Cloud Properties Retrieved by MIDAS from Near-Infrared Scattered Sunlight Spectra

John S. DanielNOAA Aeronomy Laboratory

ICARTT J31 Data Workshop9, 10 March 2005

Boulder

Outline

I. Background: Differential Optical Absorption Spectroscopy

II. Gulf of Maine - July 9, 2004

III. Barrow - September 14, 2004

foreground

€

I frg = I bkg exp − σ i n i sii

∑ ⎛ ⎝ ⎜ ⎞

⎠ ⎟

− lnI frg

I bkg

⎛ ⎝ ⎜

⎞ ⎠ ⎟ = Fλ

smooth Δ σ i n i s ii

∑ ⎛ ⎝ ⎜ ⎞

⎠ ⎟

Direct and optically thin diffuse

DOAS

€

I = I0exp − n

iσ

is

ii

∑( )

e.g., NO2, OClO, BrO

Additional Considerations• scattering affects the amount of absorber in cloud “seen” by transmitted and reflected photons

• intensity observations reflect the impact of the absorber amount and the effective path length through the cloud

€

I = I0 p l( )exp −lγ( )dl0

∞

∫

€

p α , x ; x( ) =1

Γ α( ) x /α( )α xα −1 exp −

αxx

⎡ ⎣ ⎢

⎤ ⎦ ⎥, x > 0

Equivalence Theorem

Photon PathDistribution

OpticallyThickClouds

€

I frg = I bkg exp − σ i n i sii

∑ ⎛ ⎝ ⎜ ⎞

⎠ ⎟

− lnI frg

I bkg

⎛ ⎝ ⎜

⎞ ⎠ ⎟ = Fλ

smooth Δ σ i n i s ii

∑ ⎛ ⎝ ⎜ ⎞

⎠ ⎟

Simple DOAS No Longer

€

R λ( ) = Fλ

smoothS⊗ K ′ λ ( )F λ − ′ λ ( )d ′ λ

−∞

∞

∫

S⊗ K ′ λ ( )B λ − ′ λ ( )d ′ λ −∞

∞

∫

€

F λ( ) = exp − 1− f( ) σvn

v , f+ σ

O2n

O2 , f+ σ

CO2n

CO2 , f( ){ } ×

α f

α f α f + eL

γL

ρL

LWPf + eI

γI

ρI

IWPf + f σ vnv , f + σ O2nO2 , f + σ CO2

nCO2 , f( ) ⎡ ⎣ ⎢

⎤ ⎦ ⎥−α

Zenith-Looking Summary45° SZA

0 500 1000 1500 2000LWP (g/m2)

0.0

0.5

1.0

1.5

0 500 1000 1500 2000LWP (g/m2)

0

5

10

15

20

0 10 20 30 40 50LWP (g/m2)

1.01.21.41.61.82.0

0 50 100 150 200LWP (g/m2)

0.0

0.5

1.0

1.5

Clo

ud P

ath

Clo

ud P

ath

Instrumentation7 Fixed-Grating Spectrometers

fiber optically fedcoverage ~290 - 1680 nmresolution ~0.3 - 6 nmFOV: ~10°

Liquid and Ice Sensitivity

3.0

2.0

1.0

0.018001600140012001000

Wavelength (nm)

0.01

0.1

1

10

LiquidIce

Vapor

1000 1200 1400 1600 1800Wavelength (nm)

0.0

0.2

0.4

0.6

0.8

1.0

Liquid

1000 1200 1400 1600 1800Wavelength (nm)

0.0

0.2

0.4

0.6

0.8

1.0

LiquidIce

1000 1200 1400 1600 1800Wavelength (nm)

0.0

0.2

0.4

0.6

0.8

1.0

LiquidIceVapor

1000 1200 1400 1600 1800Wavelength (nm)

0.0

0.2

0.4

0.6

0.8

1.0

LiquidIceVaporO2, O4, CO2, CH4, Continuum

O4

O2, O4

CO2

CO2, CH4

Path-IntegratedQuantities

Forward Model

Disort 2.0Liquid- and mixed-phase

Absorbers/scatters

Theoretical Approach

Vapor, liquid, ice, CO2, O2, O4, CH4

800 1000 1200 1400 1600 1800Wavelength (nm)

0.0

0.2

0.4

0.6

0.8

1.0

Spectra

Optimal Inversion

€

xi+1=xa+SaKiT KiSaKiT+Sε( )−1y−Fxi( )+Ki xi−xa( )[ ]

€

ˆ S =Sa−Saˆ K T Sε +ˆ K Saˆ K T( )−1ˆ K Sa

Intercomparison

1 10 100 1000LWP (g/m2)

