PGE06 v4.3.0 includes:       ( Aqua Forward & Reprocess [004]: ~01.Jan.2004 )

• Cloud Top Properties (v4.2.0)
  Cloud Top Pressure Improvement. Perform check on cloud pressure function to ensure intersection with observed radiance data. Eliminates many spurious high cloud retrievals. This improves the Cloud Top Pressure, as well as the Cloud Top Temperature, parameter.
  Improved Low Cloud Characterization. Use atmospherically corrected radiance data in the "window channel" method, provides improved results for low clouds especially in moist atmospheres.
  Increase CO₂-slicing retrievals. Lower noise limits (allowable clear vs. cloudy radiance values), which results in more CO₂-slicing retrievals.
  Improved Vertical Resolution. Implement new transmittance model coefficient files at 101 vertical levels. This replaces the prior 42-level coefficient files. This allows for processing at 101 discrete levels, allowing results to be reported at higher vertical resolution.
  Improved Atmospheric Transmittance Calculation. Improve atmospheric transmittance calculations by adding climatological ozone profiles as input.
• Cirrus Detection (v4.0.2)
  ECS Metadata Change. This version of the Cirrus Detection code is promoted to Aqua Collection 4. The science algorithm is identical to v4.0.1, but the ECS metadata interface is changed to support ingest into Collection 4 (for Aqua).
• Run Time Scripts
  Build and Runtime Changes. Inventory attribute VersionId (the Collection identifier) in the ECS metadata interface was changed from a value of 3 to 4 in all Aqua metadata configuration files (MCFs).
  

PGE06 v4.2.6 includes:       ( Terra Forward [004]: ~01.Jan.2004       Aqua Forward: Changes promoted in v4.3.0 )

• Cloud Optical Properties (v4.2.4)
  Bad NISE (snow cover extent) Data Checks. The NISE product is made mandatory input to PGE06. Algorithm halts processing and outputs error message when NISE (or Cloud Mask) data is unreadable or missing. The following rule now applies: First, search for data on a 6-day interval centered on the collection period midpoint. If that fails, expand the search to a centered 14-day interval. If that fails, halt processing. Previous versions allowed the Optical Properties algorithm to run if the NISE ancillary data files were corrupted. In this case, the algorithm proceeded as if the NISE data was absent.
  
• Cloud Top Properties (v4.0.6)
  Bug Fix. A minor bug in the driver routine was fixed. The quotes around argument routine_name in the call to write subroutine message following the set_archive_metadata function were removed.
  
• Run Time Scripts
  Build and Runtime Changes. 1.) The build script was modified to run under SDPTK (toolkit) 5.2.9v1 and is backward compatible to earlier SDPTK versions. A reference to the HDF5 library is required for successful compilation and linking with the 5.2.9v1 toolkit. 2.) Attribute ProcessingEnvironment was added to the Archive metadata record to identify the computer host and operating system that produced the product. MODAPS (MODIS Adaptive Processing System) currently operates on IRIX and Linux hosts.
  

PGE06 v4.2.5 includes:       ( Terra Forward: ~07.Jan.2003       Aqua Forward: ~07.Jan.2003 )

• Cloud Optical Properties (v4.2.3)
  Cloud Retrieval Processing Path (RPP) Flag Correction. Incorrect setting of the Retrieval Processing Path (RPP) Flag for polar night scenes was identified and effectively eliminated. Previously, polar night scenes were erroneously being flagged as 'clear' (RPP=1) rather than 'not processed' (RPP=0), which had a negative impact on cloud fraction computed at L3. This was corrected by implementing new logic in the retrieval code, which allows handling of the cloud mask bit as 'undetermined'. Now polar night scenes are correctly labeled as 'not processed' (effectively).   (Note: A small problem remains in this version. A thin stripe of "clear" (RPP=1) pixels are still being erroneously set in the immediate vicinity of the polar darkness boundary.)
  Water Path Correction. A small number of bad (out of bounds) cloud water path (Water_Path) data points (mostly over the Antarctic) were identified and eliminated. This was done by screening cloud optical thickness data used to calculate the cloud water path. These out of bound values were occurring when out-of-family detectors in the MODIS 1.2 µm band produced anomalous reflectances.
  Ancillary Input Removal. The NCEP TOVS ozone (OZ_DAILY) product was removed as ancillary input to MOD_PR06OD.
• Cloud Top Properties (v4.0.5)
  Bug Fix. The reference to the NCEP REYNSST product in the ECS InputPointer metadata list was replaced with a pointer to the SEA_ICE product.

