Cloud Particle In-situ Measurements

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1. Contact

Dr. Dagmar Nagel
GKSS Research Center
Institute for Atmospheric Physics
Max-Planck-Strasse
D-21502 Geesthacht
Germany

Tel.: +49-(0)4152-871502
Fax.: +49-(0)4152-872020
E- mail: dagmar.nagel@gkss.de

2. Short Description

In-situ measurements in clouds provide several microphysical parameters which describe cloud structure and properties. While the PMS probes are used to measure particle concentration and size distribution, the Nevzorov probe measures the liquid and total water content. Both can be carried by several aircraft.
The FSSP measures the forward scattered light produced by a cloud particle passing through a laser beam (He-Ne, 632.8 nm) inside the sample volume. Particles are counted and the intensity of scattered light is a direct measure of their size (e.g. van de Hulst, H.C., Light scattering by small particles, Dover Publications, Inc., New York, 1981).
If particles pass the laser beam (He-Ne, 632.8 nm) of the OAPs inside the sample volume of the probe they shadow a line of 32 detection diodes. The shadow images are used to count the particles and to determine their size.
The Nevzorov probe is a so-called hot-wire device. Two resistors are heated to evaporate all particles that touch their surface during the flight. Due to their shape they are able to catch small droplets or droplets and ice crystals. The amount of energy necessary to evaporate particles is a direct measure of the liquid water content (rectangular sensor) and the total water content (cone), respectively.

3. Goals within 4D-clouds

In-situ measurement of microphysical cloud parameters like particle concentration and size distribution with high temporal resolution and high accuracy for:

Investigation of the influence of the calibration method on the data quality.

4. Instrument Specifications

4.1 PMS FSSP-100

Measurement quantity

aerosol and cloud particles in a size range from 0.5 to 47.0 µm diameter

Resolution

from 0.5 to 3 µm (4 ranges) 15 size channels

Sample frequency

max. 50 Hz

Power Supply

115 Vac, 50 – 400 Hz, 1.5 A, 28 Vdc, 320 W (de-icing)

Dimensions

app. 100 cm x 18 cm diameter

Weight 

app. 18 kg

Manufacturer

Particle Measurement Systems, Boulder, CO, USA, (now: Particle Metrics Inc., Longmont, CO, USA)

4.2 PMS OAP-2D2-C

Measurement quantity

cloud particles in a size range from 25 to 800 µm diameter

Resolution

25 µm, 32 size channels

Sample frequency

True airspeed dependent, typical 4 MHz at 100 m/s

Power Supply

115 Vac, 50 – 400 Hz, 1.5 A 28 Vdc, 70 W (de-icing)

Dimensions

app. 100 cm x 18 cm diameter

Weight 

app. 20 kg

Manufacturer

Particle Measurement Systems, Boulder, CO, USA, (now: Particle Metrics Inc., Longmont, CO, USA)

4.3 PMS OAP-2D2-P

Measurement quantity

cloud particles and precipitation in a size range from 200 µm to 6.4 mm diameter

Resolution

200 µm, 32 size channels

Sample frequency

True airspeed dependent, typical 0.5 MHz at 100 m/s

Power Supply

115 Vac, 50 – 400 Hz, 1.5 A 28 Vdc, 220 W (de-icing)

Dimensions

app. 110 cm x 18 cm diameter 42 cm detection system width

Weight 

app. 20 kg

Manufacturer

Particle Measurement Systems, Boulder, CO, USA, (now: Particle Metrics Inc., Longmont, CO, USA)

4.4 Nevzorov Probe

Measurement quantity

liquid and total water content range from 0.003 to 3 g m-3

Sensitivity

0.003 g m-3

Sample frequency

max. 100 Hz

Power Supply

28 Vdc, max 6 A

Dimensions

app. 25 cm x 10 cm diameter

Weight 

app. 1.5 kg

Manufacturer

Sky Tech Research Inc., Richmond Hill, Ontario, Canada

5. Products

Raw data (Level 0):
typical 50 - 80 MB per flight hour

Processed data (Level 1):
typical 1.5 MB per flight hour

6. Probe mounting

PMS FSSP-100
(Forward Scattering Probe) used on the aircraft MERLIN IV within CLIWA-Net

PMS OAP 2D2-C
(Optical Array Probe) used on the aircraft Partenavia within 4D-Clouds and on the aircraft MERLIN IV within CLIWA-Net

PMS OAP 2D2-P
(Optical Array Probe) used on the aircraft MERLIN IV within CLIWA-Net

Nevzorov Probe
used on the aircraft MERLIN IV within CLIWA-Net

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