湖北神農(nóng)架近2000年來的石筍氣候記錄.pdf

1、南京師范大學(xué)碩士學(xué)位論文湖北神農(nóng)架近2000年來的石筍氣候記錄姓名：況潤元申請學(xué)位級別：碩士專業(yè)：自然地理學(xué)指導(dǎo)教師：汪永進(jìn)2003.5.1碩士論文：湖北神農(nóng)架近2000年采的石筍氣蛾記錄AbstractTopredict氆eevolutionofclimate弧thefutureitisimportant把exploreandanalyzetheprocessesandmechanismoftheclimatesystemoverth

2、epast2000yearsHeretheauthorusestwostalagmites(NO。SNwith255mmandBFtwith212mminheight)fromXiniuCave，ShennongiiatoinvestigateadecadaleenturyscaleclimaticchangesofEastAsianmonsooncovenngthemostpartofthelasttwomillenaryBasedo

3、n162’”Thdatingagesandl187dataofstableisotopiccompositionsaswellasannuallaminatedsequencesofthestalagmitesthenuthefirstlypresentstheclimaterecordsofthepast2000yearsinShennongjiaregionBycomparingthestalagmiterecordwithhist

4、oricalrecords，lakesedimentsandpollendata，theauthoranalyzescomparabilityanddifferencesofclimatechangeinEastAsiamonsoonareaandpreliminarilyinvestigatesdrivenforcesofclimatechangeAtimescaleofthesampleSNhasbeenreconstructedb

5、yapolynomialfiringwith9datedagesandfurthertestedbyannualbandcountingresultsIngeneral，thefittingpolynomiallineisconsistentwiththeannualbandgrowthrateexceptforthatthebottompartofthestalagmite(aheightbetween196to255mmfromth

6、etop)。HowcveratimescaleofthesampleBFlhasbeenestablishedbytheannualbandcountingchronologybracketedwith7Th230datesThetwochronologiesfromthedifferantagedeterminationforthetwostalagmitesagreewellinanuncertainof30yearsifusing

7、thesanle61奶signalsastiepointsAlinearregressionbetween6”0ofprecipitationandinsitutemperatureintheadjacentregionsshowsthatatemperaturedependent8‘sogradientcoefficientisdS‘SO／I‰064％d4C。Usingthegradientcoe衢cienttheauthoresti

8、matedthatthereisthemaximumamplitudeof35℃intemperatureoverthepast2000yearsinshennongjiaregionThe6”0proxyclimatictimeseriescanbedividedintosavencold／warmcyclesThe分sOrecorddisplaystwowarmperiodswitharelativecoldeventduringt

9、heMedievalWarmPeriod，andthatisquitedifferentfromotherrecordsinthestudiedareaneLittleIceAgeindicatedbythe6180cuweisdividedintofivecoldvalleysandfourwarmpeaksDuringOonghanDynastythe6”ecordofstalagmitethesameasalloftemperat

10、urerecordsintheEastAsiamonsoonareashowsasignificantwarminguptrendthatisdifferentfromotherrecordsDuringtheMedievalWarmPeriod，thelastingtimeisshorterandshorterfromthesouthtothenorthnchinaandtheeastchinaismoreobviousthanthe

11、centralchina；thebeginningtimeoftheLittleleeAgeinshennon腳iaregion(1480aAD)islaterthanthatinotherregions0420aAD)，battheyalldisplayapersistentdecreaseprocessoftemperature；Boththeannualbandinggrowthratecurveandgreylevelcurve

12、showtheevolutionprocessesoftheprecipitationoverthepast2000yearsthisregionandthatdivideintosevendry／wetcyclesBycomparingprecipitationproxiesoftheshennongjiaregionwiththedry／wetrecordsinotherregions，theauthorfindsthatthelo

13、ngtermchangetrendofallrecordsisapproximatelyconsistentAllrecordsshowthecharacteristicsofhighprecipitationandlargeswingbefore1100aAD，butthecharacteristicsoflowprecipitationandsmallswingafterlIOOaADDuringtheMedievalWarmPer

14、iodthereisavarydryperiodDuringtheLittleIceAgeprecipitationisliRleDuetodifferentresolutionevery∞cd畦hasdi蠡fenceindetailandalseflectsareacharacterBycomparing6‘sOcurvewithannualgrowthrateandgreylevelcurveinthestalagmitedurin

15、gthesameperiod，theauthorbringsforwardthatthatclimateinshennongiiaregionmostlyembodiesmatchingmodesofwarm／wetcold／dryoverthepast筠耱years。buttemperaturewasoutofharmonywithprecipitationinthecourseofclimatetransfotruingwhichs