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| Titel |
Water vapor observations up to the lower stratosphere through the Raman lidar during the Maïdo Lidar Calibration Campaign |
| VerfasserIn |
D. Dionisi, P. Keckhut, Y. Courcoux, A. Hauchecorne, J. Porteneuve, J. L. Baray, J. Leclair de Bellevue, H. Vérèmes, F. Gabarrot, G. Payen, R. Decoupes, J. P. Cammas |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 8, no. 3 ; Nr. 8, no. 3 (2015-03-20), S.1425-1445 |
| Datensatznummer |
250116225
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| Publikation (Nr.) |
 copernicus.org/amt-8-1425-2015.pdf |
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| Zusammenfassung |
A new lidar system devoted to tropospheric and lower stratospheric water
vapor measurements has been installed at the Maïdo altitude station
facility of Réunion island, in the southern subtropics.
To evaluate the performances and the capabilities of the new system with a
particular focus on UTLS (Upper Troposphere Lower Stratosphere) measurements, the Maïdo Lidar Calibration Campaign
(MALICCA) was performed in April 2013.
Varying the characteristics of the transmitter and the receiver components,
different system configuration scenarios were tested and possible parasite
signals (fluorescent contamination, rejection) were investigated. A hybrid
calibration methodology has been set up and validated to insure optimal
lidar calibration stability with time. In particular, the receiver
transmittance is monitored through the calibration lamp method that, at the
moment, can detect transmittance variations greater than 10–15%.
Calibration coefficients are then calculated through the hourly values of
IWV (Integrated Water Vapor) provided by the co-located GPS. The comparison between the constants
derived by GPS and Vaisala RS92 radiosondes launched at Maïdo during
MALICCA, points out an acceptable agreement in terms of accuracy of the mean
calibration value (with a difference of approximately 2–3%), but a
significant difference in terms of variability (14% vs. 7–9%, for
GPS and RS92 calibration procedures, respectively).
We obtained a relatively good agreement between the lidar measurements and
15 co-located and simultaneous RS92 radiosondes. A relative difference below
10% is measured in the low and middle troposphere (2–10 km). The upper
troposphere (up to 15 km) is characterized by a larger spread (approximately
20%), because of the increasing distance between the two sensors.
To measure water vapor in the UTLS region, nighttime and monthly water vapor
profiles are presented and compared. The good agreement between the lidar
monthly profile and the mean WVMR profile measured by satellite MLS (Microwave Limb Sounder) has been
used as a quality control procedure of the lidar product, attesting the
absence of significant wet biases and validating the calibration procedure.
Due to its performance and location, the MAIDO H2O lidar will become a
reference instrument in the southern subtropics, insuring the long-term
survey of the vertical distribution of water vapor. Furthermore, this system
allows the investigation of several scientific themes, such as
stratosphere–troposphere exchange, tropospheric dynamics in the subtropics,
and links between cirrus clouds and water vapor. |
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