Study on Monitoring System of Chlorophyll-a Concentration and Water Temperature in Lake using NOAA/AVHRR Observed Data

阿巴什里湖由上低盐水和下多盐水两层坚固稳定的水体组成，完全是一个微咸湖泊。两层边界层深度随时间逐渐减小。同时，这也导致了上层盐度和富营养化的增加，以及下层脱氧的加速，原因是藻华的发生和蓝水的上涌。指出当水温大于18℃，叶绿素-a浓度大于30 μg/l时，会发生藻华。首先，利用观测值描述的地表边界条件、无热传导的底边界条件和1月1日^<st>的估计值描述的垂直初始条件，计算了Abashiri湖一维水温的垂直和季节变化。利用MCSST （Multi Channel Sea surface temperature，多通道海面温度）软件对无云条件下接收到的NOAA/AVHRR数据进行估算。其次，利用北上工业大学接收的NOAA/AVHRR数据、全球水平辐射和湖岸散射太阳辐射，计算出Abashiri湖地表的光谱反射率。为了将NOAA/AVHRR Ch.1的光谱辐亮度与水面发射的光谱辐亮度关联起来，利用水平总辐射和散射太阳辐射对透过率和路径辐亮度进行了近似计算。然后，利用浮游植物荧光区与吸收区光谱反射率差的叶绿素-a浓度回归线估算了阿巴什里湖中心的叶绿素-a浓度。

The Abashiri Lake consists of two strong stable layers of upper Oligohaline water and lower Polyhaline water, which is entirely a brackish lake. The boundary depth of two layers has gradually decreased with time. At the same time, this has led to an increase in salinity and eutrophication in upper layer and to an acceleration of deoxygenating of lower layer, attributed to the occurrence of algal bloom and the upwelling of bluish water. It is pointed out that the algal bloom occurs in the Abashiri Lake on condition that the water temperature is larger than 18 ℃ and the chlorophyll-a concentration is larger than 30 μg/l.At first, the vertical and seasonal variations of one dimensional water tempera in the Abashiri Lake were calculated using a surface boundary condition described by observed values, a bottom boundary condition with no-heat conduction and a vertical initial condition described by estimated values for January 1^<st>. The surface temperature can be estimated using the software, MCSST (Multi Channel Sea Surface Temperature) for NOAA/AVHRR data received on the condition of no-cloud.In the next, the spectral reflectance of Abashiri Lake surface was formulated by using NOAA/AVHRR data received in Kitami Institute of Technology, horizontal global and scattered solar radiation at the shore. In order to correlate the spectral radiance of NOAA/AVHRR Ch.1 with the spectral radiance emitted from water surface, transmittance and path radiance were calculated approximately by using the horizontal global and the scattered solar radiation. Then, the chlorophyll-a concentration in the center of the Abashiri Lake was estimated by the regression line of the chlorophyll-a concentration on the difference of spectral reflectance between fluorescence and absorption zone of phytoplankton.