scholarly journals Differences of the inverted terrestrial ecosystem carbon flux between using GOSAT and OCO-2 XCO<sub>2</sub> retrievals

2018 ◽  
Author(s):  
Hengmao Wang ◽  
Fei Jiang ◽  
Jun Wang ◽  
Weimin Ju ◽  
Jing M. Chen
Keyword(s):  
Growth Rate ◽  
Carbon Flux ◽  
Carbon Sink ◽  
Terrestrial Ecosystem ◽  
Carbon Fluxes ◽  
Carbon Sinks ◽  
Tropical Regions ◽  
Mixing Ratios ◽  
Ecosystem Carbon ◽  
Spatial Coverage

Abstract. In this study, both the Greenhouse Gases Observing Satellite (GOSAT) and the Orbiting Carbon Observatory 2 (OCO-2) XCO2 retrievals are assimilated within the GEOS-Chem 4D-Var assimilation framework to constrain the terrestrial ecosystem carbon flux during Jul 1, 2014 to Dec 31, 2015. The inverted global and regional carbon fluxes during Jan 1 to Dec 31, 2015 are shown and discussed. Surface CO2 mixing ratios from 47 surface flask sites and XCO2 measurements from 13 TCCON sites are used to evaluate the simulated concentrations with the posteriori carbon fluxes. The results show that globally, the terrestrial ecosystem carbon sink (excluding biomass burning emissions) estimated from GOSAT data is stronger than that inferred from OCO-2 data, and the annual atmospheric CO2 growth rate estimated from GOSAT data is more consistent with the estimate of GCP 2017. Regionally, in most regions, the land sinks inferred from GOSAT data are also stronger than those from OCO-2 data. Compared with the prior fluxes, the carbon fluxes in northern temperate regions change most, followed by tropical and southern temperate regions, and the smallest changes occur in boreal regions. Basically, in temperate regions, the inferred land sinks are significantly increased, while those in tropical regions are decreased. The different changes in different regions are mainly related to the spatial coverage and the amount of XCO2 data in these regions. Compared with CT2016, the inferred carbon sinks are comparable in most temperate regions, but much weaker in boreal and tropical regions. Evaluations using flask and TCCON observations suggest that GOSAT and OCO-2 data, can effectively improve the carbon flux estimates in the northern hemisphere, while in the southern hemisphere the optimized carbon sinks may be overestimated, especially for GOSAT data.

scholarly journals Terrestrial ecosystem carbon flux estimated using GOSAT and OCO-2 XCO<sub>2</sub> retrievals

2019 ◽  
Vol 19 (18) ◽  
pp. 12067-12082 ◽  
Author(s):  
Hengmao Wang ◽  
Fei Jiang ◽  
Jun Wang ◽  
Weimin Ju ◽  
Jing M. Chen
Keyword(s):  
Carbon Flux ◽  
Carbon Sink ◽  
Terrestrial Ecosystem ◽  
Carbon Fluxes ◽  
Atmospheric Co2 ◽  
Total Carbon ◽  
Ecosystem Carbon ◽  
The Poor ◽  
Spatial Coverage

