New cross sections, indices of refraction, and reflectance spectra of atmospheric interest

S. Massie (NCAR, Boulder, CO)A. Goldman (University of Denver, Denver, CO)

9th Biennial HITRAN Database ConferenceHarvard-Smithsonian Center for Astrophysics

Cambridge, MassachusettsJune 26-28, 2006

Abstract

A brief review is presented of the indices of refraction and cross sections that are on the HITRAN 2004 compilation. New measurements of therefractive indices of ternary (H2O/H2SO4/HNO3) droplets by Myhre [2003,2005] and the indices of supercooled water by Wagner [2005] are presented and compared toprevious data. New infrared cross sections of species of atmospheric interest (e.g., the measurements of HFC-125 and HFC-143a of Lonardo and Masciarelli [2000]) are also discussed.

We finally propose to link to the “other listings” portion of the HITRAN web site several established reflectance data bases, since many current and futureremote sensing experiments are influenced by groundemission and reflectance contributions.

Outline of Presentation

Discussion of new

Indices of Refraction

Cross sections

Links to Digital surface reflectance atlases

HITRAN 2004 Refractive Indices

Water, ice

Sulfuric acid (stratospheric sulfate)

Nitric acid

Solid hydrates (NAM, NAD, NAT)nitric acid mono, di, tri hydrate

Ternary solution droplets(H2SO4, H2O, HNO3)

Tropospheric (sodium chloride, sea salt, ammonium sulfate, organic soot,quartz, sand)

Supercooled Water - Motivation

Pure water – 10 m drop nucleates at -38° C

Pruppacher and Klett, Microphysics of Clouds and Precipitation, p213, 1998

Water droplet + desert dust nucleates at -15° C(Sassen, Nature, 434, p456, 2005)

Pure watersupercooling

(°C)

Drop Diameter (cm)

10 m30

40

Supercooled Water Indices

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1000 1500 2000 2500 3000 3500 4000 4500 5000

Wagner Indices of Supercooled Water

238 K252 258 269

Rea

l In

dex

Wavenumber (cm-1)

0.0

0.1

0.2

0.3

0.4

0.5

1000 1500 2000 2500 3000 3500 4000 4500 5000

Wagner Indices of Supercooled Water

238 K252 258269

Imag

inar

y In

de

xWavenumber (cm-1)

Real Index Imaginary Index

Wagner et al., Mid-infrared Extinction Spectra and Optical Constants of Supercooled Water Droplets, J. Phys. Chem., 109, p7099, 2005.

Comparison to Room Temperature Data

0.0

0.1

0.2

0.3

0.4

0.5

1000 1500 2000 2500 3000 3500 4000 4500 5000

Cold and Room Temperature Water Indices

238 K252 258 269 300

Imag

inar

y In

de

x

Wavenumber (cm-1)

1.0

1.1

1.2

1.3

1.4

1.5

1.6

1000 1500 2000 2500 3000 3500 4000 4500 5000

Cold and Room Temperature Water Indices

238 K252 258 269 300

Rea

l In

dex

Wavenumber (cm-1)

Downing and Williams, Optical constants of water in theinfrared, J. Geophys. Res., 80, 1656-1661, 1975.

Real Index Imaginary Index

300 K

300 K

Ternary Indices - Motivation

Polar Stratospheric Clouds (PSCs)Need to know PSC composition and size

Composition: Liquid droplets (ternary),Solid hydrates (e.g. NAT, NAD)

Heterogeneous chemistry rates of reaction: = reaction probability (unitless)A = PSC surface area (m2 cm-3)v = mean molecular speed (cm sec-1)r = rate constant (sec-1)r = 10-8 A v/4 is a function of PSC composition type

Denitrification: depends upon particle size

Example: observed PSC spectrum

Kim et al., PSCs Observed by the ILAS-II in the AntarcticRegion: Dual Compositions and Variation of Compositionsduring June-August of 2003, JGR, in press, 2006.

