利用AutoPrep技术抑制型电导离子色谱法检测土壤中碘

利用AutoPrep自动样品前处理技术，对土壤燃烧吸收液进行在线预浓缩，抑制型电导进行检测，建立了一种全新思路的检测土壤样品中碘的方法。选择亲水性非常强的氢氧化物选择性IonPac AS16阴离子交换色谱柱，淋洗液发生装置在线产生KOH进行等梯度淋洗，抑制型电导检测。结果表明，对于土壤燃烧吸收液中碘离子的测定，方法检出限（S／N=3）可达1．2μg/L，线性相关系数为0．9998，方法精密度（RSD，n=7）为1．161％～4．566％，回收率在90．6％～100．8％。采用AutoPrep电导检测和脉冲安培检测离子色谱法测定不同土壤样品中的碘，两种方法的检测结果基本一致。方法在提供了稳定的系统空白的同时，还具备自动化程度高、操作简单、重现性好、灵敏度高、系统稳定、节约时间、成本低廉和对环境友好等多方面特点，适合于大批量土壤普查中碘的分析。     

Stratospheric warming effects on the tropical mesospheric temperature field

Temperature observations at 20–90 km height and 5–15°N during the winter of 1992–1993, 1993–1994 and 2003–2004, from the Wind Imaging Interferometer (WINDII) and Microwave Limb Sounder (MLS) experiments on the Upper Atmosphere Research Satellite (UARS) satellite and the Sounding the Atmosphere using Broadband Emission Radiometry (SABER) experiment on the Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics (TIMED) satellite are analyzed together with MF radar winds and UK Meteorological Office (UKMO) assimilated fields. Mesospheric cooling is observed at the time of stratospheric warming at the tropics correlative with stratospheric warming events at middle and high latitudes. Planetary waves m=1 with periods of 4–5, 6–8, 10 and 12–18 days are found to dominate the period. Westward 7- and 16-day waves at the tropics appear enhanced by stationary planetary waves during sudden stratospheric warming events.     

Space exploration and the RAS

Mike Hapgood and Ian Crawford assess the relevance of the BNSC UKSEWG Report for the Royal Astronomical Society.     

SCAP meeting no.10

Mike Bode , Phil Charles and Carlos Frenk report the minutes of the tenth meeting of the Standing Conference of Astronomy Professors, held at the RAS, Burlington House on 30 January 2001.     

A 1951–80 global land precipitation climatology for the evaluation of general circulation models

Previous evaluations of model precipitation fields have suffered from two weaknesses; they have used only mean observed climatologies which have prevented an explicit evaluation of interannual variability, and they have generally failed to quantify the significance of differences between model and observed fields. To rectify these weaknesses, a global precipitation climatology is required which is designed with model evaluation in mind. This paper describes such a climatology representative of the period 1951–80. The climatology is based on historical gauge-precipitation measurements from over 2500 land-based station time series representing over 28% of the Earth's surface. It is necessarily biased towards terrestrial areas. The climatology (CRU5180) is derived from month-by-month gridbox precipitation estimates at 5° resolution. Although other global precipitation climatologies exist, this is the first one to have used a consistent reference period for each station, and to include the details of interannual variability. Fields of mean seasonal and annual precipitation and mean temporal variability are presented, and the variability of global-mean precipitation over 1951–80 assessed. The resulting mean monthly global precipitation fields are compared briefly with two other observed climatologies used for model evaluation, those prepared by Jaeger and Legates and Willmott. The global and hemispheric means, mean seasonal cycles, and spatial patterns of the three cimatologies are compared. Although based on a smaller set of stations than Legates and Willmott, the CRU5180 precipitation estimates agree closely with their uncorrected climatology.     

Topside optical view of the dayside cleft aurora

Photometers on the ISIS-II spacecraft provide a view of the atomic oxygen 5577 and 6300 Å emissions and the $\text{N}{}_2{}^{\mathrm{+}}\text{3914}\text{A}\text{?}$ emission detected as dayside aurora in the magnetospheric cleft region. The 6300 Å emission forms a continuous and permanent band across the noon sector, at about 78° invariant latitude, with a defined region of maximum intensity that is never less than 2kR (uncorrected for albedo), and is centred near magnetic noon. There are significant differences in the intensity patterns on either side of noon and their responses to geomagnetic activity. Discrete 3914 Å auroral forms appear within this region, at preferred locations that cannot be precisely specified, but which tend to the poleward edge of the 6300 Å emission in the evening, and the equatorward edge in the morning where the difference between the two emissions is greatest. It is concluded that the discrete auroras observed by all-sky cameras in the day sector do follow the 6300 Å emission through the cleft region, though a definite cleft boundary is not defined. Substantial 6300 Å emission having a peak intensity near noon is also seen in the low latitude “outer auroral belt”, while the diffuse 3914 Å emission tends to show a relative minimum near noon. On the morning side the 3914 Å intensity is displaced to lower latitude and earlier local times, compared to the 6300 Å emission.