oemSpace Posted September 26, 2020 Share Posted September 26, 2020 (edited) 1) Referring to following link, I would like to know on how to interpret radial velocity vs plasma density for solar storm. When solar storm occurs, how to interpret radial velocity vs plasma density related to Earth's impact? REF : https://www.swpc.noaa.gov/products/wsa-enlil-solar-wind-prediction 2) Referring to following statement, what do radial-velocity actually measure? When there is no plasma density, but radial velocity is high, how to interpret this situation? https://www.l3harrisgeospatial.com/Support/Self-Help-Tools/Help-Articles/Help-Articles-Detail/ArtMID/10220/ArticleID/16675/Solar-wind-visualization-at-NOAA-SWPC Does anyone have any suggestions? Thanks in advance Edited September 26, 2020 by oemSpace Link to comment Share on other sites More sharing options...
helios Posted September 26, 2020 Share Posted September 26, 2020 (edited) The radial velocity of our sun seems to be in the one-digit m/s range, which would be negligible compared to the three- to four-digit km/s velocity of the solar wind. Edited September 26, 2020 by helios Link to comment Share on other sites More sharing options...
oemSpace Posted September 27, 2020 Author Share Posted September 27, 2020 Referring to WSA-ENLIL Solar Wind Prediction, Plasma density is referring to solar solar. From 27 Sep to 1 Oct, Plasma density seems to be lower, but the radial velocity seems to be higher, what do radial velocity refer to? Do you have any suggestions? Thank you very much for any suggestions (^v^) https://www.swpc.noaa.gov/products/wsa-enlil-solar-wind-prediction Link to comment Share on other sites More sharing options...
Christopher S. Posted September 27, 2020 Share Posted September 27, 2020 While I'm sure many are happy to answer any questions you have, it seems that a lot of these questions can be answered by a simple google search: https://en.wikipedia.org/wiki/Radial_velocity Link to comment Share on other sites More sharing options...
oemSpace Posted September 28, 2020 Author Share Posted September 28, 2020 (edited) Plasma density is good selection for monitoring solar storm. After reading Radial velocity from wikipedia, I still get no idea on why noaa selects radial velocity as monitoring items for solar storm. Referring to following link, I would like to know on why radial velocity is important items to be monitored. 27 Sep to 3 Oct, plasma density is below 5, but radial velocity is rapidly changed from 600 to 300. With low plasma density, would it be meaningless on monitoring radial velocity? https://www.swpc.noaa.gov/products/wsa-enlil-solar-wind-prediction Furthermore, even through plasma density is below 5, but Kp shows Geomagnetic Activity on Earth, it seems that forecast Kp on Earth's surface does not match Plasma density's situation on space. A. NOAA Geomagnetic Activity Observation and Forecast The greatest observed 3 hr Kp over the past 24 hours was 6 (NOAA Scale G2). The greatest expected 3 hr Kp for Sep 28-Sep 30 2020 is 6 (NOAA Scale G2). NOAA Kp index breakdown Sep 28-Sep 30 2020 Sep 28 Sep 29 Sep 30 00-03UT 5 (G1) 5 (G1) 5 (G1) 03-06UT 5 (G1) 6 (G2) 5 (G1) 06-09UT 4 5 (G1) 4 09-12UT 4 4 3 12-15UT 4 4 3 15-18UT 4 3 2 18-21UT 5 (G1) 3 2 21-00UT 6 (G2) 5 (G1) 4 Do you have any suggestions on how to relate from Space - WSA-ENLIL Solar Wind Prediction to Earth - Kp-index? Thanks, to everyone very much for any suggestions (^v^) Edited September 28, 2020 by oemSpace Link to comment Share on other sites More sharing options...
Christopher S. Posted September 29, 2020 Share Posted September 29, 2020 21 hours ago, oemSpace said: After reading Radial velocity from wikipedia, I still get no idea on why noaa selects radial velocity as monitoring items for solar storm. The model predicts the radial velocity of the solar wind which flows into, and comprises, the IMF, rather than the radial velocity around the barycenter which is the main focus of the wiki article I linked earlier. At least, that's how I've interpreted it. There can be above average wind speed without a significant geomagnetic response, and there can be below average wind speed with high plasma density that causes a significant geomagnetic response. As for the rest of your question, I'm going to leave it to Sander, I'm sure he loves to go over this stuff 😋 Link to comment Share on other sites More sharing options...
oemSpace Posted September 29, 2020 Author Share Posted September 29, 2020 (edited) 3 hours ago, Christopher S. said: There can be above average wind speed without a significant geomagnetic response, and there can be below average wind speed with high plasma density that causes a significant geomagnetic response. How to interpret wsa-enlil-solar-wind-prediction? Case 1 : below average wind speed with low plasma density, what is the geomagnetic response? Case 2 : below average wind speed with high plasma density, cause a significant geomagnetic response? Case 3 : above average wind speed with low plasma density, what is the geomagnetic response? Case 4 : above average wind speed with high plasma density, what is the geomagnetic response? Do you have any suggestions on how to interpret the geomagnetic response on above cases? Thanks, to everyone very much for any suggestions (^v^) Edited September 29, 2020 by oemSpace Link to comment Share on other sites More sharing options...
