EARTH RADIATION BUDGET SATELLITE (ERBS) TOTAL SOLAR IRRADIANCE MEASUREMENTS

                      OCTOBER 1984 TO Mar 12 2003

 Contacts: Robert B. Lee III        Robert S. Wilson
 Address: MS 420                    Science Applications International Corp.
 NASA Langley Research Center       One Enterprise Parkway Suite 300
 Hampton Va. 23681-2199             Hampton Va. 23666
 Telephone: 757-864-5679            757-827-4881
 Fax: 757-864-7996                  757-825-9129
 E-mail: r.b.lee@larc.nasa.gov      r.s.wilson@larc.nasa.gov

>From 1984 to the present, total solar irradiance (TSI) values were obtained
from the solar monitor on the Earth Radiation Budget Satellite (ERBS) nonscanner
instrument. The ERBS solar monitor is an active cavity radiometer similar in
design to the Active Cavity Radiometer Irradiance Monitors (ACRIM) which have
flown on the NASA Solar Maximum Mission (SMM), Upper Atmosphere Research
Satellite (UARS), and Atmospheric Laboratory for Applications and Science
(ATLAS) spacecraft missions. The ERBS satellite was placed into orbit on October
5, 1984 and the solar monitor is still operating properly, after almost 18
years. In Figure 1 and in Table 1, the ERBS solar monitor time series covers the
period from October 25, 1984 through March 12, 2003. The measurement
precision is approximately 0.01 percent while the accuracy is 0.2 percent. The
ERBS data reduction model is described in considerable detail in Reference 1. In
Reference 2, analyses of the ERBS time series were presented as well as
comparisons of the ERBS time series with those of the ACRIM Solar Maximum
Mission (SMM)and Nimbus 7 Earth Radiation Budget (ERB) Channel 10c
pyrheliometers. Recently, Lee and Wilson (1999) and Lee et al. (2002) presented
analyses of the enclosed 1984-2002 ERBS TSI values, and comparisons among the
ERBS values and those values from the Upper Atmosphere Research Satellite
(UARS), Solar and Heliospheric Observatory (SOHO)/Variability of solar
IRradiance and Gravity Oscillations (VIRGO), and Space Shuttle Atmospheric
Laboratory for Applications and Science (ATLAS) Solar Constant (SOLCON) 
Spacecraft missions. 

In the attached Table 1, the format for the total solar irradiance (TSI) values is:

Column 1:  Calibration date - year/month/day
Column 2:  Measurement time (universal) - hour:min:sec
Column 3:  Total Solar Irradiance (Watts/meters squared) at 1 AU
             Corrected for Off-axis viewing and normalized to
             Astronomical Almanac Earth-Sun Distance tables
Column 4:  Standard Deviation of averaged samples (Watts/meters squared)
             0.0 indicates 1 sample or very close instantaneous samples

In Figure 1, the individual total solar irradiance values represent orbital
averages of the instantaneous measurements which are corrected for the angle
between the instrument optical axis and the Sun and which are normalized to the
mean Earth/Sun distance. At least once every 14 days, the Sun is observed by the
monitor for several 64-second measurement intervals. Each interval is separated
into two 32-second periods. During the first period, the Sun drifts across the
9.2-degree unocculted field of view, and its radiation field is measured. During
the second period, a low-emittance shutter, representative of a near-zero 
irradiance source, is cycled into the field of view, and the low irradiance from
the back of the shutter is measured. The resulting averaged measurements from
the several 64-second time intervals are used to define the irradiance, using
the algorithms which are described in Reference 1. Typically, two to eleven 
values of the irradiance are determined during an orbit. Considering that these
irradiance values are derived typically during a single orbit for a few minutes,
the averaged irradiance values represent an almost instantaneous level, and not
a daily average.

Between 1984 and 1993, the solar monitor was operated continuously with the
exception of the July 2-3, 1987, September 4-9, 1992, and July 2-3, 1993 when
spacecraft attitude control or battery cell failure problems caused the monitor
to be turned off. Between July 18, 1993 and November 21, 1993, the monitor was
turned off because the spacecraft battery system and the flight operations
procedures could not provide sufficient power to all of the spacecraft sensors.
Therefore, there are no data available for this period. The 14-day measurement
schedule was resumed after November 22, 1993 when flight procedures were revised
to provide sufficient power to the monitor. Beyond Feb. 28, 1998, we have
processed with the exception of a few days, all of the 1998 ERBS TSI
measurements. During March 1998, no ERBS TSI measurements were obtained because
the ERBS/ERBE telemetry dedicated to earth and solar radiation measurement
failed. The April thru December 1998, TSI measurements were relayed in a
different format using the remaining ERBS/SAGE telemetry system. ERBS TSI 
measurements are also not available for later December 1998 and early January 
1999 because the ERBS spacecraft had another battery cell failure. The TSI
measurements started again on January 6, 1999. Also, between September 1999 and 
December 1999 no calibrations were done due to a failure in the elevation
gimbal of the non-scanner instrument. Solar measurements were resumed for the 
solar monitor only December 22, 1999 using a different command sequence. 