Wavelength (micron)

Example: PSC composition determination

Kim et al., PSCs Observed by the ILAS-II in the AntarcticRegion: Dual Compositions and Variation of Compositionsduring June-August of 2003, JGR, in press, 2006. Different letters denote different composition types.

T (K)

Date (Julian day)

Ice

NAT

195

180

0.0

0.2

0.4

0.6

0.8

1.0

180 190 200 210 220 230

Ternary droplet Composition by weight

12 ppbv HNO3 4ppmv H2O

Co

mp

os

itio

n (

by

wei

gh

t)

Temperature (K)

H2SO

4

H2O

HNO3

Carslaw, Luo, Peter, Geo Res Lett, 22, p1877, 1995

New Binary and Ternary Indices

C. E. Lund Myhre, D. H. Christensen, F. M. Nicolaisen,and C. J. Nielsen, Spectroscopic Study of Aqueous H2SO4

at Different Temperatures and Compositions: Variations in Dissociation and Optical Properties, J. Phys. Chem. A.,107, 1979-1991, 2003.

C.E. Lund Myhre, H. Grothe, A. A. Gola, and C. J. Nielsen, Optical Constants of HNO3/H2O and H2SO4/HNO3/H2O at Low Temperatures in the Infrared Region, J. Phys. Chem. A, 109, 7166-7171, 2005.

Myhre (2003, 2005) measurements

Binary (H2SO4/H2O) – 32 casesWeight % H2SO4 = 81, 81, 81, 76, 76, 76, 76, 76, 72, 72 72, 72, 72, 72, 72, 65, 65, 65, 65, 58, 58, 58, 48, 48, 48, 48, 38, 38, 38, 38, 38, 38 Temperature(k) = 298, 273, 267, 298, 273, 233, 213, 203, 298, 253, 245, 233, 223, 213, 203, 298, 263, 243, 223, 298, 243, 233, 298, 273, 234, 213, 298, 277, 257, 243, 223, 213

Binary (HNO3/H2O)30% HNO3, 70 % H2O T= 223, 233, 243, 253, 273, 293 K54% HNO3, 46 % H2O T= 243, 248, 253, 273, 293 K64% HNO3, 36% H2O T= 238, 243, 253, 273, 293 K

Ternary (HNO3/H2SO4/H2O)17% HNO3, 25% H2SO4 T=183, 193, 203, 213, 223, 253, 273, 293 K23% HNO3, 21% H2SO4 T=203, 213, 223, 253, 273 K46% HNO3, 4% H2SO4 T=223, 253, 273, 293 K

Examples of Myhre H2SO4/H2O Indices

0.0

0.2

0.4

0.6

0.8

1.0

1000 2000 3000 4000 5000 6000 7000 8000

Myhre H2SO4/H2O Indices

76% H2SO4, 233K65% H2SO4, 223K48% H2SO4, 213KIm

agin

ary

Ind

ex

Wavenumber (cm-1)

Temperaturesensitivity here is important

1.0

1.2

1.4

1.6

1.8

2.0

1000 2000 3000 4000 5000 6000 7000 8000

Myhre H2SO4/H2O Indices

76% H2SO4, 233K65% H2SO4, 223K48% H2SO4, 213K

Rea

l In

dex

Wavenumber (cm-1)

Real Index Imaginary Index

1.0

1.2

1.4

1.6

1.8

2.0

2.2

400 800 1200 1600 2000 2400 2800 3200 3600

Comparison of H2SO4/H2O Indices

Myhre 48% T=213 KTisdale 50% T=215 K

Rea

l In

dex

Wavenumber (cm-1)

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

400 800 1200 1600 2000 2400 2800 3200 3600

Comparison of H2SO4/H2O Indices

Myhre 48% T=213 KTisdale 50% T=215 K

Imag

inar

y In

de

xWavenumber (cm-1)

