Interannual Variation of Upper Tropospheric CO over the Western Pacific Linked with Indonesian Fires

Matsueda, Hidekazu; Buchholz, Rebecca R.; Ishijima, Kentaro; Worden, H. M.; Hammerling, Dorit; Machida, Toshinobu

doi:10.2151/sola.2019-037

Cited by 8 publications

(6 citation statements)

References 35 publications

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“…Given the sparse ground-based observations in Equatorial Asia, these programmes provide valuable opportunities to investigate the fire-induced emissions in the region. The long-term aircraft observation (the predecessor of CONTRAIL) observed CO2 and CO mole fraction variations associated with El Niño over the western Pacific since 1993 (Matsueda et al, 2002(Matsueda et al, , 2019. Its occasional observation flight to Singapore (Matsueda and Inoue, 1999) and a campaign flight over Australia and Indonesia (Sawa et al, 1999) captured pronounced elevations of CO from the Equatorial fires in 1997.…”

mentioning

confidence: 99%

Estimation of fire-induced carbon emission from Equatorial Asia in 2015 by using in situ aircraft and ship observations

Niwa¹,

Sawa²,

Nara³

et al. 2020

Preprint

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Abstract. The inverse analysis was used to estimate the fire carbon emission in Equatorial Asia induced by the big El Niño in 2015. This inverse analysis is unique because it extensively used high-precision atmospheric mole fraction data of carbon dioxide (CO2) from the commercial aircraft observation project. By comparisons with independent shipboard observations, especially carbon monoxide (CO) data, the validity of the estimated fire-induced carbon emission was elucidated. The best estimate, which used both aircraft and shipboard CO2 observations, indicated 273 Tg C for fire emission during September–October 2015. This two-month-long emission accounts for 75 % of the annual total fire emission and 45 % of the annual total net carbon flux within the region, indicating that fire emission is a dominant driving force of interannual variations of carbon fluxes in Equatorial Asia. Several sensitivity experiments demonstrated that aircraft observations could measure fire signals, though they showed a certain degree of sensitivity to prior fire-emission data. The inversions coherently estimated smaller fire emissions than the priors, partially because of the small contribution of peatland fires, indicated by enhancement ratios of CO and CO2 observed by the ship. In the future warmer climate condition, Equatorial Asia would experience more severe droughts and have risks for releasing a large amount of carbon into the atmosphere. Therefore, the continuation of aircraft and shipboard observations is fruitful for reliable monitoring of carbon fluxes in Equatorial Asia.

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confidence: 99%

Estimation of fire-induced carbon emission from Equatorial Asia in 2015 by using in situ aircraft and ship observations

Niwa¹,

Sawa²,

Nara³

et al. 2020

Preprint

Self Cite

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“…Large-scale dynamics and circulations can play a crucial role in transporting Indonesian pollution to long-distance downwind regions (Bowman, 2006;Nara et al, 2011;Matsueda et al, 2019). To understand the plausible mechanisms behind the transport of Indonesian fire pollution to LABS, we further examined the MERRA-2 reanalysis of geopotential height (GpH of the high-pressure anti-cyclone over SCS.…”

Section: Role Of Large-scale Dynamics and Atmospheric Circulationsmentioning

confidence: 99%

“…The lifetime of CO in the free troposphere is ∼ two months, thus can be a tracer from polluted upwind regions to remote downwind areas (Cooper et al, 2012). Some of the studies reported the influence of Indonesian fire activity and the transport of CO from Indonesia to the Indian Ocean, Southern Pacific, and western Pacific Ocean (Matsueda and Inoue, 1999;Pochanart and Akimoto, 2003;Nara et al, 2011;Matsueda et al, 2002Matsueda et al, , 2019. However, the underlying transport mechanisms sending this fire pollution to downwind northern hemisphere subtropical locations, particularly transport to high-altitude background locations in the western north Pacific are still unclear.…”

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confidence: 99%

Transport pathways of carbon monoxide from Indonesian fire pollution to a subtropical high-altitude mountain site in western North Pacific

