Experimental and Numerical Investigation of Dustfall Effect on Remote Sensing Retrieval Accuracy of Chlorophyll Content

Abstract

Chlorophyll is the dominant pigment in the photosynthetic light-harvesting complexes that is related to the physiological function of leaves and is responsible for light absorption and energy transfer. Dust pollution has become an environmental problem in many areas in China, indicating that accurately estimating chlorophyll content of vegetation using remote sensing for assessing the vegetation growth status in dusty areas is vital. However, dust deposited on the leaf may affect the chlorophyll content retrieval accuracy. Thus, quantitatively studying the dustfall effect is essential. Using selected vegetation indices (VIs), the medium resolution imaging spectrometer terrestrial chlorophyll index (MTCI), and the double difference index (DD), we studied the retrieval accuracy of chlorophyll content at the leaf scale under dusty environments based on a laboratory experiment and spectra simulation. First, the retrieval accuracy under different dustfall amounts was studied based on a laboratory experiment. Then, the relationship between dustfall amount and fractional dustfall cover (FDC) was experimentally analyzed for spectra simulation of dusty leaves. Based on spectral data simulated using a PROSPECT-based mixture model, the sensitivity of VIs to dust under different chlorophyll contents was analyzed comprehensively, and the MTCI was modified to reduce its sensitivity to dust. The results showed that (1) according to experimental investigation, the DD model provides low retrieval accuracy, the MTCI model is highly accurate when the dustfall amount is less than 80 g/m2, and the retrieval accuracy decreases significantly when the dustfall amount is more than 80 g/m2; (2) a logarithmic relationship exists between FDC and dustfall amount, and the PROSPECT-based mixture model can simulate the leaf spectra under different dustfall amounts and different chlorophyll contents with a root mean square error of 0.015; and (3) according to numerical investigation, MTCI’s sensitivity to dust in the chlorophyll content range of 25 to 60 μg/cm2 is lower than in other chlorophyll content ranges; DD’s sensitivity to dust was generally high throughout the whole chlorophyll content range. These findings may contribute to quantitatively understanding the dustfall effect on the retrieval of chlorophyll content and would help to accurately retrieve chlorophyll content in dusty areas using remote sensing.

Effect of Dust Deposition on Chlorophyll Concentration Estimation in Urban Plants from Reflectance and Vegetation Indexes

“…The sample selected in this study was shrub, which made the conclusions not applicable to different vegetation types. Simultaneously, some scholars [41] have researched strictly controlling the amount of dust manually and discussed the influence of definite dust amounts on leaf spectrum and element content, which is also an effective method to study dust deposition.…”

“…For example, Prajapati and Tripathi [40] evaluated the seasonal variation of dust accumulation on leaves of diverse vegetation and its influence on chlorophyll content. Ma et al [41] selected vegetation indexes (VIs), the medium resolution imaging spectrometer terrestrial chlorophyll index (MTCI), and the double-difference index (DD) to study the estimation accuracy of chlorophyll content at leaf scale in dusty environments. These perspectives have significantly expanded our thoughts and provided adequate references for selecting vegetation indexes to estimate pigment concentration.…”

Investigation of Vegetation Changes in Different Mining Areas in Liaoning Province, China, Using Multisource Remote Sensing Data

“…In addition to vegetation coverage, some biochemical parameters are also important for vegetation monitoring. Among them, chlorophyll is the basis of photosynthesis, and chlorophyll content is an important parameter that reflects vegetation growth and stress conditions [29]. However, the widely used NDVI is not well suited to measure chlorophyll content [30].…”