【摘要】：林下枯枝落葉層會衰減來自土壤的微波輻射信號,降低微波輻射亮溫對地表參數(shù)變化的敏感性,從而影響林下地表參數(shù)的反演精度。為了定量研究枯枝落葉層的衰減特性,基于τ-ω模型,通過嚴格的理論推導(dǎo)證明了利用不同厚度下的枯枝落葉層亮溫計算衰減系數(shù)的可行性,并基于該理論方法設(shè)計可控實驗,獲取了雙頻段(18.7GHz和36.5GHz)上不同厚度、不同重量含水量的枯枝落葉層亮溫值,然后定量分析了枯枝落葉層的衰減系數(shù)隨重量含水量的變化過程,同時根據(jù)計算的消光系數(shù),分析了不同厚度、不同重量含水量下的枯枝落葉層透過率。結(jié)果表明:較干燥的枯枝落葉層的衰減系數(shù)較小,透過率較高,但是隨著含水量增大,衰減系數(shù)會出現(xiàn)急劇的增加,從而造成透過率驟減;高頻波段的衰減系數(shù)變化更加迅速,由枯枝落葉層引起的衰減作用更加明顯;單次散射反照率ω隨重量含水量的變化趨勢為先升高后降低。該研究有利于理解森林系統(tǒng)中微波輻射傳輸過程,糾正森林區(qū)微波輻射亮溫,提高森林下地表參數(shù)遙感反演精度。
[Abstract]:The litter layer under forest will attenuate the microwave radiation signal from soil, reduce the sensitivity of microwave radiation brightness temperature to the change of land surface parameters, and thus affect the inversion accuracy of land surface parameters under forest. In order to quantitatively study the attenuation characteristics of litter layer, based on 蟿-蠅 model, the feasibility of calculating attenuation coefficient by using the brightness temperature of litter layer under different thickness is proved by strict theoretical derivation. Based on the theoretical method, controllable experiments were designed to obtain the brightness temperature of litter layer with different thickness and water content in dual-band (18.7GHz and 36.5GHz). Then the variation process of decay coefficient with water content of litter layer was quantitatively analyzed. According to the calculated extinction coefficient, the transmittance of litter layer under different thickness and different weight water content was analyzed. The results show that the attenuation coefficient of the dry litter layer is smaller and the transmittance is higher, but with the increase of water content, the attenuation coefficient will increase sharply, resulting in a sharp decrease in the transmission rate. The attenuation coefficient changes more rapidly in the high frequency band, and the attenuation caused by litter layer is more obvious, and the change trend of single scattering albedo 蠅 with weight and water content is increasing first and then decreasing. This study is helpful to understand the process of microwave radiation transfer in forest system, correct the brightness temperature of microwave radiation in forest area, and improve the precision of remote sensing retrieval of land surface parameters under forest.
【作者單位】： 中國科學(xué)院東北地理與農(nóng)業(yè)生態(tài)研究所;中國科學(xué)院大學(xué);中國科學(xué)院長春凈月潭遙感試驗站;吉林大學(xué)地球探測科學(xué)與技術(shù)學(xué)院;
【基金】：國家自然科學(xué)基金面上項目“集成光學(xué)與微波遙感蘇打鹽堿地水鹽含量的反演方法研究”(41371345);國家自然科學(xué)基金項目“東北地區(qū)森林下雪深被動微波遙感反演的關(guān)鍵影響參數(shù)觀測與研究”(41471289);國家自然科學(xué)基金項目“被動微波遙感土壤水分反演精度與空間異質(zhì)特征的相關(guān)性研究”(41301369)
【分類號】：TP722.6
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本文編號：2461980