Babu

Ou-Yang²,

Griffith³

et al. 2022

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Abstract. Dry conditions associated with El Niño and a positive Indian Ocean Dipole (IOD) are known to have caused major fire pollution events and intense carbon emissions over a vast spatial expanse of Indonesia in October 2006 and 2015. During these two events, a substantial increase in carbon monoxide (CO) mixing ratio was detected by in-situ measurements at Lulin Atmospheric Background Station (LABS, 23.47° N 120.87° E, 2,862 m ASL) in Taiwan, the only background station in the subtropical western North Pacific region. Compared to the long-term October mean (2006–2021), CO was elevated by ~47.2 ppb (37.2 %) and ∼36.7 ppb (28.9 %) in October 2006 and 2015, respectively. In this study, plausible pathways for CO transport from Indonesia to LABS are delineated by using MOPITT CO observations and MERRA-2 reanalysis products (winds and geopotential height (GpH)). Two simultaneously occurring transport pathways were identified: (i) horizontal transport in the free troposphere and (ii) vertical transport through the Hadley circulation (HC). The GpH analysis of both events revealed the presence of a high-pressure anticyclone over the northern part of the South China Sea (SCS), which played an important role in the free tropospheric horizontal transport of CO. In this scenario, CO in the free troposphere is transported on the western edge of the high-pressure system and then driven by subtropical westerlies to LABS. Simultaneously, uplifted CO over Indonesia can enter the HC and transfer to subtropical locations such as LABS. The vertical cross-section of MOPITT CO and MERRA-2 vertical pressure velocity supported the transport of CO through the HC. Further, the results revealed a distinct HC strength in two events (higher in 2006 compared to 2015) due to the different El Niño conditions. Overall, the present findings can provide some insights into understanding the regional transport of pollution over Southeast Asia and the role of climate conditions on transport pathways.

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“…The lifetime of CO in the free troposphere is ∼ 2 months and can thus be a tracer from polluted upwind regions to remote downwind areas (Cooper et al, 2012). Some of the studies reported the influence of Indonesian fire activity and the transport of CO from Indonesia to the Indian Ocean, Southern Pacific, and western Pacific Ocean (Matsueda and Inoue, 1999;Pochanart et al, 2003;Nara et al, 2011;Matsueda et al, 2002Matsueda et al, , 2019. However, the underlying transport mechanisms sending this fire pollution to downwind Northern Hemisphere subtropical locations, particularly in the form of transport to high-altitude background locations in the western North Pacific are still unclear.…”

Section: Introductionmentioning

confidence: 99%

Transport pathways of carbon monoxide from Indonesian fire pollution to a subtropical high-altitude mountain site in the western North Pacific

et al. 2023

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Abstract. Dry conditions associated with the El Niño–Southern Oscillation (ENSO) and a positive Indian Ocean Dipole (IOD) are known to have caused major fire pollution events and intense carbon emissions over a vast spatial expanse of Indonesia in October 2006 and 2015. During these two events, a substantial increase in the carbon monoxide (CO) mixing ratio was detected by in situ measurements at Lulin Atmospheric Background Station (LABS; 23.47∘ N 120.87∘ E; 2862 ma.s.l.) in Taiwan, which is the only background station in the subtropical western North Pacific region. Compared to the long-term October mean (2006–2021), CO was elevated by ∼ 47.2 ppb (parts per billion; 37.2 %) and ∼ 36.7 ppb (28.9 %) in October 2006 and 2015, respectively. This study delineates plausible pathways for the CO transport from Indonesia to LABS using Measurement of Pollution in the Troposphere (MOPITT) CO observations and Modern-Era Retrospective analysis for Research and Applications, version 2 (MERRA-2) reanalysis products (winds and geopotential height – GpH). Two simultaneously occurring transport pathways were identified, namely (i) horizontal transport in the free troposphere and (ii) vertical transport through the Hadley circulation (HC). The GpH analysis of both events revealed the presence of a high-pressure anticyclone over the northern part of the South China Sea (SCS), which played an important role in the free-tropospheric horizontal transport of CO. In this scenario, CO in the free troposphere is transported on the western edge of the high-pressure system and then driven by subtropical westerlies to LABS. Simultaneously, uplifted CO over Indonesia can enter the HC and be transferred to subtropical locations such as LABS. The vertical cross section of the MOPITT CO and MERRA-2 vertical pressure velocity supported the transport of CO through the HC. Furthermore, the results revealed a distinct HC strength in two events (higher in 2006 compared to 2015) due to the different ENSO conditions. Overall, the present findings can provide some insights into understanding the regional transport of pollution over Southeast Asia and the role of climate conditions on transport pathways.

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Interannual Variation of Upper Tropospheric CO over the Western Pacific Linked with Indonesian Fires

Cited by 8 publications

References 35 publications

Estimation of fire-induced carbon emission from Equatorial Asia in 2015 by using in situ aircraft and ship observations

Estimation of fire-induced carbon emission from Equatorial Asia in 2015 by using in situ aircraft and ship observations

Transport pathways of carbon monoxide from Indonesian fire pollution to a subtropical high-altitude mountain site in western North Pacific

Transport pathways of carbon monoxide from Indonesian fire pollution to a subtropical high-altitude mountain site in the western North Pacific

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