Abstract. In this study, both the Greenhouse Gases Observing Satellite (GOSAT) and the Orbiting Carbon Observatory 2 (OCO-2) XCO2 retrievals produced by the NASA Atmospheric CO2 Observations from Space (ACOS) project (version b7.3) are assimilated within the GEOS-Chem 4D-Var assimilation framework to constrain the terrestrial ecosystem carbon flux during 1 October 2014 to 31 December 2015. One inversion for the comparison, using in situ CO2 observations, and another inversion as a benchmark for the simulated atmospheric CO2 distributions of the real inversions, using global atmospheric CO2 trends and referred to as the poor-man inversion, are also conducted. The estimated global and regional carbon fluxes for 2015 are shown and discussed. CO2 observations from surface flask sites and XCO2 retrievals from Total Carbon Column Observing Network (TCCON) sites are used to evaluate the simulated concentrations with the posterior carbon fluxes. Globally, the terrestrial ecosystem carbon sink (excluding biomass burning emissions) estimated from GOSAT data is stronger than that inferred from OCO-2 data, weaker than the in situ inversion and matches the poor-man inversion the best. Regionally, in most regions, the land sinks inferred from GOSAT data are also stronger than those from OCO-2 data, and in North America, Asia and Europe, the carbon sinks inferred from GOSAT inversion are comparable to those from in situ inversion. For the latitudinal distribution of land sinks, the satellite-based inversions suggest a smaller boreal and tropical sink but larger temperate sinks in both the Northern and Southern Hemisphere than the in situ inversion. However, OCO-2 and GOSAT generally do not agree on which continent contains the smaller or larger sinks. Evaluations using flask and TCCON observations and the comparisons with in situ and poor-man inversions suggest that only GOSAT and the in situ inversions perform better than a poor-man solution. GOSAT data can effectively improve the carbon flux estimates in the Northern Hemisphere, while OCO-2 data, with the specific version used in this study, show only slight improvement. The differences of inferred land fluxes between GOSAT and OCO-2 inversions in different regions are mainly related to the spatial coverage, the data amount and the biases of these two satellite XCO2 retrievals.

scholarly journals A global CO<sub>2</sub> flux dataset (2015–2019) inferred from OCO-2 retrievals using the Tan-Tracker inversion system

2021 ◽  
Author(s):  
Zhe Jin ◽  
Xiangjun Tian ◽  
Rui Han ◽  
Yu Fu ◽  
Xin Li ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Carbon Cycle ◽  
Carbon Flux ◽  
Carbon Budget ◽  
Terrestrial Ecosystem ◽  
Carbon Fluxes ◽  
Global Carbon Cycle ◽  
Ocean Carbon ◽  
Global Carbon ◽  
Regional Fluxes

Abstract. Accurate assessment of the various sources and sinks of carbon dioxide (CO2), especially terrestrial ecosystem and ocean fluxes with high uncertainties, is important for understanding of the global carbon cycle, supporting the formulation of climate policies, and projecting future climate change. Satellite retrievals of the column-averaged dry air mole fractions of CO2 (XCO2) are being widely used to improve carbon flux estimation due to their broad spatial coverage. However, there is no consensus on the robust estimates of regional fluxes. In this study, we present a global and regional resolved terrestrial ecosystem carbon flux (NEE) and ocean carbon flux dataset for 2015–2019. The dataset was generated using the Tan-Tracker inversion system by assimilating Observing Carbon Observatory 2 (OCO-2) column CO2 retrievals. The posterior NEE and ocean carbon fluxes were comprehensively validated by comparing posterior simulated CO2 concentrations with OCO-2 independent retrievals and Total Carbon Column Observing Network (TCCON) measurements. The validation showed that posterior carbon fluxes significantly improved the modelling of atmospheric CO2 concentrations, with global mean biases of 0.33 ppm against OCO-2 retrievals and 0.12 ppm against TCCON measurements. We described the characteristics of the dataset at global, regional, and Tibetan Plateau scales in terms of the carbon budget, annual and seasonal variations, and spatial distribution. The posterior 5-year annual mean global atmospheric CO2 growth rate was 5.35 PgC yr−1, which was within the uncertainty of the Global Carbon Budget 2020 estimate (5.49 PgC yr−1). The posterior annual mean NEE and ocean carbon fluxes were −4.07 and −3.33 PgC yr−1, respectively. Regional fluxes were analysed based on TransCom partitioning. All 11 land regions acted as carbon sinks, except for Tropical South America, which was almost neutral. The strongest carbon sinks were located in Boreal Asia, followed by Temperate Asia and North Africa. The entire Tibetan Plateau ecosystem was estimated as a carbon sink, taking up −49.52 TgC yr−1 on average, with the strongest sink occurring in eastern alpine meadows. These results indicate that our dataset captures surface carbon fluxes well and provides insight into the global carbon cycle. The dataset can be accessed at https://doi.org/10.11888/Meteoro.tpdc.271317 (Jin et al., 2021).

