scholarly journals Influences of oceanic ozone deposition on tropospheric photochemistry

2019 ◽  
Author(s):  
Ryan J. Pound ◽  
Tomás Sherwen ◽  
Detlev Helmig ◽  
Lucy J. Carpenter ◽  
Mat J. Evans
Keyword(s):  
Atmospheric Chemistry ◽  
Surface Ozone ◽  
Deposition Velocity ◽  
Terrestrial Ecosystems ◽  
Deposition Flux ◽  
Ozone Deposition ◽  
Tropospheric Photochemistry ◽  
In Series ◽  
The Tropics ◽  
Uniform Deposition

Abstract. The deposition of ozone to seawater is an important ozone sink. Despite constituting as much as a third of the total ozone deposition, it receives significantly less attention than the deposition to terrestrial ecosystems. Models have typically calculated the deposition rate based on a resistance-in-series model with a uniform waterside resistance. This leads to models having an essentially uniform deposition velocity of approximately 0.05 cm s−1 to seawater, which is significantly higher than the limited observational dataset. Following from Luhar et al. (2018) we include a representation of the oceanic deposition of ozone into the GEOS-Chem model of atmospheric chemistry and transport based on its reaction with sea-surface iodide. The updated scheme halves the calculated annual area-weighted mean deposition velocity to water from 0.0464 cm s−1 (25th and 75th percentiles of 0.0461 cm s−1 and 0.0471 cm s−1 respectively), to 0.0231 cm s−1 (25th and 75th percentiles of 0.0121 cm s−1 and 0.0303 cm s−1 respectively). The calculated ozone deposition velocity varies from 0.009 cm s−1 in polar waters to 0.040 cm s−1 at the tropics. This improves comparisons to observations. The variability is driven mainly by the temperature dependant rate constant for the reaction between iodide and ozone, the temperature dependence of the solubility and variations in the ocean iodide concentration. The calculated annual deposition flux of ozone to the ocean is reduced from 222 Tg yr−1 to 112 Tg yr−1, and overall deposition of ozone to all surface types reduces from 862 Tg yr−1 to 758 Tg yr−1. Tropospheric ozone burdens and global mean OH increase from 324 Tg to 328 Tg, and from 1.17 × 106 molec cm−3 to 1.18 × 106 molec cm−3, respectively. 34 % of surface grid boxes experience a 10 % or greater increase in ozone concentration. Comparisons between observations of surface ozone and the model are improved with the new parameterization notably around the Southern Ocean. Process level representation of oceanic deposition of ozone thus appears essential for representing the concentration of surface ozone over the planet.

scholarly journals Influences of oceanic ozone deposition on tropospheric photochemistry

2020 ◽  
Vol 20 (7) ◽  
pp. 4227-4239 ◽  
Author(s):  
Ryan J. Pound ◽  
Tomás Sherwen ◽  
Detlev Helmig ◽  
Lucy J. Carpenter ◽  
Mat J. Evans
Keyword(s):  
Atmospheric Chemistry ◽  
Surface Ozone ◽  
Deposition Velocity ◽  
Terrestrial Ecosystems ◽  
Deposition Flux ◽  
Ozone Deposition ◽  
Dependent Rate ◽  
Tropospheric Photochemistry ◽  
In Series ◽  
The Tropics

Abstract. The deposition of ozone to seawater is an important ozone sink. Despite constituting as much as a third of the total ozone deposition, it receives significantly less attention than the deposition to terrestrial ecosystems. Models have typically calculated the deposition rate based on a resistance-in-series model with a uniform waterside resistance. This leads to models having an essentially uniform deposition velocity of approximately 0.05 cm s−1 to seawater, which is significantly higher than the limited observational dataset. Following from Luhar et al. (2018) we include a representation of the oceanic deposition of ozone in the GEOS-Chem model of atmospheric chemistry and transport based on its reaction with sea-surface iodide. The updated scheme halves the calculated annual area-weighted mean deposition velocity to water from 0.0464 cm s−1 (25th and 75th percentiles of 0.0461 cm s−1 and 0.0471 cm s−1 respectively) to 0.0231 cm s−1 (25th and 75th percentiles of 0.0121 cm s−1 and 0.0303 cm s−1 respectively). The calculated ozone deposition velocity varies from 0.009 cm s−1 in polar waters to 0.040 cm s−1 at the tropics. This improves comparisons to observations. The variability is driven mainly by the temperature-dependent rate constant for the reaction between iodide and ozone, the temperature dependence of the solubility, and variations in the ocean iodide concentration. The calculated annual deposition flux of ozone to the ocean is reduced from 222 to 122 Tg yr−1, and overall deposition of ozone to all surface types reduces from 862 to 758 Tg yr−1. Tropospheric ozone burdens and global mean OH increase from 324 to 328 Tg, and from 1.17×106 to 1.18×106 molec.cm-3, respectively. A total of 34 % of surface grid boxes experience a 10 % or greater increase in ozone concentration. Comparisons between observations of surface ozone and the model are improved with the new parameterization notably around the Southern Ocean. Process-level representation of oceanic deposition of ozone thus appears essential for representing the concentration of surface ozone over the planet.

