17:15 〜 19:15
[AAS11-P23] 西シベリアにおけるタワー、航空機、衛星観測に基ついた大気中二酸化炭素の鉛直分布の経年変動
キーワード：二酸化炭素鉛直分布、タワー観測、航空機観測、西シベリア
Abstract
The atmospheric carbon dioxide (CO2) concentration column, also known as CO2 vertical profile, provides critical information of local atmospheric and biospheric carbon exchange, as well as the large-scale CO2 latitudinal gradient [1]. The most widely used total column-averaged CO2 mixing ratio has been measured using both in-situ measurements, such as the Total Carbon Column Observing Network (TCCON), and satellites, including the Greenhouse Gas Observing Satellite (GOSAT). However, measurements in high latitudes are often spatially and/or temporally limited. In west Siberia, for instance, the vast expanse of the region has not yet been equipped with in-situ instruments, and satellite observations are absent during the winter season. Such lack of data has a fundamental influence on the estimation of carbon exchange in Siberian ecosystems, involving observational methods and model simulations like inverse studies.
Here, we constructed and validated CO2 profiles along a latitudinal gradient across southern boreal forests and northern wetlands in West Siberia, then examined the interannual variations over a 15-year timespan. The construction of CO2 profiles extending from the surface to the top of free troposphere, basing on tower network observations (Japan-Russia Siberian Tall Tower Inland Observation Network, JR-STATION) and aircraft observations [2], with references to the radiosonde-derived pressure-altitude formula. To construct column-averaged CO2 profiles, we employed the linear intrapolation approach described in Müller et al. (2021) [3]. The contructed profiles were validated via comparison with collocated GOSAT observations [4].
The results showed that despite the overall increase across all layers, CO2 in the upper layers (e.g., around 800 hPa or above) exhibited smaller annual variation than that in the planetary boundary layer (PBL). This phenomenon can be attributed to the major impact of large-scale CO2 transportation in upper layers, as compared to the more significant influence of local-scale carbon exchange in lower layers. Changes in land use and land corver modify the latter, and the spatial variation of profiles provided further evidence to support this suggestion. Lower layers of the northern wetland area exhibited smaller interannual variation compared to the southern forest area, where a significant ratio of forest coverate changed from mixed forest to savannas with lower ecosystem productivity. Such analysis may provide distinct insignts into the relationship between large-scale spatial flux patterns and local-scale temporal foux patterns at northern high latitudes.
Reference
[1] Keppel-Aleks G, Wennberg PO, Schneider T (2011) Sources of variations in total column carbon dioxide. Atmos Chem Phys 11:3581–3593. https://doi.org/10.5194/acp-11-3581-2011
[2] Sasakawa M, Machida T, Tsuda N, et al (2013) Aircraft and tower measurements of CO2 concentration in the planetary boundary layer and the lower free troposphere over southern taiga in West Siberia: Long-term records from 2002 to 2011. J Geophys Res: Atmos 118:9489–9498. https://doi.org/10.1002/jgrd.50755
[3] Müller A, Tanimoto H, Sugita T, et al (2021) New approach to evaluate satellite-derived XCO2 over oceans by integrating ship and aircraft observations. Atmos Chem Phys 21:8255–8271. https://doi.org/10.5194/acp-21-8255-2021
[4] Nguyen H, Osterman G, Wunch D, et al (2014) A method for colocating satellite XCO2 data to ground-based data and its application to ACOS-GOSAT and TCCON. Atmos Meas Tech 7:2631–2644. https://doi.org/10.5194/amt-7-2631-2014
The atmospheric carbon dioxide (CO2) concentration column, also known as CO2 vertical profile, provides critical information of local atmospheric and biospheric carbon exchange, as well as the large-scale CO2 latitudinal gradient [1]. The most widely used total column-averaged CO2 mixing ratio has been measured using both in-situ measurements, such as the Total Carbon Column Observing Network (TCCON), and satellites, including the Greenhouse Gas Observing Satellite (GOSAT). However, measurements in high latitudes are often spatially and/or temporally limited. In west Siberia, for instance, the vast expanse of the region has not yet been equipped with in-situ instruments, and satellite observations are absent during the winter season. Such lack of data has a fundamental influence on the estimation of carbon exchange in Siberian ecosystems, involving observational methods and model simulations like inverse studies.
Here, we constructed and validated CO2 profiles along a latitudinal gradient across southern boreal forests and northern wetlands in West Siberia, then examined the interannual variations over a 15-year timespan. The construction of CO2 profiles extending from the surface to the top of free troposphere, basing on tower network observations (Japan-Russia Siberian Tall Tower Inland Observation Network, JR-STATION) and aircraft observations [2], with references to the radiosonde-derived pressure-altitude formula. To construct column-averaged CO2 profiles, we employed the linear intrapolation approach described in Müller et al. (2021) [3]. The contructed profiles were validated via comparison with collocated GOSAT observations [4].
The results showed that despite the overall increase across all layers, CO2 in the upper layers (e.g., around 800 hPa or above) exhibited smaller annual variation than that in the planetary boundary layer (PBL). This phenomenon can be attributed to the major impact of large-scale CO2 transportation in upper layers, as compared to the more significant influence of local-scale carbon exchange in lower layers. Changes in land use and land corver modify the latter, and the spatial variation of profiles provided further evidence to support this suggestion. Lower layers of the northern wetland area exhibited smaller interannual variation compared to the southern forest area, where a significant ratio of forest coverate changed from mixed forest to savannas with lower ecosystem productivity. Such analysis may provide distinct insignts into the relationship between large-scale spatial flux patterns and local-scale temporal foux patterns at northern high latitudes.
Reference
[1] Keppel-Aleks G, Wennberg PO, Schneider T (2011) Sources of variations in total column carbon dioxide. Atmos Chem Phys 11:3581–3593. https://doi.org/10.5194/acp-11-3581-2011
[2] Sasakawa M, Machida T, Tsuda N, et al (2013) Aircraft and tower measurements of CO2 concentration in the planetary boundary layer and the lower free troposphere over southern taiga in West Siberia: Long-term records from 2002 to 2011. J Geophys Res: Atmos 118:9489–9498. https://doi.org/10.1002/jgrd.50755
[3] Müller A, Tanimoto H, Sugita T, et al (2021) New approach to evaluate satellite-derived XCO2 over oceans by integrating ship and aircraft observations. Atmos Chem Phys 21:8255–8271. https://doi.org/10.5194/acp-21-8255-2021
[4] Nguyen H, Osterman G, Wunch D, et al (2014) A method for colocating satellite XCO2 data to ground-based data and its application to ACOS-GOSAT and TCCON. Atmos Meas Tech 7:2631–2644. https://doi.org/10.5194/amt-7-2631-2014