Challenges in the Detection and Attribution of Northern Hemisphere Surface Temperature Trends Since 1850

Since 2007,the Intergovernmental Panel on Climate Change(IPCC)has heavily relied on the comparison between global climate model hindcasts and global surface temperature(ST)estimates for concluding that post-1950s global warming is mostly human-caused.In Connolly et al.,we cautioned that this approach to the detection and attribution of climate change was highly dependent on the choice of Total Solar Irradiance(TSI)and ST data sets.We compiled 16 TSI and five ST data sets and found by altering the choice of TSI or ST,one could(prematurely)conclude anything from the warming being“mostly human-caused”to“mostly natural.”Richardson and Benestad suggested our analysis was“erroneous”and“flawed”because we did not use a multilinear regression.They argued that applying a multilinear regression to one of the five ST series re-affirmed the IPCC's attribution statement.They also objected that many of the published TSI data sets were out-of-date.However,here we show that when applying multilinear regression analysis to an expanded and updated data set of 27 TSI series,the original conclusions of Connolly et al.are confirmed for all five ST data sets.Therefore,it is still unclear whether the observed warming is mostly human-caused,mostly natural or some combination of both.

利用探空资料验证GOME卫星臭氧数据

利用1996年3月—2003年6月部分时段拉萨、西宁、北京3个站的臭氧探空资料验证了GOME(Global Ozone Monitoring Experiment)卫星臭氧廓线及对流层臭氧柱总量。对比结果表明:在对流层中下层,拉萨和西宁两地GOME与探空的平均偏差小于5%,北京地区平均偏差小于10%;在对流层上层/平流层下层,拉萨和西宁平均偏差小于10%,北京小于20%;在平流层中上层3个站的平均偏差均小于5%。在对流层上层/平流层下层区域, GOME与臭氧探空的平均偏差在北京明显高于拉萨和西宁。3个地区对流层柱总量的平均偏差都在10%以内,表明该资料可用于研究我国对流层臭氧总量的变化规律。同时段的GOME最低层(0～2.5km)月平均臭氧浓度对比结果显示,GOME结果同地面臭氧观测值有很好的相关性,GOME臭氧浓度反映了拉萨、瓦里关、临安地面臭氧浓度的主要变化特征。

夏季青藏高原O_3低值与南亚高压东西振荡的关系

利用O3监测仪(Ozone Monitoring Instrument,OMI)卫星O3廓线资料和NCEP/NCAR再分析资料,研究了2006年夏季南亚高压偏西型和偏东型条件下青藏高原地区O3垂直结构和变化特征差异。结果表明,夏季南亚高压东西振荡与青藏高原O3分布存在密切的关系,在西(东)部型南亚高压条件下,夏季青藏高原地区大气、对流层和平流层O3柱总量低值中心均偏西(东),位于青藏高原西(东)部,尤其是在南亚高压最强的对流层顶附近,O3低值中心位于南亚高压中心。在西部型南亚高压条件下,低纬度地区含低浓度O3的空气不易到达高原上空,青藏高原上空的O3低值较弱。在东部型南亚高压条件下,从低纬度经中南半岛西北方向孟加拉湾带来的低纬地区低浓度O3,在青藏高原上空堆积,形成O3低值中心。因此,南亚高压东西振荡是影响青藏高原上空O3低值中心变化的重要因素之一,该研究对理解南亚高压东西振荡机制及提高我国气候预测具有一定的指导意义。

磁重联电流片的参数变化对电子加速的影响

通过采用试验粒子的方法,研究了在有引导磁场B_z存在的磁重联电流片中,电子被super-Dreicer电场E_z加速后的运动特征。首先,考虑了引导磁场恒定且与电场有不同方向时对粒子加速的影响。在这种情况下,B_z方向的改变直接改变了电子的运动轨迹,使其沿着不同的路径离开电流片。在B_z和E_z同向时,高能电子的pitch-angle接近于180°。然而,当2者反向时,高能电子的pitch-angle接近0°。引导磁场的取向只是使电场有选择地对不同区域的电子进行加速,不会最终影响电子的能量分布,最终得到的能谱是普遍的幂率谱E^(-γ)。在典型的日冕条件下,γ大约等于2.9。进一步的研究表明γ的大小依赖于引导磁场及磁重联电场的强弱,以及电流片的尺度。随后,也研究了包含多个X-点和O-点电流片中被加速粒子的运动特征。结果表明X-点和O-点的存在使得粒子被束缚在加速区并获得最大的加速,而且最终的能谱具有多幂率谱的特征。

灾变理论在太阳物理和天体物理其他研究领域中的应用

叙述和介绍了太阳爆发的磁通量绳灾变理论和模型的发展过程,强调了建立这样的模型所需要的观测基础。讨论了由模型所预言的爆发磁结构的几个重要特征以及观测结果对这种预言的证实。在此模型的基础上,讨论了一个典型的爆发过程中所出现的不同现象及它们之间的相互关系。最后,介绍了作者的一项最新尝试:将太阳爆发的灾变理论和模型应用到对黑洞吸积盘间歇性喷流的理论研究当中,以及研究所取得的初步结果。

超新星遗迹MSH 15-56和CTA 1

对于超新星遗迹MSH 15-56和CTA 1,本文较详细地公布了由爱因斯坦卫星得到的X射线观测资料.根据这些资料,导出其物理特性,推导和预言其射电流量,并与前人的射电观测进行了比较.

经自适应网格改造后的SHASTA程序和磁重联数值实验

SHASTA(Sharp and Smooth Transport Algorithm)是求解二维磁流体动力学问题的单一网格程序.在将其用于磁重联问题的数值模拟时,它被修改成为采用自适应网格方法的程序.修改后的程序可以针对扩散区进行细化计算.在SHASTA程序的自适应计算实现过程中,采用了插入式的自适应修改策略,原二维磁流体力学偏微分方程的求解算法被作为独立单元使用.另外,修改中使用分层的数据结构,将每个细化层次的物理量用二维可变数组描述,并标记磁场和压强分布的陡变区为细化区域,再通过插值的方法得到细化层网格点上的物理量分布和边界条件,最后细化区域的细化计算结果被赋予给其上一层网格,并对其内容进行更新.采用细化计算进行的磁重联的模拟实验表明,相比单一网格计算,细节分辨率得到提高,相应的计算时间的增加则与模拟中的参数选择有关;而自适应程序部分带来的计算精度和稳定性的影响则依赖于边界设置、单步长的推进策略和插值算法.

Dynamical and Chemical Features of a Cutoff Low over Northeast China in July 2007:Results from Satellite Measurements and Reanalysis

The European Centre for Medium-Range Weather orology and measurements from the Microwave Limb Forecasts Re-Analysis Interim （ERA-Interim） meteSounder, High Resolution Dynamics Limb Sounder, and Ozone Monitoring Instrument onboard the Earth Observing System Aura satellite were applied to analyze the dynamical and chemical features of a cutoff low （COL） event over northeast China in early July 2007. The results showed the polar stratospheric origin of an upper-level warm-core cyclone at 100 300 hPa, associated with a funnel-shaped tropopause intruding into the mid-troposphere just above the COL center. The impacts of the stratospheric intrusion on both column ozone and ozone profiles were investigated using satellite measurements. When the intensity of the COL peaked on 10 July 2007, the total column ozone （TCO） increase reached a maximum （40-70 DU）. This could be dynamically attributed to both the descent of the tropopause （~75%） and the downward transport of stratospheric ozone across the tropopause （~25%）. Analysis of the tropospheric ozone profiles provided evidence for irreversible transport/mixing of ozone-rich stratospheric air across the tropopause near the upper-level front region ahead of the COL center. This ozone intrusion underwent downstream transport by the upper tropospheric winds, leading to further increase in TCO by 12 16 DU over broad regions extending from east China toward the northern Japan Sea via South Korea. Meteorological analysis also showed the precedence of the stratospheric intrusion ahead of the development of cyclones in the middle and lower troposphere.