scholarly journals Implementation of Yale Interactive terrestrial Biosphere model v1.0 into GEOS-Chem v12.0.0: a tool for biosphere–chemistry interactions

2020 ◽  
Vol 13 (3) ◽  
pp. 1137-1153 ◽  
Author(s):  
Yadong Lei ◽  
Xu Yue ◽  
Hong Liao ◽  
Cheng Gong ◽  
Lin Zhang
Keyword(s):  
Stomatal Conductance ◽  
Atmospheric Chemistry ◽  
Dry Deposition ◽  
Transport Model ◽  
Surface Ozone ◽  
Eastern China ◽  
Deposition Velocity ◽  
Chemical Transport Model ◽  
Terrestrial Biosphere ◽  
Area Index

Abstract. The terrestrial biosphere and atmospheric chemistry interact through multiple feedbacks, but the models of vegetation and chemistry are developed separately. In this study, the Yale Interactive terrestrial Biosphere (YIBs) model, a dynamic vegetation model with biogeochemical processes, is implemented into the Chemical Transport Model GEOS-Chem (GC) version 12.0.0. Within this GC-YIBs framework, leaf area index (LAI) and canopy stomatal conductance dynamically predicted by YIBs are used for dry deposition calculation in GEOS-Chem. In turn, the simulated surface ozone (O3) by GEOS-Chem affect plant photosynthesis and biophysics in YIBs. The updated stomatal conductance and LAI improve the simulated O3 dry deposition velocity and its temporal variability for major tree species. For daytime dry deposition velocities, the model-to-observation correlation increases from 0.69 to 0.76, while the normalized mean error (NME) decreases from 30.5 % to 26.9 % using the GC-YIBs model. For the diurnal cycle, the NMEs decrease by 9.1 % for Amazon forests, 6.8 % for coniferous forests, and 7.9 % for deciduous forests using the GC-YIBs model. Furthermore, we quantify the damaging effects of O3 on vegetation and find a global reduction of annual gross primary productivity by 1.5 %–3.6 %, with regional extremes of 10.9 %–14.1 % in the eastern USA and eastern China. The online GC-YIBs model provides a useful tool for discerning the complex feedbacks between atmospheric chemistry and the terrestrial biosphere under global change.

scholarly journals Seasonal variation of ozone deposition to a tropical rain forest in southwest Amazonia

2007 ◽  
Vol 7 (20) ◽  
pp. 5415-5435 ◽  
Author(s):  
U. Rummel ◽  
C. Ammann ◽  
G. A. Kirkman ◽  
M. A. L. Moura ◽  
T. Foken ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Rain Forest ◽  
Deposition Velocity ◽  
Dry Season ◽  
Stomatal Aperture ◽  
Specific Humidity ◽  
Deposition Flux ◽  
Diel Variation ◽  
Wet Season ◽  
Ozone Deposition

