Jacobian matrix for near-infrared remote sensing based on vector radiative transfer model

Due to the polarization effects of the Earth's surface reflection and atmospheric particles' scattering, high-precision retrieval of atmospheric parameters from near-infrared satellite data requires accurate vector atmospheric radiative transfer simulations. This paper presents a near-infrared vector radiative transfer model based on the doubling and adding method. This new model utilizes approximate calculations of the atmospheric transmittance, reflection, and solar scattering radiance for a finitely thin atmospheric layer. To verify its accuracy, the results for four typical scenarios(single molecular layer with Rayleigh scattering, single aerosol layer scattering, multi-layer Rayleigh scattering, and true atmospheric with multi-layer molecular absorption, Rayleigh and aerosol scattering) were compared with benchmarks from a well-known model. The comparison revealed an excellent agreement between the results and the reference data, with accuracy within a few thousandths. Besides, to fulfill the retrieval algorithm, a numerical differentiation-based Jacobian calculation method is developed for the atmospheric and surface parameters. This is coupled with the adding and doubling process for the radiative transfer calculation. The Jacobian matrix produced by the new algorithm is evaluated by comparison with that from the perturbation method. The relative Jacobian matrix deviations between the two methods are within a few thousandths for carbon dioxide and less than 1.0×10~(-3)% for aerosol optical depth. The two methods are consistent for surface albedo, with a deviation below 2.03×10~(-4)%. All validation results suggest that the accuracy of the proposed radiative transfer model is suitable for inversion applications. This model exhibits the potential for simulating near-infrared measurements of greenhouse gas monitoring instruments.     

阻尼连体结构地震响应影响参数研究

针对阻尼连体结构,采用串并联质点系层模型,沿连体设置方向施加El Centro1940地震波,讨论了毗邻结构自振周期比与连接体阻尼刚度变化对阻尼连体结构地震响应的影响。研究结果表明:毗邻结构自振周期比与连体阻尼刚度对结构的地震响应影响较大,存在一个使结构地震响应为最优的周期比与阻尼刚度值,为实际工程应用和研究提供一些参考。     

Research on the impact assessment of urbanization on air environment with urban environmental entropy model: a case study

A new concept of urban environmental entropy was introduced to investigate the effect of urbanization on air environment considering the fact that rapid development of urbanization may have negative influence on the whole air environment system. The urban environmental entropies which were built based on the generalized thermodynamic entropy and the generalized statistic entropy, respectively. These two entropy models have been used to analyze the relationship between the development of urbanization and air environment. The negative entropy flow mechanism was proposed to reveal the advantages and approaches of regional cities in improving air environment system. A case study on 17 cities in Shandong Province of China showed that the values of urban environmental entropy were negative in most cities from 2001 to 2008, which implies that there is a positive correlation between the development of urbanization and air environment and that is a negative entropy development level in Shandong Province of China. In 2008, the urbanization of Qingdao city and Jinan city improved their air environments. Moreover, restraints for both cities in air environment improvement were recognized according to the analysis of negative entropy flow mechanism.     

海南琼海加积井水位对远大震的同震响应特征研究

In this study,we analyze the co-seismic response of water levels in the Jiaji well to strong earthquakes(MS≥7.8) from 2001 to 2010 at an epicentral distance less than 8000km.We investigated the co-seismic variation form of water levels,and analyzed the relationship between the amplitude of water level variation and the magnitude and the epicentral distance.We then checked the seismic wave phases when the changes of water level occurred.It was shown that:(1) the water level’s co-seismic response is mainly characterized by escalation with no oscillation;(2) the amplitude of water level change has a certain connection with epicentral distance and magnitude;(3) co-seismic response of water levels in the Jiaji well shows a certain directivity;(4) most of the co-seismic responses were caused by surface waves,and some by long-period S waves.     

甘肃省农村居民地震常识情况的调查分析

了解农村居民对地震常识的掌握情况是做好农村震害防御工作的重要参考.本文研究设计了调查表格,对农村居民地震常识的掌握情况进行了调查.通过甘肃省16个县(区)的现场抽样调查,得到了甘肃省农村居民的地震常识掌握情况,并通过对比研究,分析了造成农村居民地震常识掌握不足以及造成差异的影响因素.基于调查结果,本文针对农村居民地震常识的掌握情况,提出了增强农村居民防震减灾知识,提高其震害防御意识的工作建议.     

大渡河长河坝水电站区域泥石流特征及危险性评价

2009年7月23日,四川省甘孜州康定县舍联乡长河坝水电站施工区响水沟发生特大泥石流灾害,造成重大人员伤亡和财产损失。响水沟是大渡河上游段右岸一级支沟,近百年来泥石流活动不明显。由于之前近一个月的连续降雨,沟谷内的不稳定堆积物已基本处于饱水状态,当日的强降雨直接诱发了此次泥石流灾害。本文根据现场调查资料,就该沟泥石流的形成条件、灾害成因及特征进行分析,并应用灰色系统理论关联分析方法和沟谷泥石流危险度计算分析综合评价其危险性。结果表明,在极端气象条件下,响水沟仍有可能发生中等至大规模暴雨型粘性泥石流。     

Rate and historical change of direct recharge from precipitation constrained by unsaturated zone profiles of chloride and oxygen‐18 in dry river bed of North China Plain

