Further improvement and evaluation of nudging in the E3SM Atmosphere Model version 1 (EAMv1): simulations of the mean climate, weather events, and anthropogenic aerosol effects
<p>A previous study on the use of nudging in E3SM Atmosphere Model version 1 (EAMv1) had an unresolved issue; i.e., a simulation nudged to EAMv1's own meteorology showed non-negligible deviations from the free-running baseline simulation over some of the subtropical marine stratocumulus a...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2022-09-01
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| Series: | Geoscientific Model Development |
| Online Access: | https://gmd.copernicus.org/articles/15/6787/2022/gmd-15-6787-2022.pdf |
| _version_ | 1798036904435777536 |
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| author | S. Zhang K. Zhang H. Wan J. Sun J. Sun |
| author_facet | S. Zhang K. Zhang H. Wan J. Sun J. Sun |
| author_sort | S. Zhang |
| collection | DOAJ |
| description | <p>A previous study on the use of nudging in E3SM Atmosphere Model version 1 (EAMv1) had an unresolved issue; i.e., a simulation nudged to EAMv1's own meteorology showed non-negligible deviations from the free-running baseline simulation
over some of the subtropical marine stratocumulus
and trade cumulus regions. Here, we demonstrate that
the deviations can be substantially reduced by
(1) changing where the nudging tendency is calculated in the time integration loop of
a nudged EAM simulation so as to improve consistency with the free-running baseline and
(2) increasing the frequency of the constraining data so as to better capture strong sub-diurnal variations.</p>
<p>The fact that modification (2) improves the climate representativeness of the nudged simulations has motivated us to investigate
whether the use of newer reanalysis products with higher data frequency
can help improve nudged hindcast simulations by better capturing the observed weather events.
To answer this question, we present simulations conducted
at EAMv1's standard horizontal resolution (approximately 1<span class="inline-formula"><sup>∘</sup></span>)
with nudging towards 6-hourly ERA-Interim reanalysis or
6-hourly, 3-hourly, or hourly ERA5 reanalysis.
These simulations are evaluated against
the climatology of free-running EAMv1 simulations as well as
reanalyses, satellite retrievals,
and in situ measurements from the Atmospheric Radiation Measurement user facility. For the 1<span class="inline-formula"><sup>∘</sup></span> EAMv1 simulations, we recommend using the relocated
nudging tendency calculation and the ERA5 reanalysis at 3-hourly or higher frequency.</p>
<p>Simulations used for estimating the anthropogenic aerosol effects often
use nudging to help discern signal from noise.
The sensitivity of such estimates to the configuration of nudging is investigated
in EAMv1, again using the standard 1<span class="inline-formula"><sup>∘</sup></span> horizontal resolution.
We find that, when estimating the global mean effects, the frequency of constraining data has relatively small impacts,
while the choice of nudged variables can change the results substantially.
The nudging of air temperature (in addition to horizontal winds) has two non-negligible effects. First, when the constraining data come from reanalysis, the nudging-induced mean bias correction can cause significant changes in the simulated clouds
and hence substantially different estimates of the aerosol effects.
The impact of the mean bias correction on ice cloud formation has been noted in previous studies and is also seen in EAMv1.
For applications like ours, where the preferred configurations of nudging are those capable of providing results consistent with the multi-year free-running simulations, the consequence of the mean bias correction is undesirable.
The second important impact of temperature nudging is a significant suppression of adjustments to aerosol forcing, which also causes changes in the estimated aerosol effects. This effect can be seen in simulations nudged to either reanalysis or EAM's own meteorology.