Abstract. Within the project EUropean Studies on Trace gases and Atmospheric CHemistry as a contribution to Large-scale Biosphere-atmosphere experiment in Amazonia (LBA-EUSTACH), we performed tower-based eddy covariance measurements of O3 flux above an Amazonian primary rain forest at the end of the wet and dry season. Ozone deposition revealed distinct seasonal differences in the magnitude and diel variation. In the wet season, the rain forest was an effective O3 sink with a mean daytime (midday) maximum deposition velocity of 2.3 cm s−1, and a corresponding O3 flux of −11 nmol m−2 s−1. At the end of the dry season, the ozone mixing ratio was about four times higher (up to maximum values of 80 ppb) than in the wet season, as a consequence of strong regional biomass burning activity. However, the typical maximum daytime deposition flux was very similar to the wet season. This results from a strong limitation of daytime O3 deposition due to reduced plant stomatal aperture as a response to large values of the specific humidity deficit. As a result, the average midday deposition velocity in the dry burning season was only 0.5 cm s−1. The large diel ozone variation caused large canopy storage effects that masked the true diel variation of ozone deposition mechanisms in the measured eddy covariance flux, and for which corrections had to be made. In general, stomatal aperture was sufficient to explain the largest part of daytime ozone deposition. However, during nighttime, chemical reaction with nitrogen monoxide (NO) was found to contribute substantially to the O3 sink in the rain forest canopy. Further contributions were from non-stomatal plant uptake and other processes that could not be clearly identified. Measurements, made simultaneously on a 22 years old cattle pasture enabled the spatially and temporally direct comparison of O3 dry deposition values from this site with typical vegetation cover of deforested land in southwest Amazonia to the results from the primary rain forest. The mean ozone deposition to the pasture was found to be systematically lower than that to the forest by 30% in the wet and 18% in the dry season.

scholarly journals Ozone deposition impact assessments for forest canopies require accurate ozone flux partitioning on diurnal timescales

2021 ◽  
Vol 21 (24) ◽  
pp. 18393-18411
Author(s):  
Auke J. Visser ◽  
Laurens N. Ganzeveld ◽  
Ignacio Goded ◽  
Maarten C. Krol ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Dry Deposition ◽  
Land Surface ◽  
Large Scale ◽  
Crop Yields ◽  
Carbon Sink ◽  
Surface Ozone ◽  
Ozone Uptake ◽  
Ozone Deposition ◽  
Ozone Flux

Abstract. Dry deposition is an important sink of tropospheric ozone that affects surface concentrations and impacts crop yields, the land carbon sink, and the terrestrial water cycle. Dry deposition pathways include plant uptake via stomata and non-stomatal removal by soils, leaf surfaces, and chemical reactions. Observational studies indicate that ozone deposition exhibits substantial temporal variability that is not reproduced by atmospheric chemistry models due to a simplified representation of vegetation uptake processes in these models. In this study, we explore the importance of stomatal and non-stomatal uptake processes in driving ozone dry deposition variability on diurnal to seasonal timescales. Specifically, we compare two land surface ozone uptake parameterizations – a commonly applied big leaf parameterization (W89; Wesely, 1989) and a multi-layer model (MLC-CHEM) constrained with observations – to multi-year ozone flux observations at two European measurement sites (Ispra, Italy, and Hyytiälä, Finland). We find that W89 cannot reproduce the diurnal cycle in ozone deposition due to a misrepresentation of stomatal and non-stomatal sinks at our two study sites, while MLC-CHEM accurately reproduces the different sink pathways. Evaluation of non-stomatal uptake further corroborates the previously found important roles of wet leaf uptake in the morning under humid conditions and soil uptake during warm conditions. The misrepresentation of stomatal versus non-stomatal uptake in W89 results in an overestimation of growing season cumulative ozone uptake (CUO), a metric for assessments of vegetation ozone damage, by 18 % (Ispra) and 28 % (Hyytiälä), while MLC-CHEM reproduces CUO within 7 % of the observation-inferred values. Our results indicate the need to accurately describe the partitioning of the ozone atmosphere–biosphere flux over the in-canopy stomatal and non-stomatal loss pathways to provide more confidence in atmospheric chemistry model simulations of surface ozone mixing ratios and deposition fluxes for large-scale vegetation ozone impact assessments.

scholarly journals Implementation of Yale Interactive terrestrial Biosphere model version 1.0 into GEOS-Chem version 12.0.0: a tool for biosphere-chemistry interactions

2019 ◽  
Author(s):  
Yadong Lei ◽  
Xu Yue ◽  
Hong Liao ◽  
Cheng Gong ◽  
Lin Zhang
Keyword(s):  
Stomatal Conductance ◽  
Atmospheric Chemistry ◽  
Dry Deposition ◽  
Transport Model ◽  
Surface Ozone ◽  
Eastern China ◽  
Deposition Velocity ◽  
Chemical Transport Model ◽  
Terrestrial Biosphere ◽  
Area Index

