Sorry, you need to enable JavaScript to visit this website.

Monthly Issues (08_M3)

Tracking of known problems and subsequent fixes is an important issue for MODIS data users. This page will act as a repository of all known MODIS Atmosphere Data Product problems, as well as how to determine the problematic version (and the fixed version) of the HDF data -- therefore data users should check this page for updates regularly. Data Users unfamiliar with how to properly track problems and fixes by determining the version of their downloaded HDF files should refer to the documentation in the Introduction sublink (the top link along the LHS of this page).   Note that a checkmark (✔) in the tables below means Data Issue or Quality Statement applies.  A blank means it's been fixed or does not apply.




Monthly Data Issues: Table of Contents & Anchor Links  (Note: Anchor Links point to a specific place within this page.)

Collection/Platform where Issues Apply
Issue Impact C6.1/Terra C6.1/Aqua C6.0/Terra C6.0/Aqua Anchor Link
#1. Input L2 Problems propagate downstream

L

Link

#2. CT Day Granules misplaced to Night

L

 

Link

#3. 1km CTP Low Ocean in December

M

 

 

Link

Daily Data Quality Statements: Table of Contents & Anchor Links  (Note: Anchor Links point to a specific place within this page.)

Collection/Platform where Quality Statements Apply
Quality Statement Impact C6.1/Terra C6.1/Aqua C6.0/Terra C6.0/Aqua Anchor Link
#1. Missing Pixel Count SDS for CTH

Q

Link

#2. Upper Histogram Bin Limit on CTH too restrictive

Q

Link




Issue #1: Problems in input Aerosol (04_L2), Water Vapor (05_L2), Cloud (06_L2), Atm. Profile (07_L2), and Cloud Mask (35_L2) propagate into downstream products

Description: See the Known Problem pages for the input (upstream) Level-2 products 04_L2 (Aerosol), 05_L2 (Water Vapor), 06_L2 (Cloud), 07_L2 (Profiles), and 35_L2 (Cloud Mask) by clicking on the links to the left.  Users should make themselves aware of any issues in the upstream data products.

Data Dates Affected: Issues could occur for any date

Affected Platform: Terra and Aqua

Collections Affected: Issues possible in all Collections

Return to Menu at Top of Page


Issue #2: Very Intermittently occurring Cloud Top Property Granules misplaced from Daytime to Nighttime

Description: Very occasionally, a few daytime granules are misplaced to the nighttime SDS's in 06_L2.  This misplacement seems to be correlated with satellite maneuvers which occur for very brief periods (minutes) on a one to two month schedule. This problem is isolated to any 06_L2 SDS which has the suffix "_Day" or "_Night" (which corresponds to a few Cloud Top Property parameters).  The upshot is for users reading any _Day SDS in L2, there will be a few isolated missing granules, and any user reading any _Night SDS in L2, there could be a few cases where day granules are overlapping the night granules.   This is occurring in less than 0.001% of the time.  To bypass this issue, users can read the un-aggregated L2 SDS's and do the D/N aggregation using the Cloud Mask D/N Flag if needed.

PGE Versions & Production Dates of Problematic & Corrected Data:

Data Dates Affected: Can occur anytime, but very intermittent and very limited in scope

Affected Platform: Aqua and Terra

Collections Affected: All Collections

Additional Documentation:  View PDF (shows how this L2 error impact L3)

Return to Menu at Top of Page


Issue #3: Problem in C6.0 1-km Cloud Top Pressure (Low) over Ocean in December

Description: A bug was discovered in the Collection 6.0 1-km cloud top pressure low (low in the atmospheric layer, i.e. close to the Earth's Surface) over ocean algorithm for both Terra and Aqua. Low Atmosphere Cloud Top Pressure (> 600 hPa) retrievals for all oceanic L2 December data are not consistent with those of the other months and are considered to be incorrect. The impact will also be seen in daily, 8-day, and monthly L3 data, where 1km CTP data is ingested,  Note that this issue was corrected in Collection 6.1 data.

PGE Versions & Production Dates of Problematic Data:

Data Dates Affected: Decembers from launch through 2016

Affected Platform: Aqua and Terra

Collections Affected: Collection 6.0 only

Return to Menu at Top of Page




Quality Statement #1: Pixel Count SDS not defined for Cloud Top Height (CTH) 

Description:  In D3, E3, and M3, the Pixel Count SDSs for the full swath Cloud Top Height (CTH) are not defined (i.e., are missing); note that the Pixel Count SDSs are defined for the Nadir CTH scalar SDSs (see the figure below). This was an oversight in C6/C6.1 development, and breaks the “SDS inventory symmetry” in L3 where all other Cloud Top Property related parameters have Pixel Count SDSs defined. The missing CTH Pixel Count SDSs are particularly problematic given the current inability to indirectly obtain these counts from the CTH Joint Histograms and other Cloud Top Property Pixel Count SDSs (which in theory should be consistent across all Cloud Top Property parameters) given the issues noted in the Quality Statements #4 and #5 on the Daily Issues page. This oversight is expected to be remedied in future Collections.

Data Dates Affected: All Data Dates

Affected Platform: Terra and Aqua

Collections Affected: Collection 6.0 and Collection 6.1

Return to Menu at Top of Page


Quality Statement #2: Upper Histogram Bin Limit on Cloud Top Height (CTH) too restrictive

Description: A limitation was uncovered where the upper limit of the Histogram bin boundaries for CTH was set too low and some pixels with valid retrievals might be excluded. This upper limit of the CTH Histograms and Joint Histograms is currently set at 18000 meters, or 59,055 feet, which may exclude some extreme CTH cases such as the overshooting tops of supercell thunderstorms that can reach up to 75,000 feet. This limitation prevents users from crushing down the 1D Histogram Count SDSs or the 2D Joint Histogram Count SDSs for CTH in order to indirectly obtain (compute) the missing CTH Pixel Count SDSs noted in tje Quality Statement above. This limitation is expected to be remedied with a more appropriate upper CTH limit in future Collections.

Data Dates Affected: All Data Dates

Affected Platform: Terra and Aqua

Collections Affected: Collection 6.0 and Collection 6.1

Return to Menu at Top of Page