SSEC forums

DB Colleagues,

In the last few days, several people have told us that MODIS Level 1B processing is failing because the ancillary data files named leapsec.dat and utcpole.dat are not available from NASA during the US federal government shutdown. Normally these files are available from

http://oceandata.sci.gsfc.nasa.gov/Anci ... UTs/modis/

however this site is offline at present. For this reason we have posted the latest versions of leapsec.dat and utcpole.dat at

ftp://ftp.ssec.wisc.edu/pub/gumley/leapsec_utcpole/

The files were updated on 2013-09-29 and will remain valid for 90 days. The MODISL1DB and SeaDAS versions of the MODIS Level 1B geolocation code will examine the first line of leapsec.dat to check the date it was last updated, e.g.,

$ head -1 leapsec.dat
Checked(unchanged): 2013-09-29T12:15:56Z using USNO tai-utc.dat file of Sep 29 08:16

The string "2013-09-29" is compared to the current date, and it the difference is more than 90 days the geolocation code will exit. The geolocation code does not appear to check the contents of the utcpole.dat file, however as the utcpole.dat file grows older there will be small differences introduced into the computed geolocation data.

In recent versions of MODISL1DB and SeaDAS, the leapsec.dat and utcpole.dat files reside in the directory named run/var/modis. To update the files on your system, use commands as shown below (MODISL1DB used as an example):

cd $DBHOME
cd run/var/modis
mv leapsec.dat leapsec.dat.old
mv utcpole.dat utcpole.dat.old
curl -O ftp://ftp.ssec.wisc.edu/pub/gumley/leap ... eapsec.dat
curl -O ftp://ftp.ssec.wisc.edu/pub/gumley/leap ... tcpole.dat

This will download the latest versions of leapsec.dat and utcpole.dat, while preserving the old versions. It should restore the MODIS Level 1B processing to normal operation. When the NASA ocean FTP site comes back online, you can use the update scripts built into MODISL1DB or SeaDAS to update these files.

Regards,
Liam Gumley.

Hi Liam,

Do you also know of alternative sources of MET (NCEP) and OZONE (TOAST) data which are required for l2 processing and which we (NIWA) also get from the oceandata site?

cheers
Simon

Hi Liam and all,

Just wanted to let you know that there is also another way to keep your processing ongoing.

For NASA MODISL1DB_SPA there is a patch available at http://directreadout.sci.gsfc.nasa.gov/?id=software. This patch eliminates external dependencies for execution, utilizing direct readout resources only. This same patch can be used to SeaDAS ModisL1DB 1.8. Replace modis_GEO_utils.py in path ~/modisl1db1.8/run/scripts/modules/ with the one found inside the tar.gz packet and run modis_GEO.py with option --disable-download.

Regards,
Omit

Hello Simon,

IMAPP has an ancillary data site that stages all of the data that are required to create all IMAPP products. We continue to acquire and stage both TOAST and NCEP data files. All ancillary files are accessed automatically as part of the processing scripts. The ancillary data site can be found here:

ftp://ftp.ssec.wisc.edu/pub/eosdb/ancillary

Cheers,

Kathy