Model evaluation using space-borne lidar observations
| dc.contributor.author | Ahlgrimm, Maike, author | |
| dc.contributor.author | Randall, David A., advisor | |
| dc.date.accessioned | 2024-03-13T18:14:52Z | |
| dc.date.available | 2024-03-13T18:14:52Z | |
| dc.date.issued | 2008 | |
| dc.description.abstract | In this study, the use of space-borne lidar observations for the comparison with, and evaluation of modeled clouds is explored. Four version of the ECMWF Integrated Forecast System and two versions of the Goddard Earth Observing System (GEOS-5) model are assessed for their ability to produce marine boundary layer clouds. The cause of some of the model deficiencies is investigated, and specific suggestions for improvements are made and tested. In order to do so, two cloud types are defined: a stratocumulus type (Sc), and a trade cumulus or transitional cumulus type (TCu). Samples in four oceanic regions are classified into those categories, and the frequency of occurrence, location, and properties of the samples compared between models and observations. | |
| dc.description.abstract | Both models have a tendency to produce clouds with small cloud fraction too frequently, and underestimate the occurrence of stratocumulus clouds. The ECMWF model underestimates the cloud top height of the stratocumulus clouds, while the GEOS-5 model produces an excess of fog. The introduction of an eddy diffusivity - mass flux boundary layer scheme in the ECMWF leads to an increase in stratocumulus clouds and a more realistic cloud-fraction distribution. Sensitivity tests show further improvement of the location and cloud top height of stratocumulus clouds when environmental mixing of the test parcel in the boundary layer is reduced, and less lower level stability is required for generation of stratocumulus clouds. However, these improvements vary with region, indicating that the new parameterization cannot fully capture all the processes contributing to the generation of these clouds. | |
| dc.description.abstract | Improvement of the GEOS-5 model can also be demonstrated with a reduction of the fog. | |
| dc.description.abstract | In addition, Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations provide an unprecedented global view of boundary-layer clouds, and illustrate the seasonal and diurnal cycles of low-cloud top height and frequency of occurrence in the subtropical belt. The cloud-top heights observed are generally consistent with previous ground-based observations of the inversion height. | |
| dc.format.medium | born digital | |
| dc.format.medium | doctoral dissertations | |
| dc.identifier | ETDF_Ahlgrimm_2008_3321252.pdf | |
| dc.identifier.uri | https://hdl.handle.net/10217/237542 | |
| dc.language | English | |
| dc.language.iso | eng | |
| dc.publisher | Colorado State University. Libraries | |
| dc.relation.ispartof | 2000-2019 | |
| dc.rights | Copyright and other restrictions may apply. User is responsible for compliance with all applicable laws. For information about copyright law, please see https://libguides.colostate.edu/copyright. | |
| dc.rights.license | Per the terms of a contractual agreement, all use of this item is limited to the non-commercial use of Colorado State University and its authorized users. | |
| dc.subject | boundary layer clouds | |
| dc.subject | lidar | |
| dc.subject | marine boundary layer | |
| dc.subject | model evaluation | |
| dc.subject | space-borne lidar | |
| dc.subject | atmospheric sciences | |
| dc.subject | remote sensing | |
| dc.title | Model evaluation using space-borne lidar observations | |
| dc.type | Text | |
| dcterms.rights.dpla | This Item is protected by copyright and/or related rights (https://rightsstatements.org/vocab/InC/1.0/). You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). | |
| thesis.degree.discipline | Atmospheric Science | |
| thesis.degree.grantor | Colorado State University | |
| thesis.degree.level | Doctoral | |
| thesis.degree.name | Doctor of Philosophy (Ph.D.) |
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