**Proposed MODIS-Atmosphere Collection 006 Changes**

*Version 15* (02/18/09)

***[Source Key]{.underline}***

*Blue = from Bryan Baum's PPT at Atmosphere Breakout 5/16/08 (Input from
multiple team members.)*

*Green = from Steve Platnick, Michael King, & Gala Wind (06OD Cloud
Optical Properties)*

*Maroon = from Paul Hubanks (Level 3)*

*Violet = from Bo-Cai Gao (05_L2 Water Vapor and 06CD Cirrus Detection)*

*Red = from UW Jan-Feb 2009 (06_CT Cloud Top, 35_L2 Cloud Mask, & 07_L2
Atm Profile)*

**[Aerosol]{.underline} (04_L2)** Lorraine Remer, Christina Hsu, Shana
Mattoo, Rob Levy, Allen Chu

-   Extend the Deep Blue aerosol retrieval through the entire Terra
    archive

-   Create a "MODIS aerosol product" that combines the traditional and
    Deep Blue products

-   Include POLDER nonsphericity information for a better MODIS aerosol
    retrieval for nonspherical aerosol

-   Implement a better urban product

-   Further considerations

    -   Examine aerosols in the proximity of clouds

-   Urge the Aerosol team to split the following three parameters into
    \_47 and \_66 versions in L2: Mean_Reflectance_Land_All,
    Path_Radiance_Land, Critical_Reflectance_Land. This is needed since
    the QA for the 47 version is different than the 66 version. This
    will allow a cleaner implementation of these parameters in L3, where
    the proper QA can be applied to each.

-   There are two 04_L2 SDSs called "Cloud_Fraction_Ocean" and
    "Cloud_Fraction_Land", which have caused some confusion among users.
    It should be noted that these SDSs are not a cloud fraction but
    instead show the fraction of all the L2 pixels that do not make it
    into the aerosol retrieval. These pixels (scenes) where an aerosol
    retrieval cannot be performed include all clouds,
    lakes/rivers/oceans with sediments, swamps over land, snow and ice
    (both over land and ocean), bright surfaces, and ocean sun glint. A
    final decision on the SDS name is pending. Any potential change of
    these SDS names needs to be coordinated with L3 changes (to stay in
    sync).

-   Urge the Deep Blue Aerosol development team to fix their L2 "Deep
    Blue Aerosol Type" flags ... reverse smoke and sulfate flags
    (2=Sulfate, 3=Smoke) so they match the QA flags for the standard
    aerosol retrieval. (See QA Plan.)

> ![](media/image1.wmf){width="6.495833333333334in"
> height="0.7763888888888889in"}

**[Water Vapor]{.underline} (05_L2)** Bo-Cai Gao

-   Improve QA for the near-IR water vapor products, and thoroughly
    screen out pixels saturated over bright clouds.

**[Cloud]{.underline} (06_L2)**

***Cloud Optical Properties (06OD)*** Steve Platnick, Michael King, Gala
Wind

-   Integrate low cloud temperature retrievals into the MOD06OD
    algorithm to include non-unity emissivity (from optical thickness
    retrieval) (11/06)

-   Update current MOD06OD multilayer flag to include other techniques
    and approaches (e.g., Pavolonis and Heidinger). (11/06)

-   Improve cirrus cloud retrievals of τc, re

    -   Improve thin cirrus detection using a combination of IR and 1.38
        µm bands

    -   Perform additional retrieval of τc using IR and/or 1.38 µm bands
        as an augmentation of the current solar reflectance approach
        Pavolonis/Heidinger beta 1DVAR. (05/08)

    -   Phase of thin cirrus. Cloud mask correctly detects the clouds
        with IR window difference and 3.9-11 µm tests, but we are
        getting a liquid water phase while IR is undetermined. Clearly,
        if the mask can detect the cirrus then we ought to use those
        mask tests to help in the phase logic. (04/07)

> \* \[removed from STM notes\] CSR. According to Gala Wind, the default
> for 250 m tests is to set all of the 250 m pixels to clear, and then
> change to cloud upon reading such as result from cloud mask. But the
> logic should be reversed, i.e., all 250 m pixels are set to cloudy and
> then changed to clear upon reading such a result from the cloud mask.
> Either approach is irrelevant unless there are missing 250 m L1B
> pixels. This is the likely reason why CSR was showing thick ice cloud
> striping due to the faulty QA in the Jan. 2007 L1B LUT delivery. The
> old/original LUT was then used to reprocess data so isn't a cause of
> immediate widespread concern but this is an error in the logic.