Christopher S. Posted September 29, 2020 Share Posted September 29, 2020 (edited) I'm not an employee of SWPC or NOAA, I have no idea how to predict the geomagnetic response. I just take what I'm given and work with it. You should do the same, or pursue a formal education with a focus on space weather. What I mean is, we get a Kp index forecast, just below the Kp "meter" on the home page of Spaceweatherlive.com - just use that. Edited September 29, 2020 by Christopher S. Link to comment Share on other sites More sharing options...
oemSpace Posted September 30, 2020 Author Share Posted September 30, 2020 Hi Sander even through plasma density is below 5, but Kp shows Geomagnetic Activity on Earth, it seems that forecast Kp on Earth's surface does not match Plasma density's situation on space. A. NOAA Geomagnetic Activity Observation and Forecast The greatest observed 3 hr Kp over the past 24 hours was 6 (NOAA Scale G2). The greatest expected 3 hr Kp for Sep 28-Sep 30 2020 is 6 (NOAA Scale G2). NOAA Kp index breakdown Sep 28-Sep 30 2020 Sep 28 Sep 29 Sep 30 00-03UT 5 (G1) 5 (G1) 5 (G1) 03-06UT 5 (G1) 6 (G2) 5 (G1) 06-09UT 4 5 (G1) 4 09-12UT 4 4 3 12-15UT 4 4 3 15-18UT 4 3 2 18-21UT 5 (G1) 3 2 21-00UT 6 (G2) 5 (G1) 4 Do you have any suggestions on how to relate from Space - WSA-ENLIL Solar Wind Prediction to Earth - Kp-index? Thanks, to everyone very much for any suggestions (^v^) Link to comment Share on other sites More sharing options...
Vancanneyt Sander Posted September 30, 2020 Share Posted September 30, 2020 Density is indeed low, but solar wind speed is still high so that's enough to get things going. Also don't forget there's a thing like substorms. Link to comment Share on other sites More sharing options...
oemSpace Posted September 30, 2020 Author Share Posted September 30, 2020 (edited) 3 hours ago, Vancanneyt Sander said: Density is indeed low, but solar wind speed is still high so that's enough to get things going. Also don't forget there's a thing like substorms. How to interpret wsa-enlil-solar-wind-prediction? Case 1 : below average wind speed with low plasma density, is it no geomagnetic response? Case 2 : below average wind speed with high plasma density, a significant geomagnetic response Case 3 : above average wind speed with low plasma density, substorms Case 4 : above average wind speed with high plasma density, how to interpret this situation? It seems that there is a solar storm coming, which is case 2 on 4 Oct and then case 3 on 5 Oct, correct? Do you have any suggestions? Thanks, to everyone very much for any suggestions (^v^) Edited September 30, 2020 by oemSpace Link to comment Share on other sites More sharing options...
Vancanneyt Sander Posted September 30, 2020 Share Posted September 30, 2020 WSA-Enlil is only useful to get an estimate of arrival of a sector boundary crossing, coronal hole and CME. The calculated speed and density is always taken with a grain of salt as its a predictive model and not facts. coronal holes have a high density before arrival and then plummets as it arrives. With CME’s the density is high when the shock arrives and gradually decreases. you don’t use ENLIL to see if a geomagnetic storm will be strong or not. It’s useful to get a glimpse of the predicted solar wind speed and density upon arrival but it doesn’t tell the most important part: the strength of the IMF and the direction of it. You can have high solar wind speed and strong IMF but with northward direction with no storm at all. So to conclude, in any case you mentioned, it’s not possible to know if a geomagnetic storm will be produced as the parameters of the IMF aren’t there. 1 Link to comment Share on other sites More sharing options...
oemSpace Posted October 1, 2020 Author Share Posted October 1, 2020 For Kp-index, IMF keeps changing South and North all the time, I would like to know on why Kp-index still able to forecast G1 and G2 between 28 Sept and 30 Sept. Do you have any suggestions? Thanks, to everyone very much for any suggestions (^v^) Link to comment Share on other sites More sharing options...
Vancanneyt Sander Posted October 1, 2020 Share Posted October 1, 2020 Because it’s a forecast and just like the weather itself it can be a wrong forecast. If the direction of the IMF keeps on wobbling between north and south there wil be no activity. Simple as that. PS: it’s October now 1 Link to comment Share on other sites More sharing options...
oemSpace Posted October 2, 2020 Author Share Posted October 2, 2020 Thanks, to everyone very much for suggestions (^v^) Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now