A convolution of observational and model data to estimate age of air spectra in the northern hemispheric lower stratosphere
-
Published:2020-07-24
Issue:14
Volume:20
Page:8763-8785
-
ISSN:1680-7324
-
Container-title:Atmospheric Chemistry and Physics
-
language:en
-
Short-container-title:Atmos. Chem. Phys.
Author:
Hauck Marius, Bönisch HaraldORCID, Hoor PeterORCID, Keber Timo, Ploeger Felix, Schuck Tanja J.ORCID, Engel AndreasORCID
Abstract
Abstract. Derivation of mean age of air (AoA) and age spectra from
atmospheric measurements remains a challenge and often requires output from
atmospheric models. This study tries to minimize the direct influence of
model output and presents an extension and application of a previously
established inversion method to derive age spectra from mixing ratios of
long- and short-lived trace gases. For a precise description of
cross-tropopause transport processes, the inverse method is extended to
incorporate air entrainment into the stratosphere across the tropical and
extratropical tropopause. We first use simulations with the Chemical
Lagrangian Model of the Stratosphere (CLaMS) to provide a general proof of
concept of the extended principle in a controllable and consistent
environment, where the method is applied to an idealized set of 10 trace
gases with predefined constant lifetimes and compared to reference model age
spectra. In the second part of the study we apply the extended inverse
method to atmospheric measurements of multiple long- and short-lived trace
gases measured aboard the High Altitude and Long Range (HALO) research
aircraft during the two research campaigns POLSTRACC–GW-LCYCLE–SALSA (PGS)
and Wave-driven Isentropic Exchange (WISE). As some of the observed species
undergo significant loss processes in the stratosphere, a Monte Carlo
simulation is introduced to retrieve age spectra and chemical lifetimes in
stepwise fashion and to account for the large uncertainties. Results show
that in the idealized model scenario the inverse method retrieves age
spectra robustly on annual and seasonal scales. The extension to multiple
entry regions proves reasonable as our CLaMS simulations reveal that in the
model between 50 % and 70 % of air in the lowermost stratosphere has
entered through the extratropical tropopause (30–90∘ N and S) on annual average. When applied to observational data of PGS and WISE,
the method derives age spectra and mean AoA with meaningful spatial
distributions and quantitative range, yet large uncertainties. Results
indicate that entrainment of fresh tropospheric air across both the
extratropical and tropical tropopause peaked prior to both campaigns, but
with lower mean AoA for WISE than PGS data. The ratio of moments for all
retrieved age spectra for PGS and WISE is found to range between 0.52 and 2.81 years. We conclude that the method derives reasonable and
consistent age spectra using observations of chemically active trace gases.
Our findings might contribute to an improved assessment of transport with
age spectra in future studies.
Funder
Deutsche Forschungsgemeinschaft
Publisher
Copernicus GmbH
Subject
Atmospheric Science
Reference83 articles.
1. Abalos, M., Legras, B., Ploeger, F., and Randel, W. J.: Evaluating the
advective Brewer-Dobson circulation in three reanalyses for the period
1979–2012, J. Geophys. Res., 120, 7534–7554, https://doi.org/10.1002/2015JD023182,
2015. 2. Allen, D. R. and Nakamura, N.: Tracer Equivalent Latitude: A Diagnostic Tool
for Isentropic Transport Studies, J. Atmos. Sci., 60, 287–304,
https://doi.org/10.1175/1520-0469(2003)060<0287:TELADT>2.0.CO;2,
2003. 3. Andrews, A. E., Boering, K. A., Daube, B. C., Wofsy, S. C., Hintsa, E. J.,
Weinstock, E. M., and Bui, T. P.: Empirical age spectra for the lower
tropical stratosphere from in situ observations of CO2: Implications
for stratospheric transport, J. Geophys. Res., 104, 26581–26595,
https://doi.org/10.1029/1999JD900150, 1999. 4. Appenzeller, C., Holton, J. R., and Rosenlof, K. H.: Seasonal variation of
mass transport across the tropopause, J. Geophys. Res., 101, 15071–15078,
https://doi.org/10.1029/96JD00821, 1996. 5. Austin, J. and Li, F.: On the relationship between the strength of the
Brewer-Dobson circulation and the age of stratospheric air, Geophys. Res.
Lett., 33, L17807, https://doi.org/10.1029/2006GL026867, 2006.
Cited by
11 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献
|
|