mineral disintegration, a unified granulometric taxon of perennially frozen soils is proposed which generalizes the existing soil classifications.     

Distribution of wave crests in a non-Gaussian sea

The sea elevation at a fixed point is modelled as a quadratic form of a vector valued Gaussian process with arbitrary mean. With this model, saddlepoint methods are used to approximate the mean upcrossing intensity with which the sea level crosses upwards at a certain height. This estimated intensity is further used to determine the probability distribution of wave crests. The use of saddlepoint technique is particularly important here because it can approximate the crest distribution without the need to perform simulations or use fitted distributions. Several numerical examples are given, including two with measured data. In the cases of real data, the results obtained with the saddlepoint technique are also compared with the results obtained with well known methods commonly used in the industry.     

Modelling hydrographic changes in the Labrador sea over the past five decades

Inter-annual to inter-decadal changes of hydrographic structure and circulation in the subpolar North Atlantic are studied using a coarse resolution ocean circulation model. The study covers 1949 through 2001, inclusive. A “time-mean state nudging” method is applied to assimilate the observed hydrographic climatology into the model. The method significantly reduces model biases in the long-term mean distribution of temperature and salinity, which commonly exist in coarse-resolution ocean models. By reducing the time-mean biases we also significantly improve the model’s representation of inter-annual to inter-decadal variations. In the central Labrador Sea, the model broadly reproduces the heat and salt variations of the Labrador Sea Water (LSW) as revealed by hydrographic observations. Model sensitivity experiments confirm that the low-frequency hydrographic changes in the central Labrador Sea are closely related to changes in the intensity and depth of deep convection. Changes in surface heat flux associated with the winter North Atlantic Oscillation (NAO) index play a major role in driving the changes in T–S and sea surface height (SSH). Changes in wind stress play a secondary role in driving these changes but are important in driving the changes in the depth-integrated circulation. The total changes in both SSH and depth-integrated circulation are almost a linear combination of the separate influences of variable buoyancy and momentum fluxes.     

Current estimates of freshwater flux through Arctic and subarctic seas

As the world warms, the expectation is that the freshwater outflows from the Arctic Ocean to the North Atlantic will strengthen and may act to suppress the rate of the climatically-important Atlantic meridional overturning circulation. Hitherto, however, we have lacked the system of measurements required to estimate the totality of the freshwater flux through subarctic seas. Though observations remain patchy and rudimentary in places, we piece-together the results from recent large-scale observational programmes together with associated modelling, to establish preliminary maps of the rates and pathways of freshwater flux through subarctic seas. These fluxes are calculated according to two reference salinities, S = 34.8 to conform with the majority of estimates reported in the literature, and S = 35.2, the salinity of the inflowing Atlantic water, to calculate the freshwater balance of the ‘Arctic Mediterranean’. We find that 148 mSv of freshwater enters the Nordic Seas across its northern boundary. There it is supplemented by around 54 mSv of freshwater from Baltic runoff, Norwegian runoff, P − E and Greenland ice melt, so that the total freshwater contribution to the Nordic Seas from all sources is 202 mSv. Of this, around 51 mSv of freshwater is estimated to pass south to the deep Atlantic in the dense water overflows leaving an assumed balance of 151 mSv to leave the Nordic Seas in the upper water export through Denmark Strait. The corresponding estimate for the freshwater outflow west of Greenland is 103 mSv relative to 35.2 so that the total freshwater flux reaching the North Atlantic through subarctic seas is around 300 mSv.     

Long-term variability of sea surface temperature in Taiwan Strait

Long-term variability of sea surface temperature (SST) in the Taiwan Strait was studied from the U.K. Met Office Hadley Centre climatological data set HadISST1. In 1957–2011, three epochs were identified. The first epoch of cooling SST lasted through 1976. The regime shift of 1976–1977 led to an extremely rapid warming of 2.1 °C in 22 years. Another regime shift occurred in 1998–1999, resulting in a 1.0 °C cooling by 2011. The cross-frontal gradient between the China Coastal Current and offshore Taiwan Strait waters has abruptly decreased in 1992 and remained low through 2011. The long-term warming of SST increased towards the East China Sea, where the SST warming in 1957–2011 was about three times that in the South China Sea. The long-term warming was strongly enhanced in winter, with the maximum warming of 3.8 °C in February. The wintertime amplification of long-term warming has resulted in a decrease of the north–south SST range from 5 to 4 °C and a decrease in the amplitude of seasonal cycle of SST from 11 to 8 °C.     

俄罗斯高精度重力法直接预测油气藏（GONG）技术的原理及应用效果分析

本文研究一种最优化的俄罗斯油气勘探中的地球物理和实用方法．简要描述了作为该方法的基础的重力－地震综合解释，并在理论上建立了这种解释模式．用该方法可给出油气勘探阶段远景区评价，其预测探井成功率在８０％～９０％。     

Three‐dimensional vorticity and time‐constrained evolution of the Main Central Thrust zone,Garhwal Himalaya (NW India)

Vorticity estimates based on porphyroclasts analysis are limited by the extrapolation to three dimensions of two‐dimensional data. We describe a 3D approach based on the use of X‐ray micro‐computed tomography that better reflects the real 3D geometry of the porphyroclasts population. This new approach for kinematic vorticity analysis in the Munsiari Thrust mylonites, the lower boundary of the Main Central Thrust zone (MCTz) in Indian Himalaya, indicates a large pure shear component during non‐coaxial shearing. ⁴⁰Ar/³⁹Ar ages of micas along the mylonitic foliation of the Munsiari and Vaikrita thrusts (the upper boundary of the MCTz) constrain thrust activity to 5–4 and 8–9 Ma, respectively. Available kinematic vorticity analyses of the Vaikrita mylonites suggest the dominance of a simple shear component. Combining these data, we suggest that the southward and structurally downward shift of deformation along the MCTz was accompanied by a progressive increase in the pure shear component in a general shear flow.