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 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 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.

Reexamine China’s terrestrial ecosystem carbon balance under land use-type and climate change

2021 ◽  
Vol 102 ◽  
pp. 105275
Author(s):  
Jiasheng Li ◽  
Xiaomin Guo ◽  
Xiaowei Chuai ◽  
Fangjian Xie ◽  
Feng Yang ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Carbon Balance ◽  
Terrestrial Ecosystem ◽  
Land Use Type ◽  
Ecosystem Carbon ◽  
Ecosystem Carbon Balance

scholarly journals Spatial and seasonal variability of medium- and high-frequency gravity waves in the lower atmosphere revealed by US radiosonde data

2014 ◽  
Vol 32 (9) ◽  
pp. 1129-1143 ◽  
Author(s):  
S. D. Zhang ◽  
C. M. Huang ◽  
K. M. Huang ◽  
F. Yi ◽  
Y. H. Zhang ◽  
...  
Keyword(s):  
Energy Density ◽  
Gravity Waves ◽  
Seasonal Variability ◽  
High Frequency ◽  
Lower Atmosphere ◽  
Radiosonde Data ◽  
High Latitudes ◽  
Middle Latitudes ◽  
Momentum Fluxes ◽  
Horizontal Momentum

Abstract. We extended the broad spectral method proposed by Zhang et al. (2013) for the extraction of medium- and high-frequency gravity waves (MHGWs). This method was applied to 11 years (1998–2008) of radiosonde data from 92 stations in the Northern Hemisphere to investigate latitudinal, continuous vertical and seasonal variability of MHGW parameters in the lower atmosphere (2–25 km). The latitudinal and vertical distributions of the wave energy density and horizontal momentum fluxes as well as their seasonal variations exhibit considerable consistency with those of inertial gravity waves. Despite the consistency, the MHGWs have much larger energy density, horizontal momentum fluxes and wave force, indicating the more important role of MHGWs in energy and momentum transportation and acceleration of the background. For the observed MHGWs, the vertical wavelengths are usually larger than 8 km; the horizontal wavelengths peak in the middle troposphere at middle–high latitudes. These characteristics are obviously different from inertial gravity waves. The energy density and horizontal momentum fluxes have similar latitude-dependent seasonality: both of them are dominated by a semiannual variation at low latitudes and an annual variation at middle latitudes; however at high latitudes, they often exhibit more than two peaks per year in the troposphere. Compared with the inertial GWs, the derived intrinsic frequencies are more sensitive to the spatiotemporal variation of the buoyancy frequency, and at all latitudinal regions they are higher in summer. The wavelengths have a weaker seasonal variation; an evident annual cycle can be observed only at middle latitudes.

scholarly journals Annual variation characteristics of Eurasian hydrologic elements and their linkage with climate and environment changes during 1951–2015

2019 ◽  
Author(s):  
Jia Qin ◽  
Yongjian Ding ◽  
Tianding Han ◽  
Junhao Li ◽  
Shaoping Wang ◽  
...  
Keyword(s):  
Snow Water Equivalent ◽  
Discharge Pattern ◽  
River Ice ◽  
Ice Thickness ◽  
High Latitudes ◽  
Middle Latitudes ◽  
Variation Characteristics ◽  
Snow Water ◽  
The 1950S ◽  
Monthly Discharge

Abstract. In this paper, the variations of the lowest monthly discharge (LD), mean monthly discharge (MD), and highest monthly discharge value (HD) during 1951–2015, as well as spring snowmelt water and winter river ice change, in eleven major rivers, distributed respectively in the high-latitudes (55° N–70° N), middle latitudes (40° N–55° N), and lower latitudes (30° N–40° N) of Eurasia, were analysed. Energy and water budgets in different watersheds were compared to detect the reasons for Eurasian hydrological changes. We found that the annual LD in most Eurasian rivers was increasing since the 1950s, with rates of (5 %–8 %) per decade. But the increase rate slowed down after the late 1990s in the middle latitudes of Eurasia. Both the MD and HD in the lower latitudes of Eurasia had increasing trends during 1951–2015, while they had little changes in the high and middle latitudes. The river ice thickness and volume have been continuously reducing since the 1950s, as well as the maximum snow water equivalent. And ice period of the Eurasian rivers has shortened about 24 days. The LD trend is mostly dominated by temperature via impacting river ice thickness and extent, while the HD is mostly impacted by snowmelt water and rainfall respectively in different latitudes. Annual MD trend is controlled by evapotranspiration, especially after the late 1990s. After the late 1990s, a warm Arctic-large discharge pattern existed in the lower and high latitudes of Eurasia, but a warm Arctic- few discharge pattern in the middle latitudes (except the winter).

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).

scholarly journals Interannual variability of net ecosystem carbon production and its climatic and biotic mechanism during 2005-2018 in a rain-fed maize ecosystem

2020 ◽  
Author(s):  
Hui Zhang ◽  
Tianhong Zhao ◽  
Sidan Lyu ◽  
Hang Wu ◽  
Yang Yang ◽  
...  
Keyword(s):  
Climate Changes ◽  
Daily Maximum ◽  
Spring Precipitation ◽  
Area Index ◽  
Carbon Production ◽  
Ecosystem Carbon ◽  
Spring Maize ◽  
Carbon Release ◽  
Northeast Of China ◽  
Beginning Date

AbstractThe interannual variation (IAV) of net ecosystem carbon production (NEP) plays an important role in understanding the mechanisms of the carbon cycle in the agriculture ecosystem. In this study, the IAV of NEP, which were expressed as annual values and anomalies, and its climatic and biotic controls mechanism, were investigated based on an eddy covariance dataset of rain-fed spring maize during 2005–2018 in the northeast of China. The annual NEP was 270±115 g C m−2yr −1. Annual values and anomalies of NEP were positively correlated with that of precipitation (PPT), gross ecosystem production (GEP) and daily maximum NEP (NEPmax). Annual anomalies of NEP were dominantly and positively controlled by the soil water content (SWC) through GEP and the soil temperature (Ts) through RE. In comparison, annual anomalies of NEP were dominantly and negatively controlled by summer VPD through the NEPmax, positively adjusted by spring precipitation and the effective accumulative temperature through the beginning date (BDOY) of the affecting carbon uptake period (CUP), and by autumn precipitation and leaf area index through the end date (EDOY) of the affecting CUP. Residues restrained the carbon release at the beginning of the year, and accelerated the carbon release at the end of the year. Our results hightlight that NEP might be more sensitive to the change of water condition (such as PPT, SWC and VPD) induced by the climate changes.

Sign in / Sign up

Export Citation Format

Share Document