HR: 0800h
AN: A21D-0896    [Abstracts]
TI: Raman lidar water vapor measurements performed at CNR-IMAA
AU: Cornacchia, C
EM: cornacchia@imaa.cnr.it
AF: Consiglio Nazionale delle Ricerche - Istituto di Metodologie per l'Analisi Ambientale, CNR-IMAA, C.da S. Loja, Tito Scalo, I-85050 Italy
AU: Amodeo, A
EM:
AF: Consiglio Nazionale delle Ricerche - Istituto di Metodologie per l'Analisi Ambientale, CNR-IMAA, C.da S. Loja, Tito Scalo, I-85050 Italy
AU: D'Amico, G
EM:
AF: Consiglio Nazionale delle Ricerche - Istituto di Metodologie per l'Analisi Ambientale, CNR-IMAA, C.da S. Loja, Tito Scalo, I-85050 Italy
AU: Madonna, F
EM:
AF: Consiglio Nazionale delle Ricerche - Istituto di Metodologie per l'Analisi Ambientale, CNR-IMAA, C.da S. Loja, Tito Scalo, I-85050 Italy
AU: * Mona, L
EM:
AF: Consiglio Nazionale delle Ricerche - Istituto di Metodologie per l'Analisi Ambientale, CNR-IMAA, C.da S. Loja, Tito Scalo, I-85050 Italy
AU: Pappalardo, G
EM:
AF: Consiglio Nazionale delle Ricerche - Istituto di Metodologie per l'Analisi Ambientale, CNR-IMAA, C.da S. Loja, Tito Scalo, I-85050 Italy
AB: A Raman lidar system for water vapor measurements is operational at Istituto di Metodologie per l'Analisi Ambientale (IMAA),in Tito Scalo, Potenza, (Southern Italy, 40°36'N, 15°44'E, 760 m above sea level) since July 2002. The Raman technique is widely employed for tropospheric water vapor measurements with high vertical and temporal resolution. In principle, Raman lidar measurement of water vapor can be calibrated in absolute terms, but present uncertainties in the ratio of Raman lidar cross section of water vapor and nitrogen limit this calibration accuracy to about 10%. In order to obtain good accuracy, the Raman lidar water vapor measurements are typically calibrated to independent water vapor measurements. In May-June 2002, an intensive measurement campaign was performed at CNR-IMAA in order to calibrate the IMAA Raman lidar system for water vapor profiling by means of contemporary and co-located Vaisala RS80-A radiosondes measurements. The radiosonde data have been corrected for temperature dependence error and for dry bias due to chemical contamination error. Moreover, from July 2002 more than 100 lidar and radiosonde simultaneous measurements have been performed and have been used to check the stability of the lidar calibration constant, that remains within 5%. Since February 2004, a 12 channels microwave radiometer is operative at CNR-IMAA, providing temperature, relative humidity and liquid water profiles up to 10 km of altitude, and the integrated precipitable water vapor and integrated liquid water measurements. Since this radiometer provides good accuracy measurements of the integrated water vapor column content, every 5 minutes, 24 hours per day, it is the best candidate for routinely check of the stability of the Raman lidar system calibration constant: the calibration constant has been checked comparing the integrated water vapor column content measured by microwave radiometer and the corresponding quantity measured by the Raman lidar, obtained integrating lidar water vapor vertical profile from the ground up to the tropopause. This allows to overall all the problems related to radiosounding water vapor measurements, like dry bias, different investigated air volumes, and high costs. The IMAA Raman lidar system is able to provide water vapor mixing ratio vertical profiles up to the tropopause in night-time and up to 5 km of altitude in daytime conditions, with a typical temporal resolution of 10 minutes. Systematic measurements have been performed in the period July 2002 - July 2003 in the framework of the validation program of ENVISAT, in order to validate MIPAS water vapor products. Moreover, after the validation campaign, systematic measurements are still in progress. Besides systematic measurements, this system has been employed in special measurements campaigns, as the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) field campaign in summer 2004 and the European AQUA Thermodynamic Experiment (EAQUATE) Italian phase in the 6-10 September 2004. In addition, in autumn 2005, the IMAA Raman lidar system for water vapor measurements will be involved in the international Lindenberg anniversary campaign for Assessment of hUmidity aNd Cloud profiling systems and its impact on High-resolution modelling (LAUNCH- 2005). ACKNOWLEDGMENTS The financial support of this work by the European Space Agency under grant ESA-ESTEC Contract No. 16040/02/NL/SF, ``Ground based observations of water vapour and aerosol for the validation of ENVISAT products'', is gratefully acknowledged.
DE: 0365 Troposphere: composition and chemistry
DE: 0394 Instruments and techniques
DE: 3360 Remote sensing
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005