基于GIS的贵州高原复杂地形下积温的精细空间分布

Distribution of Accumulated Temperature of High Spatial Resolution over Complex Terrains across the Guizhou Plateau Based on GIS

积温是研究作物生长发育对热量的要求和评价热量资源的一种指标。本文在前人研究的基础上,对原有的模型进行了一些改进,考虑了坡度、坡向和地形相互遮蔽作用对复杂地形下太阳总辐射的影响,基于数字高程模型(DEM)数据,研制了以海拔高度、复杂地形下太阳总辐射为参数的复杂地形下积温的分布式模型,在模型中还考虑了散射辐射的各向异性及坡地反射辐射对复杂地形下太阳总辐射的影响。应用100m×100m分辨率的DEM数据及气象站常规观测气象资料,计算了贵州高原复杂地形下100m×100m分辨率的≥0℃、≥10℃、≥15℃积温。结果表明:①局地地形因子如坡度、坡向、地形遮蔽等对积温的影响显著,使得复杂地形下积温的精细空间分布具有明显的地域分布特征,纬向分布特征不明显。地形对复杂地形下积温的影响是不容忽视的;②同一纬度,由于地形差异,积温的空间分布明显不同。阳坡、海拔较低处的积温偏高,阴坡、海拔较高处的积温偏低;③在缺乏复杂地形下坡面考察资料的情况下,建立以常规气象站观测资料为主的物理经验统计模型是实现细网格热量资源计算的可行途径。

Accumulated temperature is a promising index for studying the thermal requirement for crop growth and evaluating heat resources.In this work,the influence of terrain factors,i.e.,slope,azimuth,and terrain inter-shielding on global solar radiation over complex terrains is quantified.Distributed models of accumulated temperature over complex terrains,which is a function of elevation and global solar radiation,are developed on the basis of Digital Elevation Models （DEM）.The anisotropism of diffuse radiation and the effect of reflection for sloping land surfaces on global solar radiation are accounted for in this model.Using this model,maps of accumulated temperatures of≥0℃,≥10℃,≥20℃,respectively,with a spatial resolution of 100 m×100 m from a DEM and meteorological observations across the Guizhou Plateau were generated.Results indicate that：1）the model physics is sound and has a strong capability to capture variations in the accumulated temperature under complex terrains;2）in addition to the influence of the altitude above the sea level and atmospheric circulation,local terrain factors,i.e.,slope,azimuth,and terrain inter-shielding,have a significant effect on accumulated temperature.As such,the spatial distribution of the accumulated temperature shows obvious heterogeneity as terrain whereas exhibits less zonal heterogeneity;3）the accumulated temperature is generally higher over sloping surfaces facing south,and somewhat lower over surfaces facing north for the same latitude and azimuth;4）the accumulated temperature of high spatial resolution over complex terrains varies greatly for the same latitude because of hypsography.The accumulated temperature increases gradually along with increasing slopes for the south azimuth of mountains at the same latitude,but decreases incrementally along with increasing slopes for the north azimuth of mountains at the same latitude.In general,the accumulated temperature is greater at low elevations,and becomes small at high elevations;5）in the absence of meteorological observations in mountainous areas,building an empirical statistical model primarily by observed data at routine meteorological stations would be a feasible way to estimating heat resources of refined resolution;and 6） compared with the conventional method,the proposed model can explicitly reflect the influence of terrain factors on accumulated temperature over complex terrains.Satellite remote sensing and more sophisticated statistical models can be adopted for further refinement of the model in the future.