the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 13 May 2022
Interactive Biogenic Emissions and Drought Stress Effects on Atmospheric Composition in NASA GISS ModelE
Abstract. Drought is a hydroclimatic extreme that causes perturbations to the terrestrial biosphere, and acts as a stressor on vegetation, affecting emissions patterns. During severe drought, isoprene emissions are reduced. In this paper, we focus on capturing this reduction signal by implementing a new percentile isoprene drought stress (yd) algorithm in NASA GISS ModelE based on the MEGAN3 (Model of Emissions of Gases and Aerosols from Nature Version 3) approach as a function of a photosynthetic parameter (Vc,max) and water stress (β) . Four global transient simulations from 2003–2013 are used to demonstrate the effect without yd (Default_ModelE) and with online yd (DroughtStress_ModelE). DroughtStress_ModelE is evaluated against the observed isoprene measurements at the Missouri Ozarks Ameriflux (MOFLUX) site during the 2012 severe drought where improvements in correlation coefficient indicate it is a suitable drought stress parameterization to capture the reduction signal during severe drought. The application of yd globally leads to a decadal average reduction of ~2.7 % which is equivalent to ~14.6 Tg yr-1 of isoprene. The changes have larger impacts in regions such as the Southeast U.S.. DroughtStress_ModelE is validated using satellite ΩHCHO column from the Ozone Monitoring Instrument (OMI) and surface O3 observations across regions of the U.S. to examine the effect of drought on atmospheric composition. It was found the inclusion of isoprene drought stress reduced the overestimation of ΩHCHO in Default_ModelE during the 2007 and 2011 southeastern U.S. droughts and lead to improvements in simulated O3 during drought periods. We conclude that isoprene drought stress should be tuned on a model-by-model basis, because the variables used in the parameterization responses are relative to the land surface model hydrology scheme (LSM) and the effects of yd application could be larger than seen here due to ModelE not having large biases of isoprene during severe drought.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
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Supplement
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Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2022-292', Anonymous Referee #1, 16 Jun 2022
Interactive biogenic emissions and drought stress effects on atmospheric composition in NASA GISS ModelE
By Klovenski et al.
The research in this paper implements the updated drought stress parameterisation of MEGAN3 into the NASA GISS ModelE. The new model is used to improve isoprene emission predictions at the Missouri Ozarks site in the US, which experienced a severe drought in 2012. Isoprene was measured during this severe drought period making these observations crucial to the study of impacts on BVOC emissions caused by drought. Applying the parameterisation globally also led to emission reductions of the order ~3%, and improved the model comparison with satellite HCHO measurements over the US. The paper concludes by suggesting the variables required by the drought parameterisations in MEGAN3 are quite model specific, such that they should be tuned on a model by model basis.
I think the paper is well written (particularly the discussion and conclusions section) and should be published. I have a few comments.
Line 74. The CO2 parameterisation serves to inhibit isoprene emissions (Heald et al., 2009)?
Line 80-82. Very confusing sentence. ‘During drought, increases in SOA and O3 are to be expected’. Why? What aspect of drought would cause this? (In my mind, less isoprene would mean less ozone?) Needs explanation. Then the second part of the sentence suggests isoprene reductions will decrease the magnitude of the increase.
Line 199. 1x10-9/3600 looks like it also contains the conversion from the emission factor units of ug to kg (rather than just being a timestep conversion).
Line 250 add drought stress ‘parameter’ developed by…..
Line 427 define USDM
Figure 1. there looks like a gap in the observations towards the end of the timeseries (mid august). Consider whether these time periods should be removed?
Lines 511-520. You talk about the general over/under estimation of the model but what about the shape of the fit details? Does the model hit or miss the daily peaks? What could be the reason for the missed peaks?
Section 3.2. MOFLUX_DroughtStress is not one of the models shown in the fig 1 timeseries, yet promises to be a better fit. I’d like to see it compared with the observations at the MOFLUX site.
Line 585. Soil moisture products ‘resulted in’ isoprene reductions….
Line 657. ’model agreement’ here is a bit strong since the scatter plot shows the data points well spread from the 1:1 line.
Line 669. ’As shown below’. Below where? Underneath this line is a table of global emissions, not details on the south east US.
Line 820. Affect, not ‘effect’
Line 821. Higher mean O3. I need more explanation about what is leading to the higher ozone if the isoprene is reduced.
