Abstract
Abstract. The local distribution of water vapour in the urban area of Rome has been studied using both a high resolution mesoscale model (MM5) and Earth Remote Sensing-1 (ERS-1) satellite radar data. Interferometric Synthetic Aperture Radar (InSAR) techniques, after the removal of all other geometric effects, estimate excess path length variation between two different SAR acquisitions (Atmospheric Phase Screen: APS). APS are strictly related to the variations of the water vapour content along the radar line of sight. To the aim of assessing the MM5 ability to reproduce the gross features of the Integrated Water Vapour (IWV) spatial distribution, as a first step ECMWF IWV has been used as benchmark against which the high resolution MM5 model and InSAR APS maps have been compared. As a following step, the high resolution IWV MM5 maps have been compared with both InSAR and surface meteorological data. The results show that the high resolution IWV model maps compare well with the InSAR ones. Support to this finding is obtained by semivariogram analysis that clearly shows good agreement beside from a model bias.
Highlights
Water vapour is one of the most important constituents of the atmosphere because its phase changes are responsible for clouds and precipitation, whose interaction with electromagnetic radiation is a crucial factor in atmospheric system regulation
The version 3 of Mesoscale Model 5 (MM5) (Dudhia, 1993) is used to produce high resolution water vapour fields to be compared with Interferometric Synthetic Aperture Radar (InSAR) data, which have been processed with the Permanent Scatterers (PS) technique (Ferretti et al, 2001)
The main features of the InSAR Atmospheric Phase Screen (APS) map are well reproduced by MM5 (Fig. 5), as well as the values range measured by the radar on 31 January at 10:00 UTC3 with respect to the master image
Summary
Water vapour is one of the most important constituents of the atmosphere because its phase changes are responsible for clouds and precipitation, whose interaction with electromagnetic radiation is a crucial factor in atmospheric system regulation. The high spatial resolution Numerical Weather Prediction (NWP) models are able to reproduce realistic water vapour distribution fields, but their limiting factor is the poor resolution of the initial conditions. The lack of both precise and continuous water vapour data is one of the major sources of error in short-term forecast of precipitation (Kuo et al, 1993, 1996). An improvement in monitoring the atmospheric water vapour and its assimilation in NWP models would lead to more accurate forecasts of precipitation and severe weather In this context, benefits from InSAR high resolution phase delay can be fully employed if ground motion and topography effects are effectively isolated from water vapour contribution to the signal delay. The version 3 of Mesoscale Model 5 (MM5) (Dudhia, 1993) is used to produce high resolution water vapour fields to be compared with InSAR data, which have been processed with the Permanent Scatterers (PS) technique (Ferretti et al, 2001)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