In Table 2, the solar monitor power-on/off days in 1993 thru December 2002 are
presented. In Table 1 and in Figure 1, the measurement standard deviations (STD)
increased significantly when the power was turned off for 1 to 8 day [an average
of 4 days] periods every 22 to 40 days [an average of 30 days].

In Figure 1, the ERBS irradiance values are compared with an empirical regression 
fit which serves as a quality assurance diagnostic tool. The fit was derived from 
least squares analyses between the ERBS irradiances, photometric sunspot index 
(PSI), and 10.7-cm solar flux (F10), using March 1985 thru August 1989 values. 
PSI is a proxy for irradiance decreases which are caused by the presence of large 
groups and numbers of sunspots. F10 is a proxy for irradiance brightening which 
is caused by the presence of faculae. Lee et al. (1995) describes the derivation 
of the regression fit.

Specialized irradiance measurement missions were conducted during March 23, 1992
through April 2, 1992, January 16, 1993 through January 30, 1993, April 6, 1993
through April 22, 1993, November 4, 1994 through December 13, 1994, August 8,
1997 through August 25, 1997 and October 29, 1998 through November 11, 1998. The
specialized missions included increased measurement opportunities over three to
six orbits each day compared to the typical single orbit measurements. The
missions were extended to as much as 10 consecutive days of measurements. 

                            References

         [1]  R. B. Lee III, B. R. Barkstrom, and R. D. Cess, "Characteristics
              of the Earth Radiation Budget Experiment Solar Monitors,"
              Appl. Optics, 26 (15) 3090-3096, 1987.

                
         [2]  R. B. Lee III, M. A. Gibson, R. S. Wilson, S. Thomas, "Long-term
              Total Solar Irradiance Variability During Sunspot Cycle 22,"
              Journal of Geophysical Research, Vol. 100, No. A2, pp. 
              1667-1675, February 1, 1995.

         [3]  Robert B. Lee III and Robert s. Wilson, "Validation of 1985-1997
              Active Cavity Radiometer spacecraft Measurements of Total Solar
              Irradiance Variability," Proceedings of SPIE [San Diego, CA;
              July 19-21, 1998, Vol. 3439, pp. 377-388, 1998.

         [4]  Robert B. Lee III, Robert S. Wilson, K. J. Priestley, 
              A. Al-hajjah, J. Paden, D. K. Pandey, and S. Thomas, "1978-1998
              Total Solar Irradiance Variability Trends," Proceedings of 10th
              Conference on Atmospheric Radiation [American Meteorogical
              Society, Madison, WI, June 28 - July 2, 1999], paper No. 5.12.

         [5]  Robert B. Lee III and Robert S. Wilson: Total solar irradiance (TSI) 
              variability: 1984-2002 Earth Radiation Budget Experiment (ERBE) 
              spacecraft measurements. Presented at 2002 Spring AGU meeting, 
              Washington, D. C., May 28-31, 2002, Eos Supplement, Vol. 81, No. 19, 
              S133, May 9, 2002.

        TABLE 1. ERBS Solar Irradiance Values and Standard Deviations 
                   [Watts per Square Meter]

