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Subject: Monthly Review of Solar & Geophysical Activity for Feb 1993
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Date: Mon, 15 Mar 93 17:45:13 MST
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           --  MONTHLY REVIEW OF SOLAR AND GEOPHYSICAL ACTIVITY  --
                          Summary for February 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 FEBRUARY 1993

     We are now in month 78 of solar cycle 22 (as of February 1993).  There
were 428 flares (optical and x-ray) in February.  This is over 2.5 times as
many flares as were observed in January.  This exceeds the total number of
flares observed since August 1992 when 487 flares were recorded.  Of the 428
flares, two were ranked as major events and 16 were categorized as minor
M-class events.

     A breakdown of the energetic events for the last four months follows
below, together with a summary of the percentage increase or decrease in the
number of energetic events amongst the four months.  Negative percentages
represent decreases.  For example, there were 159.4 % more energetic events
in February than in January, while January had 41.9 % fewer energetic events
than December 1992.

         ____________________________________________________________
        |                    | FEB '93 | JAN '93 | DEC '92 | NOV '92 |
        |                    | --------|---------|---------|---------|
        |              Major |      2  |     0   |     0   |     1   |
        |      Minor M-class |     16  |     2   |     4   |     7   |
        | Class C or smaller |    410  |   163   |   280   |   326   |
        |--------------------|---------|---------|---------|---------|
        |              Total |    428  |   165   |   284   |   334   |
        |--------------------|---------|---------|---------|---------|
        |                          FEB |+159.4 % |+ 50.7 % |+ 28.1 % |
        |   Percentage                  ---------|---------|---------|
        |                                    JAN |- 41.9 % |- 50.6 % |
        |     Change                              ---------|---------|
        |                                              DEC |- 15.0 % |
         ------------------------------------------------------------

     The monthly sunspot number for February was 126.1 as computed by the
SESC. The preliminary RI international sunspot number for February was 90.5.
These values compare with the sunspot numbers recorded for November (SESC
value of 124.3, RI value of 92.0) and December (SESC value of 127.4, RI value
of 83.3) of 1992.

     The monthly 10.7 cm solar radio flux for February was 142.6.  This value
also compares nicely with the mean flux values reported for November (145.2)
and December (139.0) of 1992.

     The largest flares of February were observed on 06 February and 17
February.  The first attained a class M9.6/2B rating and was the result of a
combination 3B flare in Region 7417 (then located at N15E20) and a 2B flare
in Region 7419 (then located at N11E25).  The flare was accompanied by a 660
sfu tenflare, but lacked both Types II and IV sweeps.  By 21:00 UT, the
post-xray signature of this event exhibited a fairly attractive series of
sinusoidal oscillations approximately 15 minutes in duration each.

     The major flare of 17 February was a class M5.8/SF event that peaked at
10:40 UT.  This region was near the west limb (at S07W87) during this event
which allowed detailed observations of loop and surge dynamics.  There were
no sweeps reported and the event lacked significant radio bursts.

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

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

 Date   Begin  Max   End  Xray  Op Region  Locn    2695 MHz  8800 MHz  15.4 GHz
------  ----  ----  ----  ----  -- ------ ------  --------- --------- ---------
06 Feb: 1814  1824  1950  M9.6  2B  7417  N12E26       610       700       360
17 Feb: 1032  1040  1227  M5.8  SF  7420  S07W87       110       130        83


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

 Date   Begin  Max   End  Xray  Op Region  Locn    2695 MHz  8800 MHz  15.4 GHz
------  ----  ----  ----  ----  -- ------ ------  --------- --------- ---------
01 Feb: 0155  0204  0235  M2.2                          26        76        41
        0652  0702  0710  M1.4  SF  7416  S09E90
05 Feb: 0448  0540  0631  M1.0
06 Feb: 1643  1649  1654  M1.0  SN  7420  S13E54
09 Feb: 0714  0722  0727  M1.0  SN  7420  S08E20
10 Feb: 0734  0741  0746  M1.0  2B  7420  S04E03       130        32
        0835  0839  0841  M1.5  1N  7420  S04E05        49        95        76
        2001  2007  2012  M2.4  2B  7420  S04W03        68       150       100
11 Feb: 1802  1811  1825  M1.2  1B  7420  S04W15        48
        1829  1833  1840  M2.7                         230       280       220
14 Feb: 1241  1258  1311  M2.0  2B  7427  S22E78        91       160       150
16 Feb: 1419  1429  1442  M2.1  SF  7420  S06W76                  37        32
18 Feb: 0258  0308  0337  M4.0  2B  7425  N14W02       280       170       120
        0927  1003  1037  M1.6  1N  7427  S20E28       250        90        54
        1054  1106  1141  M1.1  1B  7427  S21E21       330       160       120
21 Feb: 0024  0043  0102  M1.4  SF  7433  N13E75        23        18        15

     The geomagnetic field in February was slightly more active than in
January.  The estimated planetary A-index for February was 15, compared with
13 in January.  The average monthly estimated planetary A-index values have
been within 2 points of 15 for the last five months (since October 1992,
inclusive).  There were two sudden magnetic impulses observed during the
month.  The first was observed at 03:02 UT on 17 February.  The second was
observed at 22:20 UT on 27 February.  This latter disturbance was thought to
have been due to either a well placed coronal hole or disappearing filament
effects (or a combination thereof) and was not followed by very significant
geomagnetic activity.

