Evaluation of a new middle-lower tropospheric CO 2 product using data assimilation
TL;DR: In this paper, CO 2 data from the Atmospheric Infrared Sounder (AIRS) were assimilated into the GEOS-5 (Goddard Earth Observing System Model, Version 5) constituent assimilation system for the period 1 January 2005 to 31 December 2006.
Abstract: . Atmospheric CO 2 retrievals with peak sensitivity in the mid- to lower troposphere from the Atmospheric Infrared Sounder (AIRS) have been assimilated into the GEOS-5 (Goddard Earth Observing System Model, Version 5) constituent assimilation system for the period 1 January 2005 to 31 December 2006. A corresponding model simulation, using identical initial conditions, circulation, and CO 2 boundary fluxes was also completed. The analyzed and simulated CO 2 fields are compared with surface measurements globally and aircraft measurements over North America. Surface level monthly mean CO 2 values show a marked improvement due to the assimilation in the Southern Hemisphere, while less consistent improvements are seen in the Northern Hemisphere. Mean differences with aircraft observations are reduced at all levels, with the largest decrease occurring in the mid-troposphere. The difference standard deviations are reduced slightly at all levels over the ocean, and all levels except the surface layer over land. These initial experiments indicate that the used channels contain useful information on CO 2 in the middle to lower troposphere. However, the benefits of assimilating these data are reduced over the land surface, where concentrations are dominated by uncertain local fluxes and where the observation density is quite low. Away from these regions, the study demonstrates the power of the data assimilation technique for evaluating data that are not co-located, in that the improvements in mid-tropospheric CO 2 by the sparsely distributed partial-column retrievals are transported by the model to the fixed in situ surface observation locations in more remote areas.
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TL;DR: Tan-Tracker-Region as discussed by the authors was developed by incorporating an assimilation scheme into the Community Multiscale Air Quality (CMAQ) regional chemical transport model to resolve fine-scale CO2 variability over East Asia.
Abstract: A regional surface carbon dioxide (CO2) flux inversion system, the Tan-Tracker-Region, was developed by incorporating an assimilation scheme into the Community Multiscale Air Quality (CMAQ) regional chemical transport model to resolve fine-scale CO2 variability over East Asia. The proper orthogonal decomposition-based ensemble four-dimensional variational data assimilation approach (POD-4DVar) is the core algorithm for the joint assimilation framework, and simultaneous assimilations of CO2 concentrations and surface CO2 fluxes are applied to help reduce the uncertainty in initial CO2 concentrations. A persistence dynamical model was developed to describe the evolution of the surface CO2 fluxes and help avoid the “signal-to-noise” problem; thus, CO2 fluxes could be estimated as a whole at the model grid scale, with better use of observation information. The performance of the regional inversion system was evaluated through a group of single-observation-based observing system simulation experiments (OSSEs). The results of the experiments suggest that a reliable performance of Tan-Tracker-Region is dependent on certain assimilation parameter choices, for example, an optimized window length of approximately 3 h, an ensemble size of approximately 100, and a covariance localization radius of approximately 320 km. This is probably due to the strong diurnal variation and spatial heterogeneity in the fine-scale CMAQ simulation, which could affect the performance of the regional inversion system. In addition, because all observations can be artificially obtained in OSSEs, the performance of Tan-Tracker-Region was further evaluated through different densities of the artificial observation network in different CO2 flux situations. The results indicate that more observation sites would be useful to systematically improve the estimation of CO2 concentration and flux in large areas over the model domain. The work presented here forms a foundation for future research in which a thorough estimation of CO2 flux variability over East Asia could be performed with the regional inversion system.
12 citations
TL;DR: In this article, the authors analyzed the variations of monthly and yearly CO2 mole fraction from 2003 to 2011 for the entire China and its six geographical regions using Atmospheric Infrared Sounder (AIRS) data.
10 citations
TL;DR: In this paper, the authors use a standard collection of diagnostic fluxes which incorporate a variety of remote-sensing driver data, viz. vegetation indices, fire radiative power, and nighttime lights, to calibrate surface fluxes derived from satellite observations of the Earth's surface to be consistent with constraints from inventories and in situ CO2 datasets.
