Core-collapse supernovae and their massive progenitors

In this summary of the 10 November 2006 RAS Specialist Discussion Meeting, organizers Paul Crowther and Steve Smartt consider aspects of massive stellar evolution, their dependence upon stellar winds, progenitor models and explosion mechanisms. In addition, observations of core-collapse supernovae were discussed alongside the question of whether supernovae form significant quantities of dust, of relevance to the detection of dust in star-forming galaxies in the early universe.     

Neutron-induced nucleosynthesis

Neutron-induced nucleosynthesis plays an important role in astrophysical scenarios like in primordial nucleosynthesis in the early universe, in the s-process occurring in Red Giants, and in the -rich freeze-out and r-process taking place in supernovae of type II. A review of the three important aspects of neutron-induced nucleosynthesis is given: astrophysical background, experimental methods and theoretical models for determining reaction cross sections and reaction rates at thermonuclear energies. Three specific examples of neutron capture at thermal and thermonuclear energies are discussed in some detail.     

由地震和爆炸激发的地震P波层析成像——第一部分基本概念与理论

地震波的数字宽频带观测日益普遍,它们正在取代传统的观测,因为后者仅仅给出了地震震源产生的地震波场的部分图像.新的观测提供了远场地震波场的丰富信息,有的似乎是全部信息.然而宽带记录看上去很复杂,如果需要提取更详细的震源过程的信息和相关介质的结构的信息,就需要新的分析方法.为了识别到达观测点的地震信号的形态,我们引入谱地震图的方法.据此,传统的地震波场的显示方法不能呈现的信息细节可以被呈现出来.     

RECENT DEVELOPMENTS IN UNDERGROUND GRAVITY SURVEYS1

Underground gravity observations in deep coal mines using the conventional gravity meters Worden (type Master) and LaCoste-Romberg (model D), both of which have been adapted to the fire damp regulations, can be accurate to ± 10 and ± 3 μgal, respectively. For underground determination of the vertical gradient of gravity the LaCoste-Romberg meter is used together with a specially designed measuring tower. Using this euipment an accuracy in tower gradient observations of ± 30 E was obtained. To apply the equipment to precision gravity observations in underground situations an additional correction, i.e. a gallery correction, is needed. High accuracy in correction is achieved by a new method of three-dimensional modelling. The gravity effect is computed for bodies with a surface approximated by triangular elements, which are generated from corner points of the body. The combination of gallery correction with tower gradient data leads to a new method for in situ density determination. It offers the possibility of horizontal instead of vertical density profiling. To demonstrate the effectiveness of the developments in underground observations the localization of a pump room is presented. Microgravity and tower gradient observations were carried out to detect the cavity. The horizontal gradient was also calculated to give a more reliable location.     

高效接地树脂复合电极系统的实验观测研究

提出了一种用于地电观测的新型电极系统－高效接地树脂复合电极，通过台站场地的对比观测实验和内电化学测试的结果表明，高效接地树脂电极具有较好的接地特民生和稳定的极化特性，其电极性能优于目前普遍使用的铅电极，可以用来代替铅电极在台站中应用。     

The XMM-Newton Serendipitous Sky Survey

Mike Watson heralds the 2XMM catalogue, a valuable new X-ray astronomy resource compiled from XMM-Newton observations.     

地球现代板块运动的天文和人卫多普勒测定

本文根据作者首次得到的全球113架光学天文仪器观测纲要的数千个星组未知数G,计算研究了1962-1982年间地球板块运动的某些方面.同时还根据1973-1983年间人卫多普勒的测量结果进行了相应的研究.这两种独立的技术其测量结果符合较好,且与地球物理和VLBI的测量结果相吻合.     

Measurements of the solar wind over a wide range of heliocentric distances — a comparison of results from the first three Whole Sun Months

Co-ordinated observations of the Sun and inner heliosphere using a large number of space- and ground-based instruments were carried out in August–September 1996, August 1998 and August–September 1999 as the first, second and third Whole Sun Months. These observations provided unprecedented cover of the Sun and inner heliosphere at solar minimum (1996) and during the rising phase of the new solar cycle (1998, 1999). In this paper we review the observations made during the three Whole Sun Months and consider the changes in the large-scale structure of the heliosphere seen over the four years.     

