珠江三角洲近地层CO2通量模拟分析与评估验证

利用能分别代表珠江三角洲草地、城市绿地及地带性森林植被生态系统的番禺站、东莞站和鼎湖山站CO2净通量资料对CT-2010碳源汇反演模式系统进行了验证,并利用该模式初步分析了区域净碳通量的时空分布及不同生态系统的碳汇特征.结果表明: CT-2010模式模拟的珠江三角洲城市绿地、地带性植被、以及草地生态系统碳通量与站点观测结果具有较好的一致性,其拟合相关系数(r)高于0.60(P<0.01),小时、逐日、日变化的残差均值低于2.0μmol/(m2?s);模式一定程度上能反映3种生态系统碳通量的季节分布特征,但各月的模拟值均高于观测值,其中对城市绿地生态系统的模拟最接近,残差年均值为0.964μmol/(m2?s),对草地和地带性森林植被生态系统的模拟效果相当,残差年均值分别为 2.056,2.100μmol/(m2?s);2004~2005年期间珠江三角洲地区近地层净碳通量为3.43μmol/(m2?s),其中冬季最强,为1.4μmol/(m2?s),春季次之,为1.35μmol/(m2?s),秋季和夏季最低,分别为0.51和0.18μmol/(m2?s);在冬、春两季,珠江三角洲区域为强的碳源区,而在夏、秋季,粤北和粤东大部分地区为较弱碳汇区;2004~2005年期间珠江三角洲地区陆地生态系统的碳汇为-6.5×10-3PgC,其中农作物,草地/灌木,常绿针叶/阔叶混合林是吸收CO2的主要生态系统,其净通量占陆地生态系统的比率分别为42.01%,31.46%和26.53%.

Simulation analysis and verification of surface CO2 flux over Pearl River Delta,China

Carbon dioxide is the primary greenhouse gas involved in climate change. This gas is responsible for 85% of the increase in radiative forcing over the past decade and 81% over the last five years. Accurate estimations of strength and spatiotemporal distributions of surface sources and sinks of CO2 are thus of great interest to the scientific community and policy makers. The CO2 measurement and modeling system developed by the National Oceanic and Atmospheric Administration and called the Carbon Tracker-2010 (CT-2010) was used to analyze the seasonal and spatial distributions of net CO2 flux and CO2 sink characteristics of terrestrial ecosystems in the Pearl River Delta (PRD) region. Prior to doing simulations, the CT-2010 model was validated using in situ observations from the Panyu meteorological site (PYQXJ), the Dongguan site (DG), and the Ding Hushan site (DHS), which are representative of grassland, urban green space, and forest ecosystems in the PRD region, respectively. Net fluxes from the CT-2010model compared with observations from the three sites well. Hourly, daily, and diurnal residuals were less than 2.0 μmol/(m2?s) and correlation coefficients were greater than 0.60 (P<0.01). The CT-2010 model captured well the seasonal patterns of CO2fluxes over the PRD region. However, the magnitude of the simulated fluxes was generally greater than that of the observed fluxes. Annual residuals were 2.056, 0.964, and 2.100μmol/(m2?s) at the PYQXJ, DG, and DHS sites, respectively. From June 2004to May 2005, the mean surface net flux over the PRD region was 3.43μmol/(m2?s). In summer, fall, winter, and spring, mean surface net fluxes were 0.18, 0.51, 1.4, and 1.35 μmol/(m2?s), respectively. The mean terrestrial flux in the PRD was -6.5×10-3 PgC. The region during this time was dominated by crops (42.01%), grassland/shrubs (31.46%), and mixed (coniferous/broadleaf) forest (26.53%).