PGE06 v4.2.4 includes:       ( Terra Forward: Changes promoted in v4.2.5       Aqua Forward: Changes promoted in v4.2.5 )

• Cloud Top Properties (v4.0.4)
  Platform Dependent CO₂-Slicing Noise Thresholds. The noise thresholds for CO₂-slicing were made platform-dependent (differing values for Aqua vs. Terra). Aqua LW IR radiances are less noisy than for Terra, therefore this adjustment will allow more frequent use of the full CO₂-slicing algorithm in Aqua processing. (Note: The Terra values are unchanged.)
  Ancillary (NCEP) Input Removal. Access to the NCEP Reynolds sea surface temperature (REYNSST) and TOVS ozone (OZ_DAILY) products was removed from the ancillary data interface as these parameters are not presently used by the cloud top science algorithm.

PGE06 v4.2.3 includes:       ( Terra Forward: Changes promoted in v4.2.5       Aqua Forward: Changes promoted in v4.2.5 )

• Cloud Optical Properties (v4.2.2)
  Ancillary (NCEP) Input Changes. 1.) The Reynolds sea surface temperature file (REYNSST) can now be accessed in either the original ascii format or the new binary format. (NCEP plans to cease production of the ascii format in January 2003.) 2.) Requests for NCEP grib products (GDAS_0ZF, OZ_DAILY and SEA_ICE) are now made by separate calls for each product rather than a single call for all three. This removes a longstanding issue with the grib reader which had required access to all three grib products even if only one or two were actually needed by the science algorithm. 3.) The status of the tovs ozone (OZ_DAILY) product was changed from required input to optional.
• Cloud Top Properties (v4.0.3)
  Ancillary (NCEP) Input Changes. 1.) The Reynolds sea surface temperature file (REYNSST) can now be accessed in either the original ascii format or the new binary format. (NCEP plans to cease production of the ascii format in January 2003.) 2.) Requests for NCEP grib products (GDAS_0ZF, OZ_DAILY and SEA_ICE) are now made by separate calls for desired products rather than a single call for all three at once. This removes a longstanding issue with the grib reader which had required access to all three products even if only one or two were actually needed by the science algorithm.

PGE06 v4.2.2 includes:       ( Terra Forward: ~20.Nov.2002       Aqua Forward: Changes promoted in v4.2.5 )
                                ^* Note that this version was used to reprocess all the Terra data back to the start of the forward stream (11/1/02).
                                  Also, inadvertently, this version was not promoted into Aqua operations; changes related to this version were not promoted into Aqua operations until the v4.2.5 promotion.

• Cloud Optical Properties (v4.2.1)
  Sunglint Pixel Elimination. Activated sunglint test to help eliminate pixels in oceanic sunglint contaminated regions from being erroneously processed as clouds.
  Cloud Temperature Units Bug Fix. Corrected a bug in the units specification of cloud top temperature in the cloud retrieval algorithm.
  Library Numerical Instability Fix. Updated forward model libraries to correct a small random error in the data due to a numerical instability problem.

PGE06 v4.2.1 includes:       ( Terra Forward: ~10.Nov.2002       Aqua Forward: ~10.Nov.2002 )

• Shared Source Code - UW (v4.0.3)
  Local Attribute (long_name) Change. The long_name local attribute was updated for several cloud optical parameters: Cloud_Optical_Thickness, Effective_Particle_Radius, Effective_Radius_Difference, and Water_Path.