Conceptual design studies of the 5 m terahertz antenna for Dome A, Antarctica

As the highest, coldest and driest place in Antarctica, Dome A provides exceptionally good observing conditions for ground-based observations over terahertz wavebands. The 5 m Dome A Terahertz Explorer （DATES） has been proposed to explore new terahertz windows, primarily over wavelengths between 350 and 200 pm. DATE5 will be an open-air, fully-steerable telescope that can function by unmanned operation with remote control. The telescope will be able to endure the harsh polar environment, including high altitude, very low temperature and very low air pressure. The unique specifications, including high accuracies for surface shape and pointing and fully automatic year-around remote operation, along with a stringent limit on the periods of on-site assembly, testing and maintenance, bring a number of challenges to the design, construction, assembly and operation of this telescope. This paper intro- duces general concepts related to the design of the DATE5 antenna. Beginning from an overview of the environmental and operational limitations, the design specifications and requirements of the DATE5 antenna are listed. From these, major aspects on the conceptual design studies, including the antenna optics, the backup structure, the pan- els, the subreflector, the mounting and the antenna base structure, are explained. Some critical issues of performance are justified through analyses that use computational fluid dynamics, thermal analysis and de-icing studies, and the proposed approaches for test operation and on-site assembly. Based on these studies, we conclude that the specifications of the DATE5 antenna can generally be met by using enhanced technological approaches.

The deep optical imaging of the Extended Groth Strip

We present u＇g＇R optical images taken with the MMT/Megacam and the Subaru/Suprime telescopes of the Extended Groth Strip survey. The total survey covers an area of about -1 degree2, including four sub-fields and is optimized for the study of galaxies at z - 3. Our methods for photometric calibration in AB magnitudes, the limiting magnitude and the galaxy number count are described. A sample of 1642 photometrically selected candidate Lyman-Break Galaxies （LBGs） to an apparent RAB magnitude limit of 25.0 is presented. The average sky surface density of our LBG sample is -1.0 arcmin-2, slightly higher than the previous finding.

Scalar Wormhole at Finite Temperature

The wormhole solution of a finite temperature scalarø4 field coupled to gravity is given.It is shown that Hubble constant and the size of the wormhole neck all increase with temperature.Temperature dependences for other physical properties of wormhole are also discussed.

The kinematics of an untwisting solar jet in a polar coronal hole observed by SDO/AIA

Using the multi-wavelength data from the Atmospheric Imaging Assembly （AIA） onboard the Solar Dynamics Observatory （SDO） spacecraft, we study a jet occurring in a coronal hole near the northern pole of the Sun. The jet presented distinct upward helical motion during ejection. By tracking six identified moving features （MFs） in the jet, we found that the plasma moved at an approximately constant speed along the jet＇s axis. Meanwhile, the MFs made a circular motion in the plane transverse to the axis. Inferred from linear and trigonometric fittings to the axial and transverse heights of the six tracks, the mean values of the axial velocities, transverse velocities, angular speeds, rotation periods, and rotation radii of the jet are 114 km s-1, 136 km s-1, 0.81° s-1, 452 s and 9.8 × 10^3 km respectively. As the MFs rose, the jet width at the corresponding height increased. For the first time, we derived the height variation of the longitudinal magnetic field strength in the jet from the assumption of magnetic flux conservation. Our results indicate that at heights of 1 × 10^4 -7 × 10^4 km from the base of the jet, the flux density in the jet decreases from about 15 to 3 G as a function of B = 0.5（R/R） - 1）-0.84 （G）. A comparison was made with other results in previous studies.

