analysis of the composition of clouds with extended polarization techniques
DESCRIPTION
Analysis of the Composition of Clouds with Extended Polarization Techniques. L. Pfitzenmaier, H. Russchenbergs group (TU Delft) TROPOS , Germany KNMI METEK, Germany. Motivation. Ice particle within mixed-phase clouds growth processes(L. Pfitzenmaier , TU Delft) - PowerPoint PPT PresentationTRANSCRIPT
Remote-sensing of the environment (RSE)
ATMOS
Analysis of the Composition of Clouds with Extended Polarization
Techniques
L. Pfitzenmaier, H. Russchenbergs group (TU Delft)TROPOS, Germany
KNMIMETEK, Germany
ATMOS
DelftUniversity ofTechnology
2Remote-sensing of the environment (RSE)
•Ice particle within mixed-phase cloudsgrowth processes (L. Pfitzenmaier, TU Delft)shape categorisation (A. Myagkov, TROPOS, Germany)
•Why?• Process important for
precipitation formation• Gap between theory and observations of those processes/clouds• Improve mixed-phase cloud observations
Measuring in Cabauw
Motivation
< 0⁰C> 0⁰C
ATMOS
DelftUniversity ofTechnology
3Remote-sensing of the environment (RSE)
•Ice crystals• Shape: not spherical
• Pristine ice crystals• Aggregates• Graupel
• Phase: solid• Size: mm – cm • Lower concentration
< 100 cm-3
•Super cooled cloud droplets• Shape: spherical
• Phase: Liquid• Size: ~ 10 mm• High concentration
100 – 1000 cm-3
Microphysical description of mixed-phase clouds
Liquid phase & ice crystals
Mixed phase clouds:Mid-level clouds (~3 – 7 km) -40 ⁰C < Temperature < 0⁰
ATMOS
DelftUniversity ofTechnology
4Remote-sensing of the environment (RSE)
•Ice crystals• Shape: not spherical
• Pristine ice crystals• Aggregates• Graupel
• Phase: solid• Size: mm – cm • Lower concentration
< 100 cm-3
•Super cooled cloud droplets• Shape: spherical
• Phase: Liquid• Size: ~ 10 mm• High concentration
100 – 1000 cm-3
Microphysical description of mixed-phase clouds
Liquid phase & ice crystals
Mixed phase clouds:Mid-level clouds (~3 – 7 km) -40 ⁰C < Temperature < 0⁰
Synergy of instruments to measure the whole cloud system
ATMOS
DelftUniversity ofTechnology
5Remote-sensing of the environment (RSE)
Why Cabauw..?
•Instrumentation at Cabauw:• TARA ice phase & growth categorization
processes• CAELI liquid layer detection• Cloud radar ice and liquid• Radiometer liquid layer• Wind profiler vertical dynamic (Doppler spectra?)
ATMOS
DelftUniversity ofTechnology
6Remote-sensing of the environment (RSE)
Transportable Atmospheric Radar – TARA
•S-band profiler: • f=3.298 GHz, l=9.09 cm (Rayleigh-scattering)
•Fully polarimetric Shape/orientation of particles
•Doppler capability Velocity of hydrometeors•High temporal (> 3.5 s) and spatial resolution (> 3 m)
small scale processes
•Sensitive to large hydrometeors (size)• Precipitation (drizzle, rain, snow, hail)• Ice crystals • NOT TO CLOUD DROPLETS (~10 mm)
Direct measurement of the ice phaseUse of a second instrument to get information about the liquid phase
ATMOS
DelftUniversity ofTechnology
7Remote-sensing of the environment (RSE)
CESAR cloud, aerosol, and water vapour liadr - CAELLI
•3 wavelength Raman lidar • 1064 nm, 532 nm, 355nm – • 2 Raman channels: 387 nm and 607 nm• Water vapor channel 407 nm• Depolarization channel 532 nm
• extinction coefficient • backscatter coefficient• depolarization ratio
•High special resolution (7.5 m)
•Sensitive to small particles• Aersols • Cloud droplets
Information about liquid water layers within mixed phase clouds
ATMOS
DelftUniversity ofTechnology
8Remote-sensing of the environment (RSE)
Raman Lidar – CAELISensitive to particle
concentration Radar – TARASensitive to particle
size
Measurement set up Cabauw
𝛼≈∫0
∞
𝑛 (𝑟 ) 𝑟2𝑑𝑟
a : extinction coefficientn(r) : droplet number concentrationr : droplet radiusZ : reflectivity
Donovan and Lammeren, 2001
Y. Dufournet PhD Thesis
Microwave radiometerGives values of the liquid
water path (LWP) the amount of liquid
water present in the cloud system
𝑍 ≈∑𝑖=1
𝑁
𝑟 6
ATMOS
DelftUniversity ofTechnology
9Remote-sensing of the environment (RSE)
Why Cabauw..?
•Instrumentation at Cabauw:• TARA ice phase & growth categorization
processes• CAELI liquid layer detection• Cloud radar ice and liquid• Radiometer liquid layer• Wind profiler vertical dynamic (Doppler spectra?)
LACROS (Leipzig Aerosol and Cloud Observations System) More information on the liquid phaseFounded by ACTRIS-TNA and TROPOS
More instruments needed
ATMOS
DelftUniversity ofTechnology
10Remote-sensing of the environment (RSE)
Leipzig Aerosol and Cloud Observations System - LACROS
•Cloud radar – Mira 35 STAR mode scanningshape categorization of ice particlesscanning strategyliquid phase information
•Microwave radiometerliquid phase information
•Ceilometer Cloud base•Distrometer Rain droplet sizes•Raman lidar – PollyXT (of zenith pointing)
liquid layer detectionruns automatically – 24/7
•Doppler lidaranalyze the dynamic at cloud base
•Cloud radar – Mira35 vertical pointingComparison with other radars
•Radiosounds•Aircraft...?
TARA
Caeli
MWR
Doppler-lidar
LACROS
Mira35
ATMOS
DelftUniversity ofTechnology
11Remote-sensing of the environment (RSE)
Goals of ACCEPT
•Categorization of the ice phase in mixed-phase clouds• characterize of ice particle growth processes• testing the Mira35 STAR mode radar
•Comparison of radar measurements• comparison of particle shape measurements• TARA and Mira35-STAR mode
• sensitivity studies
•Cloud measurements with CAELI• compare with PollyXT measurements
•Creating a data set where also other studies could be doneOpen data base
More about scientific work Poster
Remote-sensing of the environment (RSE)
ATMOS
TARA – S-band precipitation radar
CAELI – Raman lidar
Wind profiler
Cloud radar - KNMI
Mira35 – STAR mode cloud radar
Mira35 – LDA mode cloud radar
PollyXT – Raman lidar
Doppler lidar
Microwave radiometer
Distrometer
Ceilometer
Radiosounds
• date: 6-10 – 16-11-2014
• Information about campaign:
http://atmos.weblog.tudelft.nl
• open data base
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