Applications of MODIS-visible bands index, greenery ratio to estimate CO2 budget of a rice paddy in Japan
Applications of MODIS-visible bands index, greenery ratio to estimate CO2 budget of a rice paddy in Japan
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DOI：
10.2480/agrmet.65.4.6
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发表时间：
2009
影响因子：
1.3
通讯作者：
Y. Harazono;K. Chikamoto;Shunsaku Kikkawa;T. Iwata;Nana Nishida;M. Ueyama;Y. Kitaya;M. Mano;A. Miyata
中科院分区：
文献类型：
--
作者：
Y. Harazono;K. Chikamoto;Shunsaku Kikkawa;T. Iwata;Nana Nishida;M. Ueyama;Y. Kitaya;M. Mano;A. Miyata
利用卫星遥感数据，采用归一化植被指数（NDVI）方法对碳收支进行了遥感估算。然而，NDVI在农业作物、北方森林和冻土带生态系统中的应用存在一些困难。本文提出了一种新的植被指数GR（greenery ratio），并将其应用于日本稻田CO2收支的遥感估算。GR是MODIS的绿色（G）与三色可见光波段（R+G+B）的比值，利用MODIS数据和Mase站稻田观测的微气象和通量，建立了GR-CO2收支经验模型。利用MODIS估算了日光合有效辐射（PAR）。参数化模型对GPP（毛初级生产力）的日变化和季节变化趋势具有较好的估计效果，但对RE（生态系统呼吸）的估计存在一定的低估，尤其是在生长季后期。与观测到的CO2预算相矛盾的是，估计的预算比GPP高2%，比RE低5%，比NEE（净生态系统交换）高9%。NEE的巨大差异是由于引流后RE的估计不佳。需要进一步研究以改进RE估计。
NDVI (Normalized Difference of Vegetation Index) was employed to estimate the carbon budget remotely with satellite data. However, NDVI has some difficulties in application to agricultural crops, boreal forest, and tundra ecosystems. We proposed a new vegetation index GR (greenery ratio) to detect the vegetation change remotely, and we applied it to estimate CO2 budget of Japanese rice paddy with MODIS satellite data. GR was ratio of green (G) to the trichromatic visible bands (R+G+B) of MODIS, and an empirical GR-CO2 budget model was developed as functions of MODIS-data and observed micrometeorology and fluxes at the rice paddy of Mase-site. The daily PAR (photosynthetically active radiation) was also estimated by MODIS. The parameterized model provided good performance to estimate daily magnitudes and seasonal trends of GPP (gross primary productivity), however, RE (ecosystem respiration) showed a little under-estimation, especially differed in late growing season. In contradiction to the observed CO2 budget, the estimated budgets were 2% greater of GPP and 5% less of RE and 9% greater of NEE (net ecosystem exchange). The large discrepancy in NEE was owing to the poor estimation of RE after drainage. Further study to improve RE estimation was needed.