PGE06 v4.2.0 includes:       ( Terra Forward: ~04.Nov.2002       Aqua Forward: ~04.Nov.2002 )

• Cloud Optical Properties (v4.2.0)
  Above-Cloud Atmosphere Emission Correction Improvement. Added a new ancillary data package module for above-cloud mean temperature by weighting by the corresponding atmospheric water vapor profile as originally intended. This improved the above-cloud atmospheric emission in the 3.7 and 11 µm bands.
  Cloud Effective Radius Improvement. Made numerous science corrections and improvements to produce more realistic 3.7 µm cloud effective radius retrievals, which were often failing for ice clouds prior to these improvements. The new ice library addresses discontinuities in single scattering albedo in moving from one set of crystal habits to another. These are now smoothed permitting the retrieval code to finish successfully for the vast majority of ice cloud pixels.
  New Solar Irradiance. Incorporated a new 3.7 µm solar irradiance value (11.297 W m^-2 µm^-1).
  Brightness Temperature Calculation Improvement. Added a new band weighted Planck brightness temperature calculation for the 3.7 and 11 µm wavelength bands. The new routine includes the latest instrument calibration information.
  Cloud Phase Determination Improvement. Implemented a correction to the cloud phase determination logic. The phase decision routine now includes separate thresholds for ice/snow covered surfaces.
  Cloud Retrieval Processing Path (RPP) Flag Correction. Fixed the Retrieval Processing Path algorithm by defining three new "failed" categories (5, 6, & 7) and correctly assigning the flags in all categories. The newly defined RPP Flags are: 0="Fill", 1="Clear/Stop", 2="Successful Water Cloud Retrieval", 3="Successful Ice Cloud Retrieval", 4="Successful Undetermined Phase Cloud Retrieval", 5="Failed Water Cloud Retrieval", 6="Failed Ice Cloud Retrieval", 7="Failed Undetermined Phase Cloud Retrieval". In previous versions, both the failed and successful retrievals were assigned to the successful category, which had a negative impact on the Cloud Fraction statistics in L3.
  Cloud Retrieval Confidence QA Bug Fix. Some problems in the new confidence QA setting code from v4.1.0 have been isolated and fixed. QA are now set properly.
  Transmittance Correction Smoothing. Performed bilinear smoothing of the transmittance correction data for each wavelength.
  Water and Ice Library Improvement. Updated the water (Library_05x_water) and ice (Library_05x_ice) library files - identified now as v2.
• Cloud Top Properties (v4.0.2)
  Cloud Top Pressure Improvement. Fixed code bug to allow proper specification of moisture profiles from input GDAS data, which improves the accuracy of cloud pressure retrievals for mid- and high-level clouds.
• Cirrus Detection (v4.0.1)
  Cirrus Detection & Cirrus Reflectance Calculation Improvement. Improved cirrus detection by raising the threshold for identifying cirrus clouds in the 1.375µm channel to compensate for the MODIS 1.375µm channel receiving a small amount of energy (crosstalk) from other MODIS channels. The cirrus reflectance product was improved by raising the threshold parameter "cirrus_refl_min" from 0.005 to 0.010.

PGE06 v4.1.1 includes:       ( Terra Forward: Changes promoted in v4.2.0       Aqua Forward: ~05.Sep.2002 )

• Cloud Optical Properties (v4.1.1)
  Ice Retrieval Bug Fix. The (hardwired) ice radii index (the number of radii in the forward calculation lookup tables) was corrected from 15 to 12. The previous incorrect value of 15 caused anomalous ice library interpolations and many failed ice retrievals.

