Year: 2020
Type: article
Abstract: The 2019–20 Australian mega-bushfires, which raged particularly over New South Wales and Victoria, released large amounts of toxic haze and CO2. Here, we investigate whether the resulting CO2 enhancement can be directly detected by satellite observations, based on National Aeronautics and Space Administration’s Orbiting Carbon Observatory-2 (OCO-2) column-averaged CO2 (XCO2) product. We find that smoke from wildfires can greatly obscure satellite observations, making the available XCO2 mainly locate over outer fringes of plumes downwind of the major mega-bushfires in eastern Australia in three orbit observations during November–December 2019, with their enhancements of approximately 1.5 ppm. This fire-induced CO2 enhancement is further confirmed using an atmospheric transport model, Goddard Earth Observing System-Chem, forced by satellite observation-derived fire product Global Fire Emissions Database, version 4.1 and wind observations, with comparable simulated XCO2 enhancements. Model simulation also suggests that the sensitivity of the downwind maximum XCO2 enhancement is 0.41 ± 0.04 ppm for 1 TgC d−1 fire emissions. In sum, though detectable to some extent, it remains a challenge to get the accurate maximum XCO2 enhancements due to the gaps in XCO2 detections obscured by smoke. Understanding the capability of OCO-2 XCO2 detection is prerequisite for monitoring and constraining wildfire CO2 emissions by inversions.
Source: Environmental Research Letters
Institutions: Ministry of Natural Resources, Earth System Science Interdisciplinary Center, University of Maryland, College Park, Nanjing University, Chinese Academy of Sciences, Institute of Atmospheric Physics, State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $3,045
Funders: National Aeronautics and Space Administration, California Institute of Technology, National Natural Science Foundation of China, China Scholarship Council, Nanjing University, National Institute of Standards and Technology, National Oceanic and Atmospheric Administration, Jet Propulsion Laboratory, Goddard Space Flight Center
Awards: G1103894859, G1128376946, G2505705642, G640750587, G8029667517, G843721641, G8831058636, ANALYSIS OF CURRENTLY-AVAILABLE RESULTS FROM THE COLLECTION OF OCO-2 INVERSE MODELS OF CO2 SUGGESTS THAT THEY SUFFER FROM SIGNIFICANT BIASES IN ATMOSPHERIC TRANSPORT. THIS IS REVEALED THROUGH FORWARD SIMULATIONS OF SF6 AND CO2 AND SUPPORTED BY EVIDENCE FROM OPTIMIZED FLUXES CONSIDERED AS AN ENSEMBLE. WE PROPOSE CONTINUED META-ANALYSIS OF THE INVERSION ENSEMBLE TO TARGET AND REMOVE SOME OF THIS TRANSPORT ERROR BY COMPARING THE MERIDIONAL TRANSPORT OF CO2 IN MODELS. WE WILL DO THIS BY DECOMPOSING THAT TRANSPORT INTO COMPONENTS ASSOCIATED WITH THE MEAN MERIDIONAL CIRCULATION STATIONARY EDDIES AND TRANSIENT EDDIES. WE WILL DEVELOP A METHOD FOR TUNING INVERSE MODELS TO MAXIMIZE INFORMATION EXTRACTION FROM OBSERVATIONS WHILE AVOIDING OVERFITTING BY INTRODUCING THE NOVEL "L-CURVE" DIAGNOSTIC. EXPECTED TROPICAL VARIABILITY WILL BE ASSESSED USING THE MULTI-SCALE TERRESTRIAL MODEL INTERCOMPARISON PROJECT (MSTMIP) ENSEMBLE. AN EMPIRICAL ORTHOGONAL FUNCTION DECOMPOSITION OF THAT VARIABILITY WILL ALLOW US TO SUMMARIZE FLUX ANOMALIES AND TO RANK THEM BY THEIR IMPORTANCE AND SPATIAL SCALE. THESE MODES WILL THEN BE PROPAGATED AS PULSED EMISSIONS THROUGH ATMOSPHERIC TRANSPORT MODELS TO ASSESS THE OBSERVABILITY OF FLUX ANOMALIES AS A FUNCTION OF OBSERVING SYSTEM AND OF ATMOSPHERIC TRANSIT TIME BETWEEN FLUX AND OBSERVATION. INTERANNUALLY-VARYING FLUX PRIORS FROM A NEAR-REAL TIME TERRESTRIAL BIOSPHERE MODEL WILL BE DEVELOPED AND APPLIED TO ATMOSPHERIC INVERSIONS WITH THE SPECIFIC GOAL OF BETTER REPRESENTING THE 2015-16 EL NINO. ATMOSPHERIC CO2 SIMULATIONS WILL BE EVALUATED AGAINST EMERGING IN SITU DATA CONSTRAINTS FROM SITES IN THE AMAZON BASIN INCLUDING NEW LIGHT AIRCRAFT PROFILE TIME SERIES. ONLINE BIAS CORRECTION WILL BE IMPLEMENTED WITHIN CARBONTRACKER BOTH IN ORDER TO REFINE STANDARD BIAS CORRECTION PARAMETERIZATIONS AND ALSO TO LOOK FOR SYSTEMATIC VARIABILITY IN RESIDUALS FROM OCO-2 RETRIEVALS. SUCH PATTERNS IN THE RESIDUALS MAY BE DUE TO HERETOFORE-UNIDENTIFIED RETRIEVAL BIASES. THE PROPOSED RESEARCH WILL ADDRESS THREE STATED GOALS OF THE SOLICITATION. FIRST IT INVOLVES PERFORMING AND SUBSTANTIALLY IMPROVING INVERSE MODEL ANALYSES OF SATELLITE XCO2 DATA. SECOND IT INCLUDES WORK TO IMPROVE EXISTING BIAS CORRECTIONS AND TO IDENTIFY ADDITIONAL SYSTEMATIC FEATURES OF THE RETRIEVALS THAT CANNOT BE EXPLAINED BY INVERSE MODELS. THESE FEATURES MAY BE CAUSED BY PREVIOUSLY UNIDENTIFIED BIASES. THIRD IT CONCENTRATES ON CROSS-VALIDATION IN THE UNDERSAMPLED TROPICS OF SOUTH AMERICA WHERE REFINED FLUX UNCERTAINTIES AND THE INTRODUCTION OF NEW DATASETS WILL HELP TO CONSTRAIN CO2 DISTRIBUTIONS AND HIGHLIGHT UNEXPLAINED FEATURES IN OCO DATASETS.
OpenAlex ID: W3095428430