Return-path: X-Andrew-Authenticated-as: 7997;andrew.cmu.edu;Ted Anderson Received: from hogtown.andrew.cmu.edu via trymail for +dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl@andrew.cmu.edu (->+dist+/afs/andrew.cmu.edu/usr11/tm2b/space/space.dl) (->ota+space.digests) ID ; Mon, 1 Apr 91 02:13:04 -0500 (EST) Message-ID: <4bxhpuq00WBwEXCk5Z@andrew.cmu.edu> Precedence: junk Reply-To: space+@Andrew.CMU.EDU From: space-request+@Andrew.CMU.EDU To: space+@Andrew.CMU.EDU Date: Mon, 1 Apr 91 02:12:59 -0500 (EST) Subject: SPACE Digest V13 #340 SPACE Digest Volume 13 : Issue 340 Today's Topics: SOLAR TERRESTRIAL FORECAST AND REVIEW - STORM EVENT SUMMARY Administrivia: Submissions to the SPACE Digest/sci.space should be mailed to space+@andrew.cmu.edu. Other mail, esp. [un]subscription requests, should be sent to space-request+@andrew.cmu.edu, or, if urgent, to tm2b+@andrew.cmu.edu ---------------------------------------------------------------------- Date: Sun, 31 Mar 91 02:13:21 MST From: oler%HG.ULeth.CA@BITNET.CC.CMU.EDU (CARY OLER) Subject: SOLAR TERRESTRIAL FORECAST AND REVIEW - STORM EVENT SUMMARY X-St-Vmsmail-To: st%"space+@andrew.cmu.edu" --- SOLAR TERRESTRIAL FORECAST AND REVIEW --- March 31 to April 09, 1991 Report Based In-Part from Data Obtained from the Space Environment Services Center Boulder Colorado -------- SOLAR TERRESTRIAL REVIEW FOR 24 MARCH TO 30 MARCH Solar activity this week was moderate to high. Several X-class events were observed from Region 6555. This region proved to be exceptionally active. Most of the major flares which were spawned by this region reached X-class x-ray intensities (the most intense class rated) and large optical sizes (3B). The most noteworthy event occurred outside of the review period, but will be covered here since it has not been covered previously. On 22 March, a powerful proton flare exploded from Region 6555 at a sensitive position of S26E28. The flare attained an exceptional class X9.4/3B rating and was associated with very significant radio emissions. The tenflare from this event was rated at 36,000 s.f.u., while the 245 MHz emission was rated at 260,000 s.f.u. (the most intense emission seen in quite some time). The flare produce moderate intensity Type II and IV sweeps. At 08:20 UT on 23 March, protons began arriving from this major flare. The ensuing proton event was moderately large (not abnormally large) and produced a long-duration PCA (polar cap absorption) event which ended on 29 March. A major geomagnetic storm warning was issued shortly thereafter. The storm began with a very powerful SSC (sudden storm commencement) shock at 03:42 UT on 24 March. The interplanetary shockwave produced by this flare was the most intensive shock observed so far this solar cycle. Magnetometers throughout the world immediately sprang into action, exhibiting the most intense geomagnetic storm activity since the major storm of March 13-14, 1989. Periods of severe storming were observed world-wide. Intense fluctuations of more than 1,500 to 2,000 gammas were observed over many areas. The storm produced the largest planetary magnetic A-indices since the March storm event of 1989. A planetary A-index of 115 (prelim) was observed at 00:00 UT on 24 March (severe storm conditions). On 25 March, the planetary A-index fell to 92 (high-intensity major storm conditions). On 26 March, the A-index dropped a bit more to 83 (still strong major storming), followed by a drop to 32 (low-intensity minor storming) on 27 March. This storm produced the most extensive and intensive auroral activity since the large auroral storm of March 1989. Areas as far south as Alabama, Kansas, Oklahoma, Mississippi and Georgia witnessed auroral activity. The activity was associated with brillient red rays, extensive and very active curtain aurora, rapid pulsations and color changes. Southern hemisphere observers in Australia also witnessed auroral activity much further north than usual. The activity remained extensively visible on 24 and 25 March for low latitude observers. The activity then receded to the middle and northern latitudes on 26 and 27 March. HF propagation was severely degraded on 24 through 26 March. Blackout conditions were observed over