低纬子午环仪器误差的测定及其处理方法

仪器误差的精确测定和消除对于提高子午环的观测精度有着至关重要的意义。本文简单介绍了低纬子午环的观测原理和仪器结构，系统地探讨了它的各种仪器误差的来源、测定和处理方法。为了进一步完善采用组合固定角距法测定对径改正的方法，在第三章，研究了提高对径改正测量精度的方法，重新推导了对径改正的计算公式，并就某些具体的条件，对其进行了模拟验证，得到了较为满意的结果     

Inferring Small-Scale Flatfields from Solar Rotation

We present a method to infer small-scale flatfields for imaging solar instruments using only regular-observation intensity images with a fixed field of view. The method is related to the flatfielding method developed by Kuhn, Lin, and Loranz (Publ. Astron. Soc. Pac. 103, 1097 – 1108, 1991), but does not require image offsets. Instead, it takes advantage of the fact that the solar image is changing in the CCD reference frame due to solar rotation. We apply the method to data sets of MDI filtergrams and compare the results to flat fields derived with other methods. Finally, we discuss the planned implementation of this method in the data processing for Helioseismic and Magnetic Imager on the Solar Dynamics Observatory.     

Variability in quartz OSL signals caused by measurement uncertainties: Problems and solutions

We simulated the variability in measured quartz optically stimulated luminescence (OSL) signals and dose response curves (DRCs) caused by measurement uncertainties, including counting statistics and instrumental irreproducibility. We find that these measurement errors can give rise to large variations in the observed luminescence signal and contribute to among-aliquot or among-grain scatter in DRCs and equivalent dose (D_e) values. Different measurement systems (i.e., luminescence readers) may have different counting statistics properties and, hence, may exhibit differing extents of variation in the observed OSL signal, even for the same sample. Our simulation shows that the random measurement uncertainties may result in some grains or aliquots being ‘saturated’ (that is, the measured natural signal is consistent with, or lies above, the saturation level of the measured DRC) and that the rejection of these ‘saturated’ grains may result in a truncated D_e distribution, with D_e underestimation for samples with natural doses close to saturation (e.g., twice the characteristic saturation dose, D₀). We propose a new method to deal with this underestimation problem, in which standardised growth curves (SGCs) are established and the weighted-mean natural signal (L_n/T_n) from all measured grains is projected on to the corresponding SGCs to determine D_e. Our simulation results show that this method can produce reliable D_e estimates up to 5D₀, which is far beyond the conventional limit of ∼2D₀ using the standard SAR procedure.     

2018年2月12日河北永清4.3级地震强震动记录分析

2018年2月12日河北省廊坊市永清县发生4.3级地震,震中位于廊固凹陷内的河西务断裂附近,国家强震动台网中心获取74组强震动记录,本文对触发台站进行场地分类,结果显示大部分为Ⅰ类场地(51.35%),其次为Ⅱ类场地(35.14%)和Ⅲ类场地(13.51%)。根据5个典型台站加速度时程记录及反应谱分析本次地震强震动特征,并对各台站峰值加速度反应谱与方位角和震中距的关系进行分析。采用克里格插值方法绘制地震仪器烈度分布图,由于台站分布不均,导致极震区附近烈度影响场计算缺值现象,本文通过拟合本次地震强震动记录得到该地区地震动衰减关系,在空白区域建立空间随机假设台站进行补点插值,解决了计算缺值问题,为缺少台站记录的震区提供准确快速制作烈度分布图的思路,为震害调查和地震应急救援提供重要依据。     

Time stability of spring and superconducting gravimeters through the analysis of very long gravity records

