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Subject: Monthly Review of Solar & Geophysical Activity for August 1993
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           --  MONTHLY REVIEW OF SOLAR AND GEOPHYSICAL ACTIVITY  --
                           Summary for August 1993

                            Report compiled by the
                          Solar Terrestrial Dispatch
                                 P.O. Box 357
                              Stirling, Alberta
                               T0K 2E0, Canada
 
                    Data Provided In-Part Courtesy of the
                   Space Environment Services Center, NOAA
                                   and the
                NRC / Dominion Radio Astrophysical Observatory
                     Penticton, British Columbia, Canada


MONTHLY ACTIVITY SUMMARY FOR AUGUST 1993

     We are now in month 85 of solar cycle 22 (as of Sept 1993).  There
were 152 flares (optical and x-ray) in August.  This is a decrease of 25%
over the number of events observed in July.  No major flares were recorded
and only 1 M-class flare was observed.

     A breakdown of the energetic events for the last four months follows
below.
         ____________________________________________________________
        |                    | AUG '93 | JUL '93 | JUN '93 | MAY '93 |
        |                    | --------|---------|---------|---------|
        |              Major |      0  |     0   |     3   |     0   |
        |      Minor M-class |      1  |     4   |    10   |     5   |
        | Class C or smaller |    151  |   198   |   315   |   280   |
        |--------------------|---------|---------|---------|---------|
        |              Total |    152  |   202   |   328   |   285   |
         ------------------------------------------------------------

     The monthly sunspot number for August was 59.4 as computed by the
SESC.  The preliminary RI international sunspot number for August was 42.0.
The preliminary smoothed international sunspot number centered on February of
this year was 69.2.

     The monthly 10.7 cm solar radio flux for August was 93.7 which
results in a preliminary smoothed mean flux value of 123.0 centered on
February 1993.  The monthly mean solar flux adjusted to 1 AU was 96.0.  The
best absolute value of the estimated 10.7 cm solar radio flux for the month
was 86.4 (Series D).

     The largest flare of August occurred on 11 August from Region 7562 at
10:23 UTC when a class M1.5/SN event erupted.  A moderate (Importance 2)
Type II sweep accompanied this event from 10:23 to 10:41 UTC.

     The most eruptive region during the month proved to be Region 7562,
which was born on August 10 at N09W31 and quickly grew to a maximum size of
220 millionths in a bipolar magnetic configuration before beginning to decay.
It was responsible for 21 small flares, 4 of which were C-class events. These
unimpressive statistics demonstrate the inactivity of the sun during this
month of the declining phase of cycle 22.

     A very weak proton enhancement at greater than 10 MeV was noticable in
proton fluence patterns during August.  The enhancement began on 08 August
and continued until approximately 14 August when protons fell back to near
background levels.  Protons at greater than 10 MeV reached a maximum of
approximately 0.6 pfu near 13:30 UTC on 11 August.  A source for this weak
enhancement was not identified.

     The list of minor M-class or greater flares and associated radio
emissions observed during August follows:


SUMMARY OF MAJOR ENERGETIC EVENTS
---------------------------------

 Date   Begin  Max   End  Xray  Op Region  Locn    2695 MHz  8800 MHz  15.4 GHz
------  ----  ----  ----  ----  -- ------ ------  --------- --------- ---------
NO MAJOR ENERGETIC EVENTS OBSERVED.


SUMMARY OF MINOR M-CLASS EVENTS
-------------------------------

 Date   Begin  Max   End  Xray  Op Region  Locn    2695 MHz  8800 MHz  15.4 GHz
------  ----  ----  ----  ----  -- ------ ------  --------- --------- ---------
11 Aug: 0954  1023  1035  M1.5  SN  7562  N07W48


REGION FLARE STATISTICS
-----------------------

                C   M   X     S   1   2   3   4   Total   (%)
               --  --  --    --  --  --  --  --    ---  ------
  Region 7556:  0   0   0     1   0   0   0   0    001  ( 0.7)
  Region 7558:  2   0   0    16   1   0   0   0    017  (11.2)
  Region 7560:  0   0   0     1   0   0   0   0    001  ( 0.7)
  Region 7562:  4   1   0    20   0   0   0   0    021  (13.8)
  Region 7563:  3   0   0     8   0   0   0   0    008  ( 5.3)
  Region 7566:  1   0   0     6   0   0   0   0    006  ( 3.9)
  Region 7568:  0   0   0     1   0   0   0   0    001  ( 0.7)
Uncorrellated: 12   0   0     0   0   0   0   0    097  (63.8)

 Total Events: 152 optical and x-ray.

