pydarn.radar.radFov

Module: pydarn.radar.radFov

This module handles generating field-of-view projctions

Classes:

• fov: field of view position

Functions:

• pydarn.radar.radFov.slantRange(): Calculate slant range
• pydarn.radar.radFov.calcAzOffBore(): Calculate off-array-normal azimuth
• pydarn.radar.radFov.calcFieldPnt(): Calculate field point projection

Based on Mike Ruohoniemi’s GEOPACK Based on R.J. Barnes radar.pro

pydarn.radar.radFov.calcAzOffBore(elevation, boreOffset0)

Calculate off-boresight azimuth as a function of elevation angle and zero-elevation off-boresight azimuth. See Milan et al. [1997] for more details on how this works.

INPUTS:

• elevation: elevation angle [degree]
• boreOffset0: zero-elevation off-boresight azimuth [degree]

OUTPUT:

• boreOffset: off-boresight azimuth [degree]

pydarn.radar.radFov.calcFieldPnt(tGeoLat, tGeoLon, tAlt, boreSight, boreOffset, slantRange, elevation=None, altitude=None, model=None, coords='geo')

Calculate coordinates of field point given the radar coordinates and boresight, the pointing direction deviation from boresight and elevation angle, and the field point slant range and altitude. Either the elevation or the altitude must be provided. If none is provided, the altitude is set to 300 km and the elevation evaluated to accomodate altitude and range.

INPUTS:

• tGeoLat: transmitter latitude [degree, N]

• tGeoLon: transmitter longitude [degree, E]

• tAlt: transmitter altitude [km]

• boreSight: boresight azimuth [degree, E]

• boreOffset: offset from boresight [degree]

• slantRange: slant range [km]

• elevation: elevation angle [degree] (estimated if None)

• altitude: altitude [km] (default 300 km)

• model:

  • ‘IS’: for ionopsheric scatter projection model
  • ‘GS’: for ground scatter projection model
  • None: if you are really confident in your elevation or altitude data
  • ... more to come

• coords: ‘geo’ (more to come)

class pydarn.radar.radFov.fov(frang=180.0, rsep=45.0, site=None, nbeams=None, ngates=None, bmsep=None, recrise=None, siteLat=None, siteLon=None, siteBore=None, siteAlt=None, elevation=None, altitude=300.0, model='IS', coords='geo')

This class calculates and stores field-of-view coordinates. Provide the input-set [nbeams, ngates, bmsep, recrise] or a SITE object. Parameters from the input-set will always take precedence over parameters from the SITE object.Make sure to provide frang and rsep, the default values are not always applicable. The full projection gives the coordinates at each corner of each gate, in the following order: looking in the beam direction, lower-left, lower-right, upper-right, upper-left.

Args:

• site: site structure for a given radar and date-time

• frang: first range gate position [km] (defaults to 180 km) (scalar or ndarray(nbeams))

• rsep: range gate separation [km] (defaults to 45 km) (scalar or ndarray(nbeams))

• nbeams: number of beams (use site information if not provided)

• ngates: number of gates (use site information if not provided)

• bmsep: beam separation [degree] (use site information if not provided)

• siteLat: geographic latitude of radar [degree] (use site information if not provided)

• siteLon: geographic longitude of radar [degree] (use site information if not provided)

• siteAlt: altitude of radar site [m] (use site information if not provided)

• siteBore: radar boresite [degree] (use site information if not provided)

• recrise: receiver rise time [us] (use site information if not provided) (scalar or ndarray(nbeams))

• elevation: elevation angle [degree] (if not provided, is evaluated using ‘model’) (scalar or ndarray(ngates) or ndarray(nbeams,ngates))

• altitude: altitude [km] (if not provided, set to 300 km) (scalar or ndarray(ngates) or ndarray(nbeams,ngates))

• model:

  • ‘IS’: for ionopsheric scatter projection model (default)
  • ‘GS’: for ground scatter projection model
  • None: if you are really confident in your elevation or altitude values
  • ... more to come

• coords: ‘geo’, ‘mag’

pydarn.radar.radFov.gