Toward Transparency and Consistency: An Open‐Source Optics Parameterization for Clouds and Precipitation
Abstract In this study, a new open‐source package for cloud and precipitation modeling is introduced. Based on Mie theory and existing ice crystal data sets, the scheme generates optical properties for user‐defined gas bands, particle size distribution, and crystal habits, ensuring continuity across...
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American Geophysical Union (AGU)
2025-03-01
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| Series: | Journal of Advances in Modeling Earth Systems |
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| Online Access: | https://doi.org/10.1029/2024MS004478 |
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| author | Jing Feng Raymond Menzel David Paynter |
| author_facet | Jing Feng Raymond Menzel David Paynter |
| author_sort | Jing Feng |
| collection | DOAJ |
| description | Abstract In this study, a new open‐source package for cloud and precipitation modeling is introduced. Based on Mie theory and existing ice crystal data sets, the scheme generates optical properties for user‐defined gas bands, particle size distribution, and crystal habits, ensuring continuity across wide spectral bands and from small particles (clouds) to large particles (precipitation). Compared with existing schemes in GFDL's AM4‐MG2, it reduces shortwave reflection of liquid clouds at the top of the atmosphere (TOA) by 1.50 Wm−2 and increases that of ice clouds by 1.62 Wm−2, based on offline radiative calculations. Using the new scheme, we find that cloud radiative effects are sensitive to microphysics variables such as particle size and habit, which affect the effective radius. Systematic flux biases may arise if the effective radius is not fully predicted in microphysics due to predefined size and habit distributions. We show that assuming spherical ice crystals underestimates ice‐cloud radiative effects by 3.20 Wm−2 in the longwave TOA and 2.76 Wm−2 in the shortwave TOA. These biases can be addressed by improving the effective radius approximation with a volume‐to‐radius ratio derived from in‐situ measurements. Combining these findings, we propose that climate models use a set of optics parameterizations for each hydrometeor type while adequently accounting for radiation effects caused by size and habit distributions. Uncertainties due to this simplification are evaluated. This study offers a consistent and physically based representation of radiative processes of clouds and precipitation in weather and climate simulations. |
| format | Article |
| id | doaj-art-c86f526be86649b7b863789bbf34b7c8 |
| institution | DOAJ |
| issn | 1942-2466 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | American Geophysical Union (AGU) |
| record_format | Article |
| series | Journal of Advances in Modeling Earth Systems |
| spelling | doaj-art-c86f526be86649b7b863789bbf34b7c82025-08-20T02:54:12ZengAmerican Geophysical Union (AGU)Journal of Advances in Modeling Earth Systems1942-24662025-03-01173n/an/a10.1029/2024MS004478Toward Transparency and Consistency: An Open‐Source Optics Parameterization for Clouds and PrecipitationJing Feng0Raymond Menzel1David Paynter2Atmospheric and Oceanic Sciences Program Princeton University Princeton NJ USAGeophysical Fluid Dynamics Laboratory Princeton NJ USAGeophysical Fluid Dynamics Laboratory Princeton NJ USAAbstract In this study, a new open‐source package for cloud and precipitation modeling is introduced. Based on Mie theory and existing ice crystal data sets, the scheme generates optical properties for user‐defined gas bands, particle size distribution, and crystal habits, ensuring continuity across wide spectral bands and from small particles (clouds) to large particles (precipitation). Compared with existing schemes in GFDL's AM4‐MG2, it reduces shortwave reflection of liquid clouds at the top of the atmosphere (TOA) by 1.50 Wm−2 and increases that of ice clouds by 1.62 Wm−2, based on offline radiative calculations. Using the new scheme, we find that cloud radiative effects are sensitive to microphysics variables such as particle size and habit, which affect the effective radius. Systematic flux biases may arise if the effective radius is not fully predicted in microphysics due to predefined size and habit distributions. We show that assuming spherical ice crystals underestimates ice‐cloud radiative effects by 3.20 Wm−2 in the longwave TOA and 2.76 Wm−2 in the shortwave TOA. These biases can be addressed by improving the effective radius approximation with a volume‐to‐radius ratio derived from in‐situ measurements. Combining these findings, we propose that climate models use a set of optics parameterizations for each hydrometeor type while adequently accounting for radiation effects caused by size and habit distributions. Uncertainties due to this simplification are evaluated. This study offers a consistent and physically based representation of radiative processes of clouds and precipitation in weather and climate simulations.https://doi.org/10.1029/2024MS004478cloud radiative effectsEarth system modelingatmospheric radiationcloud and precipitation opticscloud radiation interaction |
| spellingShingle | Jing Feng Raymond Menzel David Paynter Toward Transparency and Consistency: An Open‐Source Optics Parameterization for Clouds and Precipitation Journal of Advances in Modeling Earth Systems cloud radiative effects Earth system modeling atmospheric radiation cloud and precipitation optics cloud radiation interaction |
| title | Toward Transparency and Consistency: An Open‐Source Optics Parameterization for Clouds and Precipitation |
| title_full | Toward Transparency and Consistency: An Open‐Source Optics Parameterization for Clouds and Precipitation |
| title_fullStr | Toward Transparency and Consistency: An Open‐Source Optics Parameterization for Clouds and Precipitation |
| title_full_unstemmed | Toward Transparency and Consistency: An Open‐Source Optics Parameterization for Clouds and Precipitation |
| title_short | Toward Transparency and Consistency: An Open‐Source Optics Parameterization for Clouds and Precipitation |
| title_sort | toward transparency and consistency an open source optics parameterization for clouds and precipitation |
| topic | cloud radiative effects Earth system modeling atmospheric radiation cloud and precipitation optics cloud radiation interaction |
| url | https://doi.org/10.1029/2024MS004478 |
| work_keys_str_mv | AT jingfeng towardtransparencyandconsistencyanopensourceopticsparameterizationforcloudsandprecipitation AT raymondmenzel towardtransparencyandconsistencyanopensourceopticsparameterizationforcloudsandprecipitation AT davidpaynter towardtransparencyandconsistencyanopensourceopticsparameterizationforcloudsandprecipitation |