Abstract: . The ability to monitor and understand natural and anthropogenic variability in atmospheric carbon dioxide (CO2) is a growing need of many stakeholders across the world. Systems that assimilate satellite observations, given their short latency and dense spatial coverage, into high-resolution global models are valuable, if not essential, tools for addressing this need. A notable drawback of modern assimilation systems is the long latency of many vital input datasets, e.g., inventories, in situ measurements, and reprocessed remote-sensing data can trail the current date by months to years. This paper describes techniques for calibrating surface fluxes derived from satellite observations of the Earth's surface to be consistent with constraints from inventories and in situ CO2 datasets. The techniques are applicable in both short-term forecasts and retrospective simulations, thus taking advantage of the coverage and short latency of satellite data while reproducing the major features of long-term inventory and in situ records. Our approach begins with a standard collection of diagnostic fluxes which incorporate a variety of remote-sensing driver data, viz. vegetation indices, fire radiative power, and nighttime lights. We then apply an empirical sink to calibrate the diagnostic fluxes to match given atmospheric and oceanic growth rates for each year. This step removes coherent, systematic flux errors that produce biases in CO2 which mask the signals an assimilation system hopes to capture. Depending on the simulation mode, the empirical sink uses different choices of atmospheric growth rates: estimates based on observations in retrospective mode and projections based on seasonal forecasts of sea surface temperature in forecasting mode. The retrospective fluxes, when used in simulations with NASA's Goddard Earth Observing System (GEOS), reproduce marine boundary layer measurements with comparable skill to those using fluxes from a modern inversion system. The forecasted fluxes show promising accuracy in their application to the analysis of changes in the carbon cycle as they occur.
9 citations
Cites background from "Evaluation of a new middle-lower tr..."
...This system is currently being extended to assimilate a collection of CO2 datasets (Tangborn et al., 2013; Eldering et al., 2017) including retrievals of column averages from the Greenhouse Gases Observing Satellite (GOSAT; Kuze et al....
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...This system is currently being extended to assimilate a collection of CO2 datasets (Tangborn et al., 2013; Eldering et al., 2017) including retrievals of column averages from the Greenhouse Gases Observing Satellite (GOSAT; Kuze et al., 2009), Orbiting Carbon Observatory 2 (OCO-2; Crisp et al.,…...
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TL;DR: In this paper, the authors compared ground-based CO2 measurements with satellite retrievals and investigated the source-sink regional representativeness at China's four WMO/GAW stations.
9 citations
TL;DR: In this article, an Ensemble Kalman Filter (EnKF)-CMAQ system was developed to be a CO2 data assimilation system, which was then applied to East Asia for validation with real continuous surface CO2 concentration observations available in the study domain.
Abstract: Under an Ensemble Kalman Filter (EnKF) framework, Regional Atmospheric Modeling System and Models-3 Community Multi-scale Air Quality (RAMS–CMAQ) modeling system is developed to be a CO2 data assimilation system EnKF–CMAQ, and the EnKF–CMAQ system is then applied to East Asia for validation with real continuous surface CO2 concentration observations available in the study domain instead of using an observation simulation system experiment. Experiments with an experimental period of January 23 to February 7, 2007 are conducted, and the experimental results of the EnKF–CMAQ system and the RAMS–CMAQ model are compared against continuous surface CO2 observations from assimilation sites and independent reference sites. Distributions of daily mean CO2 concentration increments show that the EnKF–CMAQ system confines the update of daily mean CO2 within areas nearby and downwind of the assimilation sites. Both the CO2 concentration ensemble spreads and background error covariances show flow-dependent patterns. The results indicate the crucial role of wind transport in the CO2 data assimilation, which agrees with the previous studies. The average bias and the average root-mean-square error (RMSE) of daily mean CO2 concentration at the assimilation sites are reduced by 1.00 and 1.83 ppm, respectively, and those at the reference sites are reduced by 0.24 and 0.22 ppm, respectively. The results demonstrate the EnKF–CMAQ system is capable of assimilating the continuous surface CO2 concentration observations to improve the simulation accuracy of the atmospheric CO2 synoptic variation. Since growing CO2 observations over East Asia are being available nowadays, this work is our first step to generate consistent spatial and temporal atmospheric CO2 concentration fields over East Asia, particularly over China, using both in situ and satellite observations.