-   Modify table look-up libraries and solution algorithm

    -   Add more small τc in libraries to reduce interpolation errors
        for thin clouds

    -   Remove asymptotic algorithm for thick clouds, replacing it with
        more τc libraries; no impact on solutions but simplifying
        algorithm maintenance

    -   Include ocean BRDF to accommodate, especially, thin cloud
        retrievals over ocean

-   Partly cloudy pixels

    -   Better use of 250 m cloud mask (at least over ocean) for QA of
        MOD06OD and CT retrievals (11/06)

    -   Coakley-type spatial variance vs. temperature approach (Note:
        Rich Frey doesn't think the Coakley algorithm should be included
        in this list. However, he could see calculating a variance
        statistic of some kind using band 2 and including a flag in the
        L2 output that indicates a non-uniform scene. I think the cloud
        team should discuss this more before we commit to anything.)

-   Either provide scaled optical thickness in the data set AND/OR
    include a vector of ice cloud g and 0 in the data set, so: (1) users
    could scale optical thickness from our retrievals to their own
    library of g values in non-absorbing bands, and g & 0 for absorbing
    bands (e.g., a broadband code in a climate model). (2) users could
    scale our effective radius to their own library of re by scaling 0.
    (03/08)

-   Despite tradition, we don't believe that delta transmittance should
    be included in ice cloud radiative transfer calculations. For MODIS
    C5, eliminating delta transmittance reduces g for re \> 10 µm and
    reduces the slope of g vs. re. This mitigates some of the need for
    roughened particles. (05/08)

-   Pursue Aqua cold focal plane adjustment in L1B production. Jack
    Xiong says Vermote has done something along these lines. (05/08)

-   Change the multilayer cloud code so that above-cloud precipitable
    water is interpolated instead of being estimated by the nearest
    table index. (01/09)

-   Examine correcting the 0.86 µm ozone in the multilayer cloud
    detection algorithm. (01/09)

-   Use ecosystem-dependent vegetation and snow/ice thresholds in the
    multilayer cloud detection algorithm. (01/09)

-   Reduce the size of multilayer and cloud phase SDSs from 16 bit to 8
    bit to save space. (01/09)

-   Store the 1.6 and 3.7 µm retrievals as actual values instead
    of differences from 2.1 µm. (01/09)

-   Examine the effect of interpolated (advected where needed) ancillary
    data on the retrievals. (01/09)

-   Examine the effect of 1 km cloud top properties on cloud retrievals.
    (01/09)

-   Document the meaning of the settings (0 to 4) in the CDL file spec
    and HDF file for the "Cloud_Phase_Optical_Properties\" SDS. Add a
    new local attributed called "description". (01/09)

-   Change the SDS size for Cloud_Multi_Layer_Flag and
    Cloud_Phase_Optical_Properties from 16 bits to 8. This will save 5.5
    Mb/granule uncompressed. (Wind, 02/09)

-   Examine the possibility of augmenting the Surface Albedo dataset
    to include colored water albedo: sedimented / blooming / shallow.
    (Wind, 02/09)

-   Add color tests to CSR to better identify dust vs. thin uniform
    cloud. (Wind, 02/09)

***Cloud Top Properties (06CT)*** Rich Frey, Kathy Strabala, Paul Menzel

-   Implement "top-down" method of final cloud top pressure choice for
    Aqua (Frey, 01/09)

-   Avoid CO2 slicing solutions in water clouds and IRW solutions in ice
    or mixed phase clouds

-   Output cloud (geopotential) heights along with cloud top pressures

-   Use GDAS ozone profile data in stratosphere; merge with
    climatological profiles currently in use

-   Reduce NEDR thresholds for band selection in CO2-slicing algorithm

-   Implement "spectral shift" (Tobin, et al.) in forward model
    calculations involving bands 34-36 (Aqua only)

-   Investigate use of "gamma-adjusted" transmittance profiles to
    replace current clear sky radiance bias correction

-   Investigate identification of stratospheric clouds ("overshooting
    tops") by use of positive 6.7-11 μm and 13.6-11 μm BTDs; use
    stratospheric temperature profiles and IRW BTs in these cases to
    locate clouds

-   Use LEOCAT software to produce 1-km resolution products (in addition
    to current 5-km products); CTP, CTH, CTT, ECE

-   Include cloud overlap / phase at 1 km

-   Include multiple cloud top pressure solution flag for window channel
    retrievals

-   Investigate inversion detection for low level water cloud to be
    located below inversion

-   GDAS temperature profile data will be used to identify regions where
    temperature inversions exist and an alternative IRW method will be
    implemented

-   Investigating use of latitude-dependent lapse rates for calculation
    of cloud heights in inversion situations

-   UW is considering the possibility of using G. Wind's advection code
    in their C6 CT. (Wind & Frey, 02/09)

-   Hubanks to check with Frey if a new flag category should be added to
    the Cirrus Flag and High Cloud Flag. The category would be 3 = clear
    sky. Currently the category 0 = "missing" includes both missing
    satellite data and clear sky. This change would allow a true
    fraction to be implemented in L3. (Hubanks, 01/09)

***Cirrus Detection (06CD)*** Bo-Cai Gao

-   Improve cirrus reflectance retrievals over dry high elevation areas,
    such Tibet Plateau, Andes Mountains, Antarctic and Greenland. The
    collection 05 cirrus reflectance products over these areas are
    slightly contaminated by surface reflection effects.

