Cirrus C’loud Properties and Detection..

K.N. Lieu, S.C. Ou, Y. Takano, N; Rae,P. Yang, and B. Barkey

University of Utah

● Light Scattering by Ice CrystaIs: Remote Sensing Implications

● Recent Development of Light Scattering by Ice Crystals

● Remote Sounding of the Optical and Blicrophysical Properties

of Cirrus Clouds Using AVHRR Data

\

‘-’&3

“<

co.-Gc

103

102

10’

s11-

10-’

———————Cirrostratus

——— —— Ice spheres

Laborato~ Data for ColumnsuVolkovitsky et al. (1980)

k = 0.65 pm

\

\/’

\ I

\ /\ .//’

II

1 OzI 1800

Sca;;ering Angle (d~gree)

Sa+ell;te RemOti SensinJ ,.

13

6

Fig. 2.

I

N=15 00 “

.9

I I6 7 8 9 10 11 12 13

LIDAR CLOUD CENTER (km)

Comparison of surface I.idar and satellitederived cloud-center heighk over Parsons, KS. ( ~f’t’er M/”nn}~et ●!~t~fz )

n

x-

i

●

6

5

4

3

2

1

0

/

/

/

/

/

“*” ●“k

/

f

{/

/ /●.4... .

. . /. .

,.:{ /

. .. /.*

“-z. .. . . f /

/

Spheroid~exagon //

(V=3 & V-5) /

:irrus /

Sphere

/

/

/

( I 1 I 1 I.

1 2 3 4 3

111.16 - T12 (K)

;

,.

Zenith Angie, @ (deg)

o 90I i I I I I I I I I 1 I I 1

+-+.=180° +-+O=U”

II \

—

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. . . . . . . #measurement (Ci~*fi&7*I I I I I I I I I I I I I I I I I *

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0 60 120 18~phase Angle (deg)

c.

(

CLOUD TEMPERATURE (“c)

- 0’0”0959:55 0959:57

2.00

-9 -; 4 -9 -134 -9 -13”4

‘1

~~

0959:53

0 ALTITUDE (km )

~

1000:018“2”

M24 3’0

Fro. 4. Lidar field data (from ~lall et al 1~ showing Ihe considerable dacreasa in planar crystal backmttaring (in terms of Ihebackacatler coafficienl ~’) ana increasein’linear ~polarizalion (A used hare) as the lidar is scanned gfl the vertical direction (note thetirtad lima~ and lidar angles from the vertical direction), The cloud temperatures are within the expectad range for piate crystals, andan aanal sighting Of a subsurr conlirmad Wr uniform horizontal orientations,.— - —. .—-—. -. .. . .

Solid Column Solid Plate7’

Hollow Column- Dendrite

++

Fig. 2.

Bullet Rosette

Aggregate

The second and fourth columns &pict the

cbuds. The first and third

geometric model Our current

of “~e crystals includes all the

discussion).

Double Piate

o8*m,,*s,Quasi-spherical

ice crystal shape observed in cirrus

wbmns represent the shape simulated from a

capability of Aing I“ght scattering and absorption

shapes, except the aggregate (see text for further

10”

10

~o:: 10’L

u’$

f 10”

CL

1(J

10;

+“ 02

(a) A.= (~<r i,m

1./2a = ?rtn/ROum

14c,llnw(rJ.50pm) ~

—- Sollrl E

J I 1

0 60 I 20 180

(b)

——— —

(c) k = 0.55 pm

——.#

U2a= 120148pm

— ~ L/2a.200/80pm

L

\1~\

\ .-‘-\

0 60 120 180

Scattering Angle (degree)

(d)

——— —

I I b

o 60 120 180

ScatteringAngle (degree)

e) k = 0.55 pm

—.

@L/2a= 32/80pmbb= 121tm, bt=40p

– @ L/2a.32/8opnl

0 60 1?0 180

(f)

\1 I

(? 60 120 180

S,:atten~,] Anqle (clegree~ ‘

Fig. I Phase function and degree of linear polarization ab functions of the scattering angle for hollow columns (a and b), bullet rosettes

(c and d), and dendrites (e and f). The wavelength and the sizes of these ice crystals are depicted in the figure, where

hollow depth and bt and bb are the height and width (along the side of the plate surface) of the branches of a dendrite.d is the

.

t “-

*.

P - 9 $**”. P’w ..

i. ●●

T+”+:.””~~”,.. .. . ..

,’ . . .“:-+ :.’ ‘ -:”

$..e . ..*. “. -“””:. “,-:;,:: . . ..

w, . .. . . ~“.>,:”..:..”..< ,.. .. :-~._ -. . .“.. + . .

.4-..

