Retrieval of average CO2 fluxes by combining in situ CO2 measurements and backscatter lidar information

Gibert, Fabien; Schmidt, Martina; Cuesta, Juan; Ciais, Philippe; Ramonet, Michel; Xueref, I.; Larmanou, Eric; Flamant, Pierre H.

doi:10.1029/2006jd008190

Cited by 37 publications

(49 citation statements)

References 35 publications

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“…Characterization of the temporal variability of z i during entire diurnal cycle is therefore required. For instance, the ecosystem CO 2 exchange and the ABL mixing are correlated diurnally and seasonally via the "rectifier effect," which has been thoroughly documented (e.g., [39]). Thus, the assessment of the effect of carbon sequestration and/or greenhouse gas emissions reduction activities, including attribution of sources and sinks by region and sector is a challenging but important task [38][39][40][41].…”

Section: Importance Of Monitoring Shallow Atmospheric Boundary Layermentioning

confidence: 99%

“…For instance, the ecosystem CO 2 exchange and the ABL mixing are correlated diurnally and seasonally via the "rectifier effect," which has been thoroughly documented (e.g., [39]). Thus, the assessment of the effect of carbon sequestration and/or greenhouse gas emissions reduction activities, including attribution of sources and sinks by region and sector is a challenging but important task [38][39][40][41]. In estimating the CBL growth rate during the early morning transition or in studying dispersion in a shallow CBL [42][43][44], determination of z i below the height of full overlap of a LiDAR system is urgently required.…”

Section: Importance Of Monitoring Shallow Atmospheric Boundary Layermentioning

confidence: 99%

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Monitoring Depth of Shallow Atmospheric Boundary Layer to Complement LiDAR Measurements Affected by Partial Overlap

Pal

2014

Remote Sensing

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Abstract:There is compelling evidence that the incomplete laser beam receiver field-of-view overlap (i.e., partial overlap) of ground-based vertically-pointing aerosol LiDAR restricts the observational range for detecting aerosol layer boundaries to a certain height above the LiDAR. This height varies from one to few hundreds of meters, depending on the transceiver geometry. The range, or height of full overlap, is defined as the minimum distance at which the laser beam is completely imaged onto the detector through the field stop in the receiver optics. Thus, the LiDAR signal below the height of full overlap remains erroneous. In effect, it is not possible to derive the atmospheric boundary layer (ABL) top (z i ) below the height of full overlap using lidar measurements alone. This problem makes determination of the nocturnal z i almost impossible, as the nocturnal z i is often lower than the minimum possible retrieved height due to incomplete overlap of lidar. Detailed studies of the nocturnal boundary layer or of variability of low z i would require changes in the LiDAR configuration such that a complete transceiver overlap could be achieved at a much lower height. Otherwise, improvements in the system configuration or deployment (e.g., scanning LiDAR) are needed. However, these improvements are challenging due to the instrument configuration and the need for Raman channel signal, eye-safe laser transmitter for scanning deployment, etc. This paper presents a brief review of some of the challenges and opportunities in overcoming the partial overlap of the LiDAR transceiver to determine z i below the height of full-overlap using complementary approaches to derive low z i . A comprehensive discussion focusing on four different techniques is presented. These are based on the combined (1) ceilometer and LiDAR; (2) tower-based trace gas (e.g., CO 2 ) concentration profiles and LiDAR measurements; (3) 222 Rn budget approach and LiDAR-derived results; and (4) encroachment model and LiDAR observations.