**[Atmospheric Profile]{.underline} (07_L2)** Eva Borbas, Suzanne
Seemann

-   Update surface emissivity data base to current version

-   Training data improvements regarding skin temperature assignment

-   Update NedT for both Terra and Aqua

-   Investigate the dry bias in Aqua TPW for moist cases and make
    adjustments to improve.

-   Apply zero bias in the radiative transfer calculation

-   Perform a more thorough evaluation of the ozone product through
    intercomparisons with TOMS and AIRS and make adjustments to
    algorithm

-   Assess the TPW Low and TPW High products and possibly change the
    levels of integration to make them more useful.

-   Improve QA/QC flags and screening for bad input MOD02L1B data.

-   Examine the MOD07 Level 3 products for consistency with other long
    term datasets .

-   Making Aqua and Terra DAAC code uniform

-   Look into whether we can include all profiles at 101 levels in
    direct broadcast or at the DAAC, and adding ozone and water vapor
    mixing ratio profiles.

-   Change "Surface Temperature" to "Skin Temperature" in the output
    file

-   Adding pressure levels, offset/scale factor usage to the output file

-   Fix K-index valid range in the output file

-   Introduce H2O/CO2 channel spectral shifts (?)

-   Update pCRTM (CO2, NedT, shifts(?))

-   Have the Atmosphere Profile development team fix (remove the noise
    in fill regions) all 07_L2 Atmosphere Profile Usefulness and
    Confidence QA Flags. This problem might stem from the QA flags not
    being initialized as 0's; but this is unclear.

> ![](media/image2.wmf){width="3.115972222222222in"
> height="2.459722222222222in"}

**[Cloud Mask]{.underline} (35_L2)** Rich Frey, Steven Ackerman

-   Use LEOCAT software (C, C++); replaces current FORTRAN code (Frey,
    01/09)

-   Implement day/night, land/water dust detection algorithm (Frey,
    01/09)

-   Implement cloud adjacency flag (Frey, 01/09)

-   Implement lower 1.38 μm thresholds to "thin cirrus" values, but keep
    thin cirrus flag for users (all scene types except snow/ice)

-   Investigate cloud test using variability of 0.86 μm reluctances in a
    3x3 region for day ocean

-   Implement scattering angle and background NDVI-dependent 0.66 μm
    thresholds for day land

-   Investigate cloud test using variability of 3.75 μm BTs for night
    ocean

-   Implement 7.2-11 μm BTDs in polar ice-cap (Greenland, Antarctica)
    day scenes

-   Investigate use of 11 μm BTs and surface data to help screen out
    false snow from both maps (night) and NDSI (day)

-   Implement Pinty et al. version of GEMI as a cloud test for day land;
    use on all surface types including desert

-   Implement use of background NDVI map to define desert (arid and
    semi-arid) processing path

-   Eliminate tri-spectral test for oceans; replace with simple 8.6-11
    μm BTD threshold test

-   Implement additional 3.9-11 μm BTD test for low clouds over night
    ocean using TPW-dependent thresholds; keep original 3.9-11 μm BTD
    test for low-emissivity stratus clouds

-   Implement new SST test for day, night ocean

-   Tune-ups:

    -   3.9-11 μm cloud test threshold/algorithm for night coastlines
        and shallow water (eliminate uncertain results as much as
        possible)

    -   3.9-11 μm cloud test thresholds for night land in moist
        environments (e.g., Amazon)

    -   Use collocated CALIOP/MODIS data to verify or adjust cloud test
        thresholds

**[Joint Atmosphere]{.underline} (ATML2)** Paul Hubanks

-   Check with all L2 development teams to ensure any changes to L2 HDF
    files (new parameters, new or changed QA, etc.) are accounted for in
    the Joint L2.

-   Revisit SDS list for additions or deletions.

**[Level-3 Gridded Product]{.underline} (08_D3, 08_E3, 08_M3)** Paul
Hubanks

-   Add joint histogram of cloud optical thickness and cloud top
    pressure for combined phase to more easily compare with ISCCP joint
    histogram

-   Add smoke only, dust only, and sulfate only aggregations of Deep
    Blue aerosol. Aggregate aerosol single scattering albedo for dust
    from Deep Blue algorithm. Make sure to sync any L2 Deep Blue Aerosol
    Type flag change to L3.

