简介:月球是地球唯一的天然卫星,早期学者认为地月系统是普遍存在的行星一卫星系统的一员,但是月球又有许多特征,如质量异常大,挥发分和Fe元素亏损等,传统理论难以解释这些特征。因此,针对月球的起源提出了四种学说:捕获理论,共增生理论,分裂理论和大碰撞假说。目前对大碰撞假说研究较多,但研究者们始终无法较好解释地月系统氧同位素的高度一致等特征。本文试探性提出新的月球起源分裂模型,能较好的解释某些月球特征,引起研究者们对月球起源新的思考。
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简介:Glacierinventorycompilationduringthepast20yearsandmodificationsofthatfortheEasternPamirandBanggongLakeindicatethatthereare46,342modernglacierswithatotalareaandvolumeof59415km2and5601km3respectivelyinChina.Theseglacierscanbeclassifiedintomaritimeandcontinental(includingsub-continentalandextremelycontinental)types.ResearchesshowthatglaciersinChinahavebeenretreatingsincetheLittleIceAgeandthemasswastagewasacceleratedduringthepast30to40years.BeinganimportantpartofglaciologicalstudiesinChina,icecoreclimaticandenvironmentalstudiesonTibetanPlateauandintheAntarcticahaveprovidedabundant,highresolutioninformationaboutpastclimaticandenvironmentalevolutionovertheTibetanPlateauandAntarctica.ExceptfordifferentparametersrecordedinicecoresrelatingtoclimateandenvironmentchangesonTibetanPlateau,recordsfromicecoresextractedfromdifferentglaciersshowthatthediscrepanciesinclimaticandenvironmentalchangesonthenorthandsouthpartsoftheplateaumaybetheconsequenceofdifferentinfluencingeffectsfromterrestrialandsolarsources.GlaciologicalandmeteorologicalphenomenaimplythatLambertGlaciervalleyisanimportantboundaryofclimateintheeastAntarctica,whichisthoughttobeconnectedwithcyclonicactivitiesandCircum-polarWavesovertheAntarctica.
简介:PermafrostinChinaincludeshighlatitudepermafrostinnortheasternChina,alpinepermafrostinnorthwesternChinaandhighplateaupermafrostontheTibetanPlateau.Thehighaltitudepermafrostisabout92%ofthetotalpermafrostareainChina.Thesouthboundaryorlowerlimitoftheseasonallyfrozengroundisdefinedinaccordancewiththe0℃isothermallineofmeanairtemperatureinJanuary,whichisroughlycorrespondingtothelineextendingfromtheQinlingMountainstotheHuaiheRiverintheeastandtothesoutheastboundaryoftheTibetanPlateauinthewest.SeasonalfrozengroundoccursinlargepartsoftheterritoryinnorthernChina,includingNortheast,North,NorthwestChinaandtheTibetanPlateauexceptforpermafrostregions,andaccountingforabout55%ofthelandareaofChina.Thesouthernlimitofshort-termfrozengroundgenerallyswingssouthandnorthalongthe25°northernlatitudeline,occurringinthewetandwarmsubtropicmonsoonclimaticzone.Itsareaislessthan20%ofthelandareaofChina.
简介:1.1大气CO2、CH4、CO高精度观测混合标气配制方法高精度、高准确度大气CO2、CH4、CO浓度观测需使用以干洁大气为底气的标气。标气中水汽含量及CO2的δ13C对基于光学原理的观测系统有不可忽视的影响。本研究利用自组装的混合标气配制系统,以环境大气为底气,通过添加高浓度气体或利用吸附剂吸附,调节目标物种浓度。CO2和CO吸附效率分别达99.7%和99.8%,标气水汽含量小于3.7×10-6,可配制不同浓度范围的CO2、CH4、CO混合标气。在青海瓦里关全球大气本底站配制环境大气浓度范围的标气,CO2、CH4、CO实际配制浓度同目标浓度的偏差分别小于10×10-6、30×10-9和30×10-9,CO2中δ13C同实际大气接近。本方法配制的标气已应用于我国本底站大气CO2、CH4和CO高精度观测,符合世界气象组织/全球大气观测(WMO/GAW)质量要求。(姚波)