0.8

1.0

1.2

1.4

1.6

Rodgers

1 10 100 1000

LWP (g/m2)

0.00

0.05

0.10

0.15

0.20

Stan

dard

Dev

iatio

n/C

orre

ct V

alue

Strong

MediumWeak

Effect of Random Noise - Liquid Cloud

3.0

2.0

1.0

0.018001600140012001000

Wavelength (nm)

0.01

0.1

1

10weak

strongmedium

Field Campaigns

ARM SGP, OklahomaOctober, 2003

New EnglandSummer, 2004

ARM NSA, Barrow, AlaskaSept/Oct, 2004

GOES EAST, 9 July 17:45 UTLongitude

Latit

ude

July 9, 2004

Gulf ofMaine

0.300.25

0.200.15

0.100.05

0.00

LWC

17:001/1/04

17:30 18:00 18:30

Time

Time

Pre l

imin

a ry

P-LWP Retrievals

Preliminary Liquid Results

Arb

itra r

ily S

c ale

d

14

1210

8

64

2

μμ

16:301/1/04

17:00 17:30 18:00

Tiμe

FSSP vs MIDAS (Reff)

Cloud Retrievals: P-3

Courtesy: P. Pilewskie

ICARTT Plans

MIDASSSFR

FSSP

Remote Sensing Observations

In Situ

Microwave RadiometerRadar

P-3 Ron Brown

Provide a Liquid Water Path / Effective Radius Comparison

ICARTT Plans

MIDASSSFR

FSSP

Remote Sensing Observations

In Situ

Microwave RadiometerRadar

P-3 Ron Brown

Provide a Liquid Water Path / Effective Radius Comparison

Barrow, AK, Installation 2004ARM NSA Facility

MWR/AERI comparisonM-PACE

Comparison to Microwave Radiometer

Barrow, AK, 14 September 2004

LWP

(g/m

2 )

Time (ADT)

10 11 12 13 14 15 16 170

50

100

150

200

250

300preliminary

12.0 12.5 13.0 13.5 14.00

50

100

150

200

250

300

10 11 12 13 14 15 16 17

0

50

100

150

200

250

300

Time (ADT)

LWP

(g/m

2 )

preliminary

What About Ice?

Millimeter-WavelengthCloud Radar

PIW

P, I

WP

(g/m

2 )

Qualitative Ice Comparison - Spectral vs. Radar

14 Sept 2004, Barrow AK

10 11 12 13 14 15 16 17-100

0

100

200

300

400

500

Time (ADT)

Radar IWC = a Zb

ShebaMatt Shupe

preliminary

PIW

P (g

/m2 )

Ice Retrievals

16.0 16.2 16.4 16.6 16.8 17.0

0

200

400

600

800

10 11 12 13 14 15 16 17-100

0

100

200

300

400

500

Time (ADT)

preliminary

Example Spectra

1000 1200 1400 1600

010,000

20,000

30,00040,000

1000 1200 1400 1600Wavelength (nm)

0.5

0.6

0.7

0.8

1000 1200 1400 1600

010,000

20,000

30,00040,000

1000 1200 1400 1600Wavelength (nm)

0.5

0.6

0.7

0.8

Typical Fit Quality

PLWP: ~33 g/m2

PIWP: ~83 g/m2

1000 1200 1400 1600

010,000

20,000

30,00040,000

1000 1200 1400 1600Wavelength (nm)

0.5

0.6

0.7

0.8

No Ice In Retrieval

No Liquid in Retrieval

1000 1200 1400 1600

010,000

20,000

30,00040,000

1000 1200 1400 1600Wavelength (nm)

0.5

0.6

0.7

0.8

AcknowledgmentsSusan Solomon, Robert Portmann, Henry Miller

Ping Yang

Dave Turner, Matt Shupe

Excellent liquid and ice comparisons to microwaveradiometer and radar provide us with the confidenceto apply our technique to retrieve LWP and effective radius

Summary

• Evaluation of RT models• Aviation

• Climate research and monitoring- prevalence of cloud liquid and ice- effects on radiation field- photon path distribution for liquid=> processes and parameterizations for

climate models• Weather forecasting

- ground-based model initialization- liquid/ice partitioning

• SAR - “The single largest uncertainty in determining the climate sensitivity to either natural or anthropogenic changes is clouds and their effects on radiation and their role in the hydrological cycle.”• TAR - “… there has been no apparent narrowing of the uncertainty range associated with cloud feedbacks in current climate change simulations.”

Applications for Liquid and Ice Observations