MODIS Meeting, EOC Canberra, 30 August 2002

Report of discussion on MODIS Direct Broadcast reception and processing to Level 1B

Acronyms

Summary

IMAPP processing There are two software packages to process MODIS DB data to L1B: IMAPP from Wisconsin and the NASA/Miami package from GSFC. IMAPP can process full swaths but the NASA package can only process granules. IMAPP puts tags in the metadata that do not match the NASA format produced by the DAACs.

If all L2 production can be based on the IMAPP format, then Australia would probably adopt the IMAPP format as standard. Local software should preferably be able to handle granules, as well as swaths. People were tasked to find out which L2++ software packages are based or can be based on the IMAPP or NASA formats, and whether they work with full-swath data or granules only. The IMAPP developers should be pressed to change to the NASA format.

Faster delivery ACRES currently provides binary files produced from L1B data by MS2GT software for the most recent seven days on their website. ACRES will consider making limited L1B data in HDF format available in parallel. Many favoured a model of post-L1B products being generated and served at the reception site, exemplified by the Sentinel real-time fire detection system.

Aqua Aqua lacks the GPS that Terra has, so best geolocation of MODIS/Aqua requires waiting 24 hours for ancillary data. The nature of the real-time navigation uncertainties will be determined so that the feasibility of local nudging using GCPs can be assessed.

Night passes The inevitable conflicts in scheduling pass acquisitions at any one reception station would be resolved by collaboration between stations.

Archive product Archiving Level 0 data is essential, and both ACRES and DOLA are doing this. Ephemeris data are archived at Wisconsin.

AIRS data IMAPP software handles both MODIS and AIRS DB data. The meeting knew of no other software to process DB of other instruments.

Regular workshops Liam Gumley will spend five weeks in Perth from 1 November. During that time a workshop with Liam will be held in Perth, and a WASTAC meeting in Perth will probably be scheduled to enable representatives from eastern states to meet Liam. The meeting supported an annual science meeting, which BoM offered to host next year.

Other X-band satellites Australian X-Band stations could acquire data from the Indian ocean colour satellite, and a German satellite suited to 180-m burn scar mapping. ADEOS-2 will DB some data, and DB may be the only access to ADEOS-2 250-m data. BoM is receiving and archiving data from the Chinese polar orbiter FY-1C but this is not X-Band.

Action items

Discussion in detail

David Jupp (EOC) chaired the discussion. Mike Pasfield's (ACRES) slide served as the framework for discussion:

David Jupp drew a diagram outlining his "Utopia" derived from the previous day's discussion on post-L1B processing:

David Jupp reminded the meeting that yesterday some people were charged with determining access to L2++ software.

IMAPP processing

[Background: There are two software packages to process MODIS DB data to L1B: IMAPP from Wisconsin and the NASA/Miami package from GSFC. IMAPP can process full swaths but the NASA package can only process granules. IMAPP puts tags in the metadata that do not match the NASA format produced by the DAACs.]

DOLA uses IMAPP, while ACRES currently uses the NASA software. Mike Pasfield noted that the software choice is sometimes dictated by the user's requirement for full-swath products, and the NASA package deals only with granules. Ron Craig (DOLA) suggested pressing the IMAPP developers to match the NASA format for L1B. Ian Barton (CMR) suggested an alternative would be to ensure that post-L1B software can work with either L1B format. David Jupp summarised the differences between the two packages: IMAPP can process full swaths but NASA cannot; IMAPP puts tags in the metadata that do no match the NASA format produced by the DAACs. David Jupp agreed that the best solution is to press the IMAPP developers to change. Leon Majewski (Curtin University) noted that the Level 2 cloud software is "almost" able to handle either the IMAPP or NASA L1B format. Alex Held (CLW) noted that the MOD14 [hot-spot] software works with the IMAPP format.

David Jupp and Ian Barton suggested that people be tasked to find out which L2++ software packages are based or can be based on the IMAPP or NASA formats for L1B. Each product team is to be asked for this information, and whether their software works with full-swath data or granules only. It was noted that in fact NASA appears to be supporting IMAPP. A consensus (including Paul Tildesley (CMR), Ian Barton and David Jupp) agreed that if all L2 production can be based on the IMAPP format, then Australia would adopt the IMAPP format as standard. Ron Craig observed that the intention of IMAPP was always that the DB software package would include DB-version IMAPP-based software for all L2++ products, and therefore at some time in the future this problem may disappear.

Ian Barton commented that local software should be able to handle granules, as well as swaths, for users who download DAAC L1B data. Peter Turner (CAR) emphasised the need for a central software repository, say using CVS. This would serve as a local mirror of US software, and document the history of Australian processing changes and software modifications. The repository should cover all Terra and Aqua instruments, including AIRS.

Volunteers were called for to ask the L2++ software teams about IMAPP/NASA
compatibility and swath/granule capability:

The EOC will host a list server to facilitate email discussion among the meeting participants.

