fmcw cloud radar applications - tesscorn aerofluid rpg radiometer physics gmbh birkenmaarstr. 10...

RPG_FMCW_TN_2015.docx RPG Radiometer Physics GmbH Birkenmaarstr. 10 53340 Meckenheim, Germany

01/2015 +49 (0) 2225 99981 – 0

www.radiometer-physics.de [email protected]

All data and specifications are subject to change without notice! © Radiometer Physics GmbH 2014

FMCW Cloud Doppler RadarRPG‐FMCW‐94 (SP/DP)

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FMCW Cloud Radar Applications

● High resolution vertical profiles of dBz

● Velocity profiles from Doppler spectra

● LWC (Liquid Water Content) profiles

● 3D cloud studies (with optional scan mechanism)

● Dual-polarization option for hydrometeor classification

● Now-casting, cloud formation, fog observation

● Urban weather in metropolitan areas

● Weather modification, cloud process studies

● Operational deployments in all weather conditions

Unique Features ● High-Power transmitter with 2 W transmitted power (continuous wave)

● Low-Noise receiver with 300 K system noise temperature (equals 3 dB noise figure)

● Built-in passive radiometric channel at 89 GHz using the same optics and same LNA

● Provides radiometer-derived LWP to constrain synergetic LWC profile retrievals

● Corrects the received power by the thermal emission of the cloudy-sky (which can be significantly higher than the minimum detectable reflected power

● Radar centre frequency adjustable (software selectable) between 92.3 and 95.7 GHz (supporting a flexible application for operating permissions)

● Chirp parameters and selection fully adaptable to observation modes (high/low modes, emphasis on large Doppler ranges, or higher Doppler accuracy) by software

● Operating software with Z-LWC retrievals, attenuation correction, particle classification


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Concept ● Principle: time lag ∆ between

continuously emitted and received frequency chirps gives a spectrum of beat frequency ∆ .

● Beat frequency spectrum

contains ranging information with a resolution of ∆ /2∆ .

● Doppler shift provides velocity

profiles.

Design

● Bi-static design with shielded and accurately levelled optics (antenna decoupling < –100 dB).

● Generated HF signal is split up

into emitting and receiving branch. ● Receiving branch is mixed with signal from

amplified signal received via antenna. ● Mixer down-converts signal to IF range, where

it is filtered, amplified and digitized.


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First Measurements


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Specifications

Parameter Specification

Centre Frequency 94 GHz (λ=3.19 mm) ± 100 MHz typical, (adjustable by software between 92.3 and 95.7 GHz)

IF range 350 kHz to 3 MHz

Transmitter power 2 W typical (solid state amplifier)

Antenna type Bi-static Cassegrain with 500 mm aperture

Antenna gain 52.3 dB

Beam width 0.45° FWHM

Polarisation V (optional V & H)

Rx System Noise Figure 3 dB (300 K system noise temperature)

Typical Dynamic range (Sensitivity) with 2 W transmitter

-60 dBz to +20 dBz (at 500 m height / 5 m resolution) -50 dBz to +20 dBz (at 2 km height / 10 m resolution) -47 dBz to +20 dBz (at 4 km height / 30 m resolution) -36 dBz to +20 dBz (at 10 km height / 30 m resolution)

Ranging 100 m to 12 km typical, 16 km maximum

Maximum vertical resolution

1 m (range: 0.1 km – 0.6 km), 2 m (range: 0.6 km – 1.0 km), 4 m (range: 1.0 km – 2.5 km), 8 m (range: 2.5 km – 5.0 km), 16 m (range: 5.0 km – 12.0 km)

Calibrations (automatic) Power monitoring of the transmitter, plus Dicke-switch at receiver (for radar and passive radiometer channel)

Calibrations (maintenance) Liquid nitrogen receiver calibration, external reference sphere

A/D Sampling rate 8.2 MHz (data processing between 0.35 and 3 MHz)

Data processing system High-Performance embedded PC

Sampling rate (full profiles) 4 s typical (flexible, can be adjusted to 1 s, 8 s, etc)

Doppler range ± 10 m/s unambiguous velocity range

Doppler resolution ± 15 cm/s

Chirp variations 3 typical, 10 possible, re-programmable “on-the-fly”

Passive channels 89 GHz for integral LWP detection + radar sensitivity correction

Control connection TCP/IP connectivity via fibre optics data cable to internal PC

Operation software Real time visualization, real time data extraction, real time control (adaptive observation modes depending on context)

Data products (available as files)

Reflectivity, Doppler-velocity, Doppler Spectra, LWC profiles. Data level concept: L1: calibrated dBZ, L2: retrieved data

Data formats netCDF (CF convention), proprietary binary, ASCII

Additional sensors Automatic weather station with P, T, RH, RR, Snow, WS, WD

Scanning / mounting Baseline: Mounted on a fixed stand of 0.5 m height Optional: Scanner unit for full sky scanning capability

Dimensions (L × W × H with antennas): 115 cm × 56 cm × 82 cm (L × W × H main box only): 80 cm × 40 cm × 40 cm

Weight Approx. 80 kg without stand or scan mechanism

fmcw cloud radar applications - tesscorn aerofluid rpg radiometer physics gmbh birkenmaarstr. 10...

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