Evaluating Arctic clouds modelled with the Unified Model and Integrated Forecasting System
<p>By synthesising remote-sensing measurements made in the central Arctic into a model-gridded Cloudnet cloud product, we evaluate how well the Met Office Unified Model (UM) and the European Centre for Medium-Range Weather Forecasting (ECMWF) Integrated Forecasting System (IFS) capture Arctic...
| Main Authors: | , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2023-04-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://acp.copernicus.org/articles/23/4819/2023/acp-23-4819-2023.pdf |
| _version_ | 1797840351040372736 |
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| author | G. Y. McCusker J. Vüllers J. Vüllers P. Achtert P. Field P. Field J. J. Day R. Forbes R. Price E. O'Connor M. Tjernström J. Prytherch R. Neely III R. Neely III I. M. Brooks |
| author_facet | G. Y. McCusker J. Vüllers J. Vüllers P. Achtert P. Field P. Field J. J. Day R. Forbes R. Price E. O'Connor M. Tjernström J. Prytherch R. Neely III R. Neely III I. M. Brooks |
| author_sort | G. Y. McCusker |
| collection | DOAJ |
| description | <p>By synthesising remote-sensing measurements made in the central Arctic into a model-gridded Cloudnet cloud product, we evaluate how
well the Met Office Unified Model (UM) and the European Centre for Medium-Range Weather Forecasting (ECMWF) Integrated Forecasting System (IFS) capture Arctic clouds and their associated interactions with the surface energy balance and
the thermodynamic structure of the lower troposphere. This evaluation was
conducted using a 4-week observation period from the Arctic Ocean 2018 expedition, where the transition from sea ice melting to freezing conditions
was measured. Three different cloud schemes were tested within a nested
limited-area model (LAM) configuration of the UM – two regionally operational single-moment schemes (UM_RA2M and
UM_RA2T) and one novel double-moment scheme (UM_CASIM-100) – while one global simulation was conducted
with the IFS, utilising its default cloud scheme (ECMWF_IFS).</p>
<p>Consistent weaknesses were identified across both models, with both the UM
and IFS overestimating cloud occurrence below 3 km. This overestimation was
also consistent across the three cloud configurations used within the UM
framework, with <span class="inline-formula"><i>></i>90</span> % mean cloud occurrence simulated between
0.15 and 1 km in all the model simulations. However, the cloud microphysical structure, on average, was modelled reasonably well in each simulation, with
the cloud liquid water content (LWC) and ice water content (IWC)
comparing well with observations over much of the vertical profile. The key
microphysical discrepancy between the models and observations was in the
LWC between 1 and 3 km, where most simulations (all except
UM_RA2T) overestimated the observed LWC.</p>
<p>Despite this reasonable performance in cloud physical structure, both models
failed to adequately capture cloud-free episodes: this consistency in cloud
cover likely contributes to the ever-present near-surface temperature bias
in every simulation. Both models also consistently exhibited temperature and
moisture biases below 3 km, with particularly strong cold biases coinciding
with the overabundant modelled cloud layers. These biases are likely due to
too much cloud-top radiative cooling from these persistent modelled cloud layers and were consistent across the three UM configurations tested,
despite differences in their parameterisations of cloud on a sub-grid scale. Alarmingly, our findings suggest that these biases in the regional model
were inherited from the global model, driving a cause–effect relationship between the excessive low-altitude cloudiness and the coincident cold bias.