 
  YR/MO/DY HR:MN:SC          IRR      STD
  84/10/25 15:24:45         1364.8    0.1
  84/10/26 10:44:49         1365.4    0.2
  84/10/29 11:21:05         1365.2    0.0
  84/11/01 08:44:16         1366.0    0.0
  84/11/05 06:21:26         1365.4    0.1
  84/11/12 19:06:09         1365.3    0.5
  84/11/20 11:00:49         1365.3    0.2
  84/11/26 08:15:29         1364.8    0.4
  84/12/03 09:37:37         1365.3    0.4
  84/12/10 19:27:13         1365.4    0.4
  84/12/17 11:21:05         1365.5    0.2
  84/12/28 08:34:41         1364.9    0.0
  85/01/09 10:00:33         1365.1    0.1
  85/01/23 16:06:25         1365.1    0.0
  85/02/06 13:20:33         1365.5    0.2
  85/02/20 13:05:37         1364.8    0.3
  85/03/06 11:09:53         1364.9    0.3
  85/03/20 12:56:01         1364.9    0.3
  85/04/03 17:30:13         1364.5    0.2
  85/04/17 13:56:33         1364.9    0.1
  85/05/01 12:48:33         1364.1    0.2
  85/05/08 12:39:45         1364.2    0.5
  85/05/29 12:38:25         1364.2    0.5
  85/06/18 12:11:44         1364.8    0.1
  85/06/26 12:11:13         1364.7    0.2
  85/07/10 12:36:16         1363.7    0.2
  85/07/24 12:15:12         1364.3    0.2
  85/08/07 14:05:52         1365.1    0.1
  85/08/21 12:01:36         1364.5    0.3
  85/09/04 13:30:40         1364.5    0.0
  85/09/18 12:18:40         1364.7    0.2
  85/10/02 13:41:20         1364.6    0.1
  85/10/16 13:16:16         1364.9    0.3
  85/10/21 12:35:54         1365.3    0.2
  85/10/31 12:05:20         1365.7    0.2
  85/11/13 13:10:56         1365.1    0.1
  85/11/27 13:36:00         1364.7    0.4
  85/12/18 11:49:20         1364.6    0.2
  85/12/25 14:44:48         1364.8    0.2
  86/01/08 11:41:52         1365.1    0.3
  86/01/22 12:57:36         1365.1    0.1
  86/02/05 13:24:48         1364.2    0.2
  86/02/15 12:12:47         1364.5    0.1
  86/02/26 03:04:15         1364.8    0.2
  86/03/05 12:49:35         1364.7    0.1
  86/03/19 12:58:40         1364.4    0.3
  86/04/02 12:41:36         1364.8    0.2
  86/04/16 12:20:16         1364.2    0.1
  86/04/30 12:48:32         1364.6    0.1
  86/05/14 12:27:44         1364.7    0.2
  86/05/28 12:37:52         1364.4    0.3
  86/06/04 12:19:44         1364.4    0.3
  86/06/19 12:34:08         1364.7    0.1
  86/06/25 12:08:32         1364.3    0.2
  86/07/09 12:33:04         1364.3    0.0
  86/07/23 13:48:16         1365.3    0.1
  86/08/17 12:56:32         1364.6    0.3
  86/08/28 13:48:15         1364.4    0.4
  86/09/03 13:26:24         1364.9    0.3
  86/09/17 12:12:48         1364.7    0.0
  86/10/01 11:57:52         1364.6    0.3
  86/10/15 13:10:24         1364.6    0.1
  86/10/29 11:46:40         1364.8    0.3
  86/11/12 13:03:28         1364.7    0.4
  86/11/26 13:28:32         1364.5    0.3
  86/12/04 06:58:39         1364.8    0.2
  86/12/18 11:50:55         1364.5    0.9
  86/12/24 12:58:08         1364.5    0.3
  87/01/07 13:19:20         1365.0    0.4
  87/01/21 12:46:56         1365.9    0.2
  87/02/15 12:13:20         1364.7    0.3
  87/02/26 13:05:04         1364.7    0.4
  87/03/04 12:37:52         1364.7    0.4
  87/03/18 12:47:28         1365.0    0.2
  87/04/01 14:05:20         1364.6    0.2
  87/04/29 12:34:40         1364.6    0.2
  87/05/13 12:13:52         1365.4    0.1
  87/05/27 12:24:32         1364.9    0.2
  87/06/03 12:06:07         1364.9    0.1
  87/06/18 12:18:39         1364.9    0.4
  87/06/24 13:31:12         1364.4    0.3
  87/07/08 12:18:40         1365.3    0.5
  87/07/22 13:36:00         1365.0    0.1
  87/08/05 12:13:20         1364.9    0.1
  87/08/12 08:44:00         1364.8    0.0
  87/08/28 13:52:00         1365.1    0.1
  87/09/02 13:17:20         1364.9    0.0
  87/09/09 13:02:56         1364.9    0.0
  87/09/16 13:42:56         1365.4    0.1
  87/09/30 11:52:00         1364.6    0.2
  87/10/14 13:06:40         1364.4    0.3
  87/10/28 11:44:00         1364.9    0.2
  87/11/11 13:01:20         1365.4    1.1
  87/11/25 11:50:51         1365.3    1.3
  87/12/18 12:04:48         1365.4    1.1
  87/12/23 13:01:20         1365.8    1.0
  88/01/06 13:13:34         1365.7    0.1
