Subject: CHAMP/SAC-C faulty occultation processing for 19 April
         to 9 August 2003

A bug crept into our GENESIS processing software on 22 April 2003,
causing an error in the production of atmospheric profiles from the
CHAMP and SAC-C GPS occultation data.

The effect of this bug seems to be that GPS satellite clock-offsets
were not accounted for correctly.  This error was small enough to
permit the passage of the data through our quality control, but is
still a very significant error. Below is a table listing temperature
error as a function of height for all the published CHAMP
occultations on 15 May). This bug affected the L1A, L1B, and L2
products on the GENESIS website.

We are in the process of re-processing CHAMP and SAC-C data for the
affected period:  23:00 UT on 19 April 2003 to 23:00 UT on 9 August
2003.  In the meantime, we have removed these occultations from the
GENESIS ftp site, and will start replacing them today (26 Aug).
The full data set should be restored in about a week.

We are very sorry for any inconvenience.

Byron Iijima

Statistics on temperature difference caused by processing bug as a
function of height for CHAMP profiles 15 May 2003 for all published
occultations

             Statistics on temperature difference (Kelvin)
   ht   no.  mean  stddev    min    max    rms
  (km) data  diff    diff   diff   diff   diff

    0     2  -0.13   0.00  -0.13  -0.13   0.13
    1    20   0.13   0.61  -0.32   2.09   0.62
    2    81   0.12   0.30  -0.26   0.88   0.33
    3   154   0.09   0.39  -1.41   0.95   0.40
    4   280   0.14   0.50  -1.46   1.69   0.52
    5   303   0.21   0.59  -1.63   2.25   0.63
    6   385   0.33   0.69  -1.79   2.64   0.77
    7   422   0.38   0.69  -1.95   2.72   0.79
    8   458   0.38   0.74  -2.02   2.72   0.83
    9   519   0.41   0.78  -2.17   3.01   0.88
   10   474   0.51   0.88  -2.33   3.29   1.02
   11   445   0.54   0.98  -2.65   4.04   1.12
   12   441   0.59   1.04  -2.86   4.37   1.19
   13   392   0.67   1.14  -3.13   4.50   1.32
   14   369   0.73   1.24  -3.51   4.55   1.44
   15   326   0.79   1.31  -3.85   4.81   1.53
   16   309   0.88   1.39  -4.11   5.12   1.65
   17   298   0.87   1.50  -4.43   6.07   1.73
   18   286   1.02   1.69  -4.86   7.42   1.97
   19   275   1.09   1.75  -5.06   7.55   2.06
   20   252   1.12   1.82  -5.17   7.16   2.14
   21   242   1.19   1.96  -5.47   7.84   2.29
   22   231   1.15   2.02  -5.79   7.86   2.32
   23   223   1.22   1.99  -5.86   7.53   2.33
   24   208   1.16   1.95  -5.82   6.77   2.27
   25   209   1.15   1.90  -5.71   6.66   2.22
   26   194   1.02   1.65  -5.54   6.49   1.94
   27   185   0.98   1.60  -5.31   6.32   1.87
   28   166   0.68   1.05  -4.40   4.75   1.25
   29   124   0.26   0.46  -0.77   2.08   0.53