怀4井新旧自动测氦仪比测分析

为验证新WGK-1型测氦仪在怀4井观测的可行性,在相同观测条件下,将新旧测氦仪串联并行观测,经动态稳定性、内在质量及观测曲线对比发现,新测氦仪能够捕捉到更多更完整的地下流体信息,观测数据日变化规则,动态特征明显,且2台测氦仪产出数据具有同步性变化特征。为进一步验证新旧测氦仪的相关性,与同台气温测项进行对比分析,发现2台测氦仪氦气测值与气温同时存在短期负相关变化。综合分析认为,新旧测氦仪产出观测数据真实可靠,均能反映怀4井地下流体中氦气的浓度变化。     

A need for incentivizing field hydrology,especially in an era of open data: discussion of “The role of experimental work in hydrological sciences – insights from a community survey”*

The sharing of data and collection of new data are both essential, but they are not inherently complementary. When data are openly available, researchers may be motivated to use those data rather than collect more because field work has costs and risks. The competitive advantage to those who do not put resources towards fieldwork may discourage field hydrology. Allocating efforts towards generating field data, which benefits hydrological sciences, is not necessarily best for individual hydrologists, especially in an era of open data. The objective of this work is to open a conversation on whether individuals’ best interests may contrast with the community’s desire for new observations. If the community wants new field observations, there is a need to consider the shifting balance of incentives and disincentives for pursuing field studies in hydrology.     

Terrestrial carbon cycle model-data fusion: Progress and challenges

The terrestrial carbon cycle is an important component of global biogeochemical cycling and is closely related to human well-being and sustainable development. However, large uncertainties exist in carbon cycle simulations and observations.Model-data fusion is a powerful technique that combines models and observational data to minimize the uncertainties in terrestrial carbon cycle estimation. In this paper, we comprehensively overview the sources and characteristics of the uncertainties in terrestrial carbon cycle models and observations. We present the mathematical principles of two model-data fusion methods, i.e., data assimilation and parameter estimation, both of which essentially achieve the optimal fusion of a model with observational data while considering the respective errors in the model and in the observations. Based upon reviewing the progress in carbon cycle models and observation techniques in recent years, we have highlighted the major challenges in terrestrial carbon cycle model-data fusion research, such as the "equifinality" of models, the identifiability of model parameters,the estimation of representativeness errors in surface fluxes and remote sensing observations, the potential role of the posterior probability distribution of parameters obtained from sensitivity analysis in determining the error covariance matrixes of the models, and opportunities that emerge by assimilating new remote sensing observations, such as solar-induced chlorophyll fluorescence. It is also noted that the synthesis of multisource observations into a coherent carbon data assimilation system is by no means an easy task, yet a breakthrough in this bottleneck is a prerequisite for the development of a new generation of global carbon data assimilation systems. This article also highlights the importance of carbon cycle data assimilation systems to generate reliable and physically consistent terrestrial carbon cycle reanalysis data products with high spatial resolution and longterm time series. These products are critical to the accurate estimation of carbon cycles at the global and regional scales and will help future carbon management strategies meet the goals of carbon neutrality.     

A temperature prediction-correction method for estimating surface soil heat flux from soil temperature and moisture data

Surface soil heat flux is a component of surface energy budget and its estimation is needed in land-atmosphere interaction studies. This paper develops a new simple method to estimate soil heat flux from soil temperature and moisture observations. It gives soil temperature profile with the thermal diffusion equation and, then, adjusts the temperature profile with differences between observed and computed soil temperatures. The soil flux is obtained through integrating the soil temperature profile. Compared with previous methods, the new method does not require accurate thermal conductivity. Case studies based on observations, synthetic data, and sensitivity analyses show that the new method is preferable and the results obtained with it are not sensitive to the availability of temperature data in the topsoil. In addition, we pointed out that the soil heat flux measured with a heat-plate can be quite erroneous in magnitude though its phase is accurate.     

A need for incentivizing field hydrology,especially in an era of open data: discussion of “The role of experimental work in hydrological sciences – insights from a community survey”*

ABSTRACT

The sharing of data and collection of new data are both essential, but they are not inherently complementary. When data are openly available, researchers may be motivated to use those data rather than collect more because field work has costs and risks. The competitive advantage to those who do not put resources towards fieldwork may discourage field hydrology. Allocating efforts towards generating field data, which benefits hydrological sciences, is not necessarily best for individual hydrologists, especially in an era of open data. The objective of this work is to open a conversation on whether individuals’ best interests may contrast with the community’s desire for new observations. If the community wants new field observations, there is a need to consider the shifting balance of incentives and disincentives for pursuing field studies in hydrology.     

Future developments in modelling and monitoring of volcanic ash clouds: outcomes from the first IAVCEI-WMO workshop on Ash Dispersal Forecast and Civil Aviation