  88/01/20 12:52:14         1364.6    0.6
  88/02/03 16:34:06         1365.2    0.0
  88/02/14 02:38:54         1364.9    0.1
  88/02/25 11:35:58         1365.4    0.3
  88/03/02 12:46:22         1365.0    0.1
  88/03/16 11:19:26         1365.2    0.3
  88/03/29 14:13:50         1365.0    0.3
  88/04/13 12:18:38         1365.2    0.1
  88/04/27 12:45:50         1365.1    0.1
  88/05/11 12:25:02         1365.8    0.0
  88/05/25 14:13:18         1364.8    0.1
  88/06/02 06:01:34         1365.4    0.4
  88/06/17 12:43:10         1365.8    0.2
  88/06/22 13:42:22         1365.2    0.2
  88/07/06 12:29:34         1365.7    0.1
  88/07/20 13:43:58         1365.3    0.1
  88/08/03 13:56:46         1365.4    0.2
  88/08/15 06:34:06         1365.0    0.0
  88/08/26 09:02:54         1365.7    0.2
  88/08/31 13:17:50         1364.8    0.1
  88/09/14 13:40:14         1365.9    0.2
  88/09/28 13:23:10         1365.5    0.1
  88/10/12 12:57:02         1365.5    0.1
  88/10/26 13:07:10         1365.2    0.3
  88/11/09 13:44:14         1365.2    0.4
  88/11/23 13:05:34         1365.7    0.3
  88/12/02 06:45:50         1365.4    0.5
  88/12/16 08:20:14         1365.1    0.1
  88/12/21 12:28:14         1364.5    0.1
  89/01/05 12:43:42         1366.4    0.3
  89/01/18 12:03:42         1366.0    0.4
  89/02/01 12:23:58         1366.1    0.3
  89/02/12 06:26:38         1365.6    0.2
  89/02/24 05:47:42         1365.5    0.2
  89/03/01 13:09:18         1365.8    0.2
  89/03/22 12:48:30         1365.3    0.2
  89/03/29 12:36:46         1365.9    0.1
  89/04/12 12:05:18         1366.8    0.1
  89/04/26 12:19:42         1365.9    0.0
  89/05/10 11:45:34         1366.7    0.0
  89/05/24 11:41:50         1365.9    0.2
  89/06/02 06:36:14         1365.6    0.1
  89/06/15 08:10:06         1363.3    0.4
  89/06/22 13:54:38         1366.1    0.1
  89/07/06 12:24:30         1365.9    0.2
  89/07/20 13:21:02         1366.1    0.1
  89/08/03 13:17:18         1365.5    0.2
  89/08/15 05:40:14         1365.7    0.1
  89/08/25 07:55:10         1366.6    0.3
  89/08/30 12:02:38         1366.2    0.2
  89/09/13 12:07:58         1365.9    0.1
  89/09/27 11:30:38         1366.3    0.3
  89/10/11 12:21:50         1367.0    0.5
  89/10/25 13:48:46         1366.6    0.1
  89/11/08 13:05:34         1366.5    0.0
  89/11/23 13:05:34         1365.7    0.4
  89/11/30 07:58:22         1365.5    0.2
  89/12/15 07:43:26         1366.4    0.1
  89/12/20 13:19:58         1365.9    1.0
  90/01/03 13:02:21         1366.1    0.4
  90/01/17 12:10:05         1366.0    0.4
  90/01/31 13:44:29         1366.3    0.3
  90/02/11 07:30:05         1365.6    0.2
  90/02/22 08:08:29         1365.5    0.2
  90/02/28 13:45:01         1365.7    0.2
  90/03/14 11:45:01         1366.2    0.2
  90/03/28 12:29:17         1366.4    0.3
  90/04/11 13:12:29         1365.9    0.0
  90/04/25 13:04:29         1366.3    0.2
  90/05/09 12:08:29         1365.9    0.2
  90/05/24 11:51:25         1366.4    0.3
  90/05/30 07:53:01         1365.6    0.4
  90/06/14 09:03:25         1366.6    0.3
  90/06/20 13:11:57         1366.3    0.6
  90/07/04 12:58:37         1364.5    0.2
  90/07/18 13:35:25         1366.6    0.1
  90/08/01 13:09:17         1366.0    0.0
  90/08/11 06:42:37         1366.7    0.3
  90/08/23 07:15:41         1364.4    0.3
  90/08/29 12:52:45         1366.5    0.2
  90/09/12 12:36:13         1366.0    0.5
  90/09/26 13:16:13         1365.8    0.1
  90/10/10 12:09:01         1365.0    0.5
  90/10/24 11:39:41         1365.7    0.3
  90/11/07 13:50:53         1366.1    0.1
  90/11/21 13:31:41         1363.6    0.2
  90/11/28 08:06:21         1365.4    0.3
  90/12/13 07:32:13         1365.9    0.0
  90/12/19 13:09:49         1364.4    0.4
  91/01/02 07:45:00         1366.3    0.2
  91/01/16 13:03:24         1364.8    0.2
  91/01/30 12:43:08         1363.1    0.0
  91/02/09 09:20:28         1365.6    0.2
  91/02/20 09:35:56         1365.8    0.1
  91/02/27 09:35:56         1365.6    0.1
  91/03/13 13:04:28         1365.7    0.3
  91/03/27 11:55:08         1365.0    0.1
  91/04/10 12:17:00         1367.6    0.2