extensive areas in both the northern and southern hemispheres. Normally strong signals were either severely absorbed or completely absorbed. High latitudes were affected most severely. The PCA event combined with the intense auroral and geomagnetic activity produced intense radio signal absorption which lasted for many days. Complete radio blackouts occurred over most high latitude and polar regions from 24 March to 27 March. Some slight improvements were noticed on 28 March with more noticable improvements since then. Conditions are still below normal at the present time, but have improved significantly. VHF propagation conditions experienced some of the most unusual activity since the March 1989 storm. Most noteworthy were the extensive auroral backscatter communications which occurred. The lower latitudes experienced the best opportunities for auroral backscatter on 24 and 25 March. Frequencies above 400 MHz were used successfully in auroral communications. Storming subsided on 27 March to generally active conditions. Since then, activity has remained mostly unsettled. SHORT TERM SOLAR TERRESTRIAL FORECAST Region 6555 is now passing beyond the west limb (on 31 March) in a significantly simpler and less threatening configuration, although magnetic aspects of this region remained capable of producing M-class flare activity. This region is expected to continue to decay on the far side of the sun and should return as a simpler, less complex area and of smaller size (if it returns at all). Solar activity will likely remain low to moderate over the coming week, barring the emergence of any unexpected complex active regions. Occassional M-class flaring will be observed over the coming week, probably intermixed with periods of low C-class flare activity. No major flares are expected. Solar activity should become more dormant over the coming week. Geomagnetic activity is expected to remain generally unsettled over the coming week. The only possible exceptions to this are 01 April, when an increase to active levels is expected due to the last major class X2 flare, and near 5-7 April when a well placed coronal hole should increase activity levels to active conditions. No storm conditions are predicted for the coming week, except possibly at high latitudes on 01 April and 5-7 April. HF propagation conditions should return to normal this week, with a chance for above normal conditions towards the latter part of the week. MUF's should return to values between 35 and 45 MHz by the end of the week over the middle and low latitudes. Higher latitudes are expected to experience continuing below-normal propagation conditions. Ionization levels are still a bit higher than normal over these regions, which may affect long-distance communications more than usual. VHF propagation conditions will remain normal over all latitudes over the coming week. No significant auroral backscatter communications are expected. Conditions should be relatively stable. The probability for SID-induced enhancements are low this week, but may still be possible over the low and middle latitudes for brief periods due to minor M-class flaring. SUMMARY OF ALL ACTIVE REGIONS VISIBLE ON THE SOLAR DISK AS OF 31 MARCH Region # Location LO Area Class LL Spots Magnetic Type -------- -------- --- ---- ----- -- ----- ------------- 6555 S23W82 182 3300 EKI 15 029 BETA GAMMA DELTA 6556 S11W83 183 0360 DAO 09 008 BETA 6558 S15W43 143 0120 DSO 09 005 BETA 6559 N17W72 172 0450 DSO 10 005 BETA 6560 S11W64 164 0030 AXX 02 003 ALPHA 6561 S08W80 180 0480 DAI 08 005 BETA 6562 N14E42 058 1170 DAC 09 034 BETA GAMMA 6563 S10E45 055 1230 DKI 09 021 BETA 6564 N21E08 092 0030 BXO 03 003 BETA 6565 N09E71 029 0150 DSO 09 004 BETA NOTES: Area is in million square kilometers. Angular extent (LL) and solar longitude (LO) are in degree's. For more information regarding the terminology used above, request the Glossary of Solar Terrestrial Terms from: "oler@hg.uleth.ca". H-ALPHA PLAGES WITHOUT SPOTS. LOCATIONS VALID AS OF 00:00 UT ON 31 MARCH REGION LOCATION LO COMMENTS (IF ANY) ------ -------- --- ------------------------------- 6557 S21W57 157 NONE ACTIVE REGIONS DUE TO RETURN BETWEEN 31 MARCH AND 02 APRIL Region Latitude Longitude (Helio.) ------ -------- --------- 6536 N17 004 6537 S08 003 6538 S23 343 6542 S11 336 NOTES: For definitions regarding the above, request the "Glossary of Solar Terrestrial Terms" from "oler@hg.uleth.ca". GRAPHICAL ANALYSIS OF RECENT PLANETARY (GLOBAL) GEOMAGNETIC ACTIVITY ----------------------------------- DATA NOT AVAILABLE AT THIS TIME ----------------------------------- NOTES: The data above represents planetary geomagnetic activity. Data from many magnetic observatories around the world are used in constructing the above chart. The first graph line for each day represents geomagnetic activity which occurred between 00 UT and 03 UT. The second graph line represents activity which occurred between 03 UT and 06 UT, etc. For information regarding the interpretation and/or use of these charts, send a request for the document "Understanding Solar Terrestrial Reports" to: oler@hg.uleth.ca. PLANETARY 10-DAY GEOMAGNETIC ACTIVITY OUTLOOK (31 MARCH - 09 APRIL) ________________________________________________________________________ | EXTREMELY SEVERE | | | | | | | | | | | VERY HIGH! | | VERY SEVERE STORM | | | | | | | | | | | HIGH | | SEVERE STORM | | | | | | | | | | | MODERATE | | MAJOR STORM | | | | | | | | | | | LOW - MOD. | | MINOR STORM | | | | | | | | | | | LOW | | VERY ACTIVE | | * | | | | | | | | | NONE | | ACTIVE | |***|** | | | **|***|***| | | NONE | | UNSETTLED |***|***|***|***|* *|***|***|***|***|* *| NONE | | QUIET |***|***|***|***|***|***|***|***|***|***| NONE | | VERY QUIET |***|***|***|***|***|***|***|***|***|***| NONE | |-------------------|---|---|---|---|---|---|---|---|---|---|------------| | Geomagnetic Field |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| Anomaly | | Conditions | Given in 8-hour intervals | Intensity | |________________________________________________________________________| CONFIDENCE LEVEL: 75% NOTES: Predicted geomagnetic activity is based heavily on recurrent phenomena. Transient energetic solar events cannot be predicted reliably over periods in excess of several days. Hence, there may be some deviations from the predictions due to the unpredictable transient solar component. GRAPHICAL ANALYSIS OF SOLAR ACTIVITY OVER THE PAST 60 DAYS ----------------------------------- DATA NOT AVAILABLE AT THIS TIME ----------------------------------- NOTES: Left-hand column digits represent the 10.7 cm solar radio flux obtained from Ottawa. The right-hand column describes the relative solar activity for that period based on the average number of major and minor flares that can be expected for related solar flux values. Plot lines labeled with the letter "F" represent days where at least one major flare occurred (ie. class M5 or greater flare). GRAPHICAL 20-DAY SOLAR ACTIVITY PREDICTION Solar Activity _________________________________________________________________ | 270 | | | | | | | | | | | | | | | | | |**|**|**| | 265 | | | | | | | | | | | | | | | | |**| | | | | 260 | | | | | | | | | | | | | | | |**| | | | | | 255 | | | | | | | | | | | | | | |**| | | | | | | 250 | | | | | | | | | | | | | |**| | | | | | | | 245 | | | | | | | | | | | | |**| | | | | | | | | 240 | | | | | | | | | | | |**| | | | | | | | | | 235 | | | | | | | | | | |**| | | | | | | | | | | 230 | | | | | | | | | | | | | | | | | | | | | | 225 | | | | | | | | | |**| | | | | | | | | | | | 220 | | | | | | | | |**| | | | | | | | | | | | | 215 | | | | | | |**|**| | | | | | | | | | | | | | 210 | | | | |**|**| | | | | | | | | | | | | | | | 205 | | |**|**| | | | | | | | | | | | | | | | | | 200 |**|**| | | | | | | | | | | | | | | | | | | |-----|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--|--| |Solar|31|01|02|03|04|05|06|07|08|09|10|11|12|13|14|15|16|17|18|19| |Flux | | April | ----------------------------------------------------------------- CONFIDENCE LEVEL: 65% HF RADIO SIGNAL PROPAGATION PREDICTIONS (31 MARCH - 09 APRIL) High Latitude Paths ________________________________________________________ | EXTREMELY GOOD | | | | | | | | | | | | VERY GOOD | | | | | | | | | | | CONFIDENCE | GOOD | | | | | | | | | | | LEVEL | FAIR | | | | | | | | *| **|***| ------- | POOR |***|* *|***|***|***|***|***|** |* | | 65% | VERY POOR | | * | | | | | | | | | | EXTREMELY POOR | | | | | | | | | | | |----------------|---|---|---|---|---|---|---|---|---|---| | PROPAGATION |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| | QUALITY | Given in 8-Hour UT Intervals | -------------------------------------------------------- Middle Latitude Paths ________________________________________________________ | EXTREMELY GOOD | | | | | | | | | | | | VERY GOOD | | | | | | | | | | | CONFIDENCE | GOOD | | | | | | | | *|* *|***| LEVEL | FAIR |***|* *|***|***|***|***|***|** | * | | ------- | POOR | | * | | | | | | | | | 70% | VERY POOR | | | | | | | | | | | | EXTREMELY POOR | | | | | | | | | | | |----------------|---|---|---|---|---|---|---|---|---|---| | PROPAGATION |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| | QUALITY | Given in 8-Hour UT Intervals | -------------------------------------------------------- Low Latitude Paths ________________________________________________________ | EXTREMELY GOOD | | | | | | | | | | | | VERY GOOD | | | | | | | | | | | CONFIDENCE | GOOD |***|* *|* *|***|***|***|* *|* *|***|***| LEVEL | FAIR | | * | * | | | | * | * | | | ------- | POOR | | | | | | | | | | | 70% | VERY POOR | | | | | | | | | | | | EXTREMELY POOR | | | | | | | | | | | |----------------|---|---|---|---|---|---|---|---|---|---| | PROPAGATION |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| | QUALITY | Given in 8-Hour UT Intervals | -------------------------------------------------------- NOTES: High latitudes >= 55 degree's north latitude Middle latitudes >= 40 < 55 degree's north latitude Low latitudes < 40 degree's north latitude POTENTIAL VHF DX PROPAGATION PREDICTIONS (31 MARCH - 09 APRIL) INCLUDES SID AND AURORAL BACKSCATTER ENHANCEMENT PREDICTIONS HIGH LATITUDES __________________________________________________ ___________________ | SIGNAL | Given in 8 hour local time intervals | | SID ENHANCEMENT | | QUALITY |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| |S|M|T|W|T|F|S|S|M|T| |__________|___|___|___|___|___|___|___|___|___|___| |-|-|-|-|-|-|-|-|-|-| | VERY GOOD| | | | | | | | | | | 0%|*|*|*|*|*|*|*|*|*|*| |ABOVE NORM| | | | | | | | | | | 20%|*|*|*|*|*|*|*|*|*|*| | NORMAL|***| * | * |***|***| **| **|***|***|***| 40%|*|*| | | |*|*|*|*|*| |BELOW NORM| |* *|* *| | |* |* | | | | 60%| | | | | | | | | | | | VERY POOR| | | | | | | | | | | 80%| | | | | | | | | | | | BLACKOUT| | | | | | | | | | |100%| | | | | | | | | | | |==========|===|===|===|===|===|===|===|===|===|===| |-------------------| | 100% | | | | | | | | | | |100%| | | | | | | | | | | | 80% | | | | | | | | | | | 80%| | | | | | | | | | | | 60% | | *| | | | | | | | | 60%| |*| | | | | | | | | | 40% | |***|* *| | *|* *|* *|* *| | | 40%|*|*|*|*|*|*|*|*|*|*| | 20% |* *|***|***|* *|* *|***|***|***|***|***| 20%|*|*|*|*|*|*|*|*|*|*| | 0% |***|***|***|***|***|***|***|***|***|***| 0%|*|*|*|*|*|*|*|*|*|*| |----------+---|---|---|---|---|---|---|---|---|---| |-|-|-|-|-|-|-|-|-|-| |CHANCE OF |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| |S|M|T|W|T|F|S|S|M|T| | VHF DX | Given in 8 hour local time intervals | |AURORAL BACKSCATTER| |__________|_______________________________________| |___________________| MIDDLE LATITUDES __________________________________________________ ___________________ | SIGNAL | Given in 8 hour local time intervals | | SID ENHANCEMENT | | QUALITY |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| |S|M|T|W|T|F|S|S|M|T| |__________|___|___|___|___|___|___|___|___|___|___| |-|-|-|-|-|-|-|-|-|-| | VERY GOOD| | | | | | | | | | | 0%|*|*|*|*|*|*|*|*|*|*| |ABOVE NORM| | | | | | | | | | | 20%|*|*|*|*|*|*|*|*|*|*| | NORMAL|***| **|***|***|***|***| **|***|***|***| 40%|*|*| | | | |*|*|*|*| |BELOW NORM| |* | | | | |* | | | | 60%| | | | | | | | | | | | VERY POOR| | | | | | | | | | | 80%| | | | | | | | | | | | BLACKOUT| | | | | | | | | | |100%| | | | | | | | | | | |==========|===|===|===|===|===|===|===|===|===|===| |-------------------| | 100% | | | | | | | | | | |100%| | | | | | | | | | | | 80% | | | | | | | | | | | 80%| | | | | | | | | | | | 60% | | | | | | | | | | | 60%| | | | | | | | | | | | 40% | |* *|* | | | *|* *|* *| | | 40%| |*| | | | |*| | | | | 20% |***|***|***|***|***|***|***|***|***|***| 20%| |*|*| | |*|*|*|*| | | 0% |***|***|***|***|***|***|***|***|***|***| 