Faster delivery

ACRES currently use NASA software in their processing stream. They will look at using IMAPP. ACRES currently provide MS2GT output for the most recent seven days on their website. They will make limited L1B data available. Craig Smith (ACRES) noted that in the past users have not had the capability to ingest HDF but that is changing. For instance ENVI and ER Mapper now have HDF capability. Ian Shepherd (ACRES) will look at providing L1B HDF data on the web, in parallel with the existing raw binary product, and will notify the group through the list server. John Woolner (ACRES) observed this was feasible. David Griersmith said BoM would consider supplying the extra disk space required.

Ron Craig asked if the user community wanted access to products from WASTAC-X as it does from ACRES. Ian Barton favoured the Sentinel model for generating and serving products from the reception station, and would like to see this at the TERSS facility in Hobart. Paul Tildesley would also like to see a similar system in Perth.

Aqua

Near real-time (NRT) geolocation of MODIS on Aqua is an issue, since Aqua lacks the GPS that Terra has and ancillary navigation data is not available for download for about 24 hours. John Woolner (ACRES) suggested informing users that Terra NRT geolocation was good, Aqua's is poorer, and that good navigation of 250-m data from Aqua requires waiting.

Alex Held asked if a navigation correction based on ground control points (GCPs) as is now done with AVHRR could be implemented for MODIS on Aqua. There was some discussion as to what uncertainties were in the NRT Aqua navigation, with the conclusion that the group had insufficient knowledge. David Griersmith noted that NASA and/or Wisconsin are likely to know the uncertainties. Ron Craig noted that DOLA is keen for good NRT Aqua navigation to be able to locate afternoon hot-spots immediately after an Aqua pass.

Action: Ron Craig will ask Liam Gumley (Wisconsin) about MODIS/Aqua navigation uncertainties when Liam visits Perth.

Night passes

Ron Craig outlined the problem: a reception station will have acquisition scheduling conflicts no matter where in Australia it is located. Conflicts necessitate manual adjustment of scheduling. David Griersmith noted that in two years time, BoM would want all passes, day or night, for products such as fog. The consensus was that conflicts would be resolved by collaboration between the stations.

Archive

David Jupp noted that the EOC (possibly in company with CSIRO Divisions) has a similar interest in maintaining an archive of MODIS data as it has for AVHRR. Should the archive be Level 0 or Level 1B? Ron Craig felt a Level 0 archive was essential, to guard against problems in software to process to L1B, or side-A/B electronics changes. ACRES and DOLA both archive Level 0, and after a software upgrade in a few weeks time each will be able to read the other's archive. Peter Turner asked if ancillary data was archived. Paul Tildesley relied that the ephemeris is archived at Wisconsin as a service to the global community. Craig Smith noted that ACRES keeps its Level 0 archive offline, with an access time of about 2 days.

AIRS data

Ron Craig noted that the IMAPP software handles both MODIS and AIRS DB data. He asked if there was software to process DB data from other instruments, since there is none mentioned on the DB web site. Ian Barton suggested a contact person.

Regular workshops

Richard Smith noted that Liam Gumley will spend five weeks in Perth from 1 November. A workshop will be held in Perth during Liam's visit, and Richard will notify the group of the date. Ian Barton asked if Liam's visit should be extended with a few days in the eastern states, and David Griersmith expressed a desire for this. Liam's visit is a holiday, but Richard Smith will ask if he is willing to stop in the east. An alternative would be to send a few representatives from the east to Perth, for instance by holding a WASTAC meeting in Perth during Liam's visit, and the group widely supported this option.

Ian Barton asked if there was value in an annual MODIS science meeting. Several people thought there would. David Griersmith agreed, and offered to host one at BoM next year. Ian Barton expressed the hope that coordination of issues such as reception and processing will be resolved by the end of the Perth meeting later this year, and will need no more than brief revisiting next year.

Level 2 products

Level 2 products were discussed the previous day, but David Jupp commented that these will drive MODIS activity in Australia.

Other satellites

Ron Craig asked if there were other upcoming X-band satellites that should be planned for.

ADEOS-2 will DB some data, and DB may be the only access to the 250-m data.

Richard Smith noted that DOLA has considered acquiring data from the Indian ocean colour satellite, which has both ocean and land applications, but have not to date since they have not seen a need. Ron Craig noted that DOLA has the hardware capacity to do acquire this data, at additional cost. David Jupp noted that Australia has a national agreement with India covering this satellite.

Antony Rea (BoM) noted that BoM is receiving data from the Chinese polar orbiter FY-1D at Crib Point. FY-1D overpasses are at 1030 local time, and the bands are the AVHRR bands plus some ocean colour bands. BoM archives the data in ASDA format, but have not assessed its quality. There is on-board thermal calibration, but no visible calibration information at all. David Jupp suggested that coincident GMS observations could provide a visible calibration. David Griersmith invited use of the data and feedback. Peter Turner noted that an interface to FY-1D data was planned for CAPS. The FY-1D fire channel serves as a MODIS backup for BoM.

Richard Smith mentioned a German satellite suited to burn-scar detection at 180-m resolution.

Wrap up

Ian Grant (CAR) will write a report of the discussions and a list of action items for initial circulation to David Jupp and Ian Barton.

All presenters were requested to send their presentation in PowerPoint or PDF format to David Jupp for inclusion with the final program on the EOC website.

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