The Impacts of Rotational Mixing on the Precipitation Simulated by a Convection Permitting Model
Abstract With increased availability of computational resources, regional and global scale convection‐permitting model (CPM, Δx ∼ 1–10 km) simulations are becoming more common. CPMs have improved accuracy in their representation of deep convection and mesoscale convective systems (MCSs) compared to...
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| Format: | Article |
| Language: | English |
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American Geophysical Union (AGU)
2025-05-01
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| Series: | Journal of Advances in Modeling Earth Systems |
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| Online Access: | https://doi.org/10.1029/2024MS004524 |
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| author | Samson Hagos Zhe Feng Adam C. Varble Sheng‐Lun Tai Jingyi Chen |
| author_facet | Samson Hagos Zhe Feng Adam C. Varble Sheng‐Lun Tai Jingyi Chen |
| author_sort | Samson Hagos |
| collection | DOAJ |
| description | Abstract With increased availability of computational resources, regional and global scale convection‐permitting model (CPM, Δx ∼ 1–10 km) simulations are becoming more common. CPMs have improved accuracy in their representation of deep convection and mesoscale convective systems (MCSs) compared to coarser resolution models. However, CPMs still exhibit convective cloud and precipitation biases relative to observations, notably a lesser frequency of light precipitation rates and greater frequency of heavy precipitation rates. In this work we hypothesize that these CPM biases are related to under‐resolved mixing between convective updrafts and their surrounding environment. To test this hypothesis, we introduce a parameterization to the Weather Research and Forecasting model (WRF) that adds a small angular rotation of the grid‐scale flow about the axis perpendicular to the plane of convective drafts. This rotated flow is then allowed to alter advection of moisture and hydrometeors. The effects of such mixing on precipitation characteristics are evaluated in month‐long 4‐km grid spacing simulations over the Amazon. The enhanced mixing transports moisture and condensate from convective cores to other areas including downdrafts. This increases the frequency of low‐precipitable water and light precipitation. It also decreases the frequency of intense precipitation from isolated deep convection and MCSs, increases cloud top temperatures, reduces radar echo‐top heights, and increases overall precipitation by altering the relationship of precipitation with precipitable water, in better agreement with observations. The results suggest when optimized using multiple observations, such an approach may provide a path toward more accurate representation of convection and precipitation statistics in convection‐permitting simulations. |
| format | Article |
| id | doaj-art-a229d850d3a74b23b4b5024d835c1f9e |
| institution | Kabale University |
| issn | 1942-2466 |
| language | English |
| publishDate | 2025-05-01 |
| publisher | American Geophysical Union (AGU) |
| record_format | Article |
| series | Journal of Advances in Modeling Earth Systems |
| spelling | doaj-art-a229d850d3a74b23b4b5024d835c1f9e2025-08-20T03:47:57ZengAmerican Geophysical Union (AGU)Journal of Advances in Modeling Earth Systems1942-24662025-05-01175n/an/a10.1029/2024MS004524The Impacts of Rotational Mixing on the Precipitation Simulated by a Convection Permitting ModelSamson Hagos0Zhe Feng1Adam C. Varble2Sheng‐Lun Tai3Jingyi Chen4Pacific Northwest National Laboratory Richland WA USAPacific Northwest National Laboratory Richland WA USAPacific Northwest National Laboratory Richland WA USAPacific Northwest National Laboratory Richland WA USAPacific Northwest National Laboratory Richland WA USAAbstract With increased availability of computational resources, regional and global scale convection‐permitting model (CPM, Δx ∼ 1–10 km) simulations are becoming more common. CPMs have improved accuracy in their representation of deep convection and mesoscale convective systems (MCSs) compared to coarser resolution models. However, CPMs still exhibit convective cloud and precipitation biases relative to observations, notably a lesser frequency of light precipitation rates and greater frequency of heavy precipitation rates. In this work we hypothesize that these CPM biases are related to under‐resolved mixing between convective updrafts and their surrounding environment. To test this hypothesis, we introduce a parameterization to the Weather Research and Forecasting model (WRF) that adds a small angular rotation of the grid‐scale flow about the axis perpendicular to the plane of convective drafts. This rotated flow is then allowed to alter advection of moisture and hydrometeors. The effects of such mixing on precipitation characteristics are evaluated in month‐long 4‐km grid spacing simulations over the Amazon. The enhanced mixing transports moisture and condensate from convective cores to other areas including downdrafts. This increases the frequency of low‐precipitable water and light precipitation. It also decreases the frequency of intense precipitation from isolated deep convection and MCSs, increases cloud top temperatures, reduces radar echo‐top heights, and increases overall precipitation by altering the relationship of precipitation with precipitable water, in better agreement with observations. The results suggest when optimized using multiple observations, such an approach may provide a path toward more accurate representation of convection and precipitation statistics in convection‐permitting simulations.https://doi.org/10.1029/2024MS004524convectionCPMamazonWRFprecipitationclouds |
| spellingShingle | Samson Hagos Zhe Feng Adam C. Varble Sheng‐Lun Tai Jingyi Chen The Impacts of Rotational Mixing on the Precipitation Simulated by a Convection Permitting Model Journal of Advances in Modeling Earth Systems convection CPM amazon WRF precipitation clouds |
| title | The Impacts of Rotational Mixing on the Precipitation Simulated by a Convection Permitting Model |
| title_full | The Impacts of Rotational Mixing on the Precipitation Simulated by a Convection Permitting Model |
| title_fullStr | The Impacts of Rotational Mixing on the Precipitation Simulated by a Convection Permitting Model |
| title_full_unstemmed | The Impacts of Rotational Mixing on the Precipitation Simulated by a Convection Permitting Model |
| title_short | The Impacts of Rotational Mixing on the Precipitation Simulated by a Convection Permitting Model |
| title_sort | impacts of rotational mixing on the precipitation simulated by a convection permitting model |
| topic | convection CPM amazon WRF precipitation clouds |
| url | https://doi.org/10.1029/2024MS004524 |
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