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Description of the Solar Wind Summary Data Plot
John Steinberg Feb 22, 2002
All parameters shown in the Solar Wind Summary plots are determined autonomously by Genesis in onboard flight software, including the boxcar running averages. The boxcar averaging interval is nominally one hour, but can be re-configured to be up to two hours by ground command.
ABOUT SHOCK DETECTION
The label on the upper left hand corner indicates the time of the last shock identification by the onboard Genesis algorithm. Genesis always retains memory of the last time-of-shock. Note that the last shock may have occurred many days previous to the data shown in the present panel.
Vertical lines extending through all the panels indicate a shock detection by Genesis. Please be qware that the shock detection is retrospective: it is based on examination of the data collected over the previous hour. Genesis shock identification typically occurs about 30 minutes after the actual time of shock passage. Thus, the vertical shock line as well as the shock time label in the upper left hand corner are typically later by about 30 minutes than the actual time of shock passage.
ABOUT THE COLOR-CODED REGIME INDICATOR BAR
Across the top of the plot, the regime determined by the Genesis algorithm is shown as a color-coded bar:
Yellow = Slow inter-stream solar wind
Blue = Coronal Hole fast solar wind
Red = Coronal Mass Ejection solar wind
Gray = Regime Unknown (occurs for short intervals when algorithm is re-initialized)
Be aware that the goal of the Genesis algorithm is to expose the collection samples to the correct flow regime nearly all of the time, but not precisely all of the time. With that in mind, the algorithm regime may often exhibit latency relative to what an experienced observer recognizes as a clear change in the flow conditions. This behavior is built in for several reasons. First, Genesis is constrained to limit the total number of sample array changes during the mission in order to limit the number of times the array motors are operated. To meet this requirement, the Genesis algorithm has hysteresis and persistence built in. In addition, bias has been introduced to keep the Coronal Hole collection most pristine, while allowing the CME collection to accept the most cross-exposure.
CONTENT OF PLOT PANELS - TOP TO BOTTOM
Speed Panel
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The solar wind proton speed. |
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White Points |
speed at approximately 2.5 minute resolution |
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White Dotted Line |
boxcar running average speed |
Temp Panel
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The solar wind proton one-dimensional moment temperature Tp |
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White Points |
Tp at approximately 2.5 minute resolution |
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White Dotted Line |
boxcar running average Tp |
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Green Points |
Tp-expected calculated onboard from the speed. (Tp-expected is, roughly, the most probable temperature for the given solar wind speed. Excursions of Tp below Tp-expected are signatures of some CMEs) |
Tex/Tp Panel
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The ratio of the Tp-expected to Tp |
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Green Points |
Tex/Tp at the 2.5 minute time resolution |
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Green Dotted Line |
boxcar running averages of Tex/Tp. (Large values of Tex/Tp are signatures of some CMEs) |
Density Panel
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The solar wind proton number density. |
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White Points |
proton density at approximately 2.5 minute resolution |
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White Dotted Line |
boxcar running average of the proton density |
He ratio Panel
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The ratio of the alpha particle number density to the proton number density |
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White Points |
alpha/proton ratio at approximately 2.5 minute resolution |
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White Dotted Line |
boxcar running average of alpha/proton ratio |
To_CME Panel
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CME Indicator To_CME is the output parameter of a fuzzy logic scheme to determine the likelihood that measured solar wind is coronal mass ejection related. Higher values indicate greater likelihood of CME detection. The algorithm takes into account the presence or absence of bi-directional electron signatures, the proton temperature as compared with the expected proton temperature for the given speed, and the alpha particle to proton relative abundance ratio. The running averages are used in all cases. When To_CME is greater than a threshold value, then the CME regime is selected. The threshold is nominally 0.4, but can be re-configured via ground command. |
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White Solid Line |
To_CME |
BDE Panel
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Bi-Directional (or counter-streaming) Electron indicator |
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Red Hash Marks |
At each 2.5 minute data cycle, the BDE parameter is assigned a value of one or zero, depending on whether or not the measured electron spectrum shows the characteristics of bi-directional electron streaming. Red hash marks indicate a positive indication (BDE=1). |
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White Solid Line |
Running box car average of the value of BDE. At each data cycle, BDE is zero or one. Thus the running average is a value between zero and one. |
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