deltaD(H2) at the Cabauw tall tower in the Netherlands (INGOS meeting 2015)
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δD(H 2 ) at the Cabauw tall tower in the Netherlands A.M. Batenburg 1,2 , M.E. Popa 1 , A.T. Vermeulen 3 , W.C.M. van den Bulk 3 , P.A.C. Jongejan 3 and T. Röckmann 1 1 Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, the Netherlands 2 Department of Applied Physics, University of Eastern Finland, Kuopio, Finland 3 Energy research Centre of the Netherlands, Petten, the Netherlands [email protected] Fig 1: Land cover map of the region around the station (Popa et al., 2011) H 2 and the Cabauw tall tower Molecular hydrogen (H 2 ) might come into wide use as an energy carrier, but the potential atmospheric impacts are not well understood. We studied the H 2 cycle by measuring both the H 2 mixing ratio (χ(H 2 )) and its isotopic composition (δD(H 2 )) in samples taken at the Cabauw tall tower. The Cabauw tower at the CESAR site is located in a relatively rural, central part of the Netherlands, within tens of kilometers from the four major Dutch cities (Fig. 1). Its tubing system has inlets at 20, 60, 120 and 200 m. Fig 2: (a) χ(H 2 ) and (b) δD(H 2 ) timeseries of the flask samples from Cabauw and Mace Head (Batenburg et al., 2011). Grey solid lines are fits to the Mace Head data. Open symbols indicate datapoints that did not pass quality control. Time series Fig. 2 shows our time series of χ(H 2 ) and δD(H 2 ) at Cabauw, together with similar data from Mace Head on the Irish west coast. The Mace Head χ(H 2 ) data form the lower bound of the Cabauw χ(H 2 ) data (Fig. 2(a)). Especially in winter, clear excursions to high χ(H 2 ) values occur regularly at Cabauw. These χ(H 2 ) peaks are associated with very low δD(H 2 ) values (Fig. 2(b)). These features indicate that Cabauw is heavily influenced by H 2 from surface sources, which produce H 2 that is depleted in deuterium. Fig 3: (a)”Keeling“ plot of (δD(H 2 ) vs. inverse χ(H 2 )) of all Cabauw flask data, with bivariate linear fit. Grey bar indicates y-axis intercept and error. (b) Distribution of intercepts obtained from a bootstrapping procedure where the linear Keeling fit was applied to random samples of the data. Pollution δD(H 2 ) signature We estimated the isotopic signature of the Cabauw source mix from the y- intercept of a linear fit to a “Keeling” plot (δD(H 2 ) plotted vs 1/χ(H 2 ), (Fig. 3(a)). To obtain a realistic error estimate of this source signature, and to account for possible arbitrariness in our quality control, we applied a bootstrapping rou- tine where the fit is applied to random samples of the data. The resulting dis- tribution of intercepts is shown in Fig. 3(b). There is considerable spread in the intercepts, but almost all are below -400 ‰. This signature is more D-depleted than any published source signature for H 2 from combustion sources. Possible explanations are that catalytic converters and certain (congested) driving conditions can lower the fossil fuel combus- tion source signature (Vollmer et al., 2010), and/or that extremely D-depleted H 2 from microbial sources in the soil contributes to the mix (Chen et al., 2015). Flask χ(H 2 ) and δD(H 2 ) profiles Cabauw is the only location where vertical profiles of δD(H 2 ) in the boundary layer have been obtained (Fig. 4). Lower χ(H 2 ) values and higher δD(H 2 ) values are expected close to the ground at locations with strong soil uptake. Fig. 4 does not show this, probably because of the soil type (peat/clay) and high ground water table. χ(H 2 ) is significantly higher at 20 m than at 200 m, and δD(H 2 ) is significantly lower at the lower than at the higher levels. This may point to a difference in the source signature between H 2 emitted in the different footprint regions of the different levels. Fig 4: Box plots of χ(H 2 )(a) and δD(H 2 )(b) on days where more than two sampling heights were sampeled. Red lines indicate medians, box edges indicate lower and upper quartiles and whiskers indicate lower and upper 95 th percentiles Conclusions δD(H 2 ) observations at this anthropogenically influenced site complement observations at background locations, provide information on the H 2 cycle in densely populated regions and help in assessing the atmospheric impacts of future H 2 emissions. Here, emissions that add H 2 above background levels show a source signature that is more D-depleted than literature values for combustion processes. The sampling at different heights provides additional information. References M.E. Popa et al., ACP, 11,6425-6443, 2011, doi:10.5194/acp-11-6425-2011 A. M. Batenburg et al., ACP, 11, 6985-6999, 2011, doi:10.5194/acp-11-6985-2011 M. K. Vollmer et al., ACP, 10, 5707-5718, 2010, doi:10.5194/acp-10-5707-2010 Q. Chen et al., ACPD, 15, 23457-23506, doi:10.5194/acpd-15-23457-2015, 2015
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Transcript of deltaD(H2) at the Cabauw tall tower in the Netherlands (INGOS meeting 2015)
δD(H2) at the Cabauw tall tower in the NetherlandsA.M. Batenburg1,2, M.E. Popa1, A.T. Vermeulen3,
W.C.M. van den Bulk3, P.A.C. Jongejan3 and T. Röckmann1 1 Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, the Netherlands
2 Department of Applied Physics, University of Eastern Finland, Kuopio, Finland 3 Energy research Centre of the Netherlands, Petten, the Netherlands
Fig 1: Land cover map of the region around the station (Popa et al., 2011)
H2 and the Cabauw tall tower Molecular hydrogen (H2) might come into wide use as an energy carrier, but the potential atmospheric impacts are not well understood. We studied the H2 cycle by measuring both the H2 mixing ratio (χ(H2)) and its isotopic composition (δD(H2)) in samples taken at the Cabauw tall tower. The Cabauw tower at the CESAR site is located in a relatively rural, central part of the Netherlands, within tens of kilometers from the four major Dutch cities (Fig. 1). Its tubing system has inlets at 20, 60, 120 and 200 m.