&“””““.>...?

.g<d

. .-. —- .—

1iI

“i—

i

I

I

I

I

I

.

(a)

(b)

Light Scattering by Small Ice Crystals

100

n=z 10. m=l .31 + iO.Oo1=u ka=20z3uw

1-,m$

— FDTD

aa ...... GOM2~ o.1-i<

z0 :.:

z 0.01.

0.001 ,,,

Fig. 3

,,, ,.0 20 40 m Bo 100 120 140 160 Ieo

SCATTERING ANGLE ( 0 )

n=z 10 m.1.31 +iOO

oFg ka=40

3uw 1:rna

— FDTD

Ino .... GOM2

2

$

g001.

.=.

Oml I I I 1 I 4 ( 10 20406000100120140160 1

SCATTERING ANGLE ( 0 )

0

(a), The conceptual diagram for the scattering of waves by a small hexagon using thegeometric ray-tracing for the computation of the near field. The far field results are deteminedexactly by means of the electromagnetic wave theory. (b). Comparison of the phase functionsfor 2-D hexaaonal ice columns com~uted from the finite difference time domain (FDTD) and thenewgeomet;c optics model (GOM”2) for the size parameters of 20 and 40. ResuHs “from thetime consuming FDTD are considered to be exact (Yang and Lieu. 1994).

4rn=l.31+i0.0 FDTD

. GOM2

-- GOM1

“~— I-lJlu

m=l .31 +iO.O

3.5- ● GOM2

O;. !l’’’’ l’’’’’’’’” I

10 15 20 2530 35 40

24 I

TM POLARIZATION -- GOM1g

L

z

8f

TE POLARIZATION - -GOM1

I

16 ● 0(n

0.5-o~o10 15 20 25

2,

IJ-1.5:

-1.5-1

I -2 I I I I-2 - I I I I

io 15 20 25 3035 40

10 15 20 25 30 35 40

SIZE PARAMETERSIZE PARAMETER

— —

REMOTE SENSING OF CIRRUS

(CLOUDS: SCIENTIFIC OBJECTIVES

● Development of a retrieval scheme for the inference

of cirrus cloud parameters, including mean effective

ice crystal size and visible optical depth based on the

principle of radiative transfer and

parameterizations using the scattering and

absorption properties of hexagonal ice crystals and

AVHRR data, in particular, the 3.7 and 10.9 pm

channel radiances. (Ou et al., Applied Optics, April,

1993)

“ Removal of solar radiance in the 3.7 pm channel

data for application

on the correlation

channel radiances.

November, 1994)

to daytime cloud retrieval based

betw’een the 0.63 and 3.7 pm

(Rao et al., J. Appl. Meteor.,

● Verification of the retrieved cirrus cloud parameters

using available balloon-borne replicator and

sounding observations (FIRE-11-IFO).

“ Application of retrieved cirrus cloud parameters to

the computation of surface radiative fluxes using a

detailed radiative transfer model (Fu and Lieu,

1992, 1993), and comparison with ground-based

radiometer measurements. \

Algorithm Development(AVHRR Chs. 3 and 4)

● Upwellingradiances

observed,?

B(q) (l-E)Ia,.

////////////L

13 = 1=3(1- E3)+ E3B3(TC)

tIa

14 z IU4(1- E4) + E4B4(TC) > //’////’/////////’/// /

%4 = cirrus cloud IR emissivities9B3,4 = Planck intensities

Ia3.4 = upwelling cloud-base radiances

(1) Correlation between B3 and B4

(2) Parameterization of IR emissivities

&34 = 1 –exp(–k34T),9T = visible opti;al depth

Ed = 1 -(1 - &3)k”k’,k4/k3 = effective extinction ratio

Tc

(3) Evaluation of 1,3,4 from three-dimensionaldisplay of the frequency of occurrence of theAVHRR radiance pair(~3,]4)

Solution equation for cloud temperature

..

Ice crystal mean effective size is defined by

D = ice crystal width,~ = maximum dimension.

Based on radiative transfer calculations, &/k3 isparameterized in terms of I/D; as follows:

k4/k3= ;b,, (1 / De)”*co

From cloud microphysics measurements and theretrieved optical depth:

De = {T/[Az(~+~/De)IWC]]ED,Retrieve ~c and E from Chs. 3

and determine Deand T fromequations

and 4 radiances

parameterization

\

ALGORITHM DEVELOPMENT(Continued)

Ice crystal mean effective size is defined by,.