  91/04/24 13:27:24         1366.3    0.1
  91/05/08 12:11:08         1365.0    0.4
  91/05/22 13:00:12         1365.6    0.0
  91/05/28 07:17:48         1364.5    0.0
  91/06/12 09:42:20         1364.8    0.1
  91/06/19 12:13:32         1365.7    0.1
  91/07/03 11:39:40         1366.9    0.1
  91/07/17 11:55:08         1366.3    0.0
  91/07/31 12:44:12         1366.9    0.2
  91/08/09 07:23:08         1366.5    0.3
  91/08/21 07:37:00         1364.5    0.2
  91/08/28 11:45:32         1366.2    0.0
  91/09/11 12:44:12         1365.8    0.3
  91/09/25 11:26:52         1365.9    0.4
  91/10/09 11:33:16         1366.5    0.1
  91/10/23 12:19:08         1365.4    0.0
  91/11/06 12:31:24         1365.8    0.3
  91/11/20 11:49:48         1366.3    0.2
  91/11/26 07:42:20         1365.6    0.1
  91/12/10 08:13:16         1364.4    0.3
  91/12/18 12:17:00         1366.1    0.0
  92/01/01 11:20:28         1365.6    0.4
  92/01/15 11:24:44         1366.2    0.3
  92/01/29 12:17:00         1364.8    0.2
  92/02/06 08:23:56         1365.7    0.2
  92/02/18 08:28:12         1365.9    0.4
  92/02/26 12:31:24         1365.1    0.3
  92/03/11 13:03:24         1366.2    0.1
  92/03/23 16:06:52         1366.3    0.2
  92/03/24 16:14:20         1365.8    0.3
  92/03/25 13:08:44         1366.2    0.1
  92/03/26 16:29:16         1365.6    0.2
  92/03/27 03:44:28         1365.8    0.4
  92/03/28 03:51:56         1365.2    0.2
  92/03/29 02:22:20         1364.6    0.2
  92/03/30 04:05:16         1364.2    0.2
  92/03/31 13:50:52         1364.9    0.3
  92/04/01 15:33:48         1365.4    0.2
  92/04/02 14:03:40         1366.0    0.1
  92/04/08 12:22:52         1365.7    0.1
  92/04/22 12:18:04         1365.5    0.1
  92/05/06 12:15:24         1365.8    0.2
  92/05/20 12:43:08         1366.5    0.1
  92/05/24 08:16:28         1365.3    0.2
  92/06/08 08:42:36         1365.2    0.1
  92/06/17 12:50:36         1365.6    0.3
  92/07/01 11:58:19         1365.7    0.4
  92/07/15 11:54:03         1365.9    0.2
  92/08/05 06:37:47         1365.6    0.2
  92/08/18 08:20:43         1364.3    0.1
  92/08/26 12:23:55         1366.2    0.1
  92/09/12 10:13:15         1365.2    0.1
  92/10/07 12:02:35         1365.5    0.2
  92/10/21 11:52:59         1364.5    0.1
  92/11/04 11:49:47         1365.3    0.3
  92/11/18 12:29:47         1365.7    0.4
  92/11/22 08:05:47         1365.2    0.3
  92/12/06 09:58:51         1365.3    0.2
  92/12/16 12:29:47         1365.8    0.2
  92/12/30 12:58:03         1365.8    0.0
  93/01/13 11:14:03         1365.3    0.3
  93/01/16 21:10:19         1365.8    0.3
  93/01/17 19:39:39         1365.6    0.2
  93/01/18 14:56:27         1366.0    0.2
  93/01/19 07:00:11         1365.8    0.1
  93/01/20 16:02:35         1365.9    0.4
  93/01/21 12:55:23         1365.9    0.3
  93/01/22 09:48:11         1365.6    0.2
  93/01/23 06:41:31         1365.9    0.1
  93/01/24 03:34:19         1366.1    0.2
  93/01/25 00:27:39         1365.6    0.2
  93/01/26 02:03:39         1365.3    0.4
  93/01/27 11:54:03         1365.2    0.2
  93/01/28 18:25:31         1365.6    0.1
  93/01/29 13:43:23         1365.8    0.4
  93/01/30 12:13:15         1365.4    0.3
  93/02/01 07:35:55         1365.3    0.1
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  96/09/22 13:44:57         1364.8    0.2
  96/09/25 10:47:53         1365.0    0.2
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  96/10/23 11:52:25         1366.0    0.2
  96/10/25 07:13:29         1366.3    0.5
  96/10/28 11:35:53         1365.2    0.4
  96/11/06 12:22:49         1365.0    0.4
  96/11/08 07:46:01         1365.0    0.6 
  96/11/20 10:51:05         1365.0    0.5
  96/12/04 10:24:57         1364.8    0.1
  96/12/07 11:22:01         1365.3    0.3
  96/12/18 10:46:17         1364.7    0.4
  97/01/01 21:42:17         1365.1    0.6
  97/01/04 11:38:01         1365.2    0.5 
  97/01/15 12:35:37         1364.6    0.4
  97/01/17 12:47:53         1365.1    0.2
  97/01/30 11:09:13         1364.9    0.5
  97/02/12 10:36:41         1364.4    0.3
  97/02/14 11:28:25         1365.7    0.2
  97/02/26 10:55:53         1365.1    0.1  