How much has the Sun influenced Northern Hemisphere temperature trends?An ongoing debate

In order to evaluate how much Total Solar Irradiance(TSI)has influenced Northern Hemisphere surface air temperature trends,it is important to have reliable estimates of both quantities.Sixteen different estimates of the changes in TSI since at least the 19th century were compiled from the literature.Half of these estimates are"low variability"and half are"high variability".Meanwhile,five largely-independent methods for estimating Northern Hemisphere temperature trends were evaluated using:1)only rural weather stations;2)all available stations whether urban or rural(the standard approach);3)only sea surface temperatures;4)tree-ring widths as temperature proxies;5)glacier length records as temperature proxies.The standard estimates which use urban as well as rural stations were somewhat anomalous as they implied a much greater warming in recent decades than the other estimates,suggesting that urbanization bias might still be a problem in current global temperature datasets-despite the conclusions of some earlier studies.Nonetheless,all five estimates confirm that it is currently warmer than the late 19th century,i.e.,there has been some"global warming"since the 19th century.For each of the five estimates of Northern Hemisphere temperatures,the contribution from direct solar forcing for all sixteen estimates of TSI was evaluated using simple linear least-squares fitting.The role of human activity on recent warming was then calculated by fitting the residuals to the UN IPCC’s recommended"anthropogenic forcings"time series.For all five Northern Hemisphere temperature series,different TSI estimates suggest everything from no role for the Sun in recent decades(implying that recent global warming is mostly human-caused)to most of the recent global warming being due to changes in solar activity(that is,that recent global warming is mostly natural).It appears that previous studies(including the most recent IPCC reports)which had prematurely concluded the former,had done so because they failed to adequately consider all the relevant estimates of TSI and/or to satisfactorily address the uncertainties still associated with Northern Hemisphere temperature trend estimates.Therefore,several recommendations on how the scientific community can more satisfactorily resolve these issues are provided.

AFGL 5157 NH_3 : a new stellar cluster in the forming process

We present the analysis of Spitzer/IRAC and near infrared imaging obser- vation of AFGL 5157, an active star forming region. In the IRAC images, this region shows strong emissions of polycyclic aromatic hydrocarbons in channel 4 and emis- sions of H2 in channel 2. Many of the H2 features are aligned to form jet-like struc- tures. Three bipolar jets in the NHa core region and a couple of jets northwest of the core have been identified. We identify the possible driving agents of the bipolar jets and show them to be very young. An embedded cluster has been detected in the NH3 core; many members in the cluster have spectral energy distributions that increase from JHK bands toward longer wavelengths, indicative of their early evolutionary stages. Millimeter and submillimeter continuum emissions in the NH3 core and the northwest subregion are found to coincide spatially with these presumable Class0/I sources. The existence of H2 bipolar jets and very young stellar objects suggests that star formation is continuing at the present epoch in these subregions. Combining in- formation from previous studies, we propose a sequential star formation scenario in the whole AFGL 5157 region.

On the role of the uncertainty principle in superconductivity and superfluidity

We discuss the general interplay between the uncertainty principle and the onset of dissipationless transport phenomena such as superconductivity and superfluidity. We argue that these phenomena are possible because of the robustness of many-body quantum states with respect to the external environment, which is directly related to the uncertainty principle as applied to coordinates and momenta of the carriers. In the case of superconductors, this implies relationships between macroscopic quantities such as critical temperature and critical magnetic field, and microscopic quantities such as the amount of spatial squeezing of a Cooper pair and its correlation time. In the case of ultracold atomic Fermi gases, this should be paralleled by a connection between the critical temperature for the onset of superfluidity and the corresponding critical velocity. Tests of this conjecture are finally sketched with particular regard to the understanding of the behaviour of superconductors under external pressures or mesoscopic superconductors, and the possibility to mimic these effects in ultracold atomic Fermi gases using Feshbach resonances and atomic squeezed states.

The distance measurements of supernova remnants in the fourth Galactic quadrant

We take advantage of red clump stars to build the relation of the optical extinction(AV) and distance in each direction of supernova remnants(SNRs) with known extinction in the fourth Galactic quadrant.The distances of nine SNRs are determined well by this method.Their uncertainties range from 10% to30%,which are significantly improved for eight SNRs,G279.0+1.1,G284.3–1.8,G296.1–0.5,G299.2–2.9,G308.4–1.4,G309.2–0.6,G309.8–2.6 and G332.4–0.4.In addition,SNR G284.3–1.8 with the new distance of 5.5 kpc is not likely associated with the PSR J1016–5857 at 3 kpc.

