Sensitivity analysis of the potential impact of discrepancies in stratosphere–troposphere exchange on inferred sources and sinks of CO<sub>2</sub>
The upper troposphere and lower stratosphere (UTLS) represents a transition region between the more dynamically active troposphere and more stably stratified stratosphere. The region is characterized by strong gradients in the distribution of long-lived tracers, whose representation in models is sen...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2015-10-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/15/11773/2015/acp-15-11773-2015.pdf |
| _version_ | 1819145702264012800 |
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| author | F. Deng D. B. A. Jones T. W. Walker M. Keller K. W. Bowman D. K. Henze R. Nassar E. A. Kort S. C. Wofsy K. A. Walker A. E. Bourassa D. A. Degenstein |
| author_facet | F. Deng D. B. A. Jones T. W. Walker M. Keller K. W. Bowman D. K. Henze R. Nassar E. A. Kort S. C. Wofsy K. A. Walker A. E. Bourassa D. A. Degenstein |
| author_sort | F. Deng |
| collection | DOAJ |
| description | The upper troposphere and lower stratosphere (UTLS)
represents a transition region between the more dynamically active
troposphere and more stably stratified stratosphere. The region is
characterized by strong gradients in the distribution of long-lived tracers,
whose representation in models is sensitive to discrepancies in transport. We
evaluate the GEOS-Chem model in the UTLS using carbon dioxide (CO<sub>2</sub>) and
ozone (O<sub>3</sub>) observations from the HIAPER (The High-Performance
Instrumented Airborne Platform for Environmental Research) Pole-to-Pole
Observations (HIPPO) campaign in March 2010. GEOS-Chem CO<sub>2</sub>/O<sub>3</sub>
correlation suggests that there is a discrepancy in mixing across the
tropopause in the model, which results in an overestimate of CO<sub>2</sub> and an
underestimate of O<sub>3</sub> in the Arctic lower stratosphere. We assimilate
stratospheric O<sub>3</sub> data from the Optical Spectrograph and InfraRed Imager
System (OSIRIS) and use the assimilated O<sub>3</sub> fields together with the
HIPPO CO<sub>2</sub>/O<sub>3</sub> correlations to obtain an adjustment to the modeled
CO<sub>2</sub> profile in the Arctic UTLS (primarily between the 320 and 360 K
isentropic surfaces). The HIPPO-derived adjustment corresponds to a sink of
0.60 Pg C for March–August 2010 in the Arctic. Imposing this adjustment
results in a reduction in the CO<sub>2</sub> sinks inferred from GOSAT observations
for temperate North America, Europe, and tropical Asia of 19, 13, and
49 %, respectively. Conversely, the inversion increased the source of
CO<sub>2</sub> from tropical South America by 23 %. We find that the model also
underestimates CO<sub>2</sub> in the upper tropical and subtropical troposphere.
Correcting for the underestimate in the model relative to HIPPO in the
tropical upper troposphere leads to a reduction in the source from tropical
South America by 77 %, and produces an estimated sink for tropical Asia
that is only 19 % larger than the standard inversion (without the imposed
source and sink). Globally, the inversion with the Arctic and tropical
adjustment produces a sink of −6.64 Pg C, which is consistent with the
estimate of −6.65 Pg C in the standard inversion. However, the standard
inversion produces a stronger northern land sink by 0.98 Pg C to account
for the CO<sub>2</sub> overestimate in the high-latitude UTLS, suggesting that this
UTLS discrepancy can impact the latitudinal distribution of the inferred
sources and sinks. We find that doubling the model resolution from
4° × 5° to 2° × 2.5°
enhances the CO<sub>2</sub> vertical gradient in the high-latitude UTLS, and
reduces the overestimate in CO<sub>2</sub> in the extratropical lower stratosphere.
