TOMS DATA near the

2001 January 9 Total Lunar Eclipse

Calwell Lunar Observatory

The measures of four images of the recent total lunar eclipse indicated that the umbral semi-diameter decreased towards fourth contact and it is expected that this was due primarily to increased cloud cover, causing reduced transparency at a longitude near 90 degrees WEST of the observing point.

The observations were conducted at longitude 20 degrees East, so the atmospheric conditions at 70 degrees West are of interest. The only known data available is from the TOMS satellite, and two charts are presented below from this source showing Total Ozone on the eclipse date and secondly, the Reflectivity of the atmosphere also on the eclipse date.

It can be seen at the longitude of interest that the total ozone over the east coast of the USA is near 400 Dobson units with the area preceding it over the North Atlantic at around 275 to 380 Dobson units.

It can be seen at the longitude of interest that the reflectivity over the east coast of the USA is low at around 30-40 % with a clearer area preceding it over the North Atlantic.

Conclusion

The TOMS data is taken over a period of time so it is impossible to refine the effect that total ozone and reflectivity would influence the transparency of the upper atmosphere during the end of this lunar eclipse where the umbral semi-diameter change was greatest.

However, there is obviously a change in the atmospheric conditions at the longitude of observation and that at 90 degrees West of where the images were captured.

One could imply that this would cause the umbral change during this lunar eclipse, however, further study and correlation of data are obviously necessary.

Prepared by the Calwell Lunar Observatory, Australia / 2001 February 5