Abstract. The terrestrial biosphere and atmospheric chemistry interact through multiple feedbacks, but the models of vegetation and chemistry are developed separately. In this study, the Yale Interactive terrestrial Biosphere (YIBs) model, a dynamic vegetation model with biogeochemical processes, is implemented into the Chemical Transport Model GEOS-Chem version 12.0.0. Within the GC-YIBs framework, leaf area index (LAI) and canopy stomatal conductance dynamically predicted by YIBs are used for dry deposition calculation in GEOS-Chem. In turn, the simulated surface ozone (O3) by GEOS-Chem affect plant photosynthesis and biophysics in YIBs. The updated stomatal conductance and LAI improve the simulated daytime O3 dry deposition velocity for major tree species. Compared with the GEOS-Chem model, the model-to-observation correlation for dry deposition velocities increases from 0.76 to 0.85 while the normalized mean error decreases from 35 % to 27 % using the GC-YIBs model. Furthermore, we quantify O3 vegetation damaging effects and find a global reduction of annual gross primary productivity by 2–5 %, with regional extremes of 11–15 % in the eastern U.S. and eastern China. The online GC-YIBs model provides a useful tool for discerning the complex feedbacks between atmospheric chemistry and terrestrial biosphere under global change.

scholarly journals Seasonal variation of ozone deposition to a tropical rain forest in southwest Amazonia

2007 ◽  
Vol 7 (3) ◽  
pp. 7399-7450 ◽  
Author(s):  
U. Rummel ◽  
C. Ammann ◽  
G. A. Kirkman ◽  
M. A. L. Moura ◽  
T. Foken ◽  
...  
Keyword(s):  
Eddy Covariance ◽  
Rain Forest ◽  
Deposition Velocity ◽  
Dry Season ◽  
Stomatal Aperture ◽  
Specific Humidity ◽  
Deposition Flux ◽  
Diel Variation ◽  
Wet Season ◽  
Ozone Deposition

Abstract. Within the project EUropean Studies on Trace gases and Atmospheric CHemistry as a contribution to Large-scale Biosphere–atmosphere experiment in Amazonia (LBA-EUSTACH), we performed tower-based eddy covariance measurements of O3 flux above an Amazonian primary rain forest at the end of the wet and dry seasons. Ozone deposition revealed distinct seasonal differences in the magnitude and diel variation. In the wet season, the rain forest was an effective O3 sink with a mean daytime (midday) maximum deposition velocity of 2.3 cm s−1, and a corresponding O3 flux of –11 nmol m−2 s−1. At the end of the dry season, the ozone mixing ratio was about four times higher (up to maximum values of 80 ppb) than in the wet season, as a consequence of strong regional biomass burning activity. However, the typical maximum daytime deposition flux was very similar to the wet season. This results from a strong limitation of daytime O3 deposition due to reduced plant stomatal aperture as a response to large values of the specific humidity deficit. As a result, the average midday deposition velocity in the dry burning season was only 0.5 cm s−1. The large diel ozone variation caused large canopy storage effects that masked the true diel variation of ozone deposition mechanisms in the measured eddy covariance flux, and for which corrections had to be made. In general, stomatal aperture was sufficient to explain the largest part of daytime ozone deposition. However, during nighttime, chemical reaction with nitrogen monoxide (NO) was found to contribute substantially to the O3 sink in the rain forest canopy. Further contributions were from non-stomatal plant uptake and other processes that could not be clearly identified. Measurements, made simultaneously on a 22 years old cattle pasture enabled the spatially and temporally direct comparison of O3 dry deposition values from this site with typical vegetation cover of deforested land in southwest Amazonia to the results from the primary rain forest. The mean ozone deposition to the pasture was found to be systematically lower than that to the forest by 30% in the wet and 18% in the dry season.

scholarly journals How to most effectively expand the global surface ozone observing network

2015 ◽  
Vol 15 (15) ◽  
pp. 21025-21061
Author(s):  
E. D. Sofen ◽  
D. Bowdalo ◽  
M. J. Evans
Keyword(s):  
Atmospheric Chemistry ◽  
Surface Ozone ◽  
Tropospheric Chemistry ◽  
Atmospheric Composition ◽  
Model Assessment ◽  
Air Masses ◽  
The Cost ◽  
The Tropics ◽  
The Impact ◽  
Global Surface

