An update on Brewer Umkehr retrievals Dr. Irina Petropavlovskikh, ESRL/CIRES, Boulder, CO Bob Evans, NOAA/ESRL Patrick Disterhoft, ESRL/CIRES Kathy Lantz, ESRL/CIRES Sam Oltmans, ESRL/CIRES Photo courtesy GMD’s Ozone and Water Vapor Group, ozonesonde camera 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

How do we measure ozone in Boulder? Dobson and Brewer Umkehr Ground-based UV radiation and ozone absorption Only clear, sunny days Thick layers (~5 km) Up to 50 km Best information is in the stratosphere Inexpensive to operate and (mostly) automated Beginning 1978/ Middle of 2006 Ozonesonde Balloon-borne Chemical reactions of air sample Typically taken once a week High resolution (< 100 m) Usually goes as high as 30 km Good way to measure ozone in the troposphere and low stratosphere Expensive (equipment) Beginning 1979 Photos courtesy of the Ozone & Water Vapor Group and NEUBrew network at ESRL/GMDPhoto courtesy Adriana Bailey, CIRES 9/12/2011 2Brewer User Workshop, Beijing, Septemner 12-16, 2011

Umkehr curves from Dobsons 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Dobson vs Brewer, Boulder, CO Different wavelengths Wide vs narrow band-passes Polarized zenith sky radiance in Brewer Mark IV Brewer – NiSO4 filter OOB or Stray light effect Similar ozone profile retrieval algorithm for zenith sky measurements single wavelength pair Brewer has shorter record (since Fall 2006) 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Pair vs Multiple wavelength RT Brewer measures zenith sky radiation at several channels (Dobson measures difference in signal between two channels) Combine two spectral channels similar to Dobson – O3BUmkehr (Martin Stanek) Use all spectral measurements (short and long set, 306 – 329 nm) – MSBU-S2 (8 channels) Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Multi-spectral retrievals Standard UMK04 Modified Tzortziou et al., 2008 MSBU-S1MSBU-S2 Measurement timeSeveral hours< 30 min~20-30 min Data typeStandard Umkehr at 310 and 326 nm Sky scans in solar plane (only done by Brewer #171) Umkehr measuremen ts at 5 short channels Umkehr measurements at 5 short and 5 long channels Instrument requirements needed StandardSeveral hardware and software modifications Additional instrument characterization is needed. However, characterization results obtained can be used on other Brewers Potential data base to be analyzed All Brewers taking full Umkehr measurements Only Brewer #171 data Potentially many Brewers: both running full and reduced Umkehr measurement schedule, including historical data 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Umkehr measurements Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Averaging Kernels for multi- spectral RT algorithm single pair (Standard) multiple short spectral channels (MSBU-S1) combination of short and long spectral channels (MSBU-S2) 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Aerosol effects on the MSU 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Measured and Simulated offset Brewer User Workshop, Beijing, Septemner 12-16, /12/ , 313, 310, 306 nm317, 319, 323, 326, 329 nm

Multiple-spectral algorithm and noise vs vertical resolution Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Ozone x-section and stray light effects on N-values Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Slit function and ozone x-section Brewer User Workshop, Beijing, Septemner 12-16, /12/2011 No temperature Quadratic term

Effect of X-section, stray light and temperature on RT ozone profile from NEUBrew #141 (MKIV) Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Simulating ETC for Br141 Brewer User Workshop, Beijing, Septemner 12-16, /12/2011 Ozone profile Ozone x-section Temperature profile RT code synthetic ZS intensities Spectral band-pass Spectral filter response (Obs-SYNTH)= ETC

