Flow Removal Menu

Selecting Flow Removal under the Plot Tools option in the Plot Definition Menu brings up the menu:

This is a generic menu used for a number of Plot Tool definitions. For Flow Removal only the first Vector Source option line is ever enabled. The flow vector can be either input manually or taken from a UDF source. The advantage of the latter is that the flow vector is tracked in time and aligned with the data as closely as possible before each operation. If there are multiple occurrances of the flow vector within the accumulation time of a single data measurement then the average of the values is used.

Algorithm Description

The flow removal tool is designed to subtract a vector flow from a particle spectra. The algorithm assumes:

• The elevation and particle mass for the spectra have been defined in the VIDF constants section: (CONSTANT ID's 1 and 10.

• The spectra scan indices can be transformed into physical units of energy as eV.

• The flow velocity is specified in a Cartesian coordinate system with units of km/sec.

• The flow velocity and particle angular quantities (elevation and spin phase) are specified in the same coordinate system.

The basic algorithm is as shown below. Inputs to the algorithm are the particle mass, the particle energy (E), the elevation angle (T), and the phase angle (P), for each point in the spectrum. The algorithm outputs the corrected energy (E'), the corrected elevation angle (T'), and the corrected phase angle (P'). The constant K in the algorithm converts eV to (km/sec)² and includes the particle mass.

Algorithm:

V = [E/K]^½
Vx = V * cos(P) * cos (T) - V_Fx
Vy = V * sin(P) * cos (T) - V_Fy
Vz = V * sin(T) - V_Fz
P' = atan2(Vy, Vx)
T' = atan2(Vx, [Vx² + Vy²]^½)
E' = K * ( Vx² + Vy² + Vx²)

Top Section Menu Options

PARENT

PARENT This is not an option in the conventional definition but contains the name of the Plot Tool which spawned the menu page. This is given as a reference since many different Plot Tools use this menu page.

CLOSE

CLOSE closes the Plot Tool Menu window.

Main Section Menu Options

For Flow Removal, only the first set of options in the main menu panel is ever enabled.

Vector Source

The first instance of the Vector Source option line defines the flow vector to be used in the correction algorithm.

LOCATION defines the source of the Flow Removal Vector . The options are:

X is accessible only if the LOCATION option has been set to USER. The option sets the X component of the Flow Vector.

Y is accessible only if the LOCATION option has been set to USER. The option sets the Y component of the Flow Vector.

Z is accessible only if the LOCATION option has been set to USER. The option sets the Z component of the Flow Vector.

Bottom Section Menu Options

DELETE PAGE

DELETE PAGE deletes the current Plot Tool Definition and all menus associated with it.

Option Effects

Removing the solar wind velocity from a particle distribution is accomplished by the following two menu definitions: the Flow Removal definition which indicates a UDF source for the solar wind; and the Vector Source Menu which defines where the solar wind vector data is found.

The resultant plot is shown in the following figure. The upper plot shows the data without the flow removed. The lower plot shows the same data with the flow removed.