18-year variability of ultraviolet radiation penetration in the mid-latitude coastal waters of the western boundary Pacific

Victor S. Kuwahara, Sena Nozaki, Junji Nakano, Tatsuki Toda, Tomohiko Kikuchi, Satoru Taguchi

    • 2 Citations

    Abstract

    d(λ) have recurrent seasonal variability of high/low attenuation during summer/winter months, respectively, dependent on variability in water column stratification and concentrations of bio-optical properties. The mid-latitude coastal survey station displayed significant seasonality of the mixed layer depth (MLD) between 12 and 82m which modified the distribution of chlorophyll a (4.6-24.9mgm-2) and absorption of colored dissolved organic matter [aCDOM(320nm) 0.043-1.34m-1]. The median Kd(320nm) displayed significant seasonality at 0.19-0.74m-1(C.V.=44.1%) and seasonal variability within the euphotic layer [Z10%(320nm)=7-20%]. High attenuation of UVR with relatively moderate attenuation of PAR was consistently observed during the summer months when increased concentrations of terrestrially derived CDOM coupled with a shallow MLD were present. The winter season showed the opposite of low UVR and PAR attenuation due to a relatively deeper MLD coupled with low concentrations of bio-optical properties. Although the long term Kd(λ) did not vary significantly during the time-series, analysis of the interannual variability suggests there are positive and negative phases following the Pacific Decadal Oscillation (PDO) vis-a-vis variability in bio-optical properties (p<0.001).]]>

    Original languageEnglish
    Pages (from-to)1-9
    Number of pages9
    JournalEstuarine, Coastal and Shelf Science
    Volume160
    DOIs
    StatePublished - 2015 Jul 5

    Fingerprint

    ultraviolet radiation
    photosynthetically active radiation
    optical property
    mixed layer
    seasonality
    winter
    summer
    Pacific Decadal Oscillation
    time series analysis
    dissolved organic matter
    coastal water
    chlorophyll a
    stratification
    penetration
    water column
    time series

    Keywords

    • Bio-optics
    • Coastal waters
    • Japan
    • Seasonality
    • Ultraviolet radiation

    ASJC Scopus subject areas

    • Aquatic Science
    • Oceanography

    Cite this

    18-year variability of ultraviolet radiation penetration in the mid-latitude coastal waters of the western boundary Pacific. / Kuwahara, Victor S.; Nozaki, Sena; Nakano, Junji; Toda, Tatsuki; Kikuchi, Tomohiko; Taguchi, Satoru.

    In: Estuarine, Coastal and Shelf Science, Vol. 160, 05.07.2015, p. 1-9.

    Research output: Contribution to journalArticle

    Kuwahara, Victor S.; Nozaki, Sena; Nakano, Junji; Toda, Tatsuki; Kikuchi, Tomohiko; Taguchi, Satoru / 18-year variability of ultraviolet radiation penetration in the mid-latitude coastal waters of the western boundary Pacific.

    In: Estuarine, Coastal and Shelf Science, Vol. 160, 05.07.2015, p. 1-9.

    Research output: Contribution to journalArticle

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    keywords = "Bio-optics, Coastal waters, Japan, Seasonality, Ultraviolet radiation",
    author = "Kuwahara, {Victor S.} and Sena Nozaki and Junji Nakano and Tatsuki Toda and Tomohiko Kikuchi and Satoru Taguchi",
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    AU - Kuwahara,Victor S.

    AU - Nozaki,Sena

    AU - Nakano,Junji

    AU - Toda,Tatsuki

    AU - Kikuchi,Tomohiko

    AU - Taguchi,Satoru

    PY - 2015/7/5

    Y1 - 2015/7/5

    N2 - The 18-year time-series shows in situ ultraviolet radiation (UVR) and photosynthetically active radiation (PAR) diffuse attenuation coefficient Kd(λ) have recurrent seasonal variability of high/low attenuation during summer/winter months, respectively, dependent on variability in water column stratification and concentrations of bio-optical properties. The mid-latitude coastal survey station displayed significant seasonality of the mixed layer depth (MLD) between 12 and 82m which modified the distribution of chlorophyll a (4.6-24.9mgm-2) and absorption of colored dissolved organic matter [aCDOM(320nm) 0.043-1.34m-1]. The median Kd(320nm) displayed significant seasonality at 0.19-0.74m-1(C.V.=44.1%) and seasonal variability within the euphotic layer [Z10%(320nm)=7-20%]. High attenuation of UVR with relatively moderate attenuation of PAR was consistently observed during the summer months when increased concentrations of terrestrially derived CDOM coupled with a shallow MLD were present. The winter season showed the opposite of low UVR and PAR attenuation due to a relatively deeper MLD coupled with low concentrations of bio-optical properties. Although the long term Kd(λ) did not vary significantly during the time-series, analysis of the interannual variability suggests there are positive and negative phases following the Pacific Decadal Oscillation (PDO) vis-a-vis variability in bio-optical properties (p<0.001).

    AB - The 18-year time-series shows in situ ultraviolet radiation (UVR) and photosynthetically active radiation (PAR) diffuse attenuation coefficient Kd(λ) have recurrent seasonal variability of high/low attenuation during summer/winter months, respectively, dependent on variability in water column stratification and concentrations of bio-optical properties. The mid-latitude coastal survey station displayed significant seasonality of the mixed layer depth (MLD) between 12 and 82m which modified the distribution of chlorophyll a (4.6-24.9mgm-2) and absorption of colored dissolved organic matter [aCDOM(320nm) 0.043-1.34m-1]. The median Kd(320nm) displayed significant seasonality at 0.19-0.74m-1(C.V.=44.1%) and seasonal variability within the euphotic layer [Z10%(320nm)=7-20%]. High attenuation of UVR with relatively moderate attenuation of PAR was consistently observed during the summer months when increased concentrations of terrestrially derived CDOM coupled with a shallow MLD were present. The winter season showed the opposite of low UVR and PAR attenuation due to a relatively deeper MLD coupled with low concentrations of bio-optical properties. Although the long term Kd(λ) did not vary significantly during the time-series, analysis of the interannual variability suggests there are positive and negative phases following the Pacific Decadal Oscillation (PDO) vis-a-vis variability in bio-optical properties (p<0.001).

    KW - Bio-optics

    KW - Coastal waters

    KW - Japan

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    KW - Ultraviolet radiation

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