Thank you for notifying the ASDC of the missing MOPITT data. We are currently looking into this and will let you know what we are able to find out here shortly.
We apologize for any inconvenience this may have caused.
ASDC User Services
Sharing some information that you may find useful as to why there are missing data for some MOPITT data products (including MOP02J.009) made available through the ASDC.
Based on MOPITT's Data Availability https://www2.acom.ucar.edu/mopitt:
MOPITT Version 8 and Version 9 Level 2 and Level 3 products are now available for the entire MOPITT mission. MOPITT V8 and V9 products for data acquired after the most recent hot calibration (usually in March) are considered to be provisional ("beta"), subject to recalibration, while data taken before the hot calibration are considered archival quality. Generally, V8 and V9 Level 2 and Level 3 products should become available between three weeks and two months after the actual observations; this data latency is the result of the dependency on the MERRA reanalysis. Near-real-time data are also available, but should not be used for trend analysis. See Data Products https://www2.acom.ucar.edu/mopitt/products for descriptions of the different products and status of validation.
Every year, usually around March, the MOPITT Science Team do a hot calibration of MOPITT. They use the hot cal. from March 2020 and the hot cal. from March 2021 to calibrate the whole year between those events. However since they don't have the March 2022 hot cal. data yet they process V108 data (beta) as ongoing. The V108 2021 data gets replaced by V8/V9 when it is reprocessed after the March 2022 hot cal. occurs. So the bottom line is that there is no V8/V9 data after March 2021, but there will be after March 2022.
We hope you find this information of use in answering your question. Please let us know if there is anything else we can do to further assist.
ASDC User Services
Thank you for your reply. So do you mean missing dates are essentially the dates where calibration was performed?
Here is the number of missing days for each year.
The missing dates are indeed clustered insprings, but there are missing dates in other times, and the number of them is quite different for different years. So does it mean that these missing dates are indeed irrecoverably missing?
Correct, either calibration was performed or the MOPITT instrument itself experienced a malfunction or operational issue and needed to be placed in science/safe mode to recover and return to normal instrument operations. Unfortunately, data retrievals were not collected during these days and thus the data is irrecoverable.
Here is a list of dates showing MOPITT activity https://www2.acom.ucar.edu/mopitt/status which coincides with the missing days you've noted.
I will reach out to the MOPITT science team to see if they have any additional information they may be able to offer as well.