Abstract. Surface ozone observations with modern instrumentation have been made around the world for almost 50 years. Some of these observations have been made as one-off activities with short term, specific science objectives and some have been made as part of wider networks which have provided a foundational infrastructure of data collection, calibration, quality control and dissemination. These observations provide a fundamental underpinning to our understanding of tropospheric chemistry, air quality policy, atmosphere-biosphere interactions, etc. Sofen et al. (2015) brought together 8 of these networks to provide a single dataset of surface ozone observations. We investigate how representative this combined dataset is of global surface ozone using the output from a global atmospheric chemistry model. We estimate that on an area basis, 25 % of the globe is observed (34 % land, 21 % ocean). Whereas Europe and North America have almost complete coverage, other continents such as Africa, South America and Asia (12–17 %) show significant gaps. Antarctica is surprisingly well observed (78 %). Little monitoring occurs over the oceans with the tropical and southern oceans particularly poorly represented. The surface ozone over key biomes such as tropical forests and savanna is almost completely unmonitored. A chemical cluster analysis suggests that a significant number of observations are made of polluted air masses, but cleaner air masses whether over the land or ocean (especially again in the tropics) are significantly under observed. The current network is unlikely to see the impact of ENSO but may be capable of detecting other planetary scale signals. Model assessment and validation activities are hampered by a lack of observations in regions where they models differ substantially, as is the ability to monitor likely changes in surface ozone over the next century. Using our methodology we are able to suggest new sites which would help to close the gap in our ability to measure global surface ozone. An additional 20 surface ozone monitoring sites (a 20 % increase in the WMO GAW ozone sites or a 1 % increase in the total background network) located on 10 islands and in 10 continental regions would almost double the area observed. The cost of this addition to the network is small compared to other expenditure on atmospheric composition research infrastructure and would provide a significant long term benefit to our understanding of the composition of the atmosphere and in the development of policy.

scholarly journals Ozone deposition impact assessments for forest canopies require accurate ozone flux partitioning on diurnal timescales

2021 ◽  
Author(s):  
Auke J. Visser ◽  
Laurens N. Ganzeveld ◽  
Ignacio Goded ◽  
Maarten C. Krol ◽  
Ivan Mammarella ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Dry Deposition ◽  
Land Surface ◽  
Large Scale ◽  
Crop Yields ◽  
Carbon Sink ◽  
Surface Ozone ◽  
Ozone Uptake ◽  
Ozone Deposition ◽  
Ozone Flux

Abstract. Dry deposition is an important sink of tropospheric ozone that affects surface concentrations, and impacts crop yields, the land carbon sink and the terrestrial water cycle. Dry deposition pathways include plant uptake via stomata and nonstomatal removal by soils, leaf surfaces and chemical reactions. Observational studies indicate that ozone deposition exhibits substantial temporal variability that is not reproduced by atmospheric chemistry models due to a simplified representation of vegetation uptake processes in these models. In this study, we explore the importance of stomatal and non-stomatal uptake processes in driving ozone dry deposition variability on diurnal to seasonal timescales. Specifically, we compare two land surface ozone uptake parameterizations – a commonly applied ’big leaf’ parameterization (W89; Wesely, 1989) and a multi-layer model (MLC-CHEM) constrained with observations – to multi-year ozone flux observations at two European measurement sites (Ispra, Italy, and Hyytiälä, Finland). We find that W89 cannot reproduce the diurnal cycle in ozone deposition due to a mis-representation of stomatal and non-stomatal sinks at our two study sites, while MLC-CHEM accurately reproduces the different sink pathways. Evaluation of non-stomatal uptake further corroborates the previously found important roles of wet leaf uptake in the morning under humid conditions, and soil uptake during warm conditions. The misrepresentation of stomatal versus non-stomatal uptake in W89 results in an overestimation of growing-season cumulative ozone uptake (CUO), a metric for assessments of vegetation ozone damage, by 18 % (Ispra) and 28 % (Hyytiälä), while MLC-CHEM reproduces CUO within 7 % of the observation-inferred values. Our results indicate the need to accurately describe the partitioning of the ozone atmosphere-biosphere flux over the in-canopy stomatal and non-stomatal loss pathways to provide more confidence in atmospheric chemistry model simulations of surface ozone mixing ratios and deposition fluxes for large-scale vegetation ozone impact assessments.

scholarly journals Impact of uncertainties in inorganic chemical rate constants on tropospheric composition and ozone radiative forcing

2017 ◽  
Author(s):  
Ben Newsome ◽  
Mat Evans
Keyword(s):  
Rate Constant ◽  
Atmospheric Chemistry ◽  
Rate Constants ◽  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Transport Model ◽  
Surface Ozone ◽  
Photolysis Rates ◽  
The Impact ◽  
Chemical Rate

