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Summary of GEO-CAPE Aerosol Working Group Progress

Summary of GEO-CAPE Aerosol Working Group Progress. Members: Mian Chin, Pubu Ciren , Hiren Jethva , Joanna Joiner, Shobha Kondragunta , Alexei Lyapustin , Shana Mattoo , Lorraine Remer, Omar Torres, Alexander Vassilkov , Jun Wang. GEO-CAPE Aerosol Working Group tasks, FY13.

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Summary of GEO-CAPE Aerosol Working Group Progress

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  1. Summary of GEO-CAPE Aerosol Working Group Progress Members: Mian Chin, PubuCiren, HirenJethva, Joanna Joiner, ShobhaKondragunta, Alexei Lyapustin, Shana Mattoo, Lorraine Remer, Omar Torres, Alexander Vassilkov, Jun Wang

  2. GEO-CAPE Aerosol Working Group tasks, FY13

  3. High priority tasks • Can TEMPO achieve GEO-CAPE objectives by itself or by TEMPO/GOES-R synergy? • Aerosol retrieval availability: TEMPO will have 30-40% less retrieval availability then GEO-CAPE, unless the cloud screen criteria is much relaxed, which may increase AOD retrieval error • Aerosol product quality: not clear, still under investigation • Using GOES-R 2.1 μm channel to help TEMPO retrieve AOD at visible wavelength: Yes under certain conditions • How much can be gained from 2-angle retrieval (GOES-R and TEMPO or GEO-CAPE)? • Combination of UV and Vis-IR provide more information for aerosol retrieval • Can O2-B (688 nm) or O2- (628 nm) band be used to retrieval aerosol height? • Yes with O2-B, when AOD is above 0.2, SSA and surface reflectance are known

  4. GEO-CAPE vs. TEMPO

  5. H1. TEMPO aerosol retrieval availability - Using MODIS cloud mask at 0.5 km (Lorraine Remer, Shana Mattoo) • Regional statistics, 1x1 km (GEO-CAPE) and 4x2 km (TEMPO): • TEMPO would have about 55% of the retrievals that MODIS provides now • TEMPO will have 2/3 retrieval availability of GEO-CAPE (1x1 km)

  6. New Mexico (NM) Wyoming (WY) H1’. Diurnal variation of “cloud-free” fraction with different pixel size • Cloud-free fraction can be significantly reduced at TEMPO pixel resolution especially in mid-day Virginia (VA) Mexico (MX) Diurnal variation of CLOUD-FREE fraction from 1-day data of August 12, 2010 1-km 2-km 4x2 km 4-km 8-km Aqua Terra

  7. H2. Aerosol retrieval availability and product quality at TEMPO and GEO-CAPE resolution (own cloud mask)(Omar Torres, HirenJethva) σ < 0.0025 Fraction clear sky 1x1 km (GEO-CAPE) a b c σ < 0.01 σ < 0.0025 σ < 0.005 Fraction clear sky 4x2 km (TEMPO) Fraction clear sky 4x2 km (TEMPO) Fraction clear sky 4x2 km (TEMPO) • Using the same variability criteria, TEMPO would have only half coverage of GEO-CAPE on average with the most severe loss in the SW largely because of the variation of surface reflectance. The availability greatly increases with the relaxed criteria

  8. H2. Results – AOD relative quality Comparisons between 8x8 km AOD product from “GEO-CAPE” 1x1 km (x-axis) retrieval and “TEMPO” 4x2 km (y-axis) retrieval with different cloud mask criteria for April 10, 2012: a b c σ=0.0025 σ=0.005 σ=0.01 AOD 470 nm, 4x2 km AOD 470 nm, 1x1 km AOD 470 nm, 1x1 km AOD 470 nm, 1x1 km • From the preliminary results, it does not seem that the quality of AOD from more relaxed cloud mask (thus higher probability of cloud contamination) is worse than that from more strict cloud mask. More quantitative evaluation is in progress.

  9. H3. TEMPO/GOES-R Synergy – (ShobhaKondragunta, PubuCiren) (a) Surface reflectance at 2.13 μm and cloud mask July 15, 2012, UTC=19:00 GOES-R remapped to TEMPO GOES-R TEMPO • GOES-R (west) and TEMPO do not overlap over eastern part of US and Atlantic Ocean. • Synergic use of GOES-R is possible by providing surface reflectance at 2.13 μm for TEMPO aerosol retrieval over portion of eastern, middle and western part of U.S. • Observations in the early morning and later afternoon need to be avoided. Only hours close to noon time are favorable (for lambertian surface)

  10. H3. TEMPO/GOES-R Synergy – NESDIS group: (b) GOES-R cloud mask for TEMPO • MODIS 1Km cloud mask (MOD35) was mapped into GOES-R (West) first then remapped GOES-R to TEMPO Grid between latitude band (35°N to 45°N) • Fraction of cloudy (confident and probably cloudy) pixels calculated July 15, 2012 GOES-R remapped to TEMPO TEMPO • Cloud mask information from GOES-R observations seems to be sufficient for TEMPO

  11. H3. TEMPO/GOES-R Synergy (Alexei Lyapustin) • Over dark surfaces, the 2.1m BRDF from GOES-R (East) model can be used for TEMPO aerosol retrieval regardless of TEMPO’s parking longitude • Over central-eastern USA, the AOT RMSE based on GOES-R BRDF is expected to be < 0.05 (at 0.47 m). Over western USA the error is larger SNR=30 SNR=10 SNR=30 SNR=10 Summer, July 11 Winter, December 2 120°W 120°W 105°W 105°W 75°W 75°W

  12. H3. TEMPO/GOES-R Synergy (Jun Wang)Angular Analysis of Vis/NIR sfc. Ratio and implication for retrieving AOD SZA = 40° GOES-R + TEMPO/GEO-CAPE GOES-R 470, 640, 860 nm TEMPO/GEO-CAPE 340, 380, 470, 640 nm • Azimuth • 120 • Azimuth • 120 • Azimuth • 120 90 90 90  Azimuth 60  azimuth 60  azimuth 60 0.80 0.85 0 0.95 1.0 Degree of Freedom for retrieving AOD 30 30 30 150 150 150 • Assuming that surface BRDF can be characterized with uncertainty of 20%, we found that strong synergy between two GOES-R and TEMPO/GEO-CAPE during the time when one of the sensor is viewing the Earth surface at the direction close to the Sun’s illumination angle. • TEMPO/GEO-CAPE UV wavelengths improves DOFs in AOD retrieval. 75 60 45 30 15 0 15 30 45 60 75 VZA (°) 75 60 45 30 15 0 15 30 45 60 75 VZA (°) 75 60 45 30 15 0 15 30 45 60 75 VZA (°)

  13. H4. Aerosol height from O2-B and O2-(Alexander Vasilkov, Joanna Joiner) Simulated TOA spectral reflectivity SSA=1 • Radiative transfer simulations • LIDORT code: line-by-line O2 absorption,), TOA radiance with Gaussian response, FWHM=0.5, 1.0 • Aerosol: 1-km thick layer at different plume top height of 1-10 km, AOD=0.2, 0.5, 1.0, SSA=0.8, 0.9, 1.0 • Surface albedo: A=0.05, 0.1 B-band ✔ • If SSA is known, the aerosol plume height and optical depth can be derived from measurements of the band depth and continuum reflectivity at 686 nm

  14. Conclusions • Spatially, TEMPO alone (4x2 km) will have lower retrieval availability then GEO-CAPE (1x1 km) by 33% in the morning (10:30 am) • Temporally, TEMPO will have reduced AOD retrieval availability in partial cloudy scene • AOD quality from TEMPO and GEO-CAPE is still under evaluation • Synergy between TEMPO and GOES-R is very helpful in terms of utilizing the extended spectral range for (1) retrieving AOD at visible wavelength and (2) increasing the degree of freedom for AOD and fine mode AOD retrievals • O2-B band has promising sensitivity for aerosol height retrieval for both GEO-CAPE and TEMPO Bottom line: GEO-CAPE measurement requirements, as defined in STM and studied by the AeroWG, are not 100% met by TEMPO alone.

  15. However… • GEO-CAPE objectives can be mostly met by the synergy among TEMPO and GOES-R • GOES-R: high pixel res, cloud mask, DT retrieval, good for DT and ocean • TEMPO: bright surface, SSA • Combo: more aerosol retrieval • Cloud screening: 1-km, 2-channel radiometer will much enhance the AOD retrieval from TEMPO. It could be studied.

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