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Section: Importance Of Monitoring Shallow Atmospheric Boundary Layermentioning

confidence: 99%

Section: Importance Of Monitoring Shallow Atmospheric Boundary Layermentioning

confidence: 99%

Monitoring Depth of Shallow Atmospheric Boundary Layer to Complement LiDAR Measurements Affected by Partial Overlap

Pal

2014

Remote Sensing

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“…The CO 2 surface fluxes obtained by the three methods vary between 10 and 16 µmol.m −2 .s −1 , values lower than the fluxes estimated by Gibert et al (2007), over a region dominated by winter crops in May, and by Schmitgen et al (2004), in the Landes in June, which were 20 and 16 µmol.m −2 .s −1 , respectively.…”

Section: Discussionmentioning

confidence: 85%

CO2 budgeting at the regional scale using a Lagrangian experimental strategy and meso-scale modeling

Sarrat¹,

Noilhan²,

Lacarrère³

et al. 2009

Biogeosciences

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Abstract. An atmospheric Lagrangian experiment for regional CO 2 budgeting with aircraft measurements took place during the CarboEurope Regional Experiment Strategy campaign (CERES) in south-west France, in June 2005. The atmospheric CO 2 aircraft measurements taken upstream and downstream of an active and homogeneous pine forest revealed a CO 2 depletion in the same air mass, using a Lagrangian strategy. This field experiment was analyzed with a meteorological meso-scale model interactively coupled with a surface scheme, with plant assimilation, ecosystem respiration, anthropogenic CO 2 emissions and sea fluxes. First, the model was carefully validated against observations made close to the surface and in the atmospheric boundary layer. Then, the carbon budget was evaluated using the numerous CERES observations, by upscaling the surface fluxes observations, and using the modeling results, in order to estimate the relative contribution of each physical process.A good agreement is found between the two methods which use the same vegetation map: the estimation of the regional CO 2 surface flux by the Eulerian meso-scale model budget is close to the budget deduced from the upscaling of the observed surface fluxes, and found a budget between −9.4 and −12.1 µmol.m −2 .s −1 , depending on the size of the considered area. Nevertheless, the associated uncertainties are rather large for the upscaling method and reach 50%. A third method, using Lagrangian observations of CO 2Correspondence to: C. Sarrat (claire.sarrat@cnrm.meteo.fr) estimates a regional CO 2 budget a few different and more scattered, (−16.8 µmol.m −2 .s −1 for the small sub-domain and −8.6 µmol.m −2 .s −1 for the larger one). For this budgeting method, we estimate a mean of 31% error, mainly arising from the time of integration between the two measurements of the Lagrangian experiment. The paper describes in details the three methods to assess the regional CO 2 budget and the associated errors.

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“…This points to an overestimation of the mixing rate between the ABL and the FT. It is possible that the entrainment zone and the non-mixing zone at the top of the ABL are not well resolved by the model parameterization when convection is established (Gibert et al, 2007) (Hourdin et al, 2002). An overestimation of ABL-FT mixing by transport models was already shown by Yi et al (2004) using CO 2 vertical profiles along the WLEF tall tower in Wisconsin, and by Ramonet et al (2002) using ABL aircraft vertical profile data during an intensive campaign over a forest in Russia.…”

Section: Discussionmentioning

confidence: 99%

“…Schmidt et al, 2003, the boundary layer budget method (e.g. Gibert et al, 2007), and tower flux measurements (e.g. Haszpra et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

Variability and budget of CO2 in Europe: analysis of the CAATER airborne campaigns – Part 2: Comparison of CO2 vertical variability and fluxes between observations and a modeling framework

