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

UV-RSS optical layout and ray-trace UV-RSS Optics Design SLIT PLANE L1 SH IC SBF RL1 RL2 P1 P2 L2 296.7nm 313.1nm 334.1nm 340.0nm 346.0nm CCD PLANE UV-RSS #104 ASRC, SUNY, Albany,NY

Wavelength calibration RSS104 resolution and pixel-wavelength dependence 0.45 fwhm [nm] 0.40 0.35 0.30 0.25 fwhm ≈ -0.635 +0.0029*nm 1000 800 Pixels 600 Cd lines Zn lines 400 Hg lines 200 0 290 300 310 320 330 340 350 360 370 380 Wavelength (1atm. 15°) [nm]

In-band stray light RSS104 Slit function 0 10 -1 10 HeCd laser line 325nm -2 10 Slit Function -3 10 Recycled beam within prisms -4 10 -5 10 -6 10 300 320 340 360 380 400 Wavelength [nm]

UV-RSS cosine response 1.20 North East 1.15 |A(295nm)-A(385nm)| <0.5% at ±75° Normalized Angular Response 1.10 1 . 1 1 . 1 1.05 1.00 1 . 0 1 . 0 0.95 0.90 0 . 9 0 . 9 0.85 0.80 0 . 8 0 . 8 -80 -60 -40 -20 0 20 40 60 80 <----West Zenith Angle East----> 0 . 7 0 . 7 1.20 1.15 |A(295nm)-A(385nm)| <0.5% at ±75° Normalized Angular Response 1.10 1.05 West Sou th 1.00 0.95 0.90 0.85 sin( ζ ) cos( ζ )( A R ( ζ , α ) − 1) Rd α d ζ < 0.5% ∫∫ 0.80 -80 -60 -40 -20 0 20 40 60 80 <----Sount Zenith Angle North---->

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 of up to five measurements; assumed 0.015 surface albedo

Future Efforts • Check slit functions over UV spectrum • Exploit retrieval potential, specifically, ozone retrievals with 3 available x-sections • ϖ 0 (ssa) retrievals in UV • Validate models with UV inputs