PACE: Radiative Transfer studies for Atmosphere-Ocean Systems

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1 Summary Project What did we propose What did we accomplish relevant for PACE instrument design Ø PACE ST polarimeter document ACROSS Ø Perform sensitivity analyses for proposed PACE instrument options o OCI NUV-SWIR radiance o OCI/OG O2-A band radiance o OCI+ 1378, 2250 radiance o OCI-3M VIS-SWIR polarization Ø Write manuscript about sensitivity analyses results Ø Proposed PACE instrument sensitivity studies: o OCI 95 channels between 0.35 μm and 2.13 μm o OCI-3M 5 view angles between +/ 50 degrees 5 channels between 0.41 μm and 2.25 μm 1% polarization accuracy Ø Other satellite instrument sensitivity studies: o OCI-2M OCI-3M but without polarization o OCI-3M+ OCI-3M but more views & better accuracy PACE 15 Ø Compare RT computations for various atmosphere-ocean systems (AOS) o o o o 5 AOS models 2 altitudes 4 wavelengths >100 scattering angles Ø Computations with 3 different RT codes o AOS models I, II, III o all altitudes, wavelengths, angles o 3 Stokes parameters o error ~ 1e-6 ΔP < 0.1% Ø 90+ page draft manuscript Discuss tomorrow Ø Update hydrosol model o Involve input from PACE-IOP group Ø Investigated 4 multi-parameter models o ACROSS-I & -II models, c-model, IOCCG5 Ø 15+ page draft document relevant for PACE instrument design Other Ø Study aerosol height retrievals from O2-A data Ø Theoretical and actual aerosol height retrieval studies using blue/uv polarization Ø manuscript in preperation

2 1. ACROSS Test increase in information in OCI+Polarimeter versus OCI alone Less improvement in atmospheric correction More improvement in atmospheric correction

3 Motivation Simulated aerosol retrieval from space-borne observation over ocean at 865 nm view Synthetic TOA data of I, Q, & U: sun z k Aerosol candidate models: o μ 0 =0.8; μ=0.2, 0.4, 0.6, 0.8, 1.0 Δφ=60º & 120º o Fine mode aerosol, τ = 0.2 (r e = 0.4 μm; v e =0.2; m=1.45 o Rough ocean surface (W = 7 m/s) o Black water body ocean atmosphere k 0 θ 0 π ϑ 0 φ 0 = 0º ϑ φ x y o Fine mode aerosol: τ = , Δτ = 0.01 r e = μm, Δr e = 0.01 m = , Δm = 0.01 ω = , Δω = 0.02 v e = 0.2 >350,000 aerosol candidate models AOS system Source: Mishchenko and Travis, JQSRT 102:13,543-13,553 (1997)

4 Motivation Simulated aerosol retrieval from space-borne observation over ocean at 865 nm o radiance I, o 9 viewing angles o ΔI = 4% o polarization Q/I and U/I, o 9 viewing angles o ΔP = 0.2% optical thickness optical thickness ω=1.00 ω=0.94 ω=0.98 ω=0.92 Aerosol candidate models: o Fine mode aerosol: τ = , Δτ = 0.01 r e = μm, Δr e = 0.01 m = , Δm = 0.01 ω = , Δω = 0.02 v e = 0.2 >350,000 aerosol candidate models refractive index refractive index Source: Mishchenko and Travis, JQSRT 102:13,543-13,553 (1997)

5 Motivation Simulated aerosol retrieval from space-borne observation over ocean at 865 nm o radiance I, o 9 viewing angles o ΔI = 6% o polarization Q/I and U/I, o 9 viewing angles o ΔP = 0.8% optical thickness optical thickness ω=1.00 ω=0.94 ω=0.98 ω=0.92 Aerosol candidate models: o Fine mode aerosol: τ = , Δτ = 0.01 r e = μm, Δr e = 0.01 m = , Δm = 0.01 ω = , Δω = 0.02 v e = 0.2 >350,000 aerosol candidate models refractive index refractive index Source: Mishchenko and Travis, JQSRT 102:13,543-13,553 (1997)

6 Motivation Simulated aerosol retrieval from space-borne observation over ocean at 865 nm o radiance I, o 9 viewing angles o ΔI = 8% o polarization Q/I and U/I, o 9 viewing angles o ΔP = 2.0% optical thickness optical thickness ω=1.00 ω=0.94 ω=0.98 ω=0.92 Aerosol candidate models: o Fine mode aerosol: τ = , Δτ = 0.01 r e = μm, Δr e = 0.01 m = , Δm = 0.01 ω = , Δω = 0.02 v e = 0.2 >350,000 aerosol candidate models refractive index refractive index Source: Mishchenko and Travis, JQSRT 102:13,543-13,553 (1997)

7 Motivation Ø our forward RT computations need to match these accuracies! ~1e-4 absolute difference 2015: I ~1e-4 Q ~1e-4 AOS system: molecular atmosphere above ocean surface U view angle view angle

8 Results Ø our forward RT computations need to match these accuracies! 2 sun angles 13 viewing angles 4 azimuth angles k k 0 z TOA y ocean atmosphere upper lower θ 0 π ϑ 0 φ 0 = 0º ϑ φ x SRF >100 scattering geometries x 2 altitudes λ = 350 nm, 450 nm, 550 nm, 650 nm I, Q, U ΔP 0.1%

9 Results Ø our forward RT computations need to match these accuracies! 10 di (x10 6 ) dq (x10 6 ) du (x10 6 ) dp (%) AOS-I (550 nm) GSFC JPL NRL UCSD UMBC view angle view angle view angle view angle

10 Results Ø our forward RT computations need to match these accuracies! di dq du ~1e-4 ~1e-4 ~1e-4 o Benchmarked >magnitude better o Satisfies polarization accuracy view angle view angle view angle 10 di (x10 6 ) dq (x10 6 ) du (x10 6 ) dp (%) AOS-I (550 nm) GSFC JPL NRL UCSD UMBC view angle view angle view angle view angle

11 Backup Slides Raman scattering

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14 Summary ² The polarized radiative transfer equation is solved with both elastic and inelastic (Raman) scattering included. ² The angular radiation field can be provided at arbitrary vertical locations in the coupled atmosphere and ocean systems. ² Raman scattering contribution is found to be significant in visible spectrum and clear waters.