Examination of Aerosol Indirect Effects during Cirrus Cloud Evolution
- 1Department of Meteorology and Climate Science, San Jose State University, San Jose, 95192, USA
- acurrent affiliation: Department of Atmospheric Science, Colorado State University, Fort Collins, 80521, USA
- 1Department of Meteorology and Climate Science, San Jose State University, San Jose, 95192, USA
- acurrent affiliation: Department of Atmospheric Science, Colorado State University, Fort Collins, 80521, USA
Abstract. Aerosols affect cirrus formation and evolution, yet quantification of these effects remain difficult based on in-situ observations due to the complexity of nucleation mechanisms and large variabilities in ice microphysical properties. This work employed a method to distinguish five evolution phases of cirrus clouds based on in-situ aircraft-based observations from seven U.S. National Science Foundation (NSF) and five NASA flight campaigns. Both homogeneous and heterogeneous nucleation were captured in the 1-Hz aircraft observations, inferred from the distributions of relative humidity in the nucleation phase. Using linear regressions to quantify the correlations between cirrus microphysical properties and aerosol number concentrations, we found that ice water content (IWC) and ice crystal number concentration (Ni) show strong positive correlations with larger aerosols (> 500 nm) in the nucleation phase, indicating strong contributions of heterogeneous nucleation when ice crystals first start to nucleate. For the later growth phase, IWC and Ni show similar positive correlations with larger and smaller (i.e., > 100 nm) aerosols, possibly due to fewer remaining ice nucleating particles in the later growth phase that allows more homogeneous nucleation to occur. Both 200-m and 100-km observations were compared with the nudged simulations from the National Center for Atmospheric Research (NCAR) Community Atmosphere Model version 6 (CAM6). Simulated aerosol indirect effects are weaker than the observations for both larger and smaller aerosols. Observations show stronger aerosol indirect effects (i.e., positive correlations between IWC, Ni and Na) in the Southern Hemisphere (SH) compared with the Northern Hemisphere (NH), while the simulations show negative correlations in the SH. The simulations underestimate IWC by a factor of 3 – 30 in the early/later growth phase, indicating that the low bias of simulated IWC was due to insufficient ice particle growth. Such hypothesis is consistent with the model biases of lower frequencies of ice supersaturation and lower vertical velocity standard deviation in the early/later growth phases. Overall, these findings show that aircraft observations can capture the competitions between heterogeneous and homogeneous nucleation, and their contributions vary as cirrus clouds evolve. Future model development is also recommended to evaluate and improve the representation of water vapor and vertical velocity on the sub-grid scale to resolve the insufficient ice particle growth.
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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.
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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.
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Journal article(s) based on this preprint
Flor Vanessa Maciel et al.
Interactive discussion
Status: closed
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RC1: 'Comment on acp-2022-519', Anonymous Referee #1, 11 Sep 2022
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-519/acp-2022-519-RC1-supplement.pdf
- RC2: 'Comment on acp-2022-519', Anonymous Referee #2, 01 Oct 2022
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AC1: 'Comment on acp-2022-519', Minghui Diao, 22 Dec 2022
We thank the reviewers for their helpful comments. Attached is our response to individual comments from two reviewers, as well as the respective changes to the manuscript.
Please note, per the new policy of ACP manuscript review process, we are not allowed to upload the revised manuscript at this stage of responding to reviewers. Only later when encouraged, we can upload the revised manuscript. We try to be as clear as possible in our response by quoting all the text changes and new figures in the revised manuscript.
Peer review completion
Interactive discussion
Status: closed
-
RC1: 'Comment on acp-2022-519', Anonymous Referee #1, 11 Sep 2022
The comment was uploaded in the form of a supplement: https://acp.copernicus.org/preprints/acp-2022-519/acp-2022-519-RC1-supplement.pdf
- RC2: 'Comment on acp-2022-519', Anonymous Referee #2, 01 Oct 2022
-
AC1: 'Comment on acp-2022-519', Minghui Diao, 22 Dec 2022
We thank the reviewers for their helpful comments. Attached is our response to individual comments from two reviewers, as well as the respective changes to the manuscript.
Please note, per the new policy of ACP manuscript review process, we are not allowed to upload the revised manuscript at this stage of responding to reviewers. Only later when encouraged, we can upload the revised manuscript. We try to be as clear as possible in our response by quoting all the text changes and new figures in the revised manuscript.
Peer review completion
Journal article(s) based on this preprint
Flor Vanessa Maciel et al.
Flor Vanessa Maciel et al.
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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.
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