Concepts and infrastructures for gpm ground validation activity in Italy Eugenio Gorgucci

Concepts and infrastructures for GPM ground validation activity in Italy

• Eugenio Gorgucci

• Istituto di Scienze dell’Atmosfera e del Clima

• Roma, Italy

Outline

• Climatology of Italy

• Italian infrastructure for GPM GV

• Issues for radar-based GPM GV activity in Italy

Relevance of the Mediterranean region

• Uniqueness of the Mediterranean climate determined by:

• upper air circulation between the subtropical high pressure belt and the mid-latitude

Precipitation in the Mediterranean region

• Monthly average precipitation shows a maximum in autumn (or in late summer), and the minimum in summer (close to zero for the Southern and Eastern Mediterranean)

• Extreme variability: monthly average is sometimes reached in a single day

• High probability of storm hit in narrow coast lines bounded by mountains

• From rainfall statistics, Rome can be representative of an “average” Mediterranean precipitation regime

Climate and precipitation in Italy

• The Italian Peninsula, due to the role played by the Apennine range, divides two sides of the Mediterranean basin, which present different circulation characteristics.

• The climate of Italy is defined with reference to 8 subregions

• Amount and distribution of precipitation is highly variable: from max 1000 mm/year in Alps and Apennines to less than 500 mm/year in South Italy and Islands.

• Summer is not totally dry (occurrence of rainy days in Rome is 33 in winter, 29 in spring and fall, and 12 in summer)

• Peaks of precipitation intensity are recorded during summer storms.

Organizations cooperating for GPM GV

• National Research Council of Italy

• Centro di Ricerca Interuniversitario in Monitoraggio Ambientale (Savona)

• Universities through Telecommunication and Hydrology Departments

• Department of Civil Protection

• National meteorological service of the Italian Air Force

• Regional meteorological services managed by Regional Governments

Facilities for GPM GV

• CNR-ISAC Atmospheric Observatory in Rome

• Polar 55C research radar

• National meteorological radar network

• Telemetered raingauge networks

• Regional meteorological services

• CNR-IMAA Atmospheric Radiation Measurement Site of the Basilicata

ISAC-CNR Atmospheric observatory in Rome

• The observatory started its activities in 1997

ISAC-CNR Atmospheric observatory of Rome

• Polar 55c

• Multiple receiver lidar system using simultaneously the Rayleigh-Mie and Raman (RMR) techniques to profile aerosol (from few hundreds of meters up to the stratosphere), temperature (in the mesosph. and upper stratosphere) and W V.

• CIMEL Sunphotometer a sky-scanning instrument measuring direct and diffuse solar radiation between 440 and 1020 nm to provide aerosol optical depth, precipitable water, aerosol size distribution, refractive index and single scattering albedo. Part of AERONET, the NASA-Goddard photometric network.

• VHF Radar wind profiler a ground-based clear air Doppler radar that measures vertical profiles of horizontal and vertical wind by using five beams.

• Ultrasonic anemometer-thermometer based on USA1 sensor by METEK GmbH determines the virtual temperature and wind speed and direction at high accuracy and to retrieve the sensible heat and momentum flux. NET radiometer by Kipp&Zonen with two pyranometers CM3, and two pyrgeometers CG3 suitably mounted to measure the incoming and outgoing SW and LW respectively

• Automatic weather station for the measurement of standard atmospheric parameters and incoming LW and SW radiation.

• Minisodar and sodar are acoustic remote sensors of Planetary Boundary Layer (PBL). They can provide a “snapshot" of the thermal structure of the PBL and the wind profile in the whole troposphere.

• MTP5 (Meteorological Temperature Profiler) based upon the measurement of thermal radiation from the molecular oxygen absorption band (60.4 GHz) in the atmosphere gives the air temperature profile up to 600m.

• VELIS (Vehicle-mounted Lidar System) is a mobile polarization lidar (532 nm) providing aerosol profiles between 150 m and 20 km. VELIS is operational since 1999, participating so far into five EU programs. When not engaged in field campaigns VELIS is continually operated at the ISAC Rome observatory. 

• Microlidar (µLID elastic backscatter lidar) measures from 0.5 to 10 km, according to background light conditions, the volume backscattering coefficient and volume depolarization at 532 nm.

THE POLAR 55C RADAR

• Coherent dual polarization C-band radar

• Moved to Rome in 2001
• Receiver-processing chain replaced in 2002; a digital receiver is adopted
• Zh, Zdr, v, v and dp measurements
• New facilities for data displaying, system control, archiving and data distribution set up in 2002

Sensors available in the Roman area

• Telemetered raingauge network managed by the Lazio Region (resolution 10km215min)

• Sounding station at 20 km South from the Polar 55C site of Italian Air Force

Operative dual polarization radars

FOCAL ISSUES FOR RADAR GV ACTIVITY

• GV products will be derived from dual polarization C-band radars in orographic complex contexts

• Techniques to compensate the C-band measurements for rain attenuation and to recognize the presence of ground clutter and beam occultation

• Observation of the cloud vertical structure

• Investigations with cloud-profiling radar measurements of Bright Band and microphysical features

• Polarimetric radar algorithms for rainfall estimation

• Investigation on drop size distribution and drop-shape variability are ongoing

Dual polarization observations with vertically pointing antenna

Hydrometeor Classification

Scanning Strategy for GPM GV

Conclusions

• The geographical position of Italy renders it representative of the Mediterranean climate

• GPM GV represents a strong commitment of the italian operational and scientific community

• Operational and research facilities are available for GV

• ISAC observatory is suitable for being the focal site of italian GV activities