基于MODIS的光合有效辐射估算系统设计与实现

本文采用PARcalc算法,并以C#和ENVI/IDL二次开发语言,设计了主要以MODIS产品为驱动的光合有效辐射估算系统。鉴此,比较了IDL和ArcGIS Engine两者的技术特点,设计了IDL与ArcGIS Engine共存、多种开发环境相结合的技术方案。同时,对模型参数置备、光合有效辐射估算、模型分析等模块的功能,以及多种语言混合编程、数据分块处理、瞬时及日光合有效辐射批量计算等关键技术进行了分析。最后,以内蒙古地区作为研究区,估算了该区2007全年和四季的总光合有效辐射及日均光合有效辐射,并对其特征值作了对比分析。结果表明,对研究区域尺度光合有效辐射的定量化计算具有一定的参考价值。

Design and Implementation of the PAR Calculation System Based on MODIS Data

In this paper we developed a PAR (photosynthetically active radiation) calculation system based on PARcalc algorithm which was driven by MODIS data. Before designing, we compared the characteristic of IDL with ArcGIS Engine, and analyzed the requirements of system functions. Therefore we designed a technical scheme which integrated IDL with ArcGIS Engine together, and chose C# as the main programming language. The communication between C# and IDL is dependent on the IDL ActiveX component. Then we gave a detailed introduction to the main modules and functions of the system and analyzed the key techniques for the implementation such as programming with C# and IDL in the same environment, data partition, batch computation of incident PAR, and batch computation of daily PAR by LM (Levenberg-Marquardt) algorithm. Finally we calculated the annual and seasonal PAR in Inner Mongolia in 2007 by the system, and made a statistic of the characteristic value. The results showed that the system provided a friendly man-machine interaction. It was easy to use and met the demands of practical applications. It had great reference value for PAR calculation in regional scale.