Cirrus Measurements during the EAQUATE Campaign

© Crown copyright 2004

Cirrus Measurements during the EAQUATE Campaign

C. Lee, A.J. Baran, P.N. Francis, M.D. Glew, S.M. Newman and J.P. Taylor


Outline

Overview of frontal cirrus case on 15th Sept 2004

Aircraft remote sensing and in-situ instrumentation

Measurements and preliminary resultsARIES infrared interferometer

SWS visible and NIR spectrometer

Cloud physics probes

Summary and conclusions


IR satellite images at approx AQUA overpass times

1200 1400

Frontal cirrus case on 15th Sept 2004


12:23:26-12:29:25 13:59:26-14:05:25

AIRS (AQUA) 11m images on 15/09/04


FAAM BAe146-301 ARA Instrumentation

5 port turbulence probe

Total water probeJW Liq waterNevzerov total/liq water probeRosemount temp probes

Air sample inlets

FAGE InletCVI on other side

Deimos or IR Camera

TAFTS ARIES

Cloud Physics Probes

Cloud Physics Probes

MARSS

SWS on other side

BBRs

LidarSHIMS

Upward and Forward Video Cameras

BBRs

SHIMS

Rearward and Downward Video Cameras

ADA on other side

Dropsonde on other side


Remote Sensing instrumentation on FAAMon 15/09/04

Instrument Type Spectral range

SWS Short Wave Spectrometer 0.3 - 1.7µm

ARIESAirborne Research Interferometer Evaluation System 550 - 3000cm-1

MARSSMicrowave Airborne Radiometer Scanning System

89 - 183GHz (upward and downward)


In-situ instrumentation on FAAM

Core Chemistry O3, CO, NOxy, SO2

NephelometerTotal scattering and hemispheric backscattering coefficient at three visible wavelengths (450, 550 and 700nm)

SID1 Small Ice Detectors. Spherical Equivalent size spectrum (1 - 50µm)

PCASPAerosol Size Spectrum optical probe. Aerosol particle concentration, mean volume radius and size spectrum (0.1 - 3µm)

2DCTwo Dimension Cloud particle imaging probe. Particle number concentration, condensed water content, mean volume radius, precipitation rate and size spectrum (25 - 800µm)

2DPTwo Dimension Precipitation particle imaging probe. Particle number concentration, condensed water content, mean volume radius, precipitation rate and size spectrum (200 - 6400µm)

AVAPS (Dropsonde)Airborne Vertical Atmospheric Profiler System (Dropsonde). Profiles of pressure, temperature, relative humidity, wind speed and direction

Johnson Williams Liquid Water Content Probe Concentration of liquid water in clouds

General Eastern Hygrometer Water Vapour (damp atmosphere)

Nevzorov Liquid and Total Water Content Probe. Liquid and total water in clouds

TWC Total Water Content Probe Water (H2O)

FWVS Fluorescence Water Vapour Sensor Water Vapour (dry atmosphere)


FAAM BAE146 flight track


Aircraft profile

0

2000

4000

6000

8000

10000

12000

9:25:00 10:37:00 11:49:00 13:01:00 14:13:00

Time

Hei

gh

t [m

]

Take Off

Transit at FL280

Profile 1 Run 1 Profile 2

2 orbit

s

500 ft/min

1000 ft/min

P 3 R 2 P 5R 2.2 P 4 R 4R 3 R 5.2Run 5.1


ARIES average spectra at overpass 2

210

220

230

240

250

260

270

280

600 700 800 900 1000 1100 1200 1300 1400

Wavenumber [cm-1]

Bri

gh

tnes

s Te

mp

erat

ure

[K

]

start of runend of run


ARIES BTs at select wavelengths during run at 2nd overpass

230

235

240

245

250

255

260

265

270

13:58:45 14:00:45 14:02:45 14:04:45 14:06:45

Time

Bri

gh

tnes

s Te

mp

erat

ure

[K

]

0

2

4

6

8

10

12

14

B

rig

htn

ess

Tem

per

atu

re [

K]

8um10um11um12um8um-12um


Modelled IR and ARIES data

Extinction optical thickness=3.7

Re=46um

210

220

230

240

250

260

270

700 1200 1700 2200 2700Wavenumber [cm-1]

Bri

gh

tnes

s T

emp

erat

ure

[K

]

ARIES 10 cm-1 res

Edwards-Slingo Model


SWS nadir example spectra for thin and thick cirrus

0

50

100

150

200

250

300

0.4 0.6 0.8 1 1.2 1.4 1.6

Wavelength (um)

Rad

ian

ce [

W/m

2 /ste

r/u

m]

thick cirrusthin cirrus


SWS radiance variation through the flight

0

10

20

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11:00:00 11:30:00 12:00:00 12:30:00 13:00:00 13:30:00 14:00:00

Time

Rad

ian

ce [

W/m

2 /ste

r/u

m]

0.87um1.6um

Orbitszenith zenith zenithnadir


SWS radiance measured during the 2 orbits banked at 45 deg

0

50

100

150

200

250

300

0 20 40 60 80 100

Scattering angle [degrees]

Rad

ian

ce [

W/m

2/s

ter/

um

]

Orbit 1 at 0.87umOrbit 2 at 0.87umOrbit 1 at 1.6umOrbit 2 at 1.6um


Phase functions

6-branched bullet-rosette

Dist=0.12

=0.87 μm

Orbit 1 Orbit 2


Phase functions

Polycrystal (Macke et al. 1996)

Dm=100 μm for all ice crystals

Orbit 1 Orbit 2

=0.87 μm

First Results – Scaled Radiances at 10o - NO multiple scattering


Phase Functions

Analytic Phase function g=0.70 (Baran et al. 2001)=0.87 μm

Orbit 1 Orbit 2


Phase functions

Orbit 1 Orbit 2

=1.60 μm Polycrystal

50 μm100 μm800 μm


Cloud Physics in-situ observations

Full analysis still needs to be performed

Graupel

No larger than 200um diameter seen in flight

50 to 200/litre


Summary and conclusions

Remote sensing and in-situ measurements have been obtained using FAAM BAE-146, for a frontal cirrus case on 15 Sept 2004, coincident with 2 AIRS (AQUA) overpasses.

The effective particle radius is larger than 50um, of graupel (non-symmetrical) type, with a large variability in optical thickness.

The analysis of this data set is on going.

It demonstrates the importance of using coincident observations at wavelengths from visible to submm, to determine a wide range of cirrus parameters and check the physical consistency of the models.

Future flights - CASEAR campaign based in UK in Nov 2005, May 2006 and July 2007, coincident with Chilbolton radar, AQUA, Cloudsat.


Acknowledgements

FAAM

Direct Flight

BAE

Met Office instrument operators

Walter Wolf

Dave Pollard


Visible MSG satellite images at AQUA overpass times on 15 Sept 2004

1230 1400

Frontal cirrus case


AIRS 8m -12m for 2nd overpass

13:59:26-14:05:25


Phase functions

Distorted Aggregate (Yang and Liou 1998)

Dist=0.13

=0.87 μm

Orbit 1 Orbit 2

Cirrus Measurements during the EAQUATE Campaign

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