0%|*|*|*|*|*|*|*|*|*|*| |----------+---|---|---|---|---|---|---|---|---|---| |-|-|-|-|-|-|-|-|-|-| |CHANCE OF |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| |S|M|T|W|T|F|S|S|M|T| | VHF DX | Given in 8 hour local time intervals | |AURORAL BACKSCATTER| |__________|_______________________________________| |___________________| LOW LATITUDES __________________________________________________ ___________________ | SIGNAL | Given in 8 hour local time intervals | | SID ENHANCEMENT | | QUALITY |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| |S|M|T|W|T|F|S|S|M|T| |__________|___|___|___|___|___|___|___|___|___|___| |-|-|-|-|-|-|-|-|-|-| | VERY GOOD| | | | | | | | | | | 0%|*|*|*|*|*|*|*|*|*|*| |ABOVE NORM| | | | | | | | | | | 20%|*|*|*|*|*|*|*|*|*|*| | NORMAL|***|***|***|***|***|***|***|***|***|***| 40%|*|*| | | | |*|*|*|*| |BELOW NORM| | | | | | | | | | | 60%| | | | | | | | | | | | VERY POOR| | | | | | | | | | | 80%| | | | | | | | | | | | BLACKOUT| | | | | | | | | | |100%| | | | | | | | | | | |==========|===|===|===|===|===|===|===|===|===|===| |-------------------| | 100% | | | | | | | | | | |100%| | | | | | | | | | | | 80% | | | | | | | | | | | 80%| | | | | | | | | | | | 60% | | | | | | | | | | | 60%| | | | | | | | | | | | 40% | | | | | | | * | * | * | * | 40%| | | | | | | | | | | | 20% | * |***| * | * | * | * | **| **| **| **| 20%| |*| | | | | | | | | | 0% |***|***|***|***|***|***|***|***|***|***| 0%|*|*|*|*|*|*|*|*|*|*| |----------+---|---|---|---|---|---|---|---|---|---| |-|-|-|-|-|-|-|-|-|-| |CHANCE OF |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| |S|M|T|W|T|F|S|S|M|T| | VHF DX | Given in 8 hour local time intervals | |AURORAL BACKSCATTER| |__________|_______________________________________| |___________________| NOTES: These VHF DX prediction charts are defined for the 50 MHz to 150 MHz bands. They are based primarily on phenomena which can affect VHF DX propagation globally. They should be used only as a guide to potential DX conditions on VHF bands. Latitudinal boundaries are the same as those for the HF predictions charts. For more information, request the document "Understanding Solar Terrestrial Reports" from: "oler@hg.uleth.ca". AURORAL ACTIVITY PREDICTIONS (31 MARCH - 09 APRIL) High Latitude Locations ________________________________________________________ | EXTREMELY HIGH | | | | | | | | | | | CONFIDENCE | VERY HIGH | | | | | | | | | | | LEVEL | HIGH | | | | | | | | | | | ------- | MODERATE | |***| * | | | * |***|***| * | | 75% | LOW |***|***|***|***|***|***|***|***|***|***| | NOT VISIBLE |***|***|***|***|***|***|***|***|***|***| |----------------|---|---|---|---|---|---|---|---|---|---| | AURORAL |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| | INTENSITY | Eve.Twilight/Midnight/Morn.Twilight | -------------------------------------------------------- Middle Latitude Locations ________________________________________________________ | EXTREMELY HIGH | | | | | | | | | | | CONFIDENCE | VERY HIGH | | | | | | | | | | | LEVEL | HIGH | | | | | | | | | | | ------- | MODERATE | | * | | | | | | | | | 70% | LOW | |***| * | | | * |***|***| * | | | NOT VISIBLE |***|***|***|***|***|***|***|***|***|***| |----------------|---|---|---|---|---|---|---|---|---|---| | AURORAL |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| | INTENSITY | Eve.Twilight/Midnight/Morn.Twilight | -------------------------------------------------------- Low Latitude Locations ________________________________________________________ | EXTREMELY HIGH | | | | | | | | | | | CONFIDENCE | VERY HIGH | | | | | | | | | | | LEVEL | HIGH | | | | | | | | | | | ------- | MODERATE | | | | | | | | | | | 85% | LOW | | | | | | | | | | | | NOT VISIBLE |***|***|***|***|***|***|***|***|***|***| |----------------|---|---|---|---|---|---|---|---|---|---| | AURORAL |Sun|Mon|Tue|Wed|Thu|Fri|Sat|Sun|Mon|Tue| | INTENSITY | Eve.Twilight/Midnight/Morn.Twilight | -------------------------------------------------------- NOTE: For more information regarding these charts, send a request for the document, "Understanding Solar Terrestrial Reports" to: oler@hg.uleth.ca. ** End of Report ** ------------------------------ End of SPACE Digest V13 #340 *******************