Land degradation monitoring using terrestrial ecosystem carbon sinks/sources and their response to climate change in China

2018 ◽  
Vol 29 (10) ◽  
pp. 3489-3502 ◽  
Author(s):  
Xiaowei Chuai ◽  
Xinxian Qi ◽  
Xiuying Zhang ◽  
Jiasheng Li ◽  
Ye Yuan ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Degradation ◽  
Terrestrial Ecosystem ◽  
Carbon Sinks ◽  
Ecosystem Carbon ◽  
Degradation Monitoring

scholarly journals Regional CO<sub>2</sub> fluxes from 2010 to 2015 inferred from GOSAT XCO<sub>2</sub> retrievals using a new version of the Global Carbon Assimilation System

2021 ◽  
Vol 21 (3) ◽  
pp. 1963-1985
Author(s):  
Fei Jiang ◽  
Hengmao Wang ◽  
Jing M. Chen ◽  
Weimin Ju ◽  
Xiangjun Tian ◽  
...  
Keyword(s):  
Carbon Assimilation ◽  
Carbon Fluxes ◽  
Atmospheric Co2 ◽  
Interannual Variations ◽  
Carbon Sinks ◽  
Area Index ◽  
Spatial Coverage ◽  
The Impact ◽  
Global Carbon ◽  
Assimilation System

Abstract. Satellite retrievals of the column-averaged dry air mole fractions of CO2 (XCO2) could help to improve carbon flux estimation due to their good spatial coverage. In this study, in order to assimilate the GOSAT (Greenhouse Gases Observing Satellite) XCO2 retrievals, the Global Carbon Assimilation System (GCAS) is upgraded with new assimilation algorithms, procedures, a localization scheme, and a higher assimilation parameter resolution. This upgraded system is referred to as GCASv2. Based on this new system, the global terrestrial ecosystem (BIO) and ocean (OCN) carbon fluxes from 1 May 2009 to 31 December 2015 are constrained using the GOSAT ACOS (Atmospheric CO2 Observations from Space) XCO2 retrievals (Version 7.3). The posterior carbon fluxes from 2010 to 2015 are independently evaluated using CO2 observations from 52 surface flask sites. The results show that the posterior carbon fluxes could significantly improve the modeling of atmospheric CO2 concentrations, with global mean bias decreases from a prior value of 1.6 ± 1.8 ppm to −0.5 ± 1.8 ppm. The uncertainty reduction (UR) of the global BIO flux is 17 %, and the highest monthly regional UR could reach 51 %. Globally, the mean annual BIO and OCN carbon sinks and their interannual variations inferred in this study are very close to the estimates of CarbonTracker 2017 (CT2017) during the study period, and the inferred mean atmospheric CO2 growth rate and its interannual changes are also very close to the observations. Regionally, over the northern lands, the strongest carbon sinks are seen in temperate North America, followed by Europe, boreal Asia, and temperate Asia; in the tropics, there are strong sinks in tropical South America and tropical Asia, but a very weak sink in Africa. This pattern is significantly different from the estimates of CT2017, but the estimated carbon sinks for each continent and some key regions like boreal Asia and the Amazon are comparable or within the range of previous bottom-up estimates. The inversion also changes the interannual variations in carbon fluxes in most TransCom land regions, which have a better relationship with the changes in severe drought area (SDA) or leaf area index (LAI), or are more consistent with previous estimates for the impact of drought. These results suggest that the GCASv2 system works well with the GOSAT XCO2 retrievals and shows good performance with respect to estimating the surface carbon fluxes; meanwhile, our results also indicate that the GOSAT XCO2 retrievals could help to better understand the interannual variations in regional carbon fluxes.

