title: Influence of Typhoon Matsa on Phytoplankton Chlorophyll-a off East China.
abstract: Typhoons can cause strong disturbance, mixing, and upwelling in the upper layer of the oceans. Rich nutrients from the subsurface layer can be brought to the euphotic layer, which will induce the phytoplankton to breed and grow rapidly. In this paper, we investigate the impact of an intense and fast moving tropical storm, Typhoon Matsa, on phytoplankton chlorophyll-a (Chl-a) concentration off East China. By using satellite remote sensing data, we analyze the changes of Chl-a concentration, Sea Surface Temperature (SST) and wind speed in the pre- and post-typhoon periods. We also give a preliminary discussion on the different responses of the Chl-a concentration between nearshore and offshore waters. In nearshore/coastal regions where nutrients are generally rich, the Chl-a maximum occurs usually at the surface or at the layer close to the surface. And, in offshore tropical oligotrophic oceans, the subsurface maxima of Chl-a exist usually in the stratified water column. In an offshore area east of Taiwan, the Chl-a concentration rose gradually in about two weeks after the typhoon. However, in a coastal area north of Taiwan high Chl-a concentration decreased sharply before landfall, rebounded quickly to some degree after landfall, and restored gradually to the pre-typhoon level in about two weeks. The Chl-a concentration presented a negative correlation with the wind speed in the nearshore area during the typhoon, which is opposite to the response in the offshore waters. The phenomena may be attributable to onshore advection of low Chl-a water, coastal downwelling and intensified mixing, which together bring pre-typhoon surface Chl-a downward in the coastal area. In the offshore area, the typhoon may trigger increase of Chl-a concentration through uptake of nutrients by typhoon-induced upwelling and entrainment mixing.
authors.affiliation: Guangdong Key Lab of Climate, Resource and Environment in Continental Shelf Sea and Sea, College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhao
authors.affiliation: Guangdong Key Lab of Climate, Resource and Environment in Continental Shelf Sea and Sea, College of Ocean and Meteorology, Guangdong Ocean University, Zhanjiang, China.
authors.forename: Jinchao
authors.initials: J
authors.lastname: Shao
authors.affiliation: Northwest Atlantic Fisheries Centre, Fisheries and Oceans Canada, St. John's, Canada.
authors.forename: Guoqi
authors.initials: G
authors.lastname: Han
authors.affiliation: Key Laboratory of Ocean Circulation and Waves, CAS, Qingdao, China; Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China.
authors.forename: Dezhou
authors.initials: D
authors.lastname: Yang
authors.affiliation: Marine and Fishery Environment Monitoring Center of Guangzhou, Guangzhou, China.
authors.forename: Jianhai
authors.initials: J
authors.lastname: Lv
mesh_terms: D002681:China; D002734:Chlorophyll / Q000378:metabolism*; D000077194:Chlorophyll A; D055867:Cyclonic Storms; D009792:Oceans and Seas; D010839:Phytoplankton / Q000254:growth & development*
chemical_list: D002734:Chlorophyll; D000077194:Chlorophyll A