9 citations
References
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TL;DR: The Modern-Era Retrospective Analysis for Research and Applications (MERRA) was undertaken by NASA's Global Modeling and Assimilation Office with two primary objectives: to place observations from NASA's Earth Observing System satellites into a climate context and to improve upon the hydrologic cycle represented in earlier generations of reanalyses as mentioned in this paper.
Abstract: The Modern-Era Retrospective Analysis for Research and Applications (MERRA) was undertaken by NASA’s Global Modeling and Assimilation Office with two primary objectives: to place observations from NASA’s Earth Observing System satellites into a climate context and to improve upon the hydrologic cycle represented in earlier generations of reanalyses. Focusing on the satellite era, from 1979 to the present, MERRA has achieved its goals with significant improvements in precipitation and water vapor climatology. Here, a brief overview of the system and some aspects of its performance, including quality assessment diagnostics from innovation and residual statistics, is given.By comparing MERRA with other updated reanalyses [the interim version of the next ECMWF Re-Analysis (ERA-Interim) and the Climate Forecast System Reanalysis (CFSR)], advances made in this new generation of reanalyses, as well as remaining deficiencies, are identified. Although there is little difference between the new reanalyses i...
4,572 citations
Book•
17 Jul 2000
TL;DR: This book treats the inverse problem of remote sounding comprehensively, and discusses a wide range of retrieval methods for extracting atmospheric parameters of interest from the quantities such as thermal emission that can be measured remotely.
Abstract: Remote sounding of the atmosphere has proved to be a fruitful method of obtaining global information about the atmospheres of the earth and planets. This book treats the inverse problem of remote sounding comprehensively, and discusses a wide range of retrieval methods for extracting atmospheric parameters of interest from the quantities such as thermal emission that can be measured remotely. Inverse theory is treated in depth from an estimation-theory point of view, but practical questions are also emphasized, for example designing observing systems to obtain the maximum quantity of information, efficient numerical implementation of algorithms for processing of large quantities of data, error analysis and approaches to the validation of the resulting retrievals, The book is targeted at both graduate students and working scientists.
4,052 citations
"Evaluation of a new middle-lower tr..." refers background or methods in this paper
...Details of this correlation model are given in Stajner et al. (2001) and Tangborn et al. (2009). This results in a state-dependent error covariance because the error standard deviation is proportional to the CO2 fields....
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...The retrievals are a least squares inversion for linear perturbations around the local ECMWF profile, which results in a mid–lower tropospheric CO2 mixing ratio (see Rodgers, 2000)....
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...Details of this correlation model are given in Stajner et al. (2001) and Tangborn et al....
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TL;DR: Results from several months of parallel testing with the NMC spectral model have been very encouraging, and favorable features include smoother analysis increments, greatly reduced changes from initialization, and significant improvement of 1-5-day forecasts.
Abstract: At the National Meteorological Center (NMC), a new analysis system is being extensively tested for possible use in the operational global data assimilation system. This analysis system is called the spectral statistical- interpolation (SSI) analysis system because the spectral coefficients used in the NMC spectral model are analyzed directly using the same basic equations as statistical (optimal) interpolation. Results from several months of parallel testing with the NMC spectral model have been very encouraging. Favorable features include smoother analysis increments, greatly reduced changes from initialization, and significant improvement of 1-5-day forecasts. Although the analysis is formulated as a variational problem, the objective function being minimized is formally the same one that forms the basis of all existing optimal interpolation schemes. This objective function is a combination of forecast and observation deviations from the desired analysis, weighted by the invent of the correspon...
