Towards Robust Calculation of Interannual CO2 Growth Signal from TCCON (Total Carbon Column Observing Network)

Remote Sensing

Tae-Young Goo¹  Hannakaisa Lindqvist²  Shanlan Li³  Young-Hwa Byun³  Samuel Takele Kenea³  Jinwon Kim³  Lev D. Labzovskii⁴ 

[1] Convergence Meteorological Research Department, National Institute of Meteorological Sciences (NIMS), Seogwipo-si 63568, Korea;Finnish Meteorological Institute, 00560 Helsinki, Finland;Innovative Meteorological Research Department, National Institute of Meteorological Sciences (NIMS), 33, Seohobuk-ro, Seogwipo-si 63568, Korea;R&D Satellite and Observations Group, Royal Netherlands Meteorological Institute (KNMI), 3731GA De Bilt, The Netherlands;

关键词: CO₂;    carbon cycle;    FTIR;    climate change;    ENSO;   

DOI  :  10.3390/rs13193868

来源: DOAJ

【 摘 要 】

The CO₂ growth rate is one of the key geophysical quantities reflecting the dynamics of climate change as atmospheric CO₂ growth is the primary driver of global warming. As recent studies have shown that TCCON (Total Carbon Column Observing Network) measurement footprints embrace quasi-global coverage, we examined the sensitivity of TCCON to the global CO₂ growth. To this end, we used the aggregated TCCON observations (2006-2019) to retrieve Annual Growth Rate of CO₂ (AGR) at global scales. The global AGR estimates from TCCON (AGR_TCCON) are robust and independent, from (a) the station-wise seasonality, from (b) the differences in time series across the TCCON stations, and from (c) the type of TCCON stations used in the calculation (“background” or “contaminated” by neighboring CO₂ sources). The AGR_TCCON potential error, due to the irregular data sampling is relatively low (2.4–17.9%). In 2006–2019, global AGR_TCCON ranged from the minimum of 1.59 ± 2.27 ppm (2009) to the maximum of 3.27 ± 0.82 ppm (2016), whereas the uncertainties express sub-annual variability and the data gap effects. The global AGR_TCCON magnitude is similar to the reference AGR from satellite data (AGR_SAT = 1.57–2.94 ppm) and the surface-based estimates of Global Carbon Budget (AGR_GCB = 1.57–2.85). The highest global CO₂ growth rate (2015/2016), caused by the record El Niño, was nearly perfectly reproduced by the TCCON (AGR_TCCON = 3.27 ± 0.82 ppm vs. AGR_SAT = 3.23 ± 0.50 ppm). The overall agreement between global AGR_TCCON with the AGR references was yet weakened (r = 0.37 for TCCON vs. SAT; r = 0.50 for TCCON vs. GCB) due to two years (2008, 2015). We identified the drivers of this disagreement; in 2008, when only few stations were available worldwide, the AGR_TCCON uncertainties were excessively high (AGR_TCCON = 2.64 ppm with 3.92 ppm or 148% uncertainty). Moreover, in 2008 and 2015, the ENSO-driven bias between global AGR_TCCON and the AGR references were detected. TCCON-to-reference agreement is dramatically increased if the years with ENSO-related biases (2008, 2015) are forfeited (r = 0.67 for TCCON vs. SAT, r = 0.82 for TCCON vs. GCB). To conclude, this is the first study that showed promising ability of aggregated TCCON signal to capture global CO₂ growth. As the TCCON coverage is expanding, and new versions of TCCON data are being published, multiple data sampling strategies, dynamically changing TCCON global measurement footprint, and the irregular sensitivity of AGR_TCCON to strong ENSO events; all should be analyzed to transform the current efforts into a first operational algorithm for retrieving global CO₂ growth from TCCON data.

【 授权许可】

Unknown