-   Modify Cloud Effective Radius (Re) liquid water cloud histograms and
    joint histograms to start at 4.0. In addition, use the newly defined
    Research L3 boundaries for Cloud Effective Radius (Re) joint
    histograms

> New Bin Bounds for C006 = 4, 6, 8, 10, 12, 14, 16, 18, 20, 25, 30
>
> Old Bin Bounds for C005 = [2]{.mark}, 4, 6, 8, 10, [12.5, 15,
> 17.5]{.mark}, 20, 25, 30

-   Increase number of bins in the marginal histograms (especially for
    ice cloud effective radius). Check all the Research L3 histogram bin
    bounds against the Operational L3 (change the Operational L3 where
    appropriate). Increase \# of bins and reduce histogram bin sizes for
    Re Ice esp in the 20 to 32 range but perhaps along entire range.

-   Add Cloud Top Height parameter to L3. Add new marginal histograms
    for this SDS (develop a most useful definition of histogram bin
    boundaries). Q: Are new joint histograms based on this parameter
    envisioned?

-   Modify L3 code to compute median. Add median statistics to some
    parameters of L3. (esp Cloud Optical Property parameters)

-   Fix File Spec "long name" for Cloud Fraction Histogram Counts
    (delete at 10 intervals)

-   Use uncertainty to develop new QA-weighted means of Cloud Optical
    Property parameters. (check with S.Platnick)

-   Check with all L2 development teams to ensure any changes to L2 HDF
    files (new parameters, new or changed QA, etc.) are accounted for in
    the L3 (sync the L3 to L2)

-   Investigate a clean up of the Mean_Reflectance_Land_All parameter
    (using QA for 47 and QA for 66)

-   Investigate if the Standard Deviation of the Daily Means should be
    weighted in the multiday product (and if so, how should this be done
    and what does this mean). This statistic is currently weighted by D3
    pixel counts, but I am unsure if this is actually correct. The
    statistic could be more intuitive if this was unweighted.

-   Determine if the Aerosol group wants to add any of their new SDS's
    into L3.

-   Add Cloud_Phase_Infrared_Cloud_Fraction_Liquid, Ice, Mixed,
    Undetermined and Combined. Previously only Histogram Counts were
    computed in L3.

-   To allay user confusion, rename the L3 SDS
    "Aerosol_Cloud_Mask_Cloud_Fraction" SDS's. Some suggested names are
    "Fraction_Unsuitable_For_Aerosol_Retrieval" or
    "Aerosol_Retrieval_Mask". It should be noted that these SDS's are
    not a cloud fraction but instead show the fraction of all the pixels
    that do not make it into the retrieval.  These pixels (scenes) where
    an aerosol retrieval cannot be performed include all clouds,
    lakes/rivers/oceans with sediments, swamps over land, snow and ice
    (both over land and ocean), bright surfaces, and ocean sun glint. A
    final decision on the SDS name is pending.  The 04_L2 SDS, which is
    used to derive the L3 SDS, is called "Cloud_Fraction_Ocean" and
    "Cloud_Fraction_Land". SDS name changes need to be coordinated
    between L2 and L3.

-   Revisit the Cloud_Fraction_Combined, \_Liquid, \_Ice, \_Undetermined
    SDS names. Steve Platnick suggested adding the word Retrieval
    (Cloud_Retrieval_Fraction_Combined, \_Liquid, \_Ice,
    \_Undetermined), since this SDS really shows the fraction of
    successful retrievals in each cloud phase category. An alternative
    could be to simply modify the "long_name" local attribute making
    this clearer.

-   Check with Rich Frey if a new flag category should be added to the
    Cirrus Flag and High Cloud Flag. The category would be 3 = clear
    sky. This would allow a true fraction to be implemented in L3. This
    could be approximated with the current structure (format) by putting
    category (0) = missing in the denominator. It appears this category
    included both clear sky and missing satellite data. (01/09)

**[Other PGE's]{.underline}**

MOD021KM -- radiances (Chris M)

> For Collect 6, missing data in L1B files will no longer be
> interpolated. Missing data values will be used instead. This should be
> transparent to the UW Atmosphere algorithms because the destriping
> algorithm replaces missing data.

MOD_PRDS -- destriping (Liam G)

> Replace granule based destriping with global LUT from day 1 of each
> month (will require code changes).

MODCSRG -- clear sky radiances (observed and calculated) (Kathy S)

Will use new forward model if MOD_PR06CT uses a new forward model

Adjust CO2 amount daily (1.5 ppm per year using 367 for Jan 2000)

**[Delivery Estimates:]{.underline}**

UW C006 Delivery to GSFC expected by June 30, 2009.

All Other Deliveries TBD.