1,890 citations
"Evaluation of a new middle-lower tr..." refers methods in this paper
...Engelen et al. (2009) employed the NMC method (Parrish and Derber, 1992) which uses statistics from 24 and 48 h forecasts....
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...(2009) employed the NMC method (Parrish and Derber, 1992) which uses statistics from 24 and 48 h forecasts....
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TL;DR: In this paper, the authors investigated fire emissions during the 8 year period from 1997 to 2004 using satellite data and the CASA biogeochemical model, and found that on average approximately 58 Pg C year −1 was fixed by plants as NPP, and approximately 95% of this was returned back to the atmosphere via R h.
Abstract: Biomass burning represents an important source of atmospheric aerosols and greenhouse gases, yet little is known about its interannual variability or the underlying mechanisms regulating this variability at continental to global scales. Here we investigated fire emissions during the 8 year period from 1997 to 2004 using satellite data and the CASA biogeochemical model. Burned area from 2001–2004 was derived using newly available active fire and 500 m. burned area datasets from MODIS following the approach described by Giglio et al. (2006). ATSR and VIRS satellite data were used to extend the burned area time series back in time through 1997. In our analysis we estimated fuel loads, including organic soil layer and peatland fuels, and the net flux from terrestrial ecosystems as the balance between net primary production (NPP), heterotrophic respiration ( R h ), and biomass burning, using time varying inputs of precipitation (PPT), temperature, solar radiation, and satellite-derived fractional absorbed photosynthetically active radiation (fAPAR). For the 1997–2004 period, we found that on average approximately 58 Pg C year −1 was fixed by plants as NPP, and approximately 95% of this was returned back to the atmosphere via R h . Another 4%, or 2.5 Pg C year −1 was emitted by biomass burning; the remainder consisted of losses from fuel wood collection and subsequent burning. At a global scale, burned area and total fire emissions were largely decoupled from year to year. Total carbon emissions tracked burning in forested areas (including deforestation fires in the tropics), whereas burned area was largely controlled by savanna fires that responded to different environmental and human factors. Biomass burning emissions showed large interannual variability with a range of more than 1 Pg C year −1 , with a maximum in 1998 (3.2 Pg C year −1 ) and a minimum in 2000 (2.0 Pg C year −1 ).
1,639 citations
Colorado State University1, Commonwealth Scientific and Industrial Research Organisation2, National Center for Atmospheric Research3, National Oceanic and Atmospheric Administration4, Massachusetts Institute of Technology5, Princeton University6, University of California, Berkeley7, Max Planck Society8, Meteorological Service of Canada9, Japan Meteorological Agency10, University of California, Irvine11, California Institute of Technology12, National Institute of Advanced Industrial Science and Technology13, Lamont–Doherty Earth Observatory14
TL;DR: An uptake of CO2 in the southern extratropical ocean less than that estimated from ocean measurements is found, a result that is not sensitive to transport models or methodological approaches, and carbon fluxes integrated over latitudinal zones are strongly constrained by observations in the middle to high latitudes.
Abstract: Information about regional carbon sources and sinks can be derived from variations in observed atmospheric CO2 concentrations via inverse modelling with atmospheric tracer transport models. A consensus has not yet been reached regarding the size and distribution of regional carbon fluxes obtained using this approach, partly owing to the use of several different atmospheric transport models. Here we report estimates of surface-atmosphere CO2 fluxes from an intercomparison of atmospheric CO2 inversion models (the TransCom 3 project), which includes 16 transport models and model variants. We find an uptake of CO2 in the southern extratropical ocean less than that estimated from ocean measurements, a result that is not sensitive to transport models or methodological approaches. We also find a northern land carbon sink that is distributed relatively evenly among the continents of the Northern Hemisphere, but these results show some sensitivity to transport differences among models, especially in how they respond to seasonal terrestrial exchange of CO2. Overall, carbon fluxes integrated over latitudinal zones are strongly constrained by observations in the middle to high latitudes. Further significant constraints to our understanding of regional carbon fluxes will therefore require improvements in transport models and expansion of the CO2 observation network within the tropics.
1,110 citations