Problems of modeling climate and climate change

The properties of the climate system as a physical object are considered. Major concepts of the mathematical theory of climate are stated, and the problems of constructing mathematical climate models are discussed. The results of reproducing the present-day climate are analyzed, and the sensitivity of the climate system to changes in the content of greenhouse gases is considered. Major directions are formulated in which the development of the mathematical theory of climate and of modeling climate and climate change is possible.     

台湾海峡台风暴潮非线性数值计算

台湾海峡平均水深不大于50米,台风侵袭频繁.由于台湾岛的“墙壁效应”和台湾海峡的“狭管效应”的影响,台湾海峡的台风暴潮显得较为独特.以前,我们及其他兄弟单位对福建沿海台风暴潮的研究,大多数仅局限于单站的气-水动力相互作用的研究,很少涉及整个海峡.虽说我们也曾作过福建沿岸台风暴潮现场调查,但进行次数有限,了解的也仅是海峡西岸局部地区的情况,它仅能反映台湾海峡台风暴潮的一个侧面,而无法了解整个海峡地区的风暴潮全貌.     

The Huelva (Spain) Tsunami-Ready Station and Its Interaction with Storm Emma (March 2018)

Abstract

The sea level station operating since 1996 at Mazagón (Huelva, Spain) has been progressively upgraded to fit tsunami warning requirements, due to its location in one of the main regions at risk. Its radar water level sensor was complemented in 2017, with the addition of a pressure sensor. The performance of both sea level sensors and their response to sea level oscillations, at different frequencies, is assessed. Particular emphasis is put on the effect of extreme events, such as Storm Emma, when alternative methods to obtain 1-min data are tested, in contrast to the one based on arithmetic means. The overall differences are small, for the whole period of study (centered-root-mean-square-error below 1?cm, for 5-min, and hourly data; similar tidal parameters and sea level oscillations with periods between 30?s and 5?min). However, during Storm Emma, the pressure sensor presents sensibly lower readings than the radar, with the centered-root-mean-square-error rising to 80?mm on the March 2^nd 2018. A new method to compute 1-min data, based on medians, reduced this value to 10?mm for the same day.     

A low level supplementary heating system for free divers

A simple and effective method of heating divers in extreme cold water has been developed. The local heating concept utilizes a uniformly distributed granular mixture of magnesium and iron particles packed in small sachets. Upon activation by sea water, the two metal mixture behaves as a multitude of short-circuited electrolytic cells, producing thermal energy rather than electrical energy. The 45 mm-square sachets may be placed where heating is required on the diver's body, thus giving rise to the term “local heating”, obviously, the heating system requires no pumping device, or distribution network. Heating rate and duration of output of the sachets are controlled by particle size, and mixture ratio of the constituent Mg and Fe particles.This paper described the development, testing and performance of the heating sachets. Results of live tests in different dive situations are also presented and discussed.     

Robust and adaptive path following for underactuated autonomous underwater vehicles

This paper proposes a nonlinear robust adaptive control strategy to force a six degrees of freedom underactuated underwater vehicle with only four actuators to follow a predefined path at a desired speed despite of the presence of environmental disturbances and vehicle’s unknown physical parameters. The proposed controller is designed using Lyapunov’s direct method, the popular backstepping and parameter projection techniques. The closed loop path following errors can be made arbitrarily small. Interestingly, it is shown that our developed control strategy is easily extendible to situations of practical importance such as parking and point-to-point navigation. Numerical simulations are provided to illustrate the effectiveness of the proposed methodology.     

Susceptibility to genetic damage and cell types in Mediterranean mussels

Micronucleus (MN) frequency is generally accepted as a marker of chromosomal damage and has been studied in a variety of cells and species. In previous work, we detected significant dose-related MN increases in the epithelial-like gill cells and agranular haemocytes of Mytilus galloprovincialis treated with benzo[a]pyrene, a well-known mutagenic pollutant. In addition, we have studied micronuclei and other nuclear abnormalities in mussels collected from the Venice lagoon (Italy). Frequency changes, possibly related to genotoxic/toxic stress, in both granular and micronucleated cells from gills and haemolymph, were detected. Environmental data suggest the effect of genotoxic pollutants and the importance of cell replication in the interpretation of micronucleus frequencies.     

Evaluation of long-term extreme response statistics of jack-up platforms

This paper is concerned with the models appropriate for the dynamic assessment of jack-ups, concentrating particularly on the long-term response due to random ocean waves and on work-hardening plasticity models used for spud-can response. A methodology for scaling of short-term statistics, calculated using a Constrained NewWave technique, is shown in a numerical experiment for an example jack-up and central North Sea location. The difference in long-term extreme response statistics due to various footing assumptions is emphasised. Results for two environmental load conditions are described (one excluding and one including wind and current effects) and the role of sea-state severity in the variation of short-term extreme response statistics is also highlighted.     

Prediction of hydrodynamic loading on a mini TLP with free surface effects

This paper describes the extension of a fluid-flow simulations method to capture the free surface evolution around a full-scale Tension Leg Platform (TLP). The focus is on the prediction of the resulting hydrodynamic loading on the various elements of the TLP in turbulent flow conditions and, in particular, on quantifying the effects of the free surface distortion on this loading. The basic method uses finite-volume techniques to discretize the differential equations governing conservation of mass and momentum in three dimensions. The time-averaged forms of the equations are used, and the effects of turbulence are accounted for by using a two-equation, eddy-viscosity closure. The method is extended here via the incorporation of surface-tracking algorithm on a moving grid to predict the free-surface shape. The algorithm was checked against experimental measurements from two benchmark flows: the flow over a submerged semi-circular cylinder and the flow around a floating parabolic hull. Predictions of forces on a model TLP were then obtained both with and without allowing for the deformation of the free surface. The results suggest that the free surface effects on the hydrodynamic loads are small for the values of Froude number typically encountered in offshore engineering practice.     

SAS测量水体表观光学参数的方法

SeaWiFS航空模拟器（SAS）是专门为在水面之上测量水体表观光学参数的现场设备。文章在介绍SAS现场测量以及数据处理基本方法的基础上，分析了2002年黄海试验SAS的应用效果，并与剖面法测量数据进行了比对。