As a result of the serious consequences of the 2010 Eyjafjallajökull eruption (Iceland) on civil aviation, 52 volcanologists, meteorologists, atmospheric dispersion modellers and space and ground-based monitoring specialists from 12 different countries (including representatives from 6 Volcanic Ash Advisory Centres and related institutions) gathered to discuss the needs of the ash dispersal modelling community, investigate new data-acquisition strategies (i.e. quantitative measurements and observations) and discuss how to improve communication between the research community and institutions with an operational mandate. Based on a dedicated benchmark exercise and on 3 days of in-depth discussion, recommendations have been made for future model improvements, new strategies of ash cloud forecasting, multidisciplinary data acquisition and more efficient communication between different communities. Issues addressed in the workshop include ash dispersal modelling, uncertainty, ensemble forecasting, combining dispersal models and observations, sensitivity analysis, model variability, data acquisition, pre-eruption forecasting, first simulation and data assimilation, research priorities and new communication strategies to improve information flow and operational routines. As a main conclusion, model developers, meteorologists, volcanologists and stakeholders need to work closely together to develop new and improved strategies for ash dispersal forecasting and, in particular, to: (1) improve the definition of the source term, (2) design models and forecasting strategies that can better characterize uncertainties, (3) explore and identify the best ensemble strategies that can be adapted to ash dispersal forecasting, (4) identify optimized strategies for the combination of models and observations and (5) implement new critical operational strategies.     

Physical characteristics of the radio emission of solar coronal holes

This paper presents a brief overview of works dedicated to the studies of solar coronal holes (CH). Special attention is paid to CH studies at millimeter and centimeter wavelengths. The observational data in the millimeter range, combined with satellite observations in the ultraviolet and soft X-ray range, as well as solar eclipse observations of March 29, 2006, at centimeter wavelengths with RATAN-600, provide new results for understanding the physical nature of coronal holes on the Sun.     

顾及多方向观测值权比反演地球重力场的动力积分法

考虑到不同坐标系下各个方向观测值对反演地球重力场的频谱贡献不同,建立了顾及多方向观测值权比的动力积分法,并利用该方法反演了高精度的GOCE HL-SST卫星重力场模型.首先,分析了不同坐标系下各个方向观测值与地球重力场信息的响应关系,其中惯性系(IRF)下X、Z方向的观测值分别对扇谐系数、带谐系数最为敏感,Z方向的解算精度在全频段均略高于X、Y方向;地固系(EFRF)下各个方向的独立解算精度均与能量守恒法的解算精度相当;局部指北坐标系(LNOF)下X、Z和Y三个方向的解算精度依次递减,且Y方向在47阶附近有明显"驼峰"现象.其次,比较了不同坐标系下顾及三个方向观测值权比的加权解算模型,其中加权联合解算模型精度在20至70阶次均明显优于等权解算模型,在带谐项和共振阶次精度提升明显,且LNOF下的加权联合解算精度要优于IRF和EFRF.最后,比较了GOCE和CHAMP卫星的模型解算精度,采用本文计算方法,仅利用2个月GOCE轨道观测值解算的模型精度优于包含更长观测时段信息的AIUB-CHAMP01S和EIGEN-CHAMP03S模型,且略优于ASU-GOCE-2months模型.     

Some aspects of electrostatic coupling between E and F regions relevant to plasma irregularities: A review based on recent observations

This paper provides a review on some of the electrostatic coupling effects relevant for generating/modifying plasma irregularities during nighttime in the low latitude ionosphere based on recent observations. Emphasis is given to the role of large polarization electric field associated with an unstable region affecting another region remotely located. Recent radar observations on valley region and E region irregularities from low latitudes show convincing evidence in support of effective electrostatic field coupling along the magnetic field line for their manifestation. Interestingly, the low latitude observations clearly show the ineffectiveness of plasma bubble related fringe fields in generating low latitude valley region irregularities unlike that over the dip equator. Velocity perturbations associated with the unstable low latitude E region relevant for studying the seeding of equatorial spread F are also shown. These new observations have been critically examined in the light of existing experimental knowledge and current understanding of the electrostatic coupling effects for the generation/modification of plasma irregularities in a remote region.     

The puzzling structure of a sunspot

Why does a sunspot look the way it does? Steven Tobias and Nigel Weiss find answers to this question, by relating new high-resolution observations to recent theoretical studies of the spot's magnetic field.     

Hubble's long view

Peter Bond brings a round-up of space news, including X-ray observations of the galactic centre, a new sort of black hole, targets within the expanding solar system, and Hubble's longest, deepest look back in time.     

Spatial characteristics of ocean surface waves

The spatial variability of open ocean wave fields on scales of O (10km) is assessed from four different data sources: TerraSAR-X SAR imagery, four drifting SWIFT buoys, a moored waverider buoy, and WAVEWATCH III^? model runs. Two examples from the open north-east Pacific, comprising of a pure wind sea and a mixed sea with swell, are given. Wave parameters attained from observations have a natural variability, which decreases with increasing record length or acquisition area. The retrieval of dominant wave scales from point observations and model output are inherently different to dominant scales retrieved from spatial observations. This can lead to significant differences in the dominant steepness associated with a given wave field. These uncertainties have to be taken into account when models are assessed against observations or when new wave retrieval algorithms from spatial or temporal data are tested. However, there is evidence of abrupt changes in wave field characteristics that are larger than the expected methodological uncertainties.