D = ice c~stal width, ~ = maximum dimension

Based on radiative transfer calculations, &/k3 isparameterized in terms of I/D, as follows:

k4 /k3 = ~b,l(l/De)n

3.5

2.5

2

1.5

1

\

Heymsfield & Platt (1 984)

Takano & Lieu (1989)

FIRE-I-IFO Measurement 1986)

■

■

o 50 100 150

De (Pm)

Kb.410J’AL OF SOLAR COSIPOX-ENT

IN THE 3.7 pm RADIANCE

Solar Reflectance for Chs. 1 (0.63 pm) and 3 (3.7pm)

,,

Construction of a Look-up Table ReIating r] and r3

Radiative transfer program (Takano and Lieu, 1989)

Sun-satellite geometry

Mean effective ice crystal size

0.126.=71°, 6=40’,4)= 146-

Cold Cirrus (23.9 pm). Ral =0,12, Ra3=O,M6

0.08

$/ t

:l~m Cirrostratus (41.5 pm)m

m I

D D m m8

‘0”04[~. .Nov. 1 (75.1 pm)

I

A 4w w NOV. 2 (930 pm)

FCi Uncinus (123.6 pm)

nu t I I I I

o 0.2I

0.4 0.6 0.8Ch.1 Reflectance

Verification (FIRE I IFO)

(a). Mean values of the retrieved Tc, E3, E4, r, k4/k3, De, and ZC for

cirrus pixels within a l“xl” ‘“scene westUTC, 28 October 1986, along with observed

of Fort McCoy at 0930

values.

Parameter Observation Retrieval

Tc (K) ..- 244 (233-255)

&3--- 0.36 (0.17-0.70)

&4 --- 0.42 (0.20-0.76)--- 1.08 (0.41-2.77)

k4;k3 --- 1.25 (1.07-1.44)De (pm) 107 (King Air) 104 (68-156)

ZC(km) 6-8 (Lidar) 7.5* (6-9)

* based on the Fort McCoy sounding at 0930 U’T’C.

(b). Cirrus cloud temperature, cloud height, and optical depth

determined from the present retrieval program.

TC(K) zC(km) TLocation present lidar* present lidar* present GOES*

Wausau 226,5 230.7 9.5 9.0 1.54 1.43Fort

McCoy 229.7 226.5 9.1 9.5 1.5 1.41

Madison 225.6 228.1 9.6 9.3 0.6 0.56

*from Minnis et al. (1990) using lidar and GOES data at 2100UTC, October 28, 1986

.

— -.,10 19 20 21 22 2:1 24 —-.–.–-L.—- r,!........./t,f-l.,, 1 ,..’

37.25

37.15

36.85

Satellite Data and Retrieval Results at2108 UTC, 5 December, 1991

1280

270

260

250

> 240.{.:

~30

220

36.7595.8 95.6 954 95.2 950 948

Longitude (’W)

13.0

2.5

.;.. 2.0

.’,,

:, 1,5

1.0

0.5

0.0

95.8 956 95.4 952 950 948

Longitude (’W)

37.25

37.15

36.75

95.8 95.6 954 952 950 948

Longitude (W)

(b),, (a)

Fig.1.

(1) Cl:small, quasi-spherical z = 12.96 kmT = -65.4 “C

(3) A: columns+ bullets+roseltes z = 11.32 kmO: quasi-spherical, irregular T = -54.5 “C

,6‘Y

-\1 I t I 1

(4) A: columns+ bullela+plalea z = 9.77 km

O: quasi-spherical, irregular T = -42.7 “C

(5) O: sublimated, irregular z = 9.64 kmT = -42.5 “C

0 100 200Maximum ~~msion (p%~

500 600

1

0.1

E~ 0.01

c

0.001

O.ml

1

0.1

z

‘~ 0.01

c

0.001

0.0001

b Dec. 5

●: smoothed.>: raw data

0s 50%AG 30%

C, P, BR 200/0

o 100 200 ‘+ 400Maximum3D%meter (pm)

500 600

INov. 26

c: smoothedo: raw data

Qs 59%

AG 37%

C, P, BR 470

0 100 200 300 400 500 mMaximum Dimension (pm)

(a). Five representative ice crystal size distrfbutims derived from the replicator sounding on 5 December 1991 during FIR E-11-IFO. (b). Averaged icecrysatal size distributions and smoothed curves for 5 December and 26 November data sets. The percentages of shapes for each distribution are also

shown: QS denotes quasi-spherical particles, including frozen droplets and distorted plates and columns; AG, C, P, and BR denote aggregate, column,plate and bullet rosette, respectively.

Schematic diagram of replicatorsounding system

95.8 95.6 95.4 95.2

Longitude (OW)

95 94.8

(a) RELATIVE HUMIDITY (%)

o 40 80 12016 I I

[ :k14 ““”....#

......

