Joint USAF/NOAA Report of Solar and Geophysical Activity 5 April 2010

:Product: Report of Solar-Geophysical Activity
:Issued: 2010 Apr 05 2200 UTC
# Prepared jointly by the U.S. Dept. of Commerce, NOAA,
# Space Weather Prediction Center and the U.S. Air Force.
#
Joint USAF/NOAA Report of Solar and Geophysical Activity
SDF Number 095 Issued at 2200Z on 05 Apr 2010
IA. Analysis of Solar Active Regions and Activity from 04/2100Z
to 05/2100Z: Solar activity was very low. Today’s activity consisted
of a few low-level B-class events, primarily from newly emerging
Region 1061 (N14W11). Region 1061 is a small D-type sunspot group.
Region 1060 (N25E45) was quiet and stable and is a small C-type
sunspot group.
IB. Solar Activity Forecast: Solar activity is expected to be very
low for the next three days (06-08 April). There is, however a
chance for an isolated C-class event from Region 1061.
IIA. Geophysical Activity Summary 04/2100Z to 05/2100Z:
The geomagnetic field ranged from quiet to severe storm levels during
the past 24 hours. Conditions were initially quiet to unsettled, but
increased to active levels after 0300Z, and increased further to
major to severe storm levels between 0900-1200Z. The increase in
activity followed a strong shock observed at the ACE spacecraft at
0756Z which led to a sudden impulse at Earth at 0826Z (observed to
be 38 nT at the Boulder magnetometer). Numerous high-latitude
stations reported severe storm levels during the interval as did
several mid-latitude stations in the nighttime sectors. Activity
declined to active to major storm levels from 1200-1800Z and
declined further to mostly unsettled levels from 1800-2100Z. Solar
wind observations showed elevated solar wind velocity behind the
shock with speeds between 720-800 km/s with fairly strong Bz (peak
negative values around -15 nT). Solar wind speed and magnetic field
observations showed a decreasing trend during the last 4-5 hours of
the interval. The most probable source for the disturbance is the
halo CME that was observed on 03 April at 0954Z. The greater than 2
MeV electron flux reached high levels during the past 24 hours.
IIB. Geophysical Activity Forecast: The geomagnetic field is
expected to be unsettled to active during the early part of the
first day (06 April) due to persistent effects from the current
disturbance. In addition, another increase to unsettled levels with
a chance for active periods is expected late in the day and
continuing through the second day (07 April) due to the onset of a
high speed stream from a favorably positioned coronal hole. Activity
levels are expected to decline to mostly unsettled levels on the
third day (08 April).
III. Event Probabilities 06 Apr-08 Apr
Class M 01/01/01
Class X 01/01/01
Proton 01/01/01
PCAF green
IV. Penticton 10.7 cm Flux
Observed 05 Apr 079
Predicted 06 Apr-08 Apr 082/085/085
90 Day Mean 05 Apr 083
V. Geomagnetic A Indices
Observed Afr/Ap 04 Apr 011/013
Estimated Afr/Ap 05 Apr 025/025
Predicted Afr/Ap 06 Apr-08 Apr 015/017-012/012-008/008
VI. Geomagnetic Activity Probabilities 06 Apr-08 Apr
A. Middle Latitudes
Active 35/35/20
Minor storm 20/20/10
Major-severe storm 10/05/01
B. High Latitudes
Active 40/40/25
Minor storm 25/30/15
Major-severe storm 15/10/01