et al. 2011

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Abstract. Our ability to predict future climate change relies on our understanding of current and future CO 2 fluxes, particularly on a regional scale (100-1000 km). CO 2 regional sources and sinks are still poorly understood. Inverse transport modeling, a method often used to quantify these fluxes, relies on atmospheric CO 2 measurements. One of the main challenges for the transport models used in the inversions is to properly reproduce CO 2 vertical gradients between the boundary layer and the free troposphere, as these gradients impact on the partitioning of the calculated fluxes between the different model regions. Vertical CO 2 profiles are very well suited to assess the performances of the models. In this paper, we conduct a comparison between observed and modeled CO 2 profiles recorded during two CAATER campaigns that occurred in May 2001 and October 2002 over Western Europe, as described in a companion paper. We test different combinations between a global transport model (LMDZt), a mesoscale transport model (CHIMERE), and different sets of biospheric fluxes, all chosen with a diurnal cycle (CASA, SiB2 and ORCHIDEE). The vertical profile comparison shows that: 1) in most cases the influence of the biospheric flux is small but sometimes not negligible, ORCHIDEE giving the best results in the present study; 2) LMDZt is most of the time too diffuse, as it simulates a too high boundary layer height; 3) CHIMERE better reproduces the observed gradients between the boundary layer and the free troposphere, but is sometimes too variable and gives rise Correspondence to: I. Xueref-Remy (irene.xueref@lsce.ipsl.fr) to incoherent structures. We conclude there is a need for more vertical profiles to conduct further studies to improve the parameterization of vertical transport in the models used for CO 2 flux inversions.Furthermore, we use a modeling method to quantify CO 2 fluxes at the regional scale from a chosen observing point, coupling influence functions from the transport model LMDZt (that works quite well at the synoptic scale) with information on the space-time distribution of fluxes. This modeling method is compared to a dual tracer method (the so-called Radon method) for a case study on 25 May 2001 during which simultaneous well-correlated in situ CO 2 and Radon 222 measurements have been collected. Both methods give a similar result: a flux within the Radon 222 method uncertainty (35%), that is an atmospheric CO 2 sink of −4.2 to −4.4 gC m −2 day −1 . We have estimated the uncertainty of the modeling method to be at least 33% on average, and even more for specific individual events. This method allows the determination of the area that contributed to the CO 2 observed concentration. In our case, the observation point located at 1700 m a.s.l. in the north of France, is influenced by an area of 1500×700 km 2 that covers the Benelux region, part of Germany and western Poland. Furthermore, this method allows deconvolution between the different contributing fluxes. In this case study, the biospheric sink contri...

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Retrieval of average CO₂ fluxes by combining in situ CO₂ measurements and backscatter lidar information

Cited by 37 publications

References 35 publications

Monitoring Depth of Shallow Atmospheric Boundary Layer to Complement LiDAR Measurements Affected by Partial Overlap

Monitoring Depth of Shallow Atmospheric Boundary Layer to Complement LiDAR Measurements Affected by Partial Overlap

CO<sub>2</sub> budgeting at the regional scale using a Lagrangian experimental strategy and meso-scale modeling

Variability and budget of CO<sub>2</sub> in Europe: analysis of the CAATER airborne campaigns – Part 2: Comparison of CO<sub>2</sub> vertical variability and fluxes between observations and a modeling framework

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Retrieval of average CO2 fluxes by combining in situ CO2 measurements and backscatter lidar information

Cited by 37 publications

References 35 publications

Monitoring Depth of Shallow Atmospheric Boundary Layer to Complement LiDAR Measurements Affected by Partial Overlap

Monitoring Depth of Shallow Atmospheric Boundary Layer to Complement LiDAR Measurements Affected by Partial Overlap

CO&lt;sub&gt;2&lt;/sub&gt; budgeting at the regional scale using a Lagrangian experimental strategy and meso-scale modeling

Variability and budget of CO&lt;sub&gt;2&lt;/sub&gt; in Europe: analysis of the CAATER airborne campaigns – Part 2: Comparison of CO&lt;sub&gt;2&lt;/sub&gt; vertical variability and fluxes between observations and a modeling framework

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Retrieval of average CO₂ fluxes by combining in situ CO₂ measurements and backscatter lidar information

CO<sub>2</sub> budgeting at the regional scale using a Lagrangian experimental strategy and meso-scale modeling

Variability and budget of CO<sub>2</sub> in Europe: analysis of the CAATER airborne campaigns – Part 2: Comparison of CO<sub>2</sub> vertical variability and fluxes between observations and a modeling framework