Brewer ozone RT and ETC Pair does not require ETC or instrumental constant K, method relies on normalization to one of SZA to eliminate these factors Multiple spectrum algorithm requires ETCs and Ks (band-pass, filter and stray light Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Brewer #135 characterization ETC are derived from Langley plots (direct sun measurements vs. air mass (mu) Several neutral density filters are used during direct sun measurements absolute transmittance of individual filters was measured by Patrick Disterhoft at NOAA/ESRL Brewer quartz entrance window characterization – transmittance and polarization (vs Fresnel eq) Direct sun measurements were corrected prior to ETC derivation Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Temperature-dependent responsivity of Brewer #135: -10 to +40 degrees C Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Langley analysis for ETCs Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Additional work Several months of measurements over Boulder, CO Verification for clear sky condition – MFRSR and CIMEL Air-masses between 2 and 6 (change of schedule) Dead-time correction (Newton scheme) Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Polarization efficiency of polarizer in Brewer eff = (1-  )/(1+  ), and  is the deficiency of the polarizer Br 171 (double) has 70% MK IV Brewer - a Rochon polarizing prism or a glass stack and a linearly polarized HeCd laser beam to determine the extinction coefficient of the film polarizer used in the Mark IV Brewer # 135. Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Theoretical study of polarization Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Other atmospheric factors Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Stray light issue 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Measurement of Dobson slits by Gordon Labow and Bob Evans 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Stray light effect on Umkehr measurements theoretical study. Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Validating Umkehrs against Climatology Dobson, Brewer, single vs multiple, MLL climatology – ozonesonde and SAGE/MLS, monthly and latitude (10-degrees) averages (McPeters, Labow and Logan, 2007) 4D climatology – addition of the TO regression for tropospheric and low stratospheric ozone (PK Bhartia and Ch. Wellemeyer) Compare seasonal cycle and variability (RMSD) in all Umkehr layers 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Annual Cycle, Brewer (C-pair) and climatology, NEUBrew, , Boulder, CO Umkehr 4D Climatology (TO) A prior MLL Climatology (season, lat) Ozone, Layer 1 Ozone, Layer 2+3 Ozone, Layer Month 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011 Ozone, Layer 6 Ozone, Layer 7 Ozone,Layer 8

Annual, Brewer vs Dobson and climatology, NEUBrew, , Boulder, CO Umkehr 4D Climatology (TO) A prior MLL Climatology (season, lat) Month Brewer Dobson 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011 Ozone, Layer 6 Ozone, Layer 7 Ozone,Layer 8

Annual, Brewer and climatology, NEUBrew, , Boulder, CO Umkehr 4D Climatology (TO) A prior MLL Climatology (season, lat) Month Ozone, Layer 6 Ozone, Layer 7 Ozone,Layer 8 BrewerC-pair Brewer (MS8) 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011 Ozone, Layer 6 Ozone, Layer 7 Ozone,Layer 8

Annual, Dobson (OOB corr) and climatology, NOAA, , Boulder, CO Umkehr 4D Climatology (TO) A prior MLL Climatology (season, lat) Month RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer 8 No corr stray light (2e-5) RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer 8 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Annual, Brewer (OOB corr) and climatology, NEUBrew, , Boulder, CO Umkehr 4D Climatology (TO) A prior MLL Climatology (season, lat) Month No corr stray light (1e-5) RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer 8 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Brewer 171(MK3), C-pair vs MS8 Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Br 141, Boulder (MS), 4-2 hPa Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Brewer, sonde, Climatology, layer 4 Brewer User Workshop, Beijing, Septemner 12-16, /12/2011

Dobson Umkehr, OMI and NOAA-17 daily ozone, Boulder CO, Layer 4 Layer 6 Layer 8 Layer 1 OMI Umkehr NOAA-17 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Monthly mean differences Umkehr-satellite, Layer 8, Boulder CO, Drift DU/year OMI: SBUV: /12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Conclusion about annual cycle in Brewer and Dobson in Boulder vs MLL Climatology Dobson Umkehr RT show ~ 5-10 % ozone deficiency in layers 8 and above (40 km and above) as compared to climatology or satellites (OMI and SBUV) Brewer and Dobson derive less ozone in layers 4 and 5 (20-30 km) as compared to climatology or satellites MS8 vs C-pair Brewer algorithm increases RT ozone in layer 8 (but not in 7 or 6). Stray light correction in Dobson RT reduces bias in layer 8, but also slightly increase ozone in layers 7 and 6 (constant offset bias) Brewer (MKIV) has similar level of stray light but it shows seasonally dependent bias as compared to climatology or Dobson Stray light correction increases ozone in layers 7 and 8, but does not solve the seasonal offset. 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