References
Heald, C. L., Wilkinson, M. J., Monson, R. K., Alo, C. A., Wang, G., and Guenther, A.: Response of isoprene emission to ambient CO2 changes and implications for global budgets, 15, 1127–1140, https://doi.org/10.1111/j.1365-2486.2008.01802.x, 2009.
Citation: https://doi.org/10.5194/egusphere-2022-292-RC1 - AC1: 'Reply on RC1', Elizabeth Klovenski, 13 Aug 2022
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RC2: 'Comment on egusphere-2022-292', Anonymous Referee #2, 19 Jun 2022
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AC2: 'Reply on RC2', Elizabeth Klovenski, 13 Aug 2022
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-292/egusphere-2022-292-AC2-supplement.pdf
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AC2: 'Reply on RC2', Elizabeth Klovenski, 13 Aug 2022
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2022-292', Anonymous Referee #1, 16 Jun 2022
Interactive biogenic emissions and drought stress effects on atmospheric composition in NASA GISS ModelE
By Klovenski et al.
The research in this paper implements the updated drought stress parameterisation of MEGAN3 into the NASA GISS ModelE. The new model is used to improve isoprene emission predictions at the Missouri Ozarks site in the US, which experienced a severe drought in 2012. Isoprene was measured during this severe drought period making these observations crucial to the study of impacts on BVOC emissions caused by drought. Applying the parameterisation globally also led to emission reductions of the order ~3%, and improved the model comparison with satellite HCHO measurements over the US. The paper concludes by suggesting the variables required by the drought parameterisations in MEGAN3 are quite model specific, such that they should be tuned on a model by model basis.
I think the paper is well written (particularly the discussion and conclusions section) and should be published. I have a few comments.
Line 74. The CO2 parameterisation serves to inhibit isoprene emissions (Heald et al., 2009)?
Line 80-82. Very confusing sentence. ‘During drought, increases in SOA and O3 are to be expected’. Why? What aspect of drought would cause this? (In my mind, less isoprene would mean less ozone?) Needs explanation. Then the second part of the sentence suggests isoprene reductions will decrease the magnitude of the increase.
Line 199. 1x10-9/3600 looks like it also contains the conversion from the emission factor units of ug to kg (rather than just being a timestep conversion).
Line 250 add drought stress ‘parameter’ developed by…..
Line 427 define USDM
Figure 1. there looks like a gap in the observations towards the end of the timeseries (mid august). Consider whether these time periods should be removed?
Lines 511-520. You talk about the general over/under estimation of the model but what about the shape of the fit details? Does the model hit or miss the daily peaks? What could be the reason for the missed peaks?
Section 3.2. MOFLUX_DroughtStress is not one of the models shown in the fig 1 timeseries, yet promises to be a better fit. I’d like to see it compared with the observations at the MOFLUX site.
Line 585. Soil moisture products ‘resulted in’ isoprene reductions….
Line 657. ’model agreement’ here is a bit strong since the scatter plot shows the data points well spread from the 1:1 line.
Line 669. ’As shown below’. Below where? Underneath this line is a table of global emissions, not details on the south east US.
Line 820. Affect, not ‘effect’
Line 821. Higher mean O3. I need more explanation about what is leading to the higher ozone if the isoprene is reduced.
References
Heald, C. L., Wilkinson, M. J., Monson, R. K., Alo, C. A., Wang, G., and Guenther, A.: Response of isoprene emission to ambient CO2 changes and implications for global budgets, 15, 1127–1140, https://doi.org/10.1111/j.1365-2486.2008.01802.x, 2009.
Citation: https://doi.org/10.5194/egusphere-2022-292-RC1 - AC1: 'Reply on RC1', Elizabeth Klovenski, 13 Aug 2022
-
RC2: 'Comment on egusphere-2022-292', Anonymous Referee #2, 19 Jun 2022
-
AC2: 'Reply on RC2', Elizabeth Klovenski, 13 Aug 2022
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-292/egusphere-2022-292-AC2-supplement.pdf
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AC2: 'Reply on RC2', Elizabeth Klovenski, 13 Aug 2022
Peer review completion
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Elizabeth Renee Klovenski
Susanne Elizabeth Bauer
Kostas Tsigaridis
Greg Faluvegi
Igor Aleinov
Nancy Y. Kiang
Alex Guenther
Xiaoyan Jiang
Nan Lin
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(4101 KB) - Metadata XML
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Supplement
(1763 KB) - BibTeX
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- Final revised paper