Application of Remote Sensing to Monitor Ecosystem Carbon Source and Sink in China

2014 ◽  
Vol 1010-1012 ◽  
pp. 1254-1257
Author(s):  
Jing Wang ◽  
Run He Shi ◽  
Lu Zhang
Keyword(s):  
Remote Sensing ◽  
Large Scale ◽  
Carbon Sink ◽  
National Development ◽  
Terrestrial Ecosystem ◽  
Developed Countries ◽  
Related Data ◽  
Ecosystem Carbon ◽  
Sensing Technology ◽  
Global Carbon

Kyoto Protocol states that developed countries have the responsibility to reduce the amount of greenhouse gas emissions. It, also, suggests that developed countries take measures to enhance carbon sink. Therefore, every country pays more attention on the research of global carbon cycle. China, a developing country with a fast economic increasing rate, has urgent need of related data and information so as to adjust its national development plan and negotiate with other countries. Remote sensing is one of the most important technologies and data sources for large-scale carbon-related researches including terrestrial ecosystem carbon cycling law, carbon sink/source pattern and sink enhancement technology. This paper introduces recent applications of remote sensing technology to the following aspects in China: monitoring land cover, simulating carbon flux, spatial distribution of carbon sink and carbon sink enhancement measures.

Constraining the Eurasian biogenic boreal carbon-cycle with satellite-SIF

2021 ◽  
Author(s):  
Lena Schreiner ◽  
Katja Grossmann ◽  
André Butz ◽  
Sanam N. Vardag ◽  
Eva-Marie Schömann
Keyword(s):  
Carbon Cycle ◽  
Carbon Sink ◽  
Carbon Fluxes ◽  
Climatic Conditions ◽  
Satellite Observations ◽  
Essential Information ◽  
Limit Model ◽  
Spatial Coverage ◽  
Biogenic Carbon ◽  
Boreal Ecosystem

&lt;p&gt;The Eurasian boreal ecosystem acts as a major terrestrial carbon sink in the northern hemisphere. Under changing climatic conditions, it is crucial to monitor biogenic carbon fluxes in this area. The Siberian in-situ CO&lt;sub&gt;2&lt;/sub&gt; data are, however, sparse in spatial coverage and limit model-validation there. Satellite observations of CO&lt;sub&gt;2&lt;/sub&gt; and Sun-Induced Fluorescence (SIF) can provide essential information to constrain the Eurasian boreal biogenic carbon-cycle and further, to improve carbon cycle inverse models.&lt;/p&gt;&lt;p&gt;In this study, we investigate the Eurasian boreal carbon cycle with satellite observations of the Orbiting Carbon Observatory 2 (OCO-2) and the Greenhouse gase Observing SATellite (GOSAT). We compare the observed carbon cycle dynamics to model data such as provided by CarbonTracker (CT2019, CT-NRT.v2020-1) and find differences in the ppm range. Various sensitivity studies with respect to region selection, sampling biases and model choices are used to consolidate the robustness of the detected pattern. Using SIF and FLUXCOM GPP data, we will show first attempts to attribute the model-measurement differences to uncertainties in biogenic carbon fluxes.&lt;/p&gt;

Decomposing terrestrial carbon flux anomalies after El Niño: process-based predictability of land carbon sinks and sources

2020 ◽  
Author(s):  
István Dunkl ◽  
Victor Brovkin
Keyword(s):  
Primary Production ◽  
Carbon Flux ◽  
Clustering Algorithm ◽  
Southern Oscillation ◽  
Carbon Fluxes ◽  
Enso Cycle ◽  
Carbon Sinks ◽  
Potential Predictability ◽  
Ensemble Simulations

