Bourgeois, E, Bouniol, D, Couvreux, F et al. (5 more authors) (2018) Characteristics of mid‐level clouds over West Africa. Quarterly Journal of the Royal Meteorological Society, 144 (711). pp. 426-442. ISSN 0035-9009
Abstract
Mid‐level clouds, located between 2 and 9 km height, are ubiquitous in the tropical belt. However, few studies have documented their characteristics and tried to identify the associated thermodynamic properties, particularly in West Africa. This region is characterized by a strong seasonality with precipitation occurring in the Sahel from June to September (monsoon season). This period also coincides with the annual maximum of the cloud cover. Here, we document the macro‐ and microphysical properties of mid‐level clouds, the environment in which such clouds occur, as well as their radiative properties across West Africa. To do so, we combined high‐resolution observations from two ground‐based sites (including lidar and cloud radar) in contrasted environments: one in the Sahel (Niamey, AMMA campaign, 2006) and the other in the Sahara (Bordj Badji Mokhtar, Fennec campaign, June 2011) along with the merged CloudSat‐CALIPSO satellite products. The results show that mid‐level clouds are found throughout the year with a predominance around the monsoon season early in the morning. They also are preferentially observed in the southern and western parts of West Africa. They are usually thin (most of them are less than 1000 m deep) and as observed in Niamey, mainly composed of liquid water. A clustering method applied to Niamey data allows us to distinguish three different types of cloud: one with low bases, one with high bases and another with large thicknesses. The two first cloud families are capped by an inversion. The last family is associated with a large vertical moisture transport and likely has the highest radiative effect at the Earth's surface among the three cloud types.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2017 Royal Meteorological Society. This is the peer reviewed version of the following article: Bourgeois, E. , Bouniol, D. , Couvreux, F. , Guichard, F. , Marsham, J. H., Garcia‐Carreras, L. , Birch, C. E. and Parker, D. J. (2018), Characteristics of mid‐level clouds over West Africa. Q.J.R. Meteorol. Soc., 144: 426-442. doi:10.1002/qj.3215, which has been published in final form at https://doi.org/10.1002/qj.3215. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | mid‐level clouds; diurnal cycle; macrophysical and microphysical properties; thermodynamics; radiative impacts; ground‐based and space‐borne observations; West Africa |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst for Climate & Atmos Science (ICAS) (Leeds) |
Funding Information: | Funder Grant number NERC NE/L005352/1 EU - European Union EXT GOCE 004089 NERC NE/B505538/1 EU - European Union GOCE 004089 NERC NE/G018499/1 NERC NE/G017166/1 NERC NE/M020126/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 20 Dec 2017 15:33 |
Last Modified: | 24 Nov 2018 01:39 |
Status: | Published |
Publisher: | Wiley |
Identification Number: | 10.1002/qj.3215 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:125390 |