  97/03/12 12:20:41         1365.7    0.2
  97/03/18 11:16:09         1365.2    0.1
  97/03/20 10:43:37         1364.7    0.2
  97/03/26 11:16:09         1364.7    0.0
  97/04/09 11:03:53         1365.0    0.1
  97/04/22 10:37:13         1364.5    0.1
  97/04/24 11:28:57         1365.1    0.2
  97/05/07 09:18:49         1365.4    0.3
  97/05/19 10:47:21         1364.7    0.4
  97/05/21 10:59:37         1364.9    0.4
  97/06/02 10:26:01         1364.8    0.3
  97/06/05 21:12:57         1364.7    0.0
  97/06/18 11:10:49         1365.0    0.4
  97/07/02 12:26:00         1365.1    0.0
  97/07/04 11:42:16         1365.7    0.5
  97/07/16 20:40:56         1365.1    0.2
  97/07/30 12:44:08         1365.1    0.4
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  97/08/10 10:29:12         1365.2    0.4
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  97/08/13 16:27:36         1365.8    0.8
  97/08/14 06:54:16         1365.4    0.1
  97/08/16 21:31:36         1365.4    0.3
  97/08/17 00:44:08         1365.3    0.0
  97/08/18 10:27:36         1365.7    0.3
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  97/08/20 10:38:16         1365.3    0.3
  97/08/21 12:20:08         1365.2    0.3
  97/08/22 10:49:28         1365.3    0.2
  97/08/23 14:07:52         1365.2    0.6
  97/08/24 11:01:12         1365.1    0.2
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  97/09/10 11:03:52         1363.8    0.4
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  97/12/29 10:40:56         1365.4    0.0
  97/12/31 11:45:28         1365.3    0.3 
  98/01/13 11:16:40         1365.1    0.3
  98/01/26 11:15:04         1365.1    0.4
  98/01/28 11:24:08         1365.2    0.3
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  98/11/09 11:31:04         1366.0    1.0
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  98/11/12 11:47:03         1365.7    0.7
  98/11/17 10:33:27         1365.1    0.6
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  99/09/22 20:39:50         1366.1    0.4
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  99/12/29 19:21:26         1366.0    0.8
  00/01/05 19:51:18         1366.1    0.4
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  00/01/26 20:02:30         1365.4    0.2
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  00/02/09 19:59:50         1366.6    0.0
  00/02/16 20:30:15         1366.0    0.2
  00/02/23 19:26:47         1365.6    1.0
  00/03/01 19:55:35         1364.9    0.0
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  00/03/15 20:07:19         1365.3    0.3
  00/03/22 20:40:23         1365.3    0.2
  00/03/29 19:36:54         1365.8    0.1
  00/04/05 20:02:31         1366.1    0.4
  00/04/12 19:30:31         1366.2    0.1
  00/04/19 19:52:55         1366.5    0.2 
  00/04/26 20:16:23         1364.5    0.3
  00/05/03 19:21:59         1366.6    0.2
  00/05/10 19:53:27         1365.5    0.3
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  00/05/24 19:58:15         1365.2    0.8
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  00/06/07 19:15:03         1365.8    0.2
  00/06/14 19:39:35         1366.7    0.0
  00/06/22 20:46:15         1365.9    0.1
  00/06/28 19:27:19         1364.9    0.2
  00/07/05 19:45:59         1365.7    0.3  
  00/07/20 19:31:03         1365.0    0.4  
  00/07/26 19:49:11         1365.8    0.0 
  00/08/02 19:27:51         1366.1    0.0
  00/08/09 19:50:47         1365.7    0.2  
  00/08/16 20:17:59         1365.9    0.0  
  00/08/23 20:43:35         1366.1    0.0  
  00/08/30 19:28:55         1366.3    0.0  
  00/09/13 19:15:35         1366.3    0.2
  00/09/20 19:42:47         1364.3    0.2
  00/09/27 20:12:39         1366.4    0.2  
  00/10/04 20:34:31         1366.2    0.3
  00/10/11 20:11:35         1365.8    0.0
  00/10/18 20:31:51         1366.2    0.5  
  00/11/08 20:17:59         1365.9    0.0  
  00/11/15 20:35:35         1366.0    0.2  
  00/11/29 20:19:42         1365.8    0.2  
  00/12/06 20:42:38         1366.4    0.0  
  00/12/27 19:18:54         1365.8    0.4
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  01/01/24 19:18:54         1366.5    0.0
