Global budget of molecular hydrogen and its deuterium content: Constraints from ground station, cruise, and aircraft observations

Abstract

[1] The distribution and atmospheric budgets for molecular hydrogen and its deuterium component dD are simulated with the GEOS-Chem global chemical transport model and constrained by observations of H 2 from the NOAA Climate Monitoring and Diagnostics Laboratory network and dD observations from ship and ground stations. Our simulation includes a primary H 2 source of 38.8 Tg a À1 (22.7 Tg a À1 from fossil and biofuels, 10.1 Tg a À1 from biomass burning, 6.0 Tg a À1 from the ocean) (where a is years) and a secondary photochemical source from photolysis of formaldehyde of 34.3 Tg a À1 . The simulated global tropospheric mean H 2 is 525 ppbv, with a tropospheric burden of 141 Tg and tropospheric lifetime of 1.9 a. Uptake by enzymes in soils accounts for 75% of the H 2 sink, with the remainder due to reaction with OH. The model captures the observed latitudinal, vertical, and seasonal variations of H 2 . For dD we find that a photochemical source signature from methane and biogenic volatile organic compound oxidation of 162% yields a global mean atmospheric dD of 130%, consistent with atmospheric observations. The model captures the observed latitudinal gradient in dD, simulating a 21% greater enrichment in the Southern Hemisphere because of the predominance of isotopically depleted fossil fuel emissions in the Northern Hemisphere. We find that stratospheric-tropospheric exchange results in 37% enrichment of tropospheric dD. Our simulation provides new simultaneous constraints on the H 2 soil sink (55 ± 8 Tg a À1 ), the ocean source (6 ± 3 Tg a À1 ), and the isotopic signature for photochemical production (162 ± 57%).Citation: Price, H., L. Jaeglé, A. Rice, P. Quay, P. C. Novelli, and R. Gammon (2007), Global budget of molecular hydrogen and its deuterium content: Constraints from ground station, cruise, and aircraft observations,

The stable isotopic composition of molecular hydrogen in the tropopause region probed by the CARIBIC aircraft

“…Together, these processes result in typical atmospheric H 2 mixing ratios (χ (H 2 )) of around 547 ppb (nmole/mole) at ground level (Novelli et al, 1999, converted to the latest χ(H 2 ) scale established by Jordan and Steinberg (2011)), with on average 3% higher values in the Southern Hemisphere. Model results indicate that χ (H 2 ) may increase slightly with height, especially in the Northern Hemisphere extratropics (Hauglustaine and Ehhalt, 2002;Price et al, 2007;Pieterse et al, 2011). Despite the qualitative agreement, the uncertainties in the estimates of the magnitudes of the different terms in the budget are large.…”

“…Recently, isotope effects in the production processes of H 2 have been studied (Gerst and Quay, 2001;Rahn et al, 2002bRahn et al, , 2003Röckmann et al, 2003;Rhee et al, 2006a;Feilberg et al, 2007;Rhee et al, 2008;Röckmann et al, 2010a,b;Vollmer et al, 2010;Walter et al, 2011;Haumann et al, 2012), as well as the isotope effects in the H 2 uptake by soils (Gerst and Quay, 2001;Rahn et al, 2002a;Rice et al, 2011). Two chemical transport models have been adapted to incorporate the stable isotopic composition of H 2 , namely GEOS-CHEM (Price et al, 2007) and TM5 (Pieterse et al, 2009(Pieterse et al, , 2012, and many more δD data have become available for the validation of such models (Rice et al, 2010;Batenburg et al, 2011). However, for obvious practical reasons, most of these data were collected at ground level, and yield little information about processes higher up in the atmosphere, particularly in the Upper TroposphereLower Stratosphere (UTLS) region.…”

“…c Novelli et al (1999) d Depending on latitude, Batenburg et al (2011) be one of the main processes that enrich the global tropospheric H 2 reservoir. Both Price et al (2007) and Pieterse et al (2011) estimated that STE contributes several tens of ‰ to the global tropospheric δD average. Furthermore, Pieterse et al (2011) found that the magnitude of the contribution was highly sensitive to the δD value assumed for the stratosphere.…”

A new estimation of the recent tropospheric molecular hydrogen budget using atmospheric observations and variational inversion

“…In contrast to CH 4 and other trace gases sharing anthropogenic sources, the observed H 2 mixing ratios are lower in the Northern Hemisphere when compared to the Southern Hemisphere due to the distribution of the sources and sinks of H 2 (Novelli et al, 1999). The strength of each term of the H 2 budget is given hereafter as referred to in the literature (Novelli et al, 1999;Hauglustaine and Ehhalt, 2002;Sanderson et al, 2003;Rhee et al, 2006;Xiao et al, 2007;Price et al, 2007;Ehhalt and Rohrer, 2009) and compiled in Ehhalt and Rohrer (2009). The main sources of H 2 are photochemical production by the transformation of formaldehyde (HCHO) in the atmosphere and incomplete combustion processes.…”

Impact of a possible future global hydrogen economy on Arctic stratospheric ozone loss

“…The reaction of H 2 with OH and soil uptake are the major sinks of H 2 in the troposphere. The strength of each term is given in the literature [38][39][40][41][42][43][44] and compiled in Ehhalt and Rohrer 44 (2009). The current production (76 Tg yr À1 ) and loss rates (79 Tg yr À1 ) yield a tropospheric H 2 lifetime of 2 years.…”