&lt;p&gt;Anthropogenic fossil fuel emissions are increasing, and about a half of these emissions is absorbed by land and ocean. The CO2 fraction remaining in the atmosphere, the airborne fraction, is varying from year to year. Most of this variability can be explained by the land-atmosphere carbon fluxes. This variability is strongly affected by the El Ni&amp;#241;o &amp;#8211; Southern Oscillation (ENSO); however, it is difficult to determine the cause of the flux anomalies due to the complex interactions between the climatic effects of the ENSO cycle. Here, we use MPI Earth System Model, MPI-ESM, to study the mechanisms of post El Ni&amp;#241;o carbon fluxes and assess their predictability. 10-member ensemble simulations with small perturbations are initialized at six El Ni&amp;#241;o events of a 1000-year control run. After removing the long-term mean from the ensemble simulations, a density-based clustering algorithm is applied to the carbon fluxes due to primary productivity, respiration and &amp;#64257;res. This allows to identify and delimit the individual hotspots of ENSO-related carbon flux anomalies that contribute most to the atmospheric CO2 change.&lt;br&gt;We found that the main carbon sources are due to a reduction of primary production in the tropics, while the carbon sinks are due to reduced respiration or increased primary production in the extratropics. The potential predictability of the carbon fluxes from these clusters was assessed by using the perfect model approach. In accordance with this method, the predictive horizon is estimated as the time, when the variability within the ensemble members exceeds the long-term variability. As climate change will likely modify the frequency of El Ni&amp;#241;o events, this decomposition of the ENSO carbon flux anomalies could be used to improve our understanding of the future trends of land carbon sinks.&lt;/p&gt;

scholarly journals Carbon Fluxes and Stocks by Mexican Tropical Forested Wetland Soils: A Critical Review of Its Role for Climate Change Mitigation

2020 ◽  
Vol 17 (20) ◽  
pp. 7372
Author(s):  
Sergio Zamora ◽  
Luis Carlos Sandoval-Herazo ◽  
Gastón Ballut-Dajud ◽  
Oscar Andrés Del Ángel-Coronel ◽  
Erick Arturo Betanzo-Torres ◽  
...  
Keyword(s):  
Climate Change ◽  
Soil Carbon ◽  
Carbon Sink ◽  
Carbon Stocks ◽  
Response Strategy ◽  
Forested Wetland ◽  
Wetland Soils ◽  
Carbon Sinks ◽  
Tropical Regions ◽  
Global Carbon

Wetland soils are important stores of soil carbon (C) in the biosphere, and play an important role in global carbon cycles in the response strategy to climate change. However, there areknowledge gaps in our understanding of the quantity and distribution in tropical regions. Specifically, Mexican wetlands have not been considered in global carbon budgets or carbon balances for a number of reasons, such as: (1) the lack of data, (2) Spanish publications have not been selected, or (3) because such balances are mainly made in the English language. This study analyzes the literature regarding carbon stocks, sequestration and fluxes in Mexican forested wetlands (Forest-W). Soil carbon stocks of 8, 24.5 and 40.1 kg cm−2 were detected for flooded palms, mangroves, and freshwater or swamps (FW) wetland soils, respectively, indicating that FW soils are the Forest-W with more potential for carbon sinks (p = 0.023), compared to mangroves and flooded palm soils. While these assessments of carbon sequestration were ranged from 36 to 920 g-C m−2 year−1, C emitted as methane was also tabulated (0.6–196 g-C m−2 year−1). Subtracting the C emitted of the C sequestered, 318.2 g-C m−2 year−1 were obtained. Such data revealed that Forest-W function is mainly as carbon sink, and not C source. This review can help to inform practitioners in future decisions regarding sustainable projects, restoration, conservation or creation of wetlands. Finally, it is concluded that Forest-W could be key ecosystems in strategies addressing the mitigation of climate change through carbon storage. However, new studies in this research line and public policies that protect these essential carbon sinks are necessary in order to, hopefully, elaborate global models to make more accurate predictions about future climate.

scholarly journals Global Terrestrial Ecosystem Carbon Flux Inferred from TanSat XCO2 Retrievals

2022 ◽  
Vol 2022 ◽  
pp. 1-12
Author(s):  
Hengmao Wang ◽  
Fei Jiang ◽  
Yi Liu ◽  
Dongxu Yang ◽  
Mousong Wu ◽  
...  
Keyword(s):  
Carbon Flux ◽  
Net Ecosystem Exchange ◽  
Terrestrial Ecosystem ◽  
Northern Africa ◽  
High Latitudes ◽  
Middle Latitudes ◽  
Ecosystem Carbon ◽  
Prior Estimate ◽  
Carbon Release ◽  
Data Assimilation System

