Prediction Research of Climate Change Trends over North China in the Future 30 Years

A simulation of climate change trends over North China in the past 50 years and future 30 years was performed with the actual greenhouse gas concentration and IPCC SRES B2 scenario concentration by IAP/LASG GOALS 4.0 （Global Ocean-Atmosphere-Land system coupled model）, developed by the State Key Laboratory of Numerical Modelling for Atmospheric Sciences and Geophysical Fluid Dynamics （LASG）, Institute of Atmospheric Physics （IAP）, Chinese Academy of Sciences （CAS）. In order to validate the model, the modern climate during 1951-2000 was first simulated by the GOALS model with the actual greenhouse gas concentration, and the simulation results were compared with observed data. The simulation results basically reproduce the lower temperature from the 1960s to mid-1970s and the warming from the 1980s for the globe and Northern Hemisphere, and better the important cold （1950 1976） and warm （1977-2000） periods in the past 50 years over North China. The correlation coefficient is 0.34 between simulations and observations （significant at a more than 0.05 confidence level）. The range of winter temperature departures for North China is between those for the eastern and western China＇s Mainland. Meanwhile, the summer precipitation trend turning around the 1980s is also successfully simulated. The climate change trends in the future 30 years were simulated with the CO2 concentration under IPCC SRES-B2 emission scenario. The results show that, in the future 30 years, winter temperature will keep a warming trend in North China and increase by about 2.5~C relative to climate mean （1960-1990）. Meanwhile, summer precipitation will obviously increase in North China and decrease in South China, displaying a south-deficit-north-excessive pattern of precipitation.     

翁田台地电场观测受干扰的因素分析

海南省文昌翁田台地电场数据质量自2019年3月开始下降,地电场数据质量下降主要表现为日相关系数偏低、北南向长极距与短极距数据曲线呈反向变化、绝缘度趋向于零等情况.2019年3月—2020年10月,我们分别对观测室装置系统、室外外线路、连接口等逐一进行详细的排查工作和电极、电缆的对比实验工作,最终确定影响因素为电极故障和...     

Mapping the magnetosphere of PSR B1055−52

We present a geometric study of the radio and γ-ray pulsar B1055−52 based on recent observations at the Parkes radio telescope. We conclude that the pulsar's magnetic axis is inclined at an angle of 75° to its rotation axis and that both its radio main pulse and interpulse are emitted at the same height above their respective poles. This height is unlikely to be higher or much lower than 700 km, a typical value for radio pulsars.
It is argued that the radio interpulse arises from emission formed on open fieldlines close to the magnetic axis which do not pass through the magnetosphere's null (zero-charge) surface. However, the main pulse emission must originate from fieldlines lying well outside the polar cap boundary beyond the null surface, and farther away from the magnetic axis than those of the outer gap region where the single γ-ray peak is generated. This casts doubt on the common assumption that all pulsars have closed, quiescent, corotating regions stretching to the light cylinder.     

The topology and polarization of subbeams associated with the 'drifting' subpulse emission of pulsar B0943+10 – V. A new look at the low-frequency burst-mode emission

This paper reports new observations of pulsar B0943+10 carried out at the Pushchino Radio Astronomy Observatory (PRAO) at the low radio frequencies of 42, 62 and 112 MHz. B0943+10 is well known for its exquisitely regular burst-mode (B-mode) drifting subpulses as well as its weaker and chaotic quiescent mode. Earlier Arecibo investigations at 327 MHz have identified remarkable, continuous changes in its B-mode subpulse drift rate and integrated-profile shape with durations of several hours. These PRAO observations reveal that the changes in profile shape during the B-mode lifetime are strongly frequency dependent – namely the measured changes in the component amplitude ratio are more dramatic at 327 and 112 MHz as compared with those at 62 and 42 MHz. The differences, however, are most marked during the first several tens of minutes after B-mode onset; after an hour or so the profile shape changes tend to be more similar at all four frequencies. We also have found that the linear polarization of the integrated profile increases continuously throughout the lifetime of the B mode, going from hardly 10 per cent just after onset to some 40–50 per cent after several hours. Pulsar B0943+10's B mode thus provides a unique new opportunity to investigate continuous systematic changes in the plasma flow within the polar flux tube. While refraction in the pulsar's magnetosphere may well play some role, we find that the various frequency-dependent effects, both between and within the two modes, can largely be understood geometrically. If the modes and B-mode decay reflect systematic variations in the carousel-'spark' radius and emission height then a specific set of profile and linear polarization changes would be expected.     