Real Index Imaginary Index

Comparison of H2SO4/H2O Indices

0.0

0.1

0.2

0.3

0.4

0.5

1000 2000 3000 4000 5000 6000

Myhre H2O/HNO3 Indices 30 wt% HNO3 - 70 wt% H2O

293 K273253 243233223

Imag

inar

y In

de

x

Wavenumber (cm-1)

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1000 2000 3000 4000 5000 6000

Myhre H2O/HNO3 Indices 30 wt% HNO3 - 70 wt% H2O

293 K273253243233223

Rea

l In

dex

Wavenumber (cm-1)

Examples of Myhre HNO3/H2O IndicesSmall Temperature Dependence

Real Index Imaginary Index

Comparisons of HNO3/H2O Indices

0.0

0.1

0.2

0.3

0.4

0.5

0.6

800 1200 1600 2000 2400 2800 3200 3600

HNO3/H2O Indices

Myhre 30% HNO3, T=223KNorman 35% HNO3, T=220K

Imag

inar

y In

de

xWavenumber (cm-1)

1.1

1.2

1.3

1.4

1.5

1.6

1.7

1.8

800 1200 1600 2000 2400 2800 3200 3600

HNO3/H2O Indices

Myhre 30% HNO3, T=223KNorman 35% HNO3, T=220K

Rea

l In

dex

Wavenumber (cm-1)

Real Index Imaginary Index

1.2

1.3

1.4

1.5

1.6

1.7

1000 2000 3000 4000 5000 6000

Myhre Ternary IndicesH2SO4/H2O/HNO3

293 K273 253223

Rea

l In

dex

Wavenumber (cm-1)

0.0

0.1

0.2

0.3

0.4

0.5

1000 2000 3000 4000 5000 6000

Myhre Ternary IndicesH2SO4/H2O/HNO3

293 K273253223

Imag

inar

y In

de

x

Wavenumber (cm-1)

Examples of Myhre Ternary IndicesSmall Temperature Dependence

46 % HNO3, 4% H2SO4

Real Index Imaginary Index

Real Imaginary

HITRAN 2004 IncludedNorman’s Ternary Indices at 220 K

1.2

1.3

1.4

1.5

1.6

1.7

1.8

1.9

2.0

800 1000 1200 1400 1600 1800 2000

Ternary (H2O/H

2SO

4/HNO

3) Indices at 220 K

Mark Norman, 2002

10 4522 3528 3129 2633 2440 15

Rea

l In

dex

Wavenumber (cm-1)

%H2SO4 %HNO3

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

800 1000 1200 1400 1600 1800 2000

Ternary (H2O/H

2SO

4/HNO

3)

Imaginary Indices at 220 KMark Norman, 2002

10 4522 3528 3129 2633 2440 15

Imag

inar

y in

dex

Wavenumber (cm-1)

%H2SO4 %HNO3

Comparisons of Myhre data to other data sets

Percent differences in H2SO4/H2O indices Data set Real Index Imaginary Index

Niedziela 2% 10-20%

Biermann 1000-3500 cm-1 10% 10-20% v < 1000 cm-1 problematic

Tisdale 3% 10%

Which data sets to use?

Wagner et al., A quantitative test of infrared opticalconstants for supercooled sulphuric and nitric aciddroplet aerosols, Atmos. Chem. Phys., 3, 1147-1164,2003.

Compared cloud chamber measurements of H2SO4/H2O and H2SO4/HNO3 extinction spectra with spectra calculated using published indices.

Good agreementNiedziela (1999) H2SO4/H2ONorman (1999) H2SO4/HNO3

How to use the data?

Mixing rule for the complex index has been proposed:

k(, T, Ws,Wn)= (Ws/Ws+Wn) ks + (Wn/Ws+Wn) kn

complex indices ks and kn, weight percents Ws and Wn

of H2SO4/H2O (s) and HNO3/H2O (n) components

This mixing rule is likely not adequate.

