Evaluating Shallow Convection Parameterization Assumptions With a qt–w Quadrant Analysis
Abstract Uncertainties associated with the response of shallow clouds to global warming remain a great challenge for climate projection. Due to the small size of these clouds, parameterizations are required to represent them in both current‐ and next‐generation climate models. We present a quantitat...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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American Geophysical Union (AGU)
2023-08-01
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| Series: | Journal of Advances in Modeling Earth Systems |
| Subjects: | |
| Online Access: | https://doi.org/10.1029/2022MS003526 |
| _version_ | 1827363206304104448 |
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| author | Heng Xiao Mikhail Ovchinnikov Larry K. Berg Johannes Mülmenstädt |
| author_facet | Heng Xiao Mikhail Ovchinnikov Larry K. Berg Johannes Mülmenstädt |
| author_sort | Heng Xiao |
| collection | DOAJ |
| description | Abstract Uncertainties associated with the response of shallow clouds to global warming remain a great challenge for climate projection. Due to the small size of these clouds, parameterizations are required to represent them in both current‐ and next‐generation climate models. We present a quantitative evaluation of several important assumptions used in both mass‐flux and Assumed‐PDF Higher‐Order Closure parameterizations of shallow convection. We use large‐eddy simulations (LESs) of four different shallow convection regimes as benchmarks and apply a qt (total moisture)–w (vertical velocity) quadrant analysis technique to identify the “coherent structures” of moist and dry up/down‐drafts. The statistics of these coherent structures and the environment are then used to evaluate commonly used assumptions in mass‐flux parameterizations related to (a) the convective downdrafts and (b) the subplume variability of convective updrafts. For quantitative evaluation of the PDF closure used in AP‐HOCs, we perform offline calculations with the PDF closure used in the Cloud Layers Unified By Bi‐normals and the Simplified Higher‐Order Closure schemes by supplying the closure with statistical quantities directly calculated from the LESs. Then, the impact of parameterization assumptions embedded in the PDF closure in the same two categories is analyzed and understood through comparisons of the output from the closure with the statistics of the moist and dry up/down‐drafts from the LESs. |
| first_indexed | 2024-03-08T07:43:43Z |
| format | Article |
| id | doaj.art-280f121df0d9468988b3c987da39d722 |
| institution | Directory Open Access Journal |
| issn | 1942-2466 |
| language | English |
| last_indexed | 2024-03-08T07:43:43Z |
| publishDate | 2023-08-01 |
| publisher | American Geophysical Union (AGU) |
| record_format | Article |
| series | Journal of Advances in Modeling Earth Systems |
| spelling | doaj.art-280f121df0d9468988b3c987da39d7222024-02-02T16:41:18ZengAmerican Geophysical Union (AGU)Journal of Advances in Modeling Earth Systems1942-24662023-08-01158n/an/a10.1029/2022MS003526Evaluating Shallow Convection Parameterization Assumptions With a qt–w Quadrant AnalysisHeng Xiao0Mikhail Ovchinnikov1Larry K. Berg2Johannes Mülmenstädt3Pacific Northwest National Laboratory Richland WA USAPacific Northwest National Laboratory Richland WA USAPacific Northwest National Laboratory Richland WA USAPacific Northwest National Laboratory Richland WA USAAbstract Uncertainties associated with the response of shallow clouds to global warming remain a great challenge for climate projection. Due to the small size of these clouds, parameterizations are required to represent them in both current‐ and next‐generation climate models. We present a quantitative evaluation of several important assumptions used in both mass‐flux and Assumed‐PDF Higher‐Order Closure parameterizations of shallow convection. We use large‐eddy simulations (LESs) of four different shallow convection regimes as benchmarks and apply a qt (total moisture)–w (vertical velocity) quadrant analysis technique to identify the “coherent structures” of moist and dry up/down‐drafts. The statistics of these coherent structures and the environment are then used to evaluate commonly used assumptions in mass‐flux parameterizations related to (a) the convective downdrafts and (b) the subplume variability of convective updrafts. For quantitative evaluation of the PDF closure used in AP‐HOCs, we perform offline calculations with the PDF closure used in the Cloud Layers Unified By Bi‐normals and the Simplified Higher‐Order Closure schemes by supplying the closure with statistical quantities directly calculated from the LESs. Then, the impact of parameterization assumptions embedded in the PDF closure in the same two categories is analyzed and understood through comparisons of the output from the closure with the statistics of the moist and dry up/down‐drafts from the LESs.https://doi.org/10.1029/2022MS003526shallow convectionparameterizationdowndraftssubplume variabilityquadrant analysis |
| spellingShingle | Heng Xiao Mikhail Ovchinnikov Larry K. Berg Johannes Mülmenstädt Evaluating Shallow Convection Parameterization Assumptions With a qt–w Quadrant Analysis Journal of Advances in Modeling Earth Systems shallow convection parameterization downdrafts subplume variability quadrant analysis |
| title | Evaluating Shallow Convection Parameterization Assumptions With a qt–w Quadrant Analysis |
| title_full | Evaluating Shallow Convection Parameterization Assumptions With a qt–w Quadrant Analysis |
| title_fullStr | Evaluating Shallow Convection Parameterization Assumptions With a qt–w Quadrant Analysis |
| title_full_unstemmed | Evaluating Shallow Convection Parameterization Assumptions With a qt–w Quadrant Analysis |
| title_short | Evaluating Shallow Convection Parameterization Assumptions With a qt–w Quadrant Analysis |
| title_sort | evaluating shallow convection parameterization assumptions with a qt w quadrant analysis |
| topic | shallow convection parameterization downdrafts subplume variability quadrant analysis |
| url | https://doi.org/10.1029/2022MS003526 |
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