  01/01/31 20:15:58         1367.2    0.0
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  01/02/14 19:20:30         1366.6    0.3
  01/02/21 19:40:46         1366.7    0.0
  01/02/28 19:16:14         1366.4    0.3
  01/03/07 19:32:14         1365.7    0.9
  01/03/14 19:53:02         1365.7    0.2
  01/03/21 13:54:38         1366.0    0.4
  01/04/04 09:38:38         1366.7    0.0  
  01/04/11 10:33:02         1365.8    0.0
  01/04/25 09:31:43         1365.6    0.4
  01/05/02 10:01:34         1365.6    0.4
  01/05/09 10:18:06         1366.6    0.2
  01/05/16 21:02:22         1366.9    0.0
  01/05/23 10:04:14         1365.7    0.0
  01/05/30 10:21:50         1366.2    0.1
  01/06/06 10:38:54         1366.0    0.0
  01/06/13 10:52:46         1366.4    0.0
  01/06/20 10:10:06         1365.6    0.0
  01/06/27 10:20:14         1366.2    0.5
  01/07/18 09:54:38         1365.2    0.2
  01/07/25 10:06:22         1366.0    0.5
  01/08/01 09:37:34         1366.0    0.1
  01/08/08 09:54:06         1365.6    0.9
  01/08/15 10:11:42         1365.9    0.0
  01/08/22 10:26:06         1366.0    0.0
  01/08/29 11:19:58         1366.5    0.0
  01/09/05 09:55:10         1365.4    0.1
  01/09/12 10:10:06         1364.8    0.8
  01/09/19 10:33:02         1365.9    0.2
  01/09/26 10:50:06         1364.8    0.8
  01/10/03 09:24:46         1366.5    0.3
  01/10/10 10:29:18         1366.4    0.3
  01/10/17 10:43:42         1365.1    0.2
  01/10/31 09:48:14         1364.8    0.1
  01/11/07 09:56:46         1365.9    0.0
  01/11/14 10:46:22         1366.2    0.1
  01/11/21 10:55:58         1366.1    0.5
  01/11/28 09:32:46         1365.9    0.2
  01/12/05 09:44:30         1365.5    0.0
  01/12/15 09:14:06         1367.2    0.0
  01/12/19 09:17:50         1367.0    0.4
  02/01/09 10:10:06         1366.3    0.1
  02/01/30 09:28:30         1366.6    0.4
  02/02/06 09:37:34         1366.8    0.2
  02/02/13 09:47:42         1366.4    0.1
  02/02/20 09:53:34         1367.6    0.0
  02/02/27 10:52:14         1366.7    0.2
  02/03/06 09:22:06         1366.4    0.3
  02/03/13 09:35:26         1366.0    0.1
  02/03/20 09:45:34         1366.4    0.8 
  02/03/27 09:47:42         1366.4    0.3  
  02/04/03 10:29:50         1365.6    0.0  
  02/04/10 10:29:50         1366.0    0.4  
  02/04/17 10:34:07         1366.1    0.2  
  02/04/24 09:15:42         1365.7    0.2
  02/05/01 09:22:38         1366.3    0.0
  02/05/08 09:23:42         1365.7    0.1 
  02/05/15 10:19:10         1366.1    0.0  
  02/05/22 10:23:26         1365.9    0.5  
  02/05/29 10:28:14         1366.6    0.3 
  02/06/05 10:29:50         1365.8    0.0  
  02/06/12 09:34:22         1365.6    0.3  
  02/06/19 09:31:42         1366.2    0.5
  02/07/10 10:02:38         1366.2    0.5
  02/07/15 10:02:06         1364.9    0.2
  02/07/16 10:02:06         1365.3    0.0
  02/07/17 10:01:34         1364.9    0.0
  02/07/18 00:25:34         1366.0    0.0
  02/07/19 10:01:02         1364.6    0.0
  02/08/26 10:22:54         1366.4    0.1
  02/08/30 09:41:18         1365.2    1.0
  02/09/02 10:46:22         1365.2    0.1
  02/09/04 10:26:38         1365.4    0.4
  02/09/13 10:43:42         1365.0    0.3
  02/09/18 09:56:46         1365.9    0.0
  02/09/20 09:36:30         1366.0    0.3
  02/09/23 10:40:30         1366.2    0.0
  02/09/25 10:19:42         1366.0    0.0
  02/09/30 10:20:46         1366.4    0.0
  02/10/02 09:59:26         1366.6    0.0
  02/10/04 09:38:38         1365.8    0.6
  02/10/07 10:43:42         1365.9    0.3
  02/11/01 09:51:26         1366.7    0.0
  02/11/13 09:59:58         1365.3    0.2
  02/11/15 09:39:42         1365.7    0.1
  02/11/18 10:45:18         1365.7    0.1
  02/12/18 09:31:42         1365.3    0.0
  03/01/08 09:19:58         1365.9    0.0
  03/01/15 10:17:34         1367.0    0.0
  03/01/22 10:36:14         1366.4    0.1
  03/01/29 09:22:38         1366.3    0.0
  03/02/05 09:45:02         1366.4    0.0
  03/02/12 10:03:42         1366.3    0.0
  03/02/19 09:40:14         1365.7    0.7
  03/02/26 10:00:30         1365.5    0.1
  03/03/12 09:16:46         1364.9    0.1          
    
