H2 vertical profiles in the continental boundary layer: measurements at the Cabauw tall tower in The Netherlands 1Energy research Centre of the Netherlands, Petten, The Netherlands
06 Jul 2011
2Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, The Netherlands
3Australian Nuclear Science and Technology Organisation, Menai, New South Wales, Australia
Received: 02 Dec 2010 – Published in Atmos. Chem. Phys. Discuss.: 15 Feb 2011Abstract. In-situ, quasi-continuous measurements of atmospheric hydrogen (H2)
have been performed since October 2007 at the Cabauw tall tower station in
the Netherlands. Mole fractions of H2, CO and several greenhouse gases
are determined simultaneously in air sampled successively at four heights,
between 20 and 200 m above ground level. 222Rn measurements are
performed in air sampled at 20 and 200 m.
Revised: 04 Jun 2011 – Accepted: 10 Jun 2011 – Published: 06 Jul 2011
This H2 dataset represents the first in-situ, quasi-continuous
long-term measurement series of vertical profiles of H2 in the lower
continental boundary layer. Seasonal cycles are present at all heights in
both H2 and CO, and their amplitude varies with the sampling height.
The seasonality is evident in both the "baseline" values and in the short
term (diurnal to synoptic time scales) variability, the latter being
significantly larger during winter.
The observed H2 short term signals and vertical gradients are in many
cases well correlated to other species, especially to CO. On the other hand,
H2 has at times a unique behaviour, due to its particular distribution
of sources and sinks.
Our estimation for the regional H2 soil uptake flux, using the radon
tracer method, is (−1.89 ± 0.26) × 10−5 g/(m2 h),
significantly smaller than other recent results from Europe.
H2/CO ratios of the traffic emissions computed from our data, with an
average of 0.54 ± 0.07 mol:mol, are larger and more variable than
estimated in some of the previous studies in Europe. This difference can be
explained by a different driving regime, due to the frequent traffic jams in
the influence area of Cabauw. The H2/CO ratios of the large scale
pollution events have an average of 0.36 ± 0.05 mol:mol; these ratios
were observed to slightly increase with sampling height, possibly due to a
stronger influence of soil uptake at the lower sampling heights.
Citation: Popa, M. E., Vermeulen, A. T., van den Bulk, W. C. M., Jongejan, P. A. C., Batenburg, A. M., Zahorowski, W., and Röckmann, T.: H2 vertical profiles in the continental boundary layer: measurements at the Cabauw tall tower in The Netherlands, Atmos. Chem. Phys., 11, 6425-6443, doi:10.5194/acp-11-6425-2011, 2011.