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From: oler@rho.uleth.ca (Cary Oler)
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Subject: Monthly Summary of Solar & Geophysical Activity for May 1993
To: solar-monthly@lut.fi
Date: Tue, 29 Jun 93 14:50:09 MDT
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           --  MONTHLY REVIEW OF SOLAR AND GEOPHYSICAL ACTIVITY  --
                             Summary for May 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 MAY 1993

     We are now in month 81 of solar cycle 22 (as of May 1993).  There
were 285 flares (optical and x-ray) in May.  This is a drop of 14% over the
number of flares observed in April.  There were no major flares observed
during the month, while five reached minor M-class levels.

     A breakdown of the energetic events for the last four months follows
below.
         ____________________________________________________________
        |                    | MAY '93 | APR '93 | MAR '93 | FEB '93 |
        |                    | --------|---------|---------|---------|
        |              Major |      0  |     1   |     4   |     2   |
        |      Minor M-class |      5  |     2   |     9   |    16   |
        | Class C or smaller |    280  |   328   |   351   |   410   |
        |--------------------|---------|---------|---------|---------|
        |              Total |    285  |   331   |   364   |   428   |
         ------------------------------------------------------------

     The monthly sunspot number for May was 79.1 as computed by the
SESC. The preliminary RI international sunspot number for May was 61.2
which results in a smoothed sunspot number of 76.5 for October 1992.

     The monthly 10.7 cm solar radio flux for May was 112.4 which
results in a preliminary smoothed mean flux value of 130.5 for October
1992.  The monthly mean solar flux adjusted to 1 AU was 114.9.  The best
absolute value of the estimated 10.7 cm solar radio flux for the month was
103.4 (Series D).

     The largest x-ray flare of May was a class M4.4/2B tenflare from
Region 7500 from N19W48 at 23:01 UT on 14 May.  The flare was associated with
major Types II and IV spectral radio sweeps, although the Type II had a
relatively low estimated shock speed of only 600 km/sec.  The tenflare
measured 970 sfu and lasted 37 minutes.  The x-ray signature of this event
had an attractive long-decay signature typical of events capable of
accellerating protons.  Protons at greater than 10 MeV began arriving at
00:45 UT on 15 May and reached a maximum flux of approximately 3 to 4 pfu at
01:50 UT on 15 May.  This region was rather small when it produced this flare
(only 190 millionths) and had a DAI optical configuration.  It was also in a
state of gradual decay.  It failed to produce any other M-class events before
rotating out of view and dying behind the limb.

     The list of minor M-class or greater flares and associated radio
emissions observed during May 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
------  ----  ----  ----  ----  -- ------ ------  --------- --------- ---------
07 May: 2020  2138  2230  M1.6  1B  7500  N14E41       140        40        67
14 May: 2154  2301  2328  M4.4  2B  7500  N19W48       970       340       190
27 May: 1745  1755  1802  M1.2  2B  7515  N12E53        65        46        46
28 May: 0255  0310  0322  M1.4                          31        29
30 May: 0505  0533  0547  M1.0  SF  7515  N16E18       180


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

                C   M   X     S   1   2   3   4   Total   (%)
               --  --  --    --  --  --  --  --    ---  ------
  Region 7493:  1   0   0     5   0   0   0   0    005  ( 1.8)
  Region 7494:  0   0   0     1   0   0   0   0    001  ( 0.4)
  Region 7496: 15   0   0    34   0   0   0   0    034  (11.9)
  Region 7497:  0   0   0     6   0   0   0   0    006  ( 2.1)
  Region 7499:  0   0   0     3   0   0   0   0    003  ( 1.1)
  Region 7500: 14   2   0    37   1   1   0   0    039  (13.7)
  Region 7502:  0   0   0     1   0   0   0   0    001  ( 0.4)
  Region 7504:  0   0   0     6   0   0   0   0    006  ( 2.1)
  Region 7512:  0   0   0    13   0   0   0   0    013  ( 4.6)
  Region 7513:  0   0   0     2   0   0   0   0    002  ( 0.7)
  Region 7514:  1   0   0     8   0   0   0   0    008  ( 2.8)
  Region 7515: 26   2   0    49   3   1   0   0    053  (18.6)
  Region 7517:  0   0   0     1   0   0   0   0    001  ( 0.4)
  Region 7518:  0   0   0     1   0   0   0   0    001  ( 0.4)
Uncorrellated: 52   1   0     2   0   0   0   0    112  (39.3)


     The geomagnetic field in May was less active than in April. The
estimated planetary A-index for May was 13, compared with 18 for April. This
results in an estimated smooth value of 16.4 centered on October 1992. There
were no sudden magnetic impulses observed at Boulder during May (unofficial).