Fig 2: (a) χ(H2) and (b) δD(H2) timeseries of the �ask samples from Cabauw and Mace Head (Batenburg et al., 2011). Grey solid lines are �ts to the Mace Head data. Open symbols indicate datapoints that did not pass quality control.
Time seriesFig. 2 shows our time series of χ(H2) and δD(H2) at Cabauw, together with similar data from Mace Head on the Irish west coast. The Mace Head χ(H2) data form the lower bound of the Cabauw χ(H2) data (Fig. 2(a)). Especially in winter, clear excursions to high χ(H2) values occur regularly at Cabauw. These χ(H2) peaks are associated with very low δD(H2) values (Fig. 2(b)). These features indicate that Cabauw is heavily in�uenced by H2 from surface sources, which produce H2 that is depleted in deuterium.
Fig 3: (a)”Keeling“ plot of (δD(H2) vs. inverse χ(H2)) of all Cabauw �ask data, with bivariate linear �t. Grey bar indicates y-axis intercept and error. (b) Distribution of intercepts obtained from a bootstrapping procedure where the linear Keeling �t was applied to random samples of the data.
Pollution δD(H2) signatureWe estimated the isotopic signature of the Cabauw source mix from the y-intercept of a linear �t to a “Keeling” plot (δD(H2) plotted vs 1/χ(H2), (Fig. 3(a)). To obtain a realistic error estimate of this source signature, and to account for possible arbitrariness in our quality control, we applied a bootstrapping rou-tine where the �t is applied to random samples of the data. The resulting dis-tribution of intercepts is shown in Fig. 3(b). There is considerable spread in the intercepts, but almost all are below -400 ‰.This signature is more D-depleted than any published source signature for H2 from combustion sources. Possible explanations are that catalytic converters and certain (congested) driving conditions can lower the fossil fuel combus-tion source signature (Vollmer et al., 2010), and/or that extremely D-depleted H2 from microbial sources in the soil contributes to the mix (Chen et al., 2015).
Flask χ(H2) and δD(H2) pro�lesCabauw is the only location where vertical pro�les of δD(H2) in the boundary layer have been obtained (Fig. 4). Lower χ(H2) values and higher δD(H2) values are expected close to the ground at locations with strong soil uptake. Fig. 4 does not show this, probably because of the soil type (peat/clay) and high ground water table. χ(H2) is signi�cantly higher at 20 m than at 200 m, and δD(H2) is signi�cantly lower at the lower than at the higher levels. This may point to a di�erence in the source signature between H2 emitted in the di�erent footprint regions of the di�erent levels.
Fig 4: Box plots of χ(H2)(a) and δD(H2)(b) on days where more than two sampling heights were sampeled. Red lines indicate medians, box edges indicate lower and upper quartiles and whiskers indicate lower and upper 95th percentiles
ConclusionsδD(H2) observations at this anthropogenically in�uenced site complement observations at background locations, provide information on the H2 cycle in densely populated regions and help in assessing the atmospheric impacts of future H2 emissions. Here, emissions that add H2 above background levels show a source signature that is more D-depleted than literature values for combustion processes. The sampling at di�erent heights provides additional information.
ReferencesM.E. Popa et al., ACP, 11,6425-6443, 2011, doi:10.5194/acp-11-6425-2011
A. M. Batenburg et al., ACP, 11, 6985-6999, 2011, doi:10.5194/acp-11-6985-2011
M. K. Vollmer et al., ACP, 10, 5707-5718, 2010, doi:10.5194/acp-10-5707-2010
Q. Chen et al., ACPD, 15, 23457-23506, doi:10.5194/acpd-15-23457-2015, 2015
