Near Real Time and Forward Terra production resumed (updated)

Platform Terra
Instrument MODIS
Source lance-modis,production
Issue news
Last Updated 2016-04-12 18:25:00
Start 2016-04-08 00:00:00
End 2016-04-12 18:25:00
Description 2016-04-08T13:10:00Z
As of 2016-04-08 Lance-MODIS (Near Real Time) processing and distribution of C5 and C6 Terra Atmospheres products has been resumed in all nrt* instances: all NRT Terra MODIS products are again being produced and distributed. C5 and C6 Terra Atmospheres forward processing and distribution via LAADS was restarted from dataday 2016-059 (2/28) and should catch up the leading edge in about a week.

The MODIS Atmospheres Team has provided the following statement:

The MODIS Characterization and Support Team (MCST) has made post-safe mode radiance calibration adjustments to the L1B (MOD02) code. However, degraded detector performance in Terra MODIS Band 27 (6.7 um) and Band 29 (8.6 um) necessitated algorithm changes to the L2 cloud mask (MOD35) and the L1B de-striper code used in the production of the L2 atmospheric profile (MOD07/05) and cloud-top (MOD06) products. Specifically, cloud mask thresholds were adjusted to remove false positives for the 6.7 um brightness temperature (BT) test for high clouds and the 8.6-11 um BTD test over the ocean, while reference detectors in the de-striper code were modified to avoid noisy detectors.

Users are advised that further testing is needed to re-validate the current forward stream for the above products (and also down stream products, e.g., MOD06 cloud optical properties) and to document the impact (if any) of these combined sensor and algorithm changes on the use of MODIS Terra atmosphere team products for climate studies.

We previously noted that Band 29 detector crosstalk degradation resulted in artificially high cloud cover over tropical oceans in recent years. The post-safe mode adjusted threshold for the 8.6-11 um BTD test is expected to reduce the impact on cloud fraction.

2016-04-11 update from PGE03 developers: Additionally, a Band 27 crosstalk problem, that increased over time, produced incorrect water vapor profiles, with artificially low moisture content in the middle atmospheric layer and excessively high values in the upper troposphere. The MCST is still investigating possible fixes for this problem.

2016-04-12 update from Land Team: Terra MODIS has returned to science mode operation on Feb 24, 2016 following transition of the satellite and instrument to SAFE-HOLD on Feb 18. MODAPS started processing of Terra MODIS on March 07, 2015. Data from day 2016059 and onwards has been processed. No instrument data was available for the period 050-054 and data from period 054-058 are not usable. All land data products from the post safe-hold period are expected to be of nominal quality.

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