大洋海区海-气CO_2通量单参数遥感算法的适用性检验

Abstract

利用卫星遥感技术的优势,基于ldEO数据库的全球海表二氧化碳分压(PCO2)及海表温度(SST)等实测数据,初步建立东太平洋海区PCO2与SST的单参数经验算法,并采用相同区域的独立实测数据检验.结果表明,单参数算法在寡营养大洋海区具有良好的适用性,反演值与实测值之间的均方根误差(rMS)为0.51 PA(1 PA=9.869μATM),由此估算出2003年6月该海域CO2通量为-1.4 MMOl/(M2.d),与实测估算的碳通量基本相符,能够很好地反映出海区CO2源汇特征.将该遥感算法运用到西大西洋海域(15°--25°n,60°--75°W),反演值与实测值之间均方根误差(rMS)为0.69 PA.检验结果表明,在寡营养大洋海区,单参数遥感算法具有一定的适用性,在受相似因子调控的同纬度海区可以使用同一遥感算法.

Accurate estimation of the air-sea CO2 flux is the foundation of evaluating the role the ocean plays in the global carbon cycle.Previous research results have indicated that sea-surface PCO2 is dominated by the sea-surface temperature in the open ocean,and a single-parameter empirical algorithm performs well in evaluating sea-surface CO2 flux.On the basis of PCO2 and other related in situ parameters of the LDEO dataset,we used data recorded on four summer cruises(1996--2004) in the sea area near Hawaii(East Pacific Ocean) to formulate a single-parameter model based on the relationship between the sea-surface temperature and PCO2,and then validated this algorithm with two sets of in situ PCO2 data.The validation results for the East Pacific Ocean(Hawaii Sea) in June 2003 and West Atlantic Ocean(Caribbean Sea) from June to August 2002 were RMS = 0.51 Pa,n = 196 and RMS = 0.69 Pa,n=545,respectively.All results indicate that the single-parameter algorithm formulated in this study was suitable for oligotrophic open ocean.Afterward,we calculated the CO2 flux in East Pacific Ocean for June 2003 as approximately-1.4 mmol/(m2·d),which was in accordance with in situ flux.The results demonstrate that,in oligotrophic open ocean and with consideration of biological and physicochemical properties,one algorithm can be applied to identical-latitude sea areas that are under the control of similar factors.This inspires the expansion of the single-parameter algorithm to the open ocean.