A Study of the Star-forming Dwarf Galaxy NGC 855 with Spitzer

We present a study of the dwarf elliptical galaxy NGC 855 using the narrow-band Hα and Spitzer data. Both the Hα and Spitzer IRAC images confirm star-forming activity in the center of NGC 855. We obtained a star formation rate （SFR） of 0.022 and 0.025Mo yr^-1, respectively, from the Spitzer IRAC 8.0 μm and MIPS 24 #m emission data. The HI observation suggests that the star-forming activity might be triggered by a minor merger. We also find that there is a distinct IR emission region in 5.8 and 8.0 μm bands, located at about 10＂ away from the nucleus of NGC 855. Given the strong 8.0 μm but faint Hα emission, we expect that it is a heavily obscured star-forming region, which needs to be confirmed by further optical spectroscopic observations.

Does the Masing Gas Fall Inward VY CMa?

The water maser emission from the unusual supergiant,VY CMa,has been observed with the Urumqi 25 m radio telescope.A simple red-shifted maser spectrum was detected in the 1.6 Jy noise level during our monitoring observations.All of the H2O maser features are red-shifted with respect to the VY CMa stellar velocity of 17.6 km.s-1.The spectrum appears to be consisted of two striking like groups and each group has three features.The appearances and the ratio of these three features in the two maser groups are very similar.The H2O maser emission arises from a region close to the supergiant,about 10 stellar radii of the star.The simple red-shifted spectrum could be due to infall masing gas on the near side of the disk.Pulsation of the central star causes oscillations in this portion of the envelope,with shock wave propagating outward and with material falling inward.The masing gas motions are very complex,by which the dramatic changes or the quasi-sinusoidal fluctuation in flux may be explained.

Photometric redshifts of galaxies from SDSS and 2MASS

In order to find the physical parameters which determine the accuracy of pho- tometric redshifts, we compare the spectroscopic and photometric redshifts （photo-z＇s） for a large sample of -80000 SDSS-2MASS galaxies. Photo-z＇s in this paper are estimated by using the artificial neural network photometric redshift method （ANNz）. For a subset of -40000 randomly selected galaxies, we find that the photometric redshift recovers the spectroscopic redshift distribution very well with rms of 0.016. Our main results are as follows： （1） Using magnitudes directly as input parameters produces more accurate photo-z＇s than using colors; （2） The inclusion of 2MASS （J, H, Ks） bands does not improve photo-z＇s significantly, which indicates that near infrared data might not be important for the low-redshift sample; （3） Adding the concentration index （essentially the steepness of the galaxy brightness profile） as an extra input can improve the photo-z＇s estimation up to -10 percent; （4） Dividing the sample into early- and late-type galaxies by using the concentration index, normal and abnormal galaxies by using the emission line flux ratios, and red and blue galaxies by using color index （g - r）, we can improve the accuracy of photo-z＇s significantly; （5） Our analysis shows that the outliers （where there is a big difference between the spectroscopic and photometric redshifts） are mainly correlated with galaxy types, e.g., most outliers are late-type （blue） galaxies.

Formation of the CME Leading Edge Observed in the 2003 February 18 Event

This work investigates a typical coronal mass ejection （CME） observed on 2003 February 18, by various space and ground instruments, in white light, Ha, EUV and X- ray. The Ha and EUV images indicate that the CME started with the eruption of a long filament located near the solar northwest limb. The white light coronal images show that the CME initiated with the rarefaction of a region above the solar limb and followed by the formation of a bright arcade at the boundary of the rarefying region at height 0.46 Re above the solar surface. The rarefying process synchronized with the slow rising phase of the eruptive filament, and the CME leading edge was observed to form as the latter started to accelerate. The lower part of the filament brightened in Ha as the filament rose to a certain height and parts of the filament was visible in the GOES X-ray images during the rise. These brightenings imply that the filament may be heated by the magnetic reconnection below the filament in the early stage of the eruption. We suggest that a possible mechanism which leads to the formation of the CME leading edge and cavity is the magnetic reconnection which takes place below the filament after the filament has reached a certain height.