PGE06 v4.1.0 includes:       ( Terra Forward: Changes promoted in v4.2.0       Aqua Forward: Changes promoted in v4.1.1 )

• Cloud Optical Properties (v4.1.0)
  Thermodynamic Phase Test Reduces Undetermined Phase Cloud Retrievals. A bispectral threshold test (Baum), shortwave infrared tests (Riédi), and cloud top temperature sanity checks (e.g., water clouds for cloud top temperature > 273 K) were added to the cloud phase discrimination algorithm. Far fewer cloudy pixels are now labeled 'undetermined' and the confidence in the detection of ice cloud and water cloud pixels is greatly increased.
  Cloud Retrieval Confidence QA Implementation. Developed a Confidence Flag for the Cloud Retrieval algorithm using four quality settings: 0="Fill or No Confidence", 1="Marginal Confidence", 2="Good Confidence", 3="Very Good Confidence". The Level 3 gridded calculations use these flags to give less weight to lower confidence retrievals. Confidence assignments are based on the proximity of the optical thickness and effective radius solution to the limits of the solution space inherent in the forward model lookup tables. Click on thumbnail, right, for detail. Note that in previous versions, all retrievals had a quality flag of 3 (very good) assigned by default.
  Single Scattering Albedo Threshold Correction. The single scattering albedo threshold was not set consistently between the forward model code and the retrieval code, which resulted in reduction in the frequency of optical thickness retrievals in a narrow range (~13 for water, ~7 for ice clouds). Retrievals now correctly distinguish between the conservative and non-conservative calculation of optical thickness at the beginning of the retrieval.
  30 µm Liquid Water Cloud Effective Radius Set to Fill. Retrievals that hit the limit of the water libraries (30 µm) are caught as outliers and set to the fill value.
  Higher Resolution IGBP Surface Type Map. A new higher resolution version of the IGBP surface type map was implemented. Surface albedo is substantially improved in resolution and accuracy.
  Hierarchical Data Format (HDF) Lookup Tables. Forward model lookup tables were converted to consistently documented HDF files, allowing a greatly simplified reading interface.
• Cloud Top Properties (v4.0.1)
  CO₂-Slicing Confidence Flag Set to 3. Hardwired the CO₂-slicing confidence flag to 3 (highest quality), which was deemed necessary for Level 3 statistical calculations to be done properly.
• Shared Source Code - UW (v4.0.2)
  Invert Dimensions in Effective_Radius_Difference Array. Module was revised to mirror changes in the MODIS Cloud Product. The 1st and 3rd dimension of the Effective_Radius_Difference array were switched. This allows subsetting of the radius difference by band (relative to 2.1).

PGE06 v4.0.0 includes:       ( Terra Forward: Changes promoted in v4.2.0       Aqua Forward: ~24.Jun.2002 )

• Cloud Optical Properties (v4.0.0)
  Local Attribute "scale_factor" Change. Changed the scale_factor local attribute from 0.1 to 0.01 for Cloud_Optical_Thickness, Effective_Particle_Radius, and Effective_Radius_Difference. This provides more significant digits in the output arrays.
  Conflict Exit. Retrieval now exits when there is an apparent conflict between IGBP and NISE data
  Fine Changes to Library Files. All 16 flux and reflectance library files and the algorithm control file were updated with fine changes. The library files were also renamed to accurately reflect their contents.

PGE06 v3.2.0 includes:       ( Terra Forward: ~01.Apr.2002 )

• Cloud Top Properties (v3.1.0)
  Transmittance Profile Coefficient Update. Added transmittance profile coefficients for Aqua and updated those for Terra. Profiles now have 42 levels instead of 40.
  Response Function Update. Added response functions for the new Aqua channels, updated response functions for Terra.
  Fewer Missing Retrievals From Mixing Ratio Check Update. Modified the check on mixing ratio values from ancillary data. This results in many fewer missing values of cloud top pressure and cloud effective emissivity.
  Invalid Cloud Mask - Bug Fix. Pixels with invalid cloud mask results will now be listed as "missing" instead of "clear".