A new technique for timing the double pulsar system

In 2004, McLaughlin et al. discovered a phenomenon in the radio emission of PSR J0737−3039B (B) that resembles drifting subpulses. The repeat rate of the subpulses is equal to the spin frequency of PSR J0737−3039A (A); this led to the suggestion that they are caused by incidence upon B's magnetosphere of electromagnetic radiation from A. Here, we describe a geometrical model which predicts the delay of B's subpulses relative to A's radio pulses. We show that measuring these delays is equivalent to tracking A's rotation from the point of view of a hypothetical observer located near B. This has three main astrophysical applications: (i) to determine the sense of rotation of A relative to its orbital plane, (ii) to estimate where in B's magnetosphere the radio subpulses are modulated and (iii) to provide an independent estimate of the mass ratio of A and B. The latter might improve existing tests of gravitational theories using this system.     

城市测绘院办公自动化系统的设计

介绍了基于NET Framework的城市测绘院办公自动化系统的设计及开发方案。     

MERSI和MODIS卫星监测京津冀及周边地区PM2.5浓度

京津冀及周边地区是中国PM_(2.5)污染最重的区域之一,利用卫星遥感技术监测大范围的PM_(2.5)时空分布变化是一种先进的重要手段。本研究首先基于暗像元算法利用FY-3B/MERSI与AQUA/MODIS对京津冀及周边区域进行了遥感AOT反演和验证分析;然后,引入气象资料和地面观测资料利用GWR模型反演了区域PM_(2.5)浓度,并对遥感反演结果进行了交叉验证评估,综合对比分析了MERSI和MODIS的气溶胶及PM_(2.5)遥感监测能力;最后,利用MERSI数据对2017年第一季度京津冀及周边区域的PM_(2.5)月均浓度时空分布变化情况进行了初步探索分析。结果表明:FY-3B/MERSI在气溶胶及PM_(2.5)遥感监测能力方面略优于AQUA/MODIS,MERSI反演的1 km分辨率AOT和PM_(2.5)与地面站点实测结果的决定系数R2分别为0.76μg/m~3和0.79μg/m~3,均方根误差分别为0.26μg/m~3和28μg/m~3,平均绝对误差分别为0.16μg/m~3和15μg/m~3,能基本满足对京津冀及周边区域PM_(2.5)的精细化监测需要。2017年第一季度京津冀及周边区域PM_(2.5)月均浓度遥感监测结果表明该区域的PM_(2.5)空间分布格局与地形地貌关系密切,高值区整体上沿太行山脉成带成片;从时间变化来看,1—3月呈逐月下降的趋势,其中3月份PM_(2.5)区域浓度较1月和2月有大幅下降。这说明FY-3\MERSI遥感反演产品能为环境质量监测和环境管理工作效果评估提供有效参考,本研究对国产卫星在大气环境遥感业务中的大力发展应用有重要参考意义。     

策克台井下宽频带地震计GL?S120B正弦波标定衰减因子的讨论

为解决EDAS?24GN6数据采集器对策克台井下宽频带地震计GL?S120B进行正弦标定的过程中产生的响应波形限幅问题,分析了数据采集器?地震计这一系统的标定过程及原理,结合GL?S120B的幅频响应特征,推导出正弦标定频点参数中的频率f、衰减因子λ与标定响应波形限幅之间的关系。分析表明,在GL?S120B平坦响应频带内,为避免出现标定波形响应限幅,频率f与衰减因子λ的乘积应至少大于限幅下限50.93;而在其衰减响应频带内,由于地震计电压灵敏度的衰减,频率f与衰减因子λ的乘积最小取值也相应减小。据此,对衰减因子λ进行校正,并再次对GL?S120B进行正弦标定。标定及计算结果显示:标定波形未限幅,GL?S120B三分向幅频响应特征较为一致;灵敏度对出厂值的变化率保持在5%范围内。本研究结论可为采用EDAS?24GN6和GL?S120B地震观测系统的台站进行正弦波标定提供频点参数,并为其他台站解决正弦标定波形限幅问题提供分析依据。