I

Cloud Top.---- A&. ----- ----- _____ _

..12 ....O

_loEx

4

“T......,...L

.....”----- ---=- .- ”___ L-----__________.. ~

~“”””-”l--xudBa:ir’.. R.H. j

NbAti-GIA. . . . . . .

~ Retrieved Tc (average...4. . of 81 pixels):#,.. * 10.9pm BT..“-.. . . .

. . . . . . . . .. <1\ ..”,. . . . . . . . . .

...”

2 -......,...................................................

0 I T“ 1 ,,,1-

-100 -80 -60 -40 -20 0 20TEMPERATURE (“C)

16

14

12

_loEx;B

$iii16

4

2

0

(b) MEAN EFFECTIVE SIZE (De, pm)

o 40 80 120 160 200 240

.- —_____ _____0.

1[1-----___

‘..

‘*, I Columns, bullet

i rosettes, and

‘k.: quasi-spherical

crystals

i “wSublimation zone----- _____ ___ M-- ----------

Cloud BaseI

i

● : De from replicator data

I : De from replicator data weighted

by number densityT : De from retrieval

A : T from retrieval

o : T from replicator data

7OA

1 1 I I i

0.6 0.8 1 1.2 1.4 1.6 1.8VISIBLE OPTICAL DEPTH

Ftg. 5. (a). Temperature and humidity profiles obtained fmm the NCAR-CLASS sounding system on 5 December 1991. Overlapped with the

temperature profile are the mean retrieved cloud temperature and mean Ch. 4 brightness temperature over a 0.05° x 0.2° domain

around tiffeyville. (b). Display of the replicator-derived mean effective sizes at the selected height levels, their verlical average, and

the retrieved value. Also shown on the bottom scale are the optical depths derived from the replicator data and from the retrieval.

Radiation hlodel

● Radiative Transfer

Delta-four-sUeam (Lieu, et al., 1988)

.Application to nonhomogeneous atmosphere (Lieu, 1975)

● Nongray Gaseous Absorption in Scattering AtmosphereCorrelated k-distribution approach (Fu and Lieu, 1992)

Spectral Intervals: 6 solar and 12 IR bands (Fu and Lieu, 1993)

● Single-Scattering Properties of Hydrometer

Hexagonal ice crystal (Takano and Lieu, 1989)

Water droplet (Fu, 1991)

Rain, Snow, and Graupel

● Vectorized Version on Supercomputer

FIRE-11-IFO (December 5, 1991)

400 ‘a)‘E~ 380‘!

320

300I

A

A

•1

●

o

NOAA radiometer

Model simulations:

satelltie cloud parameters

replicator cloud parameters

cloud climatology

black cloud at 255 K

clear

4

260 I I I I

20 20.5 21 21.5 22

nKa 2503

g 200”

a

(b)

o

w~ 150 :Lu~ 100 I I

20 20.5 21 21.5 22

TIME (UTC)

FIHE-11-IFO (November 26, 1991)

(a) RELATIVE HUMIDITY (~0)

120

“o~

. 12

10

4

2

:. f

..... NCAR-CLASS

“.....

A.,.. -

....+.

......

-----------

.....

..... .

.... . . . .

. . . . . ..-.. . . . . . . . . . . . . . . . . . . . . .. .

b-____+ -----t.;.. . . . . . . . . . . . . . . . . . . . . .

...... . . .... . . . . . . . .

.. . . . . . . . . . .. ..#...

. ..-.. . ...

. . . . . . . ... ... ..

J.. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . ..

...”.. . . ... ... . . .... .

....”.>:......I I I I I

:100 -80 -60 -40 -20 0 20TEMPERATURE (°C)

(b) MEAN EFFECTIVE SIZE (De, pm)

12

10

8

6

I ● : De from replicator data

4 I :De from replicator data weighted !

t:

by number densityT : De from retrieval 1

:~

o 1 2 3 4 5

VISIBLE OPTICAL DEPTH

FIRE-11-IFO (November 26, 1991)

460(a)

A

A

❑

+

o

Obse watio~:

NOAA radiometer

Mod el simulations:,.

satellke cloud parameters

repl’~ator cloud parameters

cloud climatology

black cloud at 248 K

clear

oI I I

20 20.5 21 21.5 22

(b)

w:150

Lu~ 100

20 2120.5 21.5 22

TIME (UTC)

Future Research

..

● Light Scattering by Small Xce Crystals (10 < a < 30)

c Validation: Remote Sounding of the Cirrus OpticalDepth and Ice Crystal Size in Cirrus/Low CloudConditions

● Development of h’ew Techniques for the Determinationof Ice Crystal Sizes Using 1.6 pm and VisibleWavelengths

——--- .—