PGE06 v3.1.0 includes:       ( Terra Forward: ~01.Jan.2002 )

• Cirrus Detection (v3.1.0)
  Above-Cloud Water Vapor Transmittance Estimate Improvement. A new algorithm using a one-slope approach to estimate the transmittance of water vapor above cirrus clouds was implemented. This contrasts with previous versions in which a less accurate three-slope procedure was used.
  Contrail Parameters - Set To Fill. All contrail-related parameters are no longer computed.

PGE06 v3.0.5 includes:       ( Terra Forward: ~15.Nov.2001 )

• Cloud Optical Properties (v3.0.5)
  Bug Fix - Band/Albedo Sanity Checking. Corrected the band/albedo sanity checking logic, which permitted 1.24µm retrievals over snow and sea ice.
  Bug Fix - QA Array Dimension. Corrected the QA array dimension from 2D to 3D.
  Bug Fix - Total Precipitable Water Units Correction. Corrected the units specification for the above-cloud total precipitable water calculation.

PGE06 v3.0.1 includes:       ( Terra Forward: ~01.July.2001 )

• Cloud Optical Properties (v3.0.1)
  Bug Fixes. The following bug fixes were made: 1.) corrected sds read error in an ancillary input land surface temperature sds, 2.) corrected the order of the dimension arguments passed to transmittance subroutine, and 3.) corrected the units of cosine angle argument.

PGE06 v3.0.0 includes:       ( Terra Forward: ~15.June.2001 )

• Cloud Optical Properties (v3.0.0)
  Atmospheric Water Vapor Correction . Added an atmospheric water vapor correction algorithm. This is based on a lookup table derived from model calculations. Currently this algorithm corrected transmittances for bands up to 3.7 µm (2 way transmittances for the visible bands and 1 and 2 way transmittances for 3.7µm).
  New Water and Ice Libraries. Using new water and ice library calculations generated from code by P. Soulen and P. Yang. The new water libraries use a different set of effective radii, as well as measured MODIS RSR's.
  New Final Retrieval Solution Interpolation. Completely replaced the final solution interpolation in the retrieval algorithm. The previous scheme interpolated on the square of the Measurement-Library residual. This was found to be demonstrably inacccurate. The new scheme interpolates on the values of the residual and attempts to exit gracefully and set a fill value if the residual curve has an unphysical profile.
  Bug Fix - Ancillary Data. Corrected the assignment of ancillary data to the ancillary data arrays. Previously these arrays were copied incorrectly from the temporary HDF file, so that some lines of the data were corrupted.
  Bug Fix - Failed Solution Set To Fill. Corrected a logical error where failed solutions would result in an initialized array number output as the solution. Such values are now correctly set to the fill value.
  Bug Fix - Sea Ice Reflectances. Added code to use snow/ice bits correctly. Code now uses the snow/ice percentage to weight the reflectance for sea ice.
  Bug Fix - Clear Pixels Not Processed. Removed a Cloud Mask test that could return a decision to process a pixel as cirrus cloud (ice) when the cloud mask determines that the pixel is clear. Such pixels are now left as clear pixels.
  MOD12 Ecosystem Map Update. IGBP ecosystem map updated with MOD12 ecosystem map (continue to use CERES tundra classification, NISE snow/ice classifications).
  MODIS "White Sky" Albedos. CERES albedos replaced by November 2000 MOD43 "white sky" albedos aggregated versus ecosystem. Tropical albedos have no seasonal dependence. Seasonal dependencies added poleward of 30 degrees (sinusoid). A linear interpolation between 20 and 30 degrees is used (excluding desert ecosystem).
• Cirrus Detection (v3.0.0)
  Small Reflectance Cutoff. Applied the cutoff of small-reflectance pixels at 0.03. This substantially improves some cases in polar regions. Also modified the algorithm to remove the "long tail" in 1.38-0.66µm scatter plot.