| Water age is an auxiliary variable to understand the marine environmentalfunction of dynamics processes, which is important for understanding mass exchangeand transport processes. The water always consist of some water types from differentwater sources. Hence, it is necessary to understand the water age of multiple sourcescalled as multiple water age. However, there are few studies about multiple water age.In this paper, the Bohai Sea is chosen as the study area and the multiple water age wascalculated by using the Constituent-oriented Age and Residence time Theory (CART)based on the three dimension Princeton Ocean Model. This model can be used toquantify the Bohai Sea components originating from rivers, the Yellow Sea andprecipitation. The distribution differences of the water age also are studied in reentryand non-reentry processes through different open boundary. The influences oftide-induced circulation, wind-induced and baroclinic force and interaction amongpoint sources on multiple water age have been investigated through a series ofnumerical model experiments.The water in the Bohai Sea was split into three types: the water originating fromthe rivers, the water origionating from the Yellow Sea and the water from theprecipitation. The percentage of the water from the rivers, the Yellow Sea andprecipitation is12.28%,77.24%and10.48%and the volume average water age in theBohai Sea is1271d,1969d and1269d, respectively. The multiple water age of theBohai Sea is about1810d. With the increase of distance from the Bohai strait, themultiple water age increase gradually. The multiple water age of the Bohai Sea showsweak seasonal variation except estuaries. The vertical distribution of the multiplewater age also appears stratification with the seasonal pycnocline and the nearer theestuaries the more obvious. The multiple water age gradually reduces from south tonorth effected by the flow field of the Bohai Strait, where there is an inflow in the northern area and an outflow in the south.Without the reentry process, the age and concentration of the rivers, theprecipitation and the sea reduce evidently, while the characteristics of vertical averageage distribution is similar to the results under the reentry process. Tidal force andwind force are the main factors influencing the distribution of the water age in theBohai Sea, while barocline force has less effect on that. The existence of the tidalforce not only can increase the water age up to55%or more, but also can make thedistribution of vertical average water age change obviously as well. The wind forcecauses a decrease of more than30%on the water age of Bohai Sea, whereasimpacting less on the distribution of vertical average water age. In terms of baroclinicforce effects, the water age slightly decreases in the Bohai Sea except for the eastcoast of LaiZhou Bay.There isn’t any significant effects on the vertical average spatialdistribution of water age.In order to consider the effect of interaction of point and non-point sources onthe water age, this study choose the Haihe water in the Bohai Sea as an exampleconsidering the impact of typical point sources, the Yellow River, the Liaohe Riverand the Luanhe River, on the age of the Haihe water and choose the rivers andprecipitation water as an example considering the impact of the rivers point sourceson the age of the precipitation and the sea and the impact of the precipitationnon-point sources on the age of the rivers and the sea. The existence of3typicalpoint sources can decrease the concentration and the water age of the water fromHaihe River16%and12%, respectively. The existence of the rivers can decrease thewater age of the Bohai Sea22%and can decrease the water age of the precipitationand the sea19%and18%, respectively. The existence of the precipitation candecrease the water age of the Bohai Sea11%and can decrease the water age of therivers and the sea14%and7%, respectively. |
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