 
 
  

TABLE 2 ERBS Nonscanner Instrument Days of Operation up to February 28, 2003

       1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Jun 93 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  
Jul 93 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x      
Aug 93 
Sep 93
Oct 93
Nov 93                                                       x  x  x  x  x  x  x  x  x
Dec 93 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jan 94 x x x x x x x x x x  x  x  x  x  x                    x     x  x  x  x  x  x  x  x
Feb 94 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x              x  x    
Mar 94 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  
Apr 94       x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
May 94 x           x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jun 94 x x x x x x x x x x  x                 x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jul 94 x x x x x x x x x x  x           x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Aug 94 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x                 x  x  x  x  x  x
Sep 94 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x                 x
Oct 94 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x 
Nov 94       x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Dec 94 x x x x x x x x x x  x           x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jan 95 x x x x x x x x x          x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Feb 95 x x x x x x x x x x  x  x  x  x  x  x  x  x              x  x  x  x  x  x 
Mar 95 x       x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x           x  x  x
Apr 95 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
May 95   x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jun 95 x x x x x x x x x          x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jul 95 x x x x x x x x x       x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Aug 95 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x     x  x  x  x  x  x  x  x  x  x
Sep 95 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x        x  x  x  x  x
Oct 95 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x        x
Nov 95 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Dec 95 x x x x x x x x      x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jan 96 x x x x x x       x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Feb 96 x x x x x x x x x x  x  x  x  x  x           x  x  x  x  x  x  x  x  x  x 
Mar 96 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x        x  x  x  x  x  x  x
Apr 96 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x        x  x  x
May 96 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jun 96 x x x x x     x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  
Jul 96 x x x x     x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Aug 96 x x x x x x x x x x  x  x  x  x        x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Sep 96 x x x x x x x x x x  x  x  x  x  x  x  x  x        x  x  x  x  x  x  x  x  x  x
Oct 96 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x     x  x  x  x  x
Nov 96 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Dec 96 x x x x   x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jan 97 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Feb 97 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x 
Mar 97 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Apr 97 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
May 97 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jun 97 x x   x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jul 97 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Aug 97 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Sep 97 x x x x x x x x x x  x  x  x  x     x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Oct 97 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Nov 97 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  
Dec 97 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jan 98 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Feb 98 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x 
Mar 98 x x x x x 
Apr 98                   x  x  x  x  x  x  x  x        x  x  x  x  x  x  x  x  x  x  x
May 98 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x        x
Jun 98 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x     x  x
Jul 98 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Aug 98 x x x x x x x     x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Sep 98 x x x x x x x x x x     x  x  x     x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Oct 98 x x x x x x x x x x  x  x  x  x  x  x     x  x  x  x  x  x  x  x  x  x  x  x  x  x
Nov 98 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x        x  x  x  
Dec 98 x x x x x x x
Jan 99         x x x x x x  x  x  x  x  x  x
Feb 99         x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Mar 99 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Apr 99 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
May 99 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jun 99 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jul 99 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Aug 99 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Sep 99 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Oct 99 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Nov 99 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  
Dec 99 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jan 00 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Feb 00 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Mar 00 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Apr 00 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
May 00 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jun 00 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jul 00 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Aug 00 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Sep 00 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Oct 00 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Nov 00 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  
Dec 00 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jan 01 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Feb 01 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Mar 01 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Apr 01 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
May 01 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jun 01 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jul 01 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Aug 01 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Sep 01 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Oct 01 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Nov 01 x x x x x x x x x x  x  x  x  x  x  x  x     x  x  x  x  x  x  x  x  x  x  x  x  
Dec 01 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jan 02 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Feb 02 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Mar 02 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Apr 02 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
May 02 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jun 02 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jul 02 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x     x  x                    x
Aug 02 x x x x x x x x                                    x  x  x  x  x  x  x  x  x  x  x
Sep 02 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Oct 02 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Nov 02 x x x x x x x x x x  x  x  x  x  x  x  x     x  x  x  x  x  x  x  x  x  x  x  x  
Dec 02 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Jan 03 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Feb 03 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x
Mar 03 x x x x x x x x x x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x  x

   Figure 1. Earth Radiation Budget Satellite (ERBS) total solar irradiance
values and the standard deviations for each value with an empirical model fit
represented by solid line.