Our results illustrate that discrepancies in the CO<sub>2</sub> distribution in the
UTLS can affect CO<sub>2</sub> flux inversions and suggest the need for more
careful evaluation of model errors in the UTLS. |
| first_indexed | 2024-12-22T13:02:14Z |
| format | Article |
| id | doaj.art-50567fc171654d5095b63471ac22aa32 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-22T13:02:14Z |
| publishDate | 2015-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-50567fc171654d5095b63471ac22aa322022-12-21T18:24:58ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242015-10-011520117731178810.5194/acp-15-11773-2015Sensitivity analysis of the potential impact of discrepancies in stratosphere–troposphere exchange on inferred sources and sinks of CO<sub>2</sub>F. Deng0D. B. A. Jones1T. W. Walker2M. Keller3K. W. Bowman4D. K. Henze5R. Nassar6E. A. Kort7S. C. Wofsy8K. A. Walker9A. E. Bourassa10D. A. Degenstein11Department of Physics, University of Toronto, Toronto, ON, CanadaDepartment of Physics, University of Toronto, Toronto, ON, CanadaDepartment of Physics, University of Toronto, Toronto, ON, CanadaDepartment of Physics, University of Toronto, Toronto, ON, CanadaJoint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles, CA, USADepartment of Mechanical Engineering, University of Colorado, Boulder, CO, USAClimate Research Division, Environment Canada, Toronto, ON, CanadaDepartment of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, MI, USAHarvard University, Cambridge, MA, USADepartment of Physics, University of Toronto, Toronto, ON, CanadaInstitute of Space and Atmospheric Studies, University of Saskatchewan, Saskatoon, CanadaInstitute of Space and Atmospheric Studies, University of Saskatchewan, Saskatoon, CanadaThe upper troposphere and lower stratosphere (UTLS) represents a transition region between the more dynamically active troposphere and more stably stratified stratosphere. The region is characterized by strong gradients in the distribution of long-lived tracers, whose representation in models is sensitive to discrepancies in transport. We evaluate the GEOS-Chem model in the UTLS using carbon dioxide (CO<sub>2</sub>) and ozone (O<sub>3</sub>) observations from the HIAPER (The High-Performance Instrumented Airborne Platform for Environmental Research) Pole-to-Pole Observations (HIPPO) campaign in March 2010. GEOS-Chem CO<sub>2</sub>/O<sub>3</sub> correlation suggests that there is a discrepancy in mixing across the tropopause in the model, which results in an overestimate of CO<sub>2</sub> and an underestimate of O<sub>3</sub> in the Arctic lower stratosphere. We assimilate stratospheric O<sub>3</sub> data from the Optical Spectrograph and InfraRed Imager System (OSIRIS) and use the assimilated O<sub>3</sub> fields together with the HIPPO CO<sub>2</sub>/O<sub>3</sub> correlations to obtain an adjustment to the modeled CO<sub>2</sub> profile in the Arctic UTLS (primarily between the 320 and 360 K isentropic surfaces). The HIPPO-derived adjustment corresponds to a sink of 0.60 Pg C for March–August 2010 in the Arctic. Imposing this adjustment results in a reduction in the CO<sub>2</sub> sinks inferred from GOSAT observations for temperate North America, Europe, and tropical Asia of 19, 13, and 49 %, respectively. Conversely, the inversion increased the source of CO<sub>2</sub> from tropical South America by 23 %. We find that the model also underestimates CO<sub>2</sub> in the upper tropical and subtropical troposphere. Correcting for the underestimate in the model relative to HIPPO in the tropical upper troposphere leads to a reduction in the source from tropical South America by 77 %, and produces an estimated sink for tropical Asia that is only 19 % larger than the standard inversion (without the imposed source and sink). Globally, the inversion with the Arctic and tropical adjustment produces a sink of −6.64 Pg C, which is consistent with the estimate of −6.65 Pg C in the standard inversion. However, the standard inversion produces a stronger northern land sink by 0.98 Pg C to account for the CO<sub>2</sub> overestimate in the high-latitude UTLS, suggesting that this UTLS discrepancy can impact the latitudinal distribution of the inferred sources and sinks. We find that doubling the model resolution from 4° × 5° to 2° × 2.5° enhances the CO<sub>2</sub> vertical gradient in the high-latitude UTLS, and reduces the overestimate in CO<sub>2</sub> in the extratropical lower stratosphere. Our results illustrate that discrepancies in the CO<sub>2</sub> distribution in the UTLS can affect CO<sub>2</sub> flux inversions and suggest the need for more careful evaluation of model errors in the UTLS.http://www.atmos-chem-phys.net/15/11773/2015/acp-15-11773-2015.pdf |
| spellingShingle | F. Deng D. B. A. Jones T. W. Walker M. Keller K. W. Bowman D. K. Henze R. Nassar E. A. Kort S. C. Wofsy K. A. Walker A. E. Bourassa D. A. Degenstein Sensitivity analysis of the potential impact of discrepancies in stratosphere–troposphere exchange on inferred sources and sinks of CO<sub>2</sub> Atmospheric Chemistry and Physics |
| title | Sensitivity analysis of the potential impact of discrepancies in stratosphere–troposphere exchange on inferred sources and sinks of CO<sub>2</sub> |
| title_full | Sensitivity analysis of the potential impact of discrepancies in stratosphere–troposphere exchange on inferred sources and sinks of CO<sub>2</sub> |
| title_fullStr | Sensitivity analysis of the potential impact of discrepancies in stratosphere–troposphere exchange on inferred sources and sinks of CO<sub>2</sub> |
| title_full_unstemmed | Sensitivity analysis of the potential impact of discrepancies in stratosphere–troposphere exchange on inferred sources and sinks of CO<sub>2</sub> |
| title_short | Sensitivity analysis of the potential impact of discrepancies in stratosphere–troposphere exchange on inferred sources and sinks of CO<sub>2</sub> |
| title_sort | sensitivity analysis of the potential impact of discrepancies in stratosphere troposphere exchange on inferred sources and sinks of co sub 2 sub |
| url | http://www.atmos-chem-phys.net/15/11773/2015/acp-15-11773-2015.pdf |
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