Abstract. Chemical rate constants determine the composition of the atmosphere and how this composition has changed over time. They are central to our understanding of climate change and air quality degradation. Atmospheric chemistry models, whether online or offline, box, regional or global use these rate constants. Expert panels synthesise laboratory measurements, making recommendations for the rate constants that should be used. This results in very similar or identical rate constants being used by all models. The inherent uncertainties in these recommendations are, in general, therefore ignored. We explore the impact of these uncertainties on the composition of the troposphere using the GEOS-Chem chemistry transport model. Based on the JPL and IUPAC evaluations we assess 50 mainly inorganic rate constants and 10 photolysis rates, through simulations where we increase the rate of the reactions to the 1σ upper value recommended by the expert panels. We assess the impact on 4 standard metrics: annual mean tropospheric ozone burden, surface ozone and tropospheric OH concentrations, and tropospheric methane lifetime. Uncertainty in the rate constants for NO2 + OH    M →  HNO3, OH + CH4 → CH3O2 + H2O and O3 + NO → NO2 + O2 are the three largest source of uncertainty in these metrics. We investigate two methods of assessing these uncertainties, addition in quadrature and a Monte Carlo approach, and conclude they give similar outcomes. Combining the uncertainties across the 60 reactions, gives overall uncertainties on the annual mean tropospheric ozone burden, surface ozone and tropospheric OH concentrations, and tropospheric methane lifetime of 11, 12, 17 and 17 % respectively. These are larger than the spread between models in recent model inter-comparisons. Remote regions such as the tropics, poles, and upper troposphere are most uncertain. This chemical uncertainty is sufficiently large to suggest that rate constant uncertainty should be considered when model results disagree with measurement. Calculations for the pre-industrial allow a tropospheric ozone radiative forcing to be calculated of 0.412 ± 0.062 Wm−2. This uncertainty (15 %) is comparable to the inter-model spread in ozone radiative forcing found in previous model-model inter-comparison studies where the rate constants used in the models are all identical or very similar. Thus the uncertainty of tropospheric ozone radiative forcing should expanded to include this additional source of uncertainty. These rate constant uncertainties are significant and suggest that refinement of supposedly well known chemical rate constants should be considered alongside other improvements to enhance our understanding of atmospheric processes.

scholarly journals On what scales can GOSAT flux inversions constrain anomalies in terrestrial ecosystems?

2019 ◽  
Author(s):  
Brendan Byrne ◽  
Dylan B. A. Jones ◽  
Kimberly Strong ◽  
Saroja M. Polavarapu ◽  
Anna B. Harper ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Net Ecosystem Exchange ◽  
Terrestrial Ecosystems ◽  
Atmospheric Co2 ◽  
Strong Correlations ◽  
Climate Anomalies ◽  
Temperature And Precipitation ◽  
The Tropics ◽  
Emergent Constraint ◽  
The Impact

Abstract. Interannual variations in temperature and precipitation impact the carbon balance of terrestrial ecosystems, leaving an imprint in atmospheric CO2. Quantifying the impact of climate anomalies on the net ecosystem exchange (NEE) of terrestrial ecosystems can provide a constraint to evaluate terrestrial biosphere models against, and may provide an emergent constraint on the response of terrestrial ecosystems to climate change. We investigate the spatial scales over which interannual variability in NEE can be constrained using atmospheric CO2 observations from the Greenhouse Gases Observing Satellite (GOSAT). NEE anomalies are calculated by performing a series of inversion analyses using the GEOS-Chem model to assimilate GOSAT observations. Monthly NEE anomalies are compared to proxies, variables which are associated with anomalies in the terrestrial carbon cycle, and to upscaled NEE estimates from FLUXCOM. Strong agreement is found in the timing of anomalies in the GOSAT flux inversions with soil temperature and FLUXCOM. Strong correlations are obtained (P  RNINO3.4) in the tropics on continental and larger scales, and in the northern extratropics on sub-continental scales during the summer (R2 ≥ 0.49). These results, in addition to a series of observing system simulation experiments that were conducted, provide evidence that GOSAT flux inversions can isolate anomalies in NEE on continental and larger scales. However, in both the tropics and northern extratropics, the agreement between the inversions and the proxies/FLUXCOM is sensitive to the flux inversion configuration. Our results suggest that regional scales are likely the minimum scales that can be resolved in the tropics using GOSAT observations, but obtaining robust NEE anomaly estimates on these scales may be difficult.

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