Non-Gaussian statistics in global atmospheric dynamics: a study with a 10 240-member ensemble Kalman filter using an intermediate atmospheric general circulation model
<p>We previously performed local ensemble transform Kalman filter (LETKF) experiments with up to 10 240 ensemble members using an intermediate atmospheric general circulation model (AGCM). While the previous study focused on the impact of localization on the analysis accuracy, the p...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2019-08-01
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| Series: | Nonlinear Processes in Geophysics |
| Online Access: | https://www.nonlin-processes-geophys.net/26/211/2019/npg-26-211-2019.pdf |
| _version_ | 1818300412535504896 |
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| author | K. Kondo K. Kondo T. Miyoshi T. Miyoshi T. Miyoshi T. Miyoshi T. Miyoshi |
| author_facet | K. Kondo K. Kondo T. Miyoshi T. Miyoshi T. Miyoshi T. Miyoshi T. Miyoshi |
| author_sort | K. Kondo |
| collection | DOAJ |
| description | <p>We previously performed local ensemble transform Kalman filter (LETKF)
experiments with up to 10 240 ensemble members using an intermediate
atmospheric general circulation model (AGCM). While the previous study
focused on the impact of localization on the analysis accuracy, the present
study focuses on the probability density functions (PDFs) represented by the
10 240-member ensemble. The 10 240-member ensemble can resolve the detailed
structures of the PDFs and indicates that non-Gaussianity is caused in those
PDFs by multimodality and outliers. The results show that the spatial
patterns of the analysis errors are similar to those of non-Gaussianity.
While the outliers appear randomly, large multimodality corresponds well
with large analysis error, mainly in the tropical regions and storm track
regions where highly nonlinear processes appear frequently. Therefore, we
further investigate the life cycle of multimodal PDFs, and show that they
are mainly generated by the on–off switch of convective
parameterization in the tropical regions and by the instability associated
with advection in the storm track regions. Sensitivity to the ensemble size
suggests that approximately 1000 ensemble members are necessary in the
intermediate AGCM-LETKF system to represent the detailed structures of
non-Gaussian PDFs such as skewness and kurtosis; the higher-order
non-Gaussian statistics are more vulnerable to the sampling errors due to a
smaller ensemble size.</p> |
| first_indexed | 2024-12-13T05:06:42Z |
| format | Article |
| id | doaj.art-c6b399353da6463c8a7485fb1d139885 |
| institution | Directory Open Access Journal |
| issn | 1023-5809 1607-7946 |
| language | English |
| last_indexed | 2024-12-13T05:06:42Z |
| publishDate | 2019-08-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Nonlinear Processes in Geophysics |
| spelling | doaj.art-c6b399353da6463c8a7485fb1d1398852022-12-21T23:58:39ZengCopernicus PublicationsNonlinear Processes in Geophysics1023-58091607-79462019-08-012621122510.5194/npg-26-211-2019Non-Gaussian statistics in global atmospheric dynamics: a study with a 10 240-member ensemble Kalman filter using an intermediate atmospheric general circulation modelK. Kondo0K. Kondo1T. Miyoshi2T. Miyoshi3T. Miyoshi4T. Miyoshi5T. Miyoshi6RIKEN Center for Computational Science, Kobe, JapanMeteorological Research Institute, Japan Meteorological Agency, Tsukuba, JapanRIKEN Center for Computational Science, Kobe, JapanRIKEN Cluster for Pioneering Research, Kobe, JapanRIKEN Interdisciplinary Theoretical and Mathematical Sciences Program, Kobe, JapanDepartment of Atmospheric and Oceanic Science, University of Maryland, College Park, Maryland, USAJapan Agency for Marine-Earth Science and Technology, Yokohama, Japan<p>We previously performed local ensemble transform Kalman filter (LETKF) experiments with up to 10 240 ensemble members using an intermediate atmospheric general circulation model (AGCM). While the previous study focused on the impact of localization on the analysis accuracy, the present study focuses on the probability density functions (PDFs) represented by the 10 240-member ensemble. The 10 240-member ensemble can resolve the detailed structures of the PDFs and indicates that non-Gaussianity is caused in those PDFs by multimodality and outliers. The results show that the spatial patterns of the analysis errors are similar to those of non-Gaussianity. While the outliers appear randomly, large multimodality corresponds well with large analysis error, mainly in the tropical regions and storm track regions where highly nonlinear processes appear frequently. Therefore, we further investigate the life cycle of multimodal PDFs, and show that they are mainly generated by the on–off switch of convective parameterization in the tropical regions and by the instability associated with advection in the storm track regions. Sensitivity to the ensemble size suggests that approximately 1000 ensemble members are necessary in the intermediate AGCM-LETKF system to represent the detailed structures of non-Gaussian PDFs such as skewness and kurtosis; the higher-order non-Gaussian statistics are more vulnerable to the sampling errors due to a smaller ensemble size.</p>https://www.nonlin-processes-geophys.net/26/211/2019/npg-26-211-2019.pdf |
| spellingShingle | K. Kondo K. Kondo T. Miyoshi T. Miyoshi T. Miyoshi T. Miyoshi T. Miyoshi Non-Gaussian statistics in global atmospheric dynamics: a study with a 10 240-member ensemble Kalman filter using an intermediate atmospheric general circulation model Nonlinear Processes in Geophysics |
| title | Non-Gaussian statistics in global atmospheric dynamics: a study with a 10 240-member ensemble Kalman filter using an intermediate atmospheric general circulation model |
| title_full | Non-Gaussian statistics in global atmospheric dynamics: a study with a 10 240-member ensemble Kalman filter using an intermediate atmospheric general circulation model |
| title_fullStr | Non-Gaussian statistics in global atmospheric dynamics: a study with a 10 240-member ensemble Kalman filter using an intermediate atmospheric general circulation model |
| title_full_unstemmed | Non-Gaussian statistics in global atmospheric dynamics: a study with a 10 240-member ensemble Kalman filter using an intermediate atmospheric general circulation model |
| title_short | Non-Gaussian statistics in global atmospheric dynamics: a study with a 10 240-member ensemble Kalman filter using an intermediate atmospheric general circulation model |
| title_sort | non gaussian statistics in global atmospheric dynamics a study with a 10 thinsp 240 member ensemble kalman filter using an intermediate atmospheric general circulation model |
| url | https://www.nonlin-processes-geophys.net/26/211/2019/npg-26-211-2019.pdf |
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