简介:AnAcousticDopplerCurrentProfiler(ADCP)observationsitewassetupintheWesternSouthYellowSeafrom2012to2013tostudythelocalsuspendedparticlematters(SPM)distributionpattern.TheSPMconcentrationcouldbesemi-quantitativelyrepresentedbybackscatterintensity(Sv),convertedbytheechointensity(EI)ofADCP.ResultsshowtwotypesofSPMinthewatercolumn:thequasi-biologicalSPMandquasi-mineralSPM.Thequasi-biologicalSPMmainlyexistsinsummerhalfyearandisconcentratedabovethethermocline.Ithasperiodicallydiurnalvariationswithhighconcentrationatnightandlowconcentrationinthedaytime.Thequasi-mineralSPMislocatedinlowerpartofthewatercolumn,withsimilarrelationtomonthlytidalcurrentvariationallyearround.However,thedailyquasi-mineralSPMdistributionpatternsvarybetweensummerandwinterhalfyear.Thesunlightisthoughttobetheoriginfactorleadingtothediurnallyverticalmotionofthebiologicalfeatures,whichmightcausethediurnalSvvariation.UnlikeinwinterhalfyearwhentidalcurrentisrelativelysingledrivingforceofthemonthlySPMpattern,thehighspeedcurrentnearthethermoclineisalsoresponsiblefortheconcentrationofquasi-mineralSPMinsummerhalfyear.Thesedimentinputdifferencebetweensummerandwinterhalfyearcontributetothevarieddailyvariationofquasi-mineralSPMwithre-suspendedSPMinwinterandsedimentsfromYellowSeaMudArea(YSMA)insummer.Theseasonalvariationsinhydrodynamics,waterstructureandheavy-windincidentsaretheprimaryfactorsinfluencingthedifferentialseasonalSPMdistributionpatterns.
简介:摘要在初中物理中,“速度”和“密度”的相关知识较为抽象,公式应用比较繁杂,学生不易理解掌握,是教学中的一个难点。本文根据它们的一些相关性,从概念、实验、公式运用三个方面进行了类比分析。