Measurement Method of Mountain Leaf Area Index Based on Correction of Radiative Transmission Path Length

Abstract

The invention discloses a mountain leaf area index measurement method based on radiation transmission path length correction, and the method comprises the following steps: S1, obtaining mountain vegetation porosity data through a measurement instrument, and collecting mountain gradient, mountain slope direction, observation zenith angle and observation azimuth angle data; S2, calculating a conversion coefficient between the porosity of the mountain vegetation and the porosity of the flat land vegetation; S3, converting the mountain vegetation porosity data into flat land vegetation porosity data through the conversion coefficient; and S4, performing calculating to obtain a leaf area index through the flat ground vegetation porosity data. According to the method, firstly, the mountain porosity is converted into the equivalent flat ground porosity, and then the mountain leaf area index is estimated through the equivalent flat ground porosity, so that the defects that an existing method violates vegetation geotropism and is inconvenient to operate practically are overcome, and the measurement precision of the leaf area index under the mountain condition is remarkably improved.

Description

technical field [0001] The invention relates to the field of ground measurement, in particular to a method for measuring mountain leaf area index based on correction of radiation transmission path length. Background technique [0002] The ground measurement of leaf area index is the premise of resource environment investigation in mountainous areas and the establishment of remote sensing inversion algorithm of leaf area index. Observation methods, commonly used instruments include fisheye camera, LAI-2000, etc. These measurement methods already have high accuracy in the case of flat terrain, but when they are directly applied to the surface with complex topographic features such as mountains, they will bring greater uncertainty. [0003] The uncertainty of mountain leaf area index measurement stems from the modulation of terrain on the macroscopic structural characteristics of vegetation. It is intuitively shown that under the same observation altitude angle, the vegetation...

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Problems solved by technology

In order to suppress the uncertainty brought by topography to the ground measurement of LAI, the existing processing method is to place the instrument parallel to the inclined surface, although this processing method reduces the asymmetry of the porosity in the azimuthal direction to a certain extent , but because the spatial distribution characteristics of leaf inclination angles of vegetation are mainly affected by gravity, and its rotation invariance is expressed in the global coordinate system rather than the local coordinate system, so placing the instrument parallel to the slope will seriously violate the growth of vegetation to the ground. Finally, it will cause errors in the measurement of leaf area index; and it is difficult to place the instrument in a posture strictly parallel to the slope in actual field operations; therefore, it is necessary to study a method for measuring leaf area index suitable for mountains to improve mountain leaf area index. measurement accuracy

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