These results suggest that nudging horizontal winds but not temperature is a better choice for estimating the anthropogenic aerosol
effects.</p> |
| first_indexed | 2024-04-11T21:19:22Z |
| format | Article |
| id | doaj.art-4f865169664b4f04af41c7d5a4188589 |
| institution | Directory Open Access Journal |
| issn | 1991-959X 1991-9603 |
| language | English |
| last_indexed | 2024-04-11T21:19:22Z |
| publishDate | 2022-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Geoscientific Model Development |
| spelling | doaj.art-4f865169664b4f04af41c7d5a41885892022-12-22T04:02:42ZengCopernicus PublicationsGeoscientific Model Development1991-959X1991-96032022-09-01156787681610.5194/gmd-15-6787-2022Further improvement and evaluation of nudging in the E3SM Atmosphere Model version 1 (EAMv1): simulations of the mean climate, weather events, and anthropogenic aerosol effectsS. Zhang0K. Zhang1H. Wan2J. Sun3J. Sun4Pacific Northwest National Laboratory, Richland, Washington, USAPacific Northwest National Laboratory, Richland, Washington, USAPacific Northwest National Laboratory, Richland, Washington, USAPacific Northwest National Laboratory, Richland, Washington, USANational Center for Atmospheric Research, Boulder, Colorado, USA <p>A previous study on the use of nudging in E3SM Atmosphere Model version 1 (EAMv1) had an unresolved issue; i.e., a simulation nudged to EAMv1's own meteorology showed non-negligible deviations from the free-running baseline simulation over some of the subtropical marine stratocumulus and trade cumulus regions. Here, we demonstrate that the deviations can be substantially reduced by (1) changing where the nudging tendency is calculated in the time integration loop of a nudged EAM simulation so as to improve consistency with the free-running baseline and (2) increasing the frequency of the constraining data so as to better capture strong sub-diurnal variations.</p> <p>The fact that modification (2) improves the climate representativeness of the nudged simulations has motivated us to investigate whether the use of newer reanalysis products with higher data frequency can help improve nudged hindcast simulations by better capturing the observed weather events. To answer this question, we present simulations conducted at EAMv1's standard horizontal resolution (approximately 1<span class="inline-formula"><sup>∘</sup></span>) with nudging towards 6-hourly ERA-Interim reanalysis or 6-hourly, 3-hourly, or hourly ERA5 reanalysis. These simulations are evaluated against the climatology of free-running EAMv1 simulations as well as reanalyses, satellite retrievals, and in situ measurements from the Atmospheric Radiation Measurement user facility. For the 1<span class="inline-formula"><sup>∘</sup></span> EAMv1 simulations, we recommend using the relocated nudging tendency calculation and the ERA5 reanalysis at 3-hourly or higher frequency.</p> <p>Simulations used for estimating the anthropogenic aerosol effects often use nudging to help discern signal from noise. The sensitivity of such estimates to the configuration of nudging is investigated in EAMv1, again using the standard 1<span class="inline-formula"><sup>∘</sup></span> horizontal resolution. We find that, when estimating the global mean effects, the frequency of constraining data has relatively small impacts, while the choice of nudged variables can change the results substantially. The nudging of air temperature (in addition to horizontal winds) has two non-negligible effects. First, when the constraining data come from reanalysis, the nudging-induced mean bias correction can cause significant changes in the simulated clouds and hence substantially different estimates of the aerosol effects. The impact of the mean bias correction on ice cloud formation has been noted in previous studies and is also seen in EAMv1. For applications like ours, where the preferred configurations of nudging are those capable of providing results consistent with the multi-year free-running simulations, the consequence of the mean bias correction is undesirable. The second important impact of temperature nudging is a significant suppression of adjustments to aerosol forcing, which also causes changes in the estimated aerosol effects. This effect can be seen in simulations nudged to either reanalysis or EAM's own meteorology. These results suggest that nudging horizontal winds but not temperature is a better choice for estimating the anthropogenic aerosol effects.</p>https://gmd.copernicus.org/articles/15/6787/2022/gmd-15-6787-2022.pdf |
| spellingShingle | S. Zhang K. Zhang H. Wan J. Sun J. Sun Further improvement and evaluation of nudging in the E3SM Atmosphere Model version 1 (EAMv1): simulations of the mean climate, weather events, and anthropogenic aerosol effects Geoscientific Model Development |
| title | Further improvement and evaluation of nudging in the E3SM Atmosphere Model version 1 (EAMv1): simulations of the mean climate, weather events, and anthropogenic aerosol effects |
| title_full | Further improvement and evaluation of nudging in the E3SM Atmosphere Model version 1 (EAMv1): simulations of the mean climate, weather events, and anthropogenic aerosol effects |
| title_fullStr | Further improvement and evaluation of nudging in the E3SM Atmosphere Model version 1 (EAMv1): simulations of the mean climate, weather events, and anthropogenic aerosol effects |
| title_full_unstemmed | Further improvement and evaluation of nudging in the E3SM Atmosphere Model version 1 (EAMv1): simulations of the mean climate, weather events, and anthropogenic aerosol effects |
| title_short | Further improvement and evaluation of nudging in the E3SM Atmosphere Model version 1 (EAMv1): simulations of the mean climate, weather events, and anthropogenic aerosol effects |
| title_sort | further improvement and evaluation of nudging in the e3sm atmosphere model version 1 eamv1 simulations of the mean climate weather events and anthropogenic aerosol effects |
| url | https://gmd.copernicus.org/articles/15/6787/2022/gmd-15-6787-2022.pdf |
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