     The most disturbed day of the month was 17 February.  An initially quiet
field became disturbed following the sudden magnetic impulse at 03:02 UT.
Minor to major storming ensued at middle latitudes and major to severe
storming was attained at high latitudes between 09:00 UT and 18:00 UT.  The
source of this activity was not clear, but could have been related to a
filament which erupted off the disk on between 18:20 UT on 13 February and
17:57 UT on 14 February.  The filament measured approximately 14 degrees in
extent.

     There were no satellite proton events during the month.  However, by the
end of the month, proton fluence at greater than 10 MeV was showing a
definite upward trend, possibly related to a proton-producing region (Region
7440) that was within several days of the east limb.


    RECENT SOLAR INDICES (PRELIMINARY) OF THE OBSERVED MONTHLY MEAN VALUES 
                         Last Updated March 15, 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   16.5*
Aug:   99.5   64.5  .65       124.4   84.0*    122.1  138.8*   15   15.8*
Sep:   93.8   63.9  .68                        116.8           25

Oct:  136.2   88.3  .65                        130.8           15
Nov:  124.3   92.0  .74                        145.2           14
Dec:  127.4   83.3  .65                        139.0           13

                                 YEAR = 1993
Jan:   92.1   59.1* .64*                       121.0           13*
Feb:  126.1   90.5* .72*                       142.6           15*

 
* = 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 February 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          125.1                121.5           109.3
             2          128.3                124.7           112.2
             3          136.9                133.0           119.7
             4          147.4                143.2           128.9
             5          160.1                155.6           140.0
             6          183.8                178.8           160.9
             7          175.9                171.2           154.1
             8          188.4                183.4           165.1
             9          185.1                180.3           162.3
            10          179.6                175.0           157.5

            11          173.2                168.8           151.9
            12          148.6                144.9           130.4
            13          135.0                131.7           118.5
            14          141.4                137.9           124.1
            15          134.8                131.6           118.4
            16          133.7                130.5           117.4
            17          124.3                121.4           109.3
            18          126.0                123.2           110.9
            19          116.0                113.4           102.1
            20          123.3                120.6           108.5

            21          122.9                120.3           108.3
            22          133.1                130.3           117.3
            23          132.3                129.6           116.6
            24          135.4                132.7           119.4
            25          128.0                125.5           112.9
            26          126.2                123.8           111.4
            27          124.0                121.6           109.4
            28          123.6                121.4           109.3

            Mean:       142.6                139.1           125.2


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

      06   3  S   Simple II         1650.3  1653.3    12.6   19.0    3
         Z 45 GB  Great Burst      incompl  1819      <17    627    --- A
         @ 29 PBI P.B.Increase     incompl 1832.5     130     47    --- A

      07   4  S/F Simple II F       1846.3  1850.7    18.2   36.1    9

      08 Z 4  S/F Simple II F       1706.6  1709.1     5.8   51.7   21
         @ 29 PBI P.B.Increase      1712.5  1712.5     15    12.5    5

      09 Z 4  S/F Simple II F       1659.4  1702.7     4.5   30.0    6
         @ 29 PBI P.B.Increase      1704    1705       60     6.3    3

      10   3  S   Simple II         2002.0  2004.5    >4.5   34.6   --- A

      11   3  S   Simple I          1830.0  1831.8     5.7  271.3   46

      12   3  S   Simple II         2257.4  2259.2     7.9   18.5    5
           3  S   Simple II         0000.6  0001.8     3.0   22.2    7

      14 Z 3  S   Simple II         2301.9  2305.0     8.0   18.2    6
         @ 29 PBI P.B.Increase      2310    2310.5     34     4.2    2

      18   4  S/F Simple II F       2238.2  2247.3    14.3   13.7    6

      24 Z 4  S/F Simple II F       1646.0  1647.5     6.8   27.4    7
         @ 29 PBI P.B.Increase      1653    1658       42     5.3    4
           24 R   Rise only         1944    2130     >300    16.7   13

      A. Maximum observed value for incomplete record.


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

10.7 cm Solar Radio Flux: 142.59
Sunspot Number: 130.21
Boulder A-Index:  11.82
Planetary A-Index:  13.64
Background X-Ray Flux (1-8A): B5.64

Proton Fluence at > 1 MeV: 1.6311e+06
Total (non-averaged) Fluence at > 1 MeV: 4.4040e+07
Proton Fluence at > 10 MeV: 1.1544e+04
Total (non-averaged) Fluence at > 10 MeV: 3.1170e+05

Average Daily Deviation of the Boulder Magnetometer:  20.18 nT

Short Wave Fadouts (SWFs):   0.64
Total Number of SWFs during Interval:   18
SWF Durations:  10.07 minutes
Total Duration of SWFs during Interval:   282 minutes

Average Daily X-Ray Flux: C1.11
Average Neutron Counts:  -0.04%
Average Daily PCA:  -0.01 dB


**  End of Monthly Report  **