Quantifying of direct recharge derived from precipitation is crucial for assessing sustainability of well‐irrigated agriculture. In the North China Plain, the land use is dominated by groundwater‐irrigated farmland where the direct recharge derived from precipitation and irrigation. To characterize the mean rate and historical variance of direct recharge derived from precipitation, unsaturated zone profiles of chloride and δ¹⁸O in the dry river bed of the Beiyishui River were employed. The results show that archival time scale of the profile covers the duration from 1980 to 2002 (corresponding to depths from 5 to 2 m) which is indicated by matching the δ¹⁸O peaks in the isotope profile with the aridity indexes gained by instrumental records of annual precipitation and annual potential evaporation. Using the chloride mass balance method, the mean rate of the direct recharge corresponding to the archival time scale is estimated to be 3·8 ± 0·8 mm year^?1, which accounts for about 0·7% of the long‐term average annual precipitation. Further, the direct recharge rates vary from 2·1 to 6·8 mm year^?1 since 1980. Despite the subhumid climate, the estimate of recharge rates is in line with other findings in semiarid regions. The low rate of direct recharge is considered as a result of the relative dry climate in recent decades. In dry river bed, unsaturated zone profiles of chloride and δ¹⁸O combined with instrumental records could offer valuable information about the direct recharge derived from precipitation during droughts. Copyright © 2011 John Wiley & Sons, Ltd.     

Influence of heterogeneity on unsaturated hydraulic properties: (1) local heterogeneity and scale effect

Spatial heterogeneity is ubiquitous in nature, which may significantly affect the soil hydraulic property curves. The models of a closed‐form functional relationship of soil hydraulic property curves (e.g. VG model or exponential model) are valid at point or local scale based on a point‐scale hydrological process, but how do scale effects of heterogeneity have an influence on the parameters of these models when the models are used in a larger scale process? This paper uses a two‐dimensional variably saturated flow and solute transport finite element model (VSAFT2) to simulate variations of pressure and moisture content in the soil flume under a constant head boundary condition. By changing different numerical simulation block sizes, a quantitative evaluation of parameter variations in the VG model, resulting from the scale effects, is presented. Results show that the parameters of soil hydraulic properties are independent of scale in homogeneous media. Parameters of α and n in homogeneous media, which are estimated by using the unsaturated hydraulic conductivity curve (UHC) or the soil water retention curve (WRC), are identical. Variations of local heterogeneities strongly affect the soil hydraulic properties, and the scale affects the results of the parameter estimations when numerical experiments are conducted. Furthermore, the discrepancy of each curve becomes considerable when moisture content becomes closer to a dry situation. Parameters estimated by UHC are totally different from the ones estimated by WRC. Copyright © 2012 John Wiley & Sons, Ltd.     

Gravity field and tectonic features of Block L2 in the Lamu basin,Kenya

A gravity survey on the scale of 1: 250 000 was carried out in Block L2 located in the Lamu basin of south‐east Kenya in order to study tectonic features and find out favourable petroleum prospects in the block. This paper, through data processing and synthetic interpretation of the measured gravity data in the block, discusses characteristics of the gravity field and their geological implications, determines the fault system and the basement depth, analyses features of the main strata, divides structure units and predicts favourable petroleum zones. In the block, the regional gravity anomaly is mainly caused by the inclined Moho surface that rises in the east and subsides in the west topographically and the Bouguer gravity anomaly primarily reflects the superimposition of the gravity effect derived from the Moho surface and the basement relief. Two groups of faults extending NW (NWW) and NE (NEE) respectively are dominant in the block and their activities resulted in the framework of east‐west zoning and south‐north blocking. The basement depth greatly changes in an alternative high and low pattern. The Permian‐Triassic, Jurassic and Tertiary strata are extensively developed, while the Cretaceous is only developed in the east of the block. Structurally, the block can be divided into five units, of which the Tana sag shows excellent source‐reservoir‐seal associations and is a favourable target for future petroleum exploration.     

The thermal history and uplift process of the Ouxidaban pluton in the South Tianshan orogen: Evidence from Ar-Ar and (U-Th)/He

The uplift and exhumation process in the Tianshan orogen since the late Paleozoic were likely related to the preservation of ore deposits. This study involved reconstructing the whole tectonic thermal history of the Ouxidaban pluton in central South Tianshan Mountains based on hornblende/plagioclase Ar-Ar and zircon/apatite(U-Th)/He methods. The thermal history and uplift process of central South Tianshan Mountains since the late Paleozoic were analyzed according to the results of previous works and cooling/exhumation rate features. The hornblende yields a plateau age of 382.6±3.6 Ma, and the plagioclase yields a weighted mean age of 265.8±4.9 Ma. The Ouxidaban pluton yields weighted mean zircon(U-Th)/He age of 185.8±4.3 Ma and apatite(U-Th)/He age of 31.1±2.9 Ma, respectively. Five stages of tectonic thermal history of South Tianshan Mountains since the late Paleozoic could be discriminated by the cooling curve and modeling simulation:(1) from the latest Silurian to Late Devonian, the average cooling rate of the Ouxidaban pluton was 7.84°C/Ma;(2) from the Late Devonian to the latest Middle Permian, the average cooling rate was about 2.07°C/Ma;(3) from the latest Middle Permian to the middle Eocene, the cooling rate decreased to about 0.68°C/Ma, suggesting that the tectonic activity was gentle at this time;(4) a sudden increase of the cooling rate(5.00°C/Ma) and the exhumation rate(0.17 mm/a), and crustal exhumation of ~1.83 km indicated that the Ouxidaban pluton would suffer a rapid uplift event during the Eocene(~46?35 Ma);(5) since the middle Eocene, the rapid uplift was sustained, and the average cooling rate since then has been 1.14°C/Ma with an exhumation rate of about 0.04 mm/a and an exhumation thickness of 1.33 km. The strong uplift since the Cenozoic would be related to a far-field effect from the Indian and Eurasian plates' collision. However, it was hysteretic that the remote effect was observed in the Tianshan orogenic belt.