Meteorological data play a crucial role in the heat budget of water bodies. Previous research has primarily focused on collecting meteorological data from a single location. This study develops a simple method for collecting meteorological data in a reservoir and investigates the spatial variability of wind vector and solar radiation (SR) across different locations in the Ogouchi Reservoir, a meandering reservoir surrounded by mountains. The weather stations were installed using two methods: a floating frame and a floating platform. Stations were placed at six locations on the surface of the reservoir, considering factors such as sky openness and valley line angles. The electro-magnetic current meter and the camera were installed to evaluate the orientation of the frame, which confirmed the rotational stability of the floating frame. The results showed that the timing of increasing and decreasing SR varied at each location. It increased in the down-stream areas earlier than in the upstream areas. The brightness plot demonstrated that these variations in SR correspond to the timing of the switching between sunlight and shadow. The comparison between the SR of each location for six sunny days with Tokyo Metropolitan Government (TMG) data showed that the SR values in the downstream areas are up to 10% higher and the upstream areas up to 21% lower than the TMG data. Moreover, wind vectors also exhibited significant variation across locations, with wind speed being maximum 8% higher in the downstream areas (open water areas) and 90% lower in the upstream area (narrow, meandering sections). Additionally, wind direction followed the terrain of the reservoir. This study suggests that the spatial distribution of meteorological data should be incorporated into numerical simulations, as it affects surface water temperature, which plays an important role in physical processes.
Kheiri et al. (2025) studied this question.