Analysis of stereoscopictemperature difference in Three Gorges Dem area and numerical simulation of water feedback

The Three Gorges Project provides significant benefits but also poses environmental and climatic concerns. Although studies suggested the reservoir's climate effect is spatially limited, its impact on stereoscopic climate is litter known. Based on 8 stereoscopic observation data of meteorological stations in the Three Gorges Dem (TGD) from 2009-2024, the difference of stereoscopic temperature characteristics in the TDG during July and possible mechanism of water feedback were analyzed by combining statistical and numerical simulation. It is found that the temperature on the southern slope of the dam area is generally higher than that on the north slope from the multi-year average analysis. Temperatures on both slopes decrease with increasing altitude and the temperature lapse rate on the north slope is greater than that on the south slope. During different water level operation, the differences of stereoscopic temperature distribution are mainly reflected in the temperature difference and temperature lapse rate between the north and south slopes. The higher the water level, the smaller the temperature difference and temperature lapse rate between the north and south slopes, and the correlation is more significant below the altitude of 800m. The model results show that the local vertical temperature distribution is mainly affected by altering the vertical movement and heat flux in the lower troposphere related to the reservoir. Due to the narrow terrain of the valley, the temperature advection caused by water area change is relatively weak. When the operating at high water levels, a local sinking motion was formed due to the increase of water area in the valley, resulting in a decrease in the rate of temperature lapse rate in the lower troposphere. At the same time, a decrease in land exposure area will lead to a reduction in sensible heat flux, further reducing the thermal difference near the ground. Large scale circulation plays a modulating role in the local thermal forcing effect of the reservoir. Under drought conditions, the thermal forcing effect in intensity and vertical extent of the water body is more pronounced than flood conditions.