TanSat is China’s first greenhouse gases observing satellite. In recent years, substantial progresses have been achieved on retrieving column-averaged CO2 dry air mole fraction (XCO2). However, relatively few attempts have been made to estimate terrestrial net ecosystem exchange (NEE) using TanSat XCO2 retrievals. In this study, based on the GEOS-Chem 4D-Var data assimilation system, we infer the global NEE from April 2017 to March 2018 using TanSat XCO2. The inversion estimates global NEE at −3.46 PgC yr-1, evidently higher than prior estimate and giving rise to an improved estimate of global atmospheric CO2 growth rate. Regionally, our inversion greatly increases the carbon uptakes in northern mid-to-high latitudes and significantly enhances the carbon releases in tropical and southern lands, especially in Africa and India peninsula. The increase of posterior sinks in northern lands is mainly attributed to the decreased carbon release during the nongrowing season, and the decrease of carbon uptakes in tropical and southern lands basically occurs throughout the year. Evaluations against independent CO2 observations and comparison with previous estimates indicate that although the land sinks in the northern middle latitudes and southern temperate regions are improved to a certain extent, they are obviously overestimated in northern high latitudes and underestimated in tropical lands (mainly northern Africa), respectively. These results suggest that TanSat XCO2 retrievals may have systematic negative biases in northern high latitudes and large positive biases over northern Africa, and further efforts are required to remove bias in these regions for better estimates of global and regional NEE.

scholarly journals Projected Changes in Terrestrial Vegetation and Carbon Fluxes under 1.5 °C and 2.0 °C Global Warming

Atmosphere ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 42
Author(s):  
Xiaobin Peng ◽  
Miao Yu ◽  
Haishan Chen
Keyword(s):  
Carbon Sink ◽  
Carbon Sources ◽  
Terrestrial Ecosystem ◽  
Carbon Fluxes ◽  
Vegetation Coverage ◽  
High Latitudes ◽  
Terrestrial Vegetation ◽  
Vegetation Density ◽  
The Future ◽  
Warming World

The terrestrial ecosystem plays a vital role in regulating the exchange of carbon between land and atmosphere. This study investigates how terrestrial vegetation coverage and carbon fluxes change in a world stabilizing at 1.5 °C and 2 °C warmer than pre-industrial level. Model results derived from 20 Earth System Models (ESMs) under low, middle, and high greenhouse emission scenarios from CMIP5 and CMIP6 are employed to supply the projected results. Although the ESMs show a large spread of uncertainties, the ensemble means of global LAI are projected to increase by 0.04 ± 0.02 and 0.08 ± 0.04 in the 1.5 and 2.0 °C warming worlds, respectively. Vegetation density is projected to decrease only in the Brazilian Highlands due to the decrease of precipitation there. The high latitudes in Eurasia are projected to have stronger increase of LAI in the 2.0 °C warming world compared to that in 1.5 °C warming level caused by the increase of tree coverage. The largest zonal LAI is projected around 70° N while the largest zonal NPP is projected around 60° N and equator. The zonally inhomogeneous increase of vegetation density and productivity relates to the zonally inhomogeneous increase of temperature, which in turn could amplify the latitudinal gradient of temperature with additional warming. Most of the ESMs show uniform increases of global averaged NPP by 10.68 ± 8.60 and 15.42 ± 10.90 PgC year−1 under 1.5 °C and 2.0 °C warming levels, respectively, except in some sparse vegetation areas. The ensemble averaged NEE is projected to increase by 3.80 ± 7.72 and 4.83 ± 10.13 PgC year−1 in the two warming worlds. The terrestrial ecosystem over most of the world could be a stronger carbon sink than at present. However, some dry areas in Amazon and Central Africa may convert to carbon sources in a world with additional 0.5 °C warming. The start of the growing season in the northern high latitudes is projected to advance by less than one month earlier. Five out of 10 CMIP6 ESMs, which use the Land Use Harmonization Project (LUH2) dataset or a prescribed potential vegetation distribution to constrain the future change of vegetation types, do not reduce the model uncertainties in projected LAI and terrestrial carbon fluxes. This may suggest the challenge in optimizing the carbon fluxes modeling in the future.

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