Using representative cloud condensation nuclei concentrations in our
double-moment UM configuration while improving cloud microphysical structure does little to alleviate these biases; therefore, no matter how
comprehensive we make the cloud physics in the nested LAM configuration used
here, its cloud and thermodynamic structure will continue to be
overwhelmingly biased by the meteorological conditions of its driving model.</p> |
| first_indexed | 2024-04-09T16:13:31Z |
| format | Article |
| id | doaj.art-88accd69fe074e9495809a763e0ce791 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-04-09T16:13:31Z |
| publishDate | 2023-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-88accd69fe074e9495809a763e0ce7912023-04-24T07:51:05ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242023-04-01234819484710.5194/acp-23-4819-2023Evaluating Arctic clouds modelled with the Unified Model and Integrated Forecasting SystemG. Y. McCusker0J. Vüllers1J. Vüllers2P. Achtert3P. Field4P. Field5J. J. Day6R. Forbes7R. Price8E. O'Connor9M. Tjernström10J. Prytherch11R. Neely III12R. Neely III13I. M. Brooks14Institute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UKInstitute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UKnow at: Institute of Meteorology and Climate Research & Institute of Photogrammetry and Remote Sensing, Karlsruhe Institute of Technology, Karlsruhe, GermanyMeteorological Observatory, German Weather Service, Hohenpeißenberg, GermanyInstitute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UKMet Office, Exeter, UKEuropean Centre for Medium-Range Weather Forecasts, Reading, UKEuropean Centre for Medium-Range Weather Forecasts, Reading, UKInstitute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UKFinnish Meteorological Institute, Helsinki, FinlandDepartment of Meteorology, Stockholm University, Stockholm, SwedenDepartment of Meteorology, Stockholm University, Stockholm, SwedenInstitute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UKNational Centre for Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UKInstitute for Climate and Atmospheric Science, School of Earth and Environment, University of Leeds, Leeds, UK<p>By synthesising remote-sensing measurements made in the central Arctic into a model-gridded Cloudnet cloud product, we evaluate how well the Met Office Unified Model (UM) and the European Centre for Medium-Range Weather Forecasting (ECMWF) Integrated Forecasting System (IFS) capture Arctic clouds and their associated interactions with the surface energy balance and the thermodynamic structure of the lower troposphere. This evaluation was conducted using a 4-week observation period from the Arctic Ocean 2018 expedition, where the transition from sea ice melting to freezing conditions was measured. Three different cloud schemes were tested within a nested limited-area model (LAM) configuration of the UM – two regionally operational single-moment schemes (UM_RA2M and UM_RA2T) and one novel double-moment scheme (UM_CASIM-100) – while one global simulation was conducted with the IFS, utilising its default cloud scheme (ECMWF_IFS).</p> <p>Consistent weaknesses were identified across both models, with both the UM and IFS overestimating cloud occurrence below 3 km. This overestimation was also consistent across the three cloud configurations used within the UM framework, with <span class="inline-formula"><i>></i>90</span> % mean cloud occurrence simulated between 0.15 and 1 km in all the model simulations. However, the cloud microphysical structure, on average, was modelled reasonably well in each simulation, with the cloud liquid water content (LWC) and ice water content (IWC) comparing well with observations over much of the vertical profile. The key microphysical discrepancy between the models and observations was in the LWC between 1 and 3 km, where most simulations (all except UM_RA2T) overestimated the observed LWC.</p> <p>Despite this reasonable performance in cloud physical structure, both models failed to adequately capture cloud-free episodes: this consistency in cloud cover likely contributes to the ever-present near-surface temperature bias in every simulation. Both models also consistently exhibited temperature and moisture biases below 3 km, with particularly strong cold biases coinciding with the overabundant modelled cloud layers. These biases are likely due to too much cloud-top radiative cooling from these persistent modelled cloud layers and were consistent across the three UM configurations tested, despite differences in their parameterisations of cloud on a sub-grid scale. Alarmingly, our findings suggest that these biases in the regional model were inherited from the global model, driving a cause–effect relationship between the excessive low-altitude cloudiness and the coincident cold bias. Using representative cloud condensation nuclei concentrations in our double-moment UM configuration while improving cloud microphysical structure does little to alleviate these biases; therefore, no matter how comprehensive we make the cloud physics in the nested LAM configuration used here, its cloud and thermodynamic structure will continue to be overwhelmingly biased by the meteorological conditions of its driving model.</p>https://acp.copernicus.org/articles/23/4819/2023/acp-23-4819-2023.pdf |
| spellingShingle | G. Y. McCusker J. Vüllers J. Vüllers P. Achtert P. Field P. Field J. J. Day R. Forbes R. Price E. O'Connor M. Tjernström J. Prytherch R. Neely III R. Neely III I. M. Brooks Evaluating Arctic clouds modelled with the Unified Model and Integrated Forecasting System Atmospheric Chemistry and Physics |
| title | Evaluating Arctic clouds modelled with the Unified Model and Integrated Forecasting System |
| title_full | Evaluating Arctic clouds modelled with the Unified Model and Integrated Forecasting System |
| title_fullStr | Evaluating Arctic clouds modelled with the Unified Model and Integrated Forecasting System |
| title_full_unstemmed | Evaluating Arctic clouds modelled with the Unified Model and Integrated Forecasting System |
| title_short | Evaluating Arctic clouds modelled with the Unified Model and Integrated Forecasting System |
| title_sort | evaluating arctic clouds modelled with the unified model and integrated forecasting system |
| url | https://acp.copernicus.org/articles/23/4819/2023/acp-23-4819-2023.pdf |
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