Long gravity records are of great interest when performing tidal analyses. Indeed, long series enable to separate contributions of near-frequency waves and also to detect low frequency signals (e.g. long period tides and polar motion). In addition to the length of the series, the quality of the data and the temporal stability of the noise are also very important. We study in detail some of the longest gravity records available in Europe: 3 data sets recorded with spring gravimeters in Black Forest Observatory (Germany, 1980–2012), Walferdange (Luxemburg, 1980–1995) and Potsdam (Germany, 1974–1998) and several superconducting gravimeters (SGs) data sets, with at least 9 years of continuous records, at different European GGP (Global Geodynamics Project) sites (Bad Homburg, Brussels, Medicina, Membach, Moxa, Vienna, Wettzell and Strasbourg). The stability of each instrument is investigated using the temporal variations of tidal parameters (amplitude factor and phase difference) for the main tidal waves (O1, K1, M2 and S2) as well as the M2/O1 factor ratio, the later being insensitive to the instrumental calibration. The long term stability of the tidal observations is also dependent on the stability of the scale factor of the relative gravimeters. Therefore we also check the time stability of the scale factor for the superconducting gravimeter C026 installed at the J9 Gravimetric Observatory of Strasbourg (France), using numerous calibration experiments carried out by co-located absolute gravimeter (AG) measurements during the last 15 years. The reproducibility of the scale factor and the achievable precision are investigated by comparing the results of different calibration campaigns. Finally we present a spectrum of the 25 years of SG records at J9 Observatory, with special attention to small amplitude tides in the semi-diurnal and diurnal bands, as well as to the low frequency part.     

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Testing potential bias in marine plankton respiration rates by dark bottle incubations in the NW Iberian shelf: incubation time and bottle volume

The accurate determination of the balance between plankton production and respiration in the ocean is important for C budgets and global change predictions. Disagreements on the measurement of such a balance at different scales (from microbiological to biogeochemical) have produced a controversy over the trophic status of the ocean. This is especially striking in the oligotrophic open ocean, where plankton community O₂ consumption rates in 24 h incubations have frequently produced a net heterotrophic balance, but similar difficulties emerge in coastal systems. These results have been criticised due to the possibility that the standard 24 h in vitro incubations are biased because of the long incubation time needed and the so-called “bottle effect”.To study the influence of the incubation time and bottle volume on the measurement of plankton net metabolism, we carried out several time series experiments in the NW Iberian coastal system. Here we present measurements of plankton community respiration rates concurrently obtained through (1) standard in vitro changes in dissolved oxygen concentration after different incubation times ranging from 2 to 48 h, and with bottle volumes of 50, 125 and 570 mL, and (2) the decrease in the oxygen concentration measured every 20 s with oxygen microsensors, during 48 h. Our results refute the contention that 24 h dark 125 mL bottle incubations are systematically biased, and highlight the validity of oxygen microsensors to study the dynamics of natural marine plankton respiration.     

河南区域地震前兆台网运行维护与管理

对近两年河南区域地震前兆台网的观测仪器和技术系统中出现的典型情况进行了全面分析总结,阐述了维护过程中的一些方法,提出了对仪器与技术系统的一些问题与建议。     

Long-term Stability and Oceanic Mean State Simulated by the Coupled Model FGOALS-s2

We describe the long-term stability and mean climatology of oceanic circulations simulated by version 2 of the Flexible Global Ocean-Atmosphere-Land System model(FGOALS-s2).Driven by pre-industrial forcing,the integration of FGOALS-s2 was found to have remained stable,with no obvious climate drift over 600 model years.The linear trends of sea SST and sea surface salinity(SSS) were 0.04°C(100yr)-1 and 0.01 psu(100yr)-1,respectively.The simulations of oceanic temperatures,wind-driven circulation and thermohaline circulation in FGOALS-s2 were found to be comparable with observations,and have been substantially improved over previous FGOALS-s versions(1.0 and 1.1).However,significant SST biases(exceeding 3°C) were found around strong western boundary currents,in the East China Sea,the Sea of Japan and the Barents Sea.Along the eastern coasts in the Pacific and Atlantic Ocean,a warm bias(>3°C) was mainly due to overestimation of net surface shortwave radiation and weak oceanic upwelling.The difference of SST biases in the North Atlantic and Pacific was partly due to the errors of meridional heat transport.For SSS,biases exceeding 1.5 psu were located in the Arctic Ocean and around the Gulf Stream.In the tropics,freshwater biases dominated and were mainly caused by the excess of precipitation.Regarding the vertical dimension,the maximal biases of temperature and salinity were located north of 65°N at depths of greater than 600 m,and their values exceeded 4°C and 2 psu,respectively.