Joint USAF/NOAA Report of Solar and Geophysical Activity 17 Jul 2002

:Product: Report of Solar-Geophysical Activity

:Issued: 2002 Jul 17 2210 UTC

# Prepared jointly by the U.S. Dept. of Commerce, NOAA,

#Space Environment Center and the U.S. Air Force.

#

Joint USAF/NOAA Report of Solar and Geophysical Activity

SDF Number 198 Issued at 2200Z on 17 Jul 2002

IA.  Analysis of Solar Active Regions and Activity from  16/2100Z

to 17/2100Z:  Solar activity was at high levels.  Region 30 (N19W25)

produced an M8/1b flare at 17/0713 UTC with an associated Type II

radio burst.  A CME was associated with this event but there does

not appear to be an Earth directed component.  Region 30 has shown

slight decay in the leader spots but remains a large

beta-gamma-delta spot group.  As Region 36 (S09E51) rotates further

into view it has developed into a moderately sized spot group with a

beta-gamma-delta magnetic configuration.  Activity from Region 36 so

far has been C-Class events.

IB.  Solar Activity Forecast:  Solar activity is expected to be

moderate.  Region 30 and Region 36 are expected to produce M-class

activity.  They are also capable of producing a major flare during

the period.

IIA.  Geophysical Activity Summary 16/2100Z to 17/2100Z:

The geomagnetic field has been quiet to active.  A sudden impulse

occurred at 17/1604 UTC and measured 18 nT on the San Juan

magnetometer.  Active conditions followed the sudden commencement.

Greater than 10 MeV protons exceeded the 100 pfu threshold at

17/1250 UTC, reached a peak value of 234 pfu at 17/1600 UTC and

ended at 17/1710 UTC.  Greater than 10 MeV protons remain above the

10 pfu threshold as of this forecast issue.  A PCA event began at

16/2215 UTC and reached a peak absorption 4.8 Db on the Thule 30 MHz

riometer.  Greater than 2 MeV electron at geo-synchronous orbit

reached moderate levels.

IIB.  Geophysical Activity Forecast:  The geomagnetic field is

expected to be quiet to active.  Active conditions are possible

early on day one due to the CME shock from the X3 event on 15 July.

Isolated active conditions are possible on day three due to coronal

hole effects and the possibility of a weak shock from the M8 event

earlier today.  The greater than 10 MeV proton event is expected to

continue to decline and should end on day one of the forecast

period.  The PCA event in progress is expected to last until 19/0000

UTC.  Maximum daytime absorption is expected to be about 6 Db, while

maximum nighttime adsorption will be about 2 Db.

III.  Event Probabilities 18 Jul-20 Jul

Class M    75/75/75

Class X    20/20/20

Proton     99/50/15

PCAF       in progress

IV.  Penticton 10.7 cm Flux

Observed           17 Jul 180

Predicted   18 Jul-20 Jul  180/190/185

90 Day Mean        17 Jul 161

V.  Geomagnetic A Indices

Observed Afr/Ap 16 Jul  009/011

Estimated Afr/Ap 17 Jul  020/020

Predicted Afr/Ap 18 Jul-20 Jul  015/015-010/012-012/020

VI.  Geomagnetic Activity Probabilities 18 Jul-20 Jul

A.  Middle Latitudes

Active                40/25/25

Minor storm           20/10/05

Major-severe storm    10/01/01

B.  High Latitudes

Active                45/30/30

Minor storm           20/15/15

Major-severe storm    10/05/05