Myhre et al. (2005) state that: “a reliable model of the optical constants of ternaryH2SO4/HNO3/H2O solutions requires a thoroughunderstanding of ionic speciation in the system”

Cross Sections

HITRAN 2004 - 28 molecules

Rothman et al., The HITRAN 2004 molecularspectroscopic database, J. Quant. Spect. and Radiat.Transfer, 96, 139-204, 2005.

Data to be added to HITRAN: Lonardo and Masciarelli, Infrared absorption cross-sections and integrated absorption intensities of HFC-125 and HFC-143a,J. Quant. Spect. and Radiat. Transf., 66, p129-142, 2000.

16 HFC 125 and 19 HFC 143a setsTemperature range: 203 – 293 KPressure: pure vapor, 50, 200, 800 hPaSpectral resolution: 0.03 cm-1

HFC-125 HFC-143a

0.0 100

1.0 10-18

2.0 10-18

3.0 10-18

4.0 10-18

5.0 10-18

400 600 800 1000 1200 1400 1600

HCFC-125, 200 hPaLonardo

203 K213233 253 293

Cro

ss S

ecti

on

(cm

2 )

Wavenumber (cm-1)

0.0 100

5.0 10-18

1.0 10-17

1.5 10-17

2.0 10-17

2.5 10-17

3.0 10-17

3.5 10-17

600 800 1000 1200 1400 1600

HCFC-143a, 200 hPaLonardo

203 K213 233 253273

Cro

ss S

ecti

on

(cm

2 ) Wavenumber (cm-1)

HFC-143a Temperature Dependence

0 100

1 10-17

2 10-17

3 10-17

4 10-17

5 10-17

1275 1280 1285

HCFC-143a, 200 hPaLonardo

203 K293

Cro

ss S

ecti

on

(cm

2)

Wavenumber (cm-1)

Comparisons to Other Data

0.0 100

5.0 10-19

1.0 10-18

1.5 10-18

2.0 10-18

2.5 10-18

3.0 10-18

3.5 10-18

4.0 10-18

1280 1290 1300 1310 1320 1330 1340

HFC-125

Lonardo293 KSmith 287 K

Cro

ss

Sec

tio

n (

cm

2)

Wavenumber (cm-1)

0.0 100

5.0 10-18

1.0 10-17

1.5 10-17

2.0 10-17

1275 1280 1285

HFC-143a213 K, pure vapor

Lonardo Smith

Cro

ss

Se

ctio

n (

cm

2)

Wavenumber (cm-1)

Reflectance Spectra - Motivation

Recent interest focuses on the troposphereTo probe into the troposphere, onefrequently encounters radiative transferphysics that is influenced by the surface

Nadir retrievals over bright surfaces are difficult- MODIS experiment can not detect desert dust over bright deserts

Reflectance Spectra

Reflectance Spectra

USGS Digital Spectral Library

http://pubs.usgs.gov/of/2003/ofr-03-395/ofr-03-395.html

Over 800 spectra, including:13 mineral classes

borate, carbonate, chloride, element, halide,..7 series

olivine, garnet, scapolite,..Representative spectra of

H2O ice, kerogen, desert varnish, evaporite,..Vegetation

treees, shrubs, grasses, flowers,..Man-made materials

roofing material, plastics, paint,..

Spectral range: 0.2 to 5.2 m

Reflectance Spectra

ASTER spectral librarySimon.J. Hook@jpl.nasa.gov

http://speclib.jpl.nasa.gov/

The ASTER spectral library includes data from three otherspectral libraries: the Johns Hopkins University (JHU) Spectral Library, the Jet Propulsion Laboratory (JPL) Spectral Library, and the United States Geological Survey (USGS - Reston) Spectral Library

~2000 spectra of natural and man-made materials

Conclusions

Refractive IndicesThere’s still work to be done withthe ternary indices!

Cross sectionsTropospheric species will drive interest

Surface reflectance dataLink to existing libraries