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

Daily Issues (08_D3)

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.




Daily 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 issues 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 Granules Aug 2017

Q

 

 ✔

 

Link

#2. Missing Granules Sep-Nov 2014

Q

 

 

 

Link

#3. Missing Pixel Count SDS for CTH

Q

Link

#4. 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: Missing Terra Data Granules/Orbits between 5 Aug 2017 and 6 Aug 2017

Description: Following the Terra Deep Space Calibration on August 5th, 2017 (2017 217) there were some faulty C6 Terra MODIS Atmosphere data as the focal plane temperatures did not return to nominal values until the day after - August 6th, 2017 (2017 218) 1420 UTC. So the granules for the time period between 2017 217 23:00 UTC and 2017 218 14:15 UTC were removed before the downstream Atmosphere processing. Data users will notice missing MODIS Atmosphere Data during this period for all Level-2 (L2) and Level-3 (L3) Daily atmosphere products.

Here is a sample L3 animation of Scattering Angle for 6 Aug 2017, which shows the missing data issue fairly clearly.  The animation loops between the C6.0 data and the C6.1 data. The C6.1 data is improved showing less missing data, however a gap still exists in C6.1


  C6.0 vs C6.1 comparison of missing data gap (slight improvement shown in C6.1)

Data Dates Affected: Note there will be Missing Terra Data between 2017 217 (5 Aug 2017) at 23:00 UTC and 2017 218 (6 Aug 2017) at 14:15 UTC for all MODIS Atmosphere L2 and L3 Daily products.

Affected Platform: Terra Only

Collections Affected: Collection 6.0 and Collection 6.1 (some improvement noted in C6.1)

Return to Menu at Top of Page


Quality Statement #2: Missing Aqua Data Granules/Orbits between 9 Sep 2014 and 20 Nov 2014

Description: Incorrect production rules in MODAPS caused the initial release of Aqua MOD08_D3 data to be missing some granules/orbits in the September to November 2014 time period. Data was rerun and new corrected files are now available for download. Since a picture is worth a thousand words, an example animation showing this problem (before and after correction) is displayed below. Just to clarify, this was not a software/code bug, but instead a problem in the operational production rules.

PGE Versions & Production Dates of Problematic & Corrected Data:

Problematic Data Corrected Data
PGE Versions Production Dates PGE Versions Production Dates
≤ PGE56 v6.1.5 ≤ 2014 252 (9/9/2014) ≥ PGE56 v6.1.9 ≥ 2014 324 (11/20/2014)

Data Dates Affected: 9 September 2014 to 20 November 2014

Affected Platform: Aqua Only

Collections Affected: Collection 6.0

Return to Menu at Top of Page


Quality Statement #3: 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 Quality Statements #4 and #5 below. 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 #4: 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 Quality Statement #3 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