     The geomagnetic field was slightly more active in August than in July.
The estimated planetary A-index for August was 12, compared with 10 for July.
This gives an estimated smoothed value of 15.9 centered on February 1993.
There were no sudden magnetic impulses recorded during August.

     The most active days of the month were 16 and 17 August.  The estimated
planetary A-indices for these days were 66 and 35 respectively.  This
disturbance was produced by a high-speed solar wind stream from a well-placed
positive-polarity transequatorial coronal hole, as inferred from Yohkoh x-ray
imagery.  It is interesting to note that this coronal feature has been
responsible for producing recurrent 27-day enhancements in geophysical
activity over the last several solar rotations.  Its recurrence in September
was responsible for major to severe geomagnetic storming (see the September
review of activity to be released in October for additional detailed
information).  Minor to major storming was associated with this August storm
event.  Periods of severe geomagnetic storming were reported by many high and
polar latitude stations.

     There is fairly high confidence that this coronal hole, which joined
with the northern polar crown and expanded longitudinally in September, will
continue to prove geoeffective around October 9 or 10 during Carrington
rotation 1874.


    RECENT SOLAR INDICES (PRELIMINARY) OF THE OBSERVED MONTHLY MEAN VALUES
                       Last Updated 17 September, 1993
 
              Sunspot Numbers                   Radio Flux    Geomagnetic 
      ------------------------------------    --------------  -----------
       Observed     Ratio    Smooth Values   Penticton Smooth   Smooth
      SESC    RI   RI/SESC    SESC    RI      10.7 cm  Value   Ap  Value
      ------------------------------------    --------------  -----------
                                 YEAR = 1989
Jan:  203.2  161.6  .80       189.2  141.9     235.4  190.2    19   16.7 
Feb:  211.0  164.5  .78       196.0  144.7     222.4  194.0    15   17.0 
Mar:  176.8  131.0  .74       204.1  149.4     205.1  199.7    41   17.6 
 
Apr:  172.3  129.3  .75       209.9  153.1     189.6  204.4    23   18.2 
May:  207.0  138.4  .67       216.4  156.5     190.1  209.3    16   18.8 
Jun:  297.3  196.0  .66       220.1  157.9     239.6  213.1    17   19.2 
 
Jul:  193.9  126.8  .65       221.1  158.1     181.9  212.6     8   19.1 
Aug:  243.0  166.8  .69       221.5  157.4     217.1  209.7    20   19.3 
Sep:  240.7  176.8  .74       221.3  156.3     225.9  207.2    17   18.8 
 
Oct:  217.4  158.5  .73       223.2  157.1     208.7  206.3    21   18.3 
Nov:  255.0  173.0  .68       223.4  157.3     235.1  206.1    19   18.4 
Dec:  217.8  166.1  .76       217.3  153.3     213.0  203.3    16   18.4 
 
                                 YEAR = 1990
Jan:  239.3  177.3  .74       212.4  150.6     210.1  200.4    14   18.6 
Feb:  184.7  130.5  .71       213.9  152.9     178.3  200.5    23   18.8 
Mar:  198.6  140.3  .71       212.7  152.0     188.8  198.7    23   18.6 
 
Apr:  196.1  140.3  .72       210.5  149.3     185.3  195.6    27   18.3 
May:  187.7  132.2  .70       208.1  147.0     189.7  192.4    16   17.6 
Jun:  168.9  105.4  .62       205.3  143.8     170.9  189.9    16   16.8 
 
