Comparison of UV-RSS Spectral Measurements and TUV Model Runs for - - PowerPoint PPT Presentation

Comparison of UV-RSS Spectral Measurements and TUV Model Runs for the May 2003 ARM Aerosol Intensive Observation Period Joseph Michalsky (NOAA) and Piotr Kiedron (CIRES)

• The Ultraviolet-Rotating Shadowband

Spectroradiometer

• Model inputs (most are extrapolations from visible) to the

Tropospheric UV Visible (TUV) Radiative Transfer model

• The trouble with extraterrestrial solar spectra
• Comparisons of diffuse and direct transmittance

Deployments

10/97 Intercomparison, Table Mt., CO Prototype NMOS: 512 pixels 09/01 Diffuse IOP, SPG, OK 05/03 Aerosols IOP, SPG, OK 06/03 Intercomparison, Table Mt., CO

SBF RL1 RL2 L1 P1 P2 L2 SLIT PLANE IC SH 296.7nm 313.1nm 334.1nm 340.0nm 346.0nm CCD PLANE

UV-RSS #104

ASRC, SUNY, Albany,NY

UV-RSS Optics Design

UV-RSS optical layout and ray-trace

1000 800 600 400 200 Pixels 380 370 360 350 340 330 320 310 300 290 Wavelength (1atm. 15°) [nm] 0.45 0.40 0.35 0.30 0.25 fwhm [nm] fwhm≈ -0.635 +0.0029*nm Cd lines Zn lines Hg lines

Wavelength calibration

RSS104 resolution and pixel-wavelength dependence

10

• 6

10

• 5

10

• 4

10

• 3

10

• 2

10

• 1

10 Slit Function 400 380 360 340 320 300 Wavelength [nm]

Recycled beam within prisms

HeCd laser line 325nm

In-band stray light

RSS104 Slit function

1.20 1.15 1.10 1.05 1.00 0.95 0.90 0.85 0.80 Normalized Angular Response

• 80
• 60
• 40
• 20

20 40 60 80 <----West Zenith Angle East----> |A(295nm)-A(385nm)| <0.5% at ±75° 1.20 1.15 1.10 1.05 1.00 0.95 0.90 0.85 0.80 Normalized Angular Response

• 80
• 60
• 40
• 20

20 40 60 80 <----Sount Zenith Angle North----> |A(295nm)-A(385nm)| <0.5% at ±75°

0 . 7 0 . 8 0 . 9 1 . 0 1 . 1 0 . 7 0 . 8 0 . 9 1 . 0 1 . 1 Sou th West East North

sin(ζ ) ∫∫ cos(ζ )(AR(ζ ,α) −1)Rdαdζ < 0.5% UV-RSS cosine response

Tropospheric UV Visible (TUV) RT Model (Madronich@NCAR)

• Run at 0.1 nm resolution from 300-360 nm
• Bernhard ET spectrum (JGR-Atmos 2004)
• Inputs: 550 nm ssa; 550 nm asymmetry

parameter; AOD and alpha based on τ @ 332, 415, and 500 nm; ozone was average

• f up to five measurements; assumed 0.015

surface albedo

Future Efforts

• Check slit functions over UV spectrum
• Exploit retrieval potential, specifically,
• zone retrievals with 3 available x-sections
• ϖ0 (ssa) retrievals in UV
• Validate models with UV inputs