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MODAPS Services




Quality Assurance - Tasks in Development

Last Update: September 27, 2007

Science QA will generate and evaluate trending plots, diagnostic images, and product summaries to support longer-term product investigations into any problems not evident at the granule level:

Science QA staff will work with the Science Team to identify any other desired QA products, and will provide them as time is available.

Input Product Metrics

MODAPS Quality Assurance will generate, monitor and post online time summaries (table and/or plots) of

  • The number of actual vs. expected inputs to each product
  • Ancillary Data availability and changes

Possible enhancements:

  • Flag when a non-optimal ancillary input is used - for instance, a 3-day old REYNSST file should never be used in reprocessing
  • Overlay times of Lookup Table updates, code changes, and known data outages on trending plots

Metadata Trending

MODAPS Quality Assurance will generate, monitor and post online trending plots of values to be extracted from Level 2 product metadata.

Easily-accessed values included in each Atmosphere product's metadata may be used for processing and/or science diagnostics, and could quickly show massive failure in the retrieval algorithm.

Specific trending plots will be coordinated with the Science Team. Trending values may be time-averaged as appropriate, and may include:

  • Single parameters vs. time:
    • Cloud Fractions (water, ice, ...)
    • Cloud Mask ("Cloudy" = UncertainConfidentClearPct + LowConfidentClearPct)
    • Cloud Optical Properties percent successful retrieval
  • Parameter ratios:
    • Cloud Optical Properties percent successful retrieval vs. Cloud Mask "Cloudy"

Level 2 Image Gallery

MODAPS Quality Assurance will generate and post online a user-friendly L2 granule image gallery, similar to the Collection 4 images at Although it is expected that Science QA will monitor this gallery, it is being provided largely for the convenience of the MODIS Atmosphere Science Team.

One display page will be generated for each orbit of the first available day of each month processed, for each instrument.

Each page will contain:

  • a menu to select day and orbit
  • an orbit track map to help orient the user
  • all granules containing day-mode scans for a single orbit, in successive 5-minute rows.

Each row will show images of the following parameters, in columns from left to right:

>Level 2 Image Gallery Parameters
1 True color RGB from L1B
(using MODIS bands 1:4:3 = R:G:B)
2 False color RGB using SWIR bands from L1B
(using MODIS bands 2:6:7 = R:G:B)
3 Ecosystem Map
4 Cloud Mask (cloud confidence)
5 Cloud Phase (IR)
6 Cloud Phase (VIS)
7 Cloud Top Pressure
8 Cloud Optical Thickness
9 Cloud Effective Radius
10 Cirrus Reflectance
11 Aerosol Optical Depth
12 Aerosol Optical Depth Ratio Small
(small mode to total ratio)
13 Precipitable Water (NIR) - aka Water Vapor NIR
14 Precipitable Water (IR) - aka Atmospheric Water Vapor

Each image will be:

  • displayed unmapped
  • contiguous in time with the images directly above and below
  • clickable to show a full-sized image.

Monthly Zonal Averages

MODAPS Quality Assurance will generate, monitor and post online monthly zonal averages of several atmospheric parameters, extracted from the MOD08_M3 at one-degree resolution. One set of plots will be generated for each month of data processed, similar to those at

At present, that site shows a single plot for each combination of Collection 4 and Collection 5, over Land and Ocean, for each of the following monthly zonal average parameters:

  • Cirrus_Reflectance
  • Cloud_Effective_Radius_1621_Ice
  • Cloud_Effective_Radius_1621_Ice_QA
  • Cloud_Effective_Radius_1621_Liquid
  • Cloud_Effective_Radius_1621_Liquid_QA
  • Cloud_Effective_Radius_Ice
  • Cloud_Effective_Radius_Ice_QA
  • Cloud_Effective_Radius_Liquid
  • Cloud_Effective_Radius_Liquid_QA
  • Cloud_Fraction_Day
  • Cloud_Fraction_Ice_Fraction
  • Cloud_Fraction_Liquid_Fraction
  • Cloud_Fraction
  • Cloud_Optical_Thickness_1621_Ice
  • Cloud_Optical_Thickness_1621_Ice_QA
  • Cloud_Optical_Thickness_1621_Liquid
  • Cloud_Optical_Thickness_1621_Liquid_QA
  • Cloud_Optical_Thickness_Ice
  • Cloud_Optical_Thickness_Ice_QA
  • Cloud_Optical_Thickness_Liquid
  • Cloud_Optical_Thickness_Liquid_QA
  • Cloud_Water_Path_Ice
  • Cloud_Water_Path_Ice_QA
  • Cloud_Water_Path_Liquid
  • Cloud_Water_Path_Liquid_QA
  • Optical_Depth_Ratio_Small_Land_QA
  • Optical_Depth_Ratio_Small_Ocean_QA
  • Water_Vapor_Near_Infrared_Cloud_QA

Enhancements to the current format will initially include a user-friendly web interface, and grouping or comparison of parameters by category:

  • Land vs. Ocean
  • Water Cloud vs. Ice Cloud
  • Terra vs. Aqua

Countless other parameter combinations could be plotted as a QA need arises, or as desired by Science Team members.

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