Jul:  204.3  149.4  .73       203.8  140.6     180.7  190.4    14   16.2 
Aug:  269.4  200.3  .74       206.3  140.5     222.6  193.9    19   15.4 
Sep:  186.4  125.2  .67       211.1  142.1     177.4  198.3    14   15.0 
 
Oct:  219.0  145.5  .66       213.1  142.1     182.0  200.6    15   14.8 
Nov:  196.1  131.4  .67       213.7  141.7     184.3  201.2     9   14.4 
Dec:  208.0  129.7  .62       216.1  143.9     204.9  202.7     7   15.7 
 
                                 YEAR = 1991
Jan:  213.5  136.9  .64       220.5  147.6     229.4  205.5     8   17.4 
Feb:  270.2  167.5  .62       221.5  147.6     243.0  206.3    10   18.4 
Mar:  227.9  141.9  .62       220.7  146.6     230.0  205.9    27   19.1   

Apr:  215.9  140.0  .65       220.7  146.5     198.8  206.8    17   20.0
May:  182.5  121.3  .66       219.6  145.5     190.3  207.1    18   21.7
Jun:  231.8  169.7  .73       218.9  145.2     206.8  207.4    44   23.0
 
Jul:  245.7  173.7  .71       219.5  146.3     212.0  207.7    27   23.6
Aug:  251.5  176.3  .70       218.3  146.5     210.3  206.8    30   24.7
Sep:  185.8  125.3  .67       214.2  144.7     180.6  203.9    20   25.0
 
Oct:  220.1  144.1  .65       208.4  141.6     201.3  199.7    31   24.3
Nov:  169.0  108.2  .64       202.2  137.9     172.0  195.4    33   24.1
Dec:  217.7  144.4  .66       193.7  131.6     223.9  188.9    15   23.0

                                 YEAR = 1992
Jan:  217.9  149.3  .69       183.3  123.6     217.6  181.8    14   21.1
Feb:  238.2  159.6  .67       171.8  115.2     232.1  174.8    31   19.8
Mar:  160.5  106.9  .67       161.6  108.0     171.3  168.5    14   19.4

Apr:  144.0   99.8  .69       154.3  103.1     158.5  162.9    11   18.9
May:  106.3   73.8  .69       148.9  100.1     125.4  158.8    21   17.5
Jun:  104.7   65.2  .62       143.3   96.9     116.7  154.2    15   16.6

Jul:  121.4   85.7  .71       134.3   90.6     132.3  146.6    10   16.6
Aug:   99.5   64.5  .65       124.4   84.0     122.1  138.9    15   16.1
Sep:   93.8   63.9  .68       117.5   79.6     116.8  133.7    25   15.9

Oct:  136.2   88.3  .65       113.4   76.5     130.8  130.5    15   16.7
Nov:  124.3   92.0  .74       110.4   74.4     145.2  128.2    14   16.6
Dec:  127.4   83.3  .65       107.7   73.2     139.1  127.3    13   16.2

                                 YEAR = 1993
Jan:   92.1   59.1  .64       104.5   71.3     121.0  125.6    17   16.0
Feb:  126.1   90.5  .72       101.2   69.2*    142.6  123.0*   16   15.9*
Mar:  107.4   70.5  .66                        136.4           24

Apr:   98.6   61.9  .63                        115.9           19
May:   79.1   61.2  .77                        112.0           12
Jun:   68.5   49.1  .72                        109.3           12

Jul:   81.6   57.3  .70                         99.0           10
Aug:   59.4   42.0* .71*                        93.7*          12*
 
* = Preliminary estimates,  Unmarked = Final Values.
 
The lowest smoothed sunspot number for Cycle 21, RI = 12.3, occurred in 
September 1986.  The sunspot maximum for this cycle (cycle 22) occurred in 
July 1989, with a peak smoothed sunspot number (RI) of 158.1.

Note: Prior to June 1991, the 10.7 cm solar radio flux measurements
originated from the Algonquin Radio Observatory near Ottawa.  From June 1991
onward, the flux has been (and will continue to be) measured from the
Dominion Radio Astrophysical Observatory at Penticton, British Columbia,
Canada.


      ------------------------------------------------------------------
      DAILY VALUES OF SOLAR FLUX AT 2800 MHz (PENTICTON-DRAO) AT 2000 UT
      ------------------------------------------------------------------
                          Data Valid for August 1993

           Data Courtesy of the National Research Council of Canada
                      Herzberg Institute of Astrophysics
                   Dominion Radio Astrophysical Observatory
                         Penticton, British Columbia
                                    CANADA

Series D is the best estimate of absolute value and is obtained by using the
multiplier 0.90 recommended by Commission V of URSI.

            1993       Observed                   Adj to 1 AU

                       Series C             Series C        Series D

             1           99.8                102.8            92.5
             2          100.7                103.7            93.3
             3           97.9                100.8            90.7
             4           96.1                 98.9            89.0
             5           94.3                 97.0            87.3
             6           94.4                 97.1            87.4
             7           91.3                 93.8            84.4
             8           90.9                 93.4            84.1
             9           96.5                 99.1            89.2
            10          101.8                104.5            94.1

            11          108.3                111.2           100.1
            12          100.5                103.2            92.9
            13           96.7                 99.2            89.3
            14           92.2                 94.6            85.1
            15           90.5                 92.8            83.5
            16           90.1                 92.4            83.2
            17           92.8                 95.1            85.6
            18           92.1                 94.3            84.9
            19           91.7                 93.9            84.5
            20           91.6                 93.8            84.4

            21           94.8                 97.0            87.3
            22           94.0                 96.2            86.6
            23           92.8                 94.8            85.3
            24           90.6                 92.5            83.3
            25           88.7                 90.6            81.5
            26           88.3                 90.2            81.2
            27           87.6                 89.4            80.5
            28           88.4                 90.2            81.2
            29           90.0                 91.7            82.5
            30           89.0                 90.7            81.6

            31           89.0                 90.6            81.5

            Mean:        93.7                 96.0            86.4


              OUTSTANDING EVENTS - SOLAR RADIATION AT 2800 MHZ **
    ---------------------------------------------------------------------
     DATE  KEY        CLASS         START  MAXIMUM DURATION  PEAK   MEAN
                                     U.T.    U.T.            FLUX   FLUX
    ---------------------------------------------------------------------
     August                         HOURS   HOURS   MINUTES


      02   3  S   Simple II         1926.8  1927.5    3.8    10.0    2

      10   22 GRF Simple III F GRF  1847.6  1903.0   88.1    25.9    5

      12   20 GRF Simple III GRF    2203.6  2225.1   127      7.8    4

      21   20 GRF Simple III GRF    1521.8  1540.0   120      7.2    3

     ** All bursts are now observed only at DRAO, Penticton BC


  --------------------------------------------------------------------------
       SUMMARY OF AVERAGE SOLAR AND GEOPHYSICAL INDICES FOR AUGUST 1993
  --------------------------------------------------------------------------
                 (Based on SGDB data released by the S.T.D.)

10.7 cm Solar Radio Flux:  93.65
Sunspot Number:  59.35
Boulder A-Index:   9.13
Planetary A-Index:  12.06
Background X-Ray Flux (1-8A): B1.23

Proton Fluence at > 1 MeV: 1.3689e+06
Total (non-averaged) Fluence at > 1 MeV: 4.2437e+07
Proton Fluence at > 10 MeV: 1.4355e+04
Total (non-averaged) Fluence at > 10 MeV: 4.4500e+05

Average Daily Deviation of the Boulder Magnetometer:  17.16 nT

Short Wave Fadouts (SWFs):   0.03
Total Number of SWFs during Interval:    1
SWF Durations:   0.39 minutes
Total Duration of SWFs during Interval:    12 minutes

Average Daily X-Ray Flux: B1.97
Average Neutron Counts:  -0.04%
Average Daily PCA:  -0.00 dB


**  End of Monthly Report  **