     The most disturbed day of the month was 10 May where the estimated
planetary A-index was near 54 (major storm levels).  Major to severe
geomagnetic storming was reported from the middle and high latitude regions
during this event.  The source of the activity appeared to be a well-placed
coronal hole.  However, it may have been enhanced by an M-class flare-related
CME that occurred on 07 May from Region 7500.  This flare was associated with
a Type IV sweep.  This particular geomagnetic disturbance exhibited a strong
recurrent tendency, extending back at least two solar rotations.  Recent
observations (Carrington Rotation 1870) seem to indicate that the same hole
responsible for this disturbance has become an extension of the southern
polar crown.  It is expected to produce a similar enhancement in geomagnetic
activity near the end of June or early July.



    RECENT SOLAR INDICES (PRELIMINARY) OF THE OBSERVED MONTHLY MEAN VALUES 
                          Last Updated June 20, 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   15.8*

Oct:  136.2   88.3  .65       113.4   76.5*    130.8  130.5*   15   16.4*
Nov:  124.3   92.0  .74                        145.2           14
Dec:  127.4   83.3  .65                        139.1           13

                                 YEAR = 1993
Jan:   92.1   59.1  .64                        121.0           17
Feb:  126.1   90.5  .72                        142.6           16
Mar:  107.4   70.5* .66*                       136.4           21*

Apr:   98.6   61.9* .63*                       115.9           18*
May:   79.1   61.2* .77*                       112.4           13*

 
* = 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 May 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          102.6                104.2            93.8
             2          103.1                104.7            94.2
             3          107.1                108.9            98.0
             4          110.6                112.4           101.2
             5          117.9                120.0           108.0
             6          120.0                122.2           110.0
             7          130.6                133.0           119.7
             8          128.7                131.2           118.1
             9          129.0                131.5           118.3
            10          134.1                136.8           123.1

            11          132.0                134.7           121.2
            12          126.4                129.0           116.1
            13          119.8                122.4           110.2
            14          112.1                114.6           103.1
            15          104.4                106.7            96.0
            16           98.8                101.1            91.0
            17           96.2                 98.4            88.6
            18           91.3                 93.5            84.2
            19           90.9                 93.1            83.8
            20           91.1                 93.4            84.1

            21           91.0                 93.3            84.0
            22           91.8                 94.1            84.7
            23           94.9                 97.3            87.6
            24           98.4                100.9            90.8
            25           99.8                102.4            92.2
            26          107.5                110.4            99.4
            27          119.5                122.7           110.4
            28          125.8                129.2           116.3
            29          129.0                132.5           119.3
            30          140.1                144.1           129.7

            31          138.2                142.1           127.9

            Mean:       112.4                114.9           103.4


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


      07   4  S/F Simple II F       1456.3  1459.0     6.5   26.3     3
         Z 4  S/F Simple II F       2038.3  2127.6    146    119     28
         @ 3  S   Simple II A       2155.6  2200.9    38.1   89.2    26

      11 Z 22 GRF Simple III GRF F  2122    2149.5    154    11.8     6
         3 4  S/F Simple II F A     2154.1  2154.9     5.5   10.7     3
         @ 4  S/F Simple II F A     2200.6  2202.8     3.4    4.4     1

      14 Z 4  S/F Simple II F       2158.9  2205.2    10.4   81.4    24
         3 29 PBI P.B.Increase      2209    2209     >180    11.8     8
         @ 4  S/F Simple II F A     2240   incomp      41   >316    ----

      27 Z 3  S   Simple II         1744.2  1747.8     6.8   65.5    14
         @ 29 PBI P.B.Increase      1751    1815      227     8.1     4

      28 Z 22 GRF Simple III GRF F  2034.5  2054      254     14      8
         @ 3  S   Simple II A       2357.7  2359.1     3.3     6      2


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

10.7 cm Solar Radio Flux: 112.33
Sunspot Number:  79.06
Boulder A-Index:  10.39
Planetary A-Index:  12.61
Background X-Ray Flux (1-8A): B3.03

Proton Fluence at > 1 MeV: 1.2889e+06
Total (non-averaged) Fluence at > 1 MeV: 3.9955e+07
Proton Fluence at > 10 MeV: 1.5258e+04
Total (non-averaged) Fluence at > 10 MeV: 4.7300e+05

Average Daily Deviation of the Boulder Magnetometer:  20.87 nT

Short Wave Fadouts (SWFs):   0.23
Total Number of SWFs during Interval:    7
SWF Durations:   5.94 minutes
Total Duration of SWFs during Interval:   184 minutes

Average Daily X-Ray Flux: B6.06
Average Neutron Counts:  +0.29%
Average Daily PCA:  -0.00 dB


**  End of Monthly Report  **


