随着全球气候变暖加剧,台风强度和强台风数量不断增加,加剧了磨刀门水道咸潮灾害的变化形势。本文采用SCHISM(semi-implicit cross-scale hydroscience integrated system model)模型建立磨刀门水道三维水流盐度数值模型,分析台风路径对磨刀门水道盐水入侵的影响。选取以"纳沙"为代表的西径型台风和以"天兔"为代表的东径型台风,发现二者对盐度输运和层化过程的动力响应具有差异性。东径型台风导致外海减水,平流通量向海增大;而西径型台风引起外海增水,逆转了原本向口外输出盐度的平流通量,会引起严重的盐水入侵。台风不仅引起外海的增减水效应,还带来强劲的局地风作用,对水道流速和盐度分布产生重要影响。在西径型台风下,顺河口向上游的风会减弱盐淡水分层,并加强平流项的向海输出;而在东径型台风下,一定强度顺河口向下游的风加强盐淡水分层,但当风速过强时,则会削弱盐淡水分层。
英文摘要:
As global warming intensifies,the intensity of typhoon and the number of powerful typhoons have been increasing,which exacerbate the changing situation of salty tide disaster in the Modaomen Waterway.A three-dimensional baroclinic model was applied with SCHISM (semi-implicit cross-scale hydroscience integrated system model) in the Modaomen Waterway to analyze the effect of typhoon path on saltwater intrusion.Taking Typhoon Nesat (the west-path typhoon) and Typhoon Usagi (the east-path typhoon) as examples,different dynamic responses of saltwater transport and stratification were revealed.The east-path typhoon led to the set-down of coastal sea level,which increased the oceanward advective flux.However,the west-path typhoon led to the set-up of coastal sea level,which promoted the oceanward advective flux landward and caused more serious saltwater intrusion.Apart from the effect on coastal sea level,typhoons also cause strong local winds,which have important influences on velocity field and saltwater transport.The up-estuary local wind caused by the west-path typhoon tended to reduce stratification and increase the oceanward advective flux.However,the down-estuary local wind caused by the east-path typhoon tended to enhance stratification under moderate wind,but it reduced stratification when the wind stress increased.