What’s Next Continue with optical characterization of spectral channels in Brewer MKIV – depolarization, stray light and SZA noise Study aerosol effects on the noise in MS8 RT ozone Study the benefit of 5 vs 8 spectral channels and the retrieval noise limitations to the accuracy of the retrieved ozone 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Acknowledgements P K Bhartia, G. Labow, R. McPeters and A. Cede at NASA/Goddard P. Disterhoft and NEUBrew group at NOAA, Boulder R. Evans and OZWV group at NOAA, Boulder K. Miyagawa, Japan Meteorological Agency M. Stanek, International Ozone Service, Canada G6D /12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Expected outcome Characterization of internal stray light, extinction ratio of the thin film polarizer and absolute transmittance of the neutral density filters in the Brewer Mark IV. Accounting for instrumental characteristics in the RT. Assessment of retrieval errors due to instrumental noise in Brewer data based on measured count rate. Replacement of a nominal, large SZA range set of Umkehr data with the limited set of daily-collected Umkehr data between 88 and 90 SZA - greatly reducing operational time. Implementation of the internal, self-consistent screening of data for overhead cloud/aerosol interference Increase in # RT ozone profiles Providing new algorithms to the site operators to encourage worldwide expansion of the Brewer Umkehr measurements in collaboration with the WMO and NDSC, and expand geographical coverage and frequency of the ground-based measurements for the future satellite (NPOESS and Aura) validation. 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Variability or RMSD MLL has variance for mixing ratio dataset based on ozone sounding and SAGE Mixing ratio is converted to DU Brewer/Dobson daily profiles are selected by month and layer ozone variance is calculated in DU 4-D climatology is used to create daily profiles based on Julian day and TO, and RMSD is calculated for each month Climatology is used to assess noise in RT ozone 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Variability, Brewer C-pair and climatology, NEUBrew, , Boulder, CO Umkehr 4D Climatology (TO) A prior MLL Climatology (season, lat) RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer 8 RMSD, Layer 1 RMSD, Layer 2+3 RMSD, Layer Month 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

RMSD, Brewer (C-pair), sonde, MLL Brewer User Workshop, Beijing, Septemner 12-16, /12/2011 RMSD, Brewer (MS8), sonde, MLL

RMSD difference between two Brewers Mark IV, Boulder, CO 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Variability, Brewer (meas. error) and climatology, NEUBrew, , Boulder, CO Umkehr 4D Climatology (TO) A prior MLL Climatology (season, lat) RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer Month Se=STD Se=STD*2=DB RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer 8 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Variability, Brewer (OOB error) and climatology, NEUBrew, , Boulder, CO Umkehr 4D Climatology (TO) A prior MLL Climatology (season, lat) RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer Month No correction stray light (1e-4) RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer 8 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Variability, Dobson vs Brewer (stratosphere) and climatology, , Boulder, CO Umkehr 4D Climatology (TO) A prior MLL Climatology (season, lat) Month RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer 8 Brewer Dobson RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer 8 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Variability, Brewer Cpair vs MS8 and climatology, , Boulder, CO Umkehr 4D Climatology (TO) A prior MLL Climatology (season, lat) Month RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer 8 C-pair MS8 (Se=MKIV) RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer 8 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Variability, Dobson vs Brewer (troposphere) and climatology, , Boulder, CO Umkehr 4D Climatology (TO) A prior MLL Climatology (season, lat) Month Brewer Dobson RMSD, Layer 1 RMSD, Layer 2+3 RMSD, Layer 4 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Variability, Dobson (OOB corr) and climatology, NEUBrew, , Boulder, CO Umkehr 4D Climatology (TO) A prior MLL Climatology (season, lat) RMSD, Layer 6 RMSD, Layer 7 RMSD, Layer 8 RMSD, Layer 1 RMSD, Layer 2+3 RMSD, Layer Month 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011

Conclusion about variability in Brewer and Dobson in Boulder vs MLL Climatology Brewer C-pair shows considerably larger RMSD in RT ozone in layers 7, 8 and above (35 km and above) as compared to climatology Brewer MS8 ozone variability is reduced. The RMSD in Dobson and Brewer RT ozone does not decrease in summer in layers 6, 7 and 8, while climatology does (?) Brewer and Dobson RT ozone variability in layers 1, 2+3, 4 and 5 (below 30 km) is similar to climatology Brewer Mark IV has similar level of noise in C-pair Umkehrs as compared to Dobson, but increase of the measurement error does not significantly reduce RT noise, while noise at individual channels is much higher Stray light correction in Dobson and Brewer RT does not change variability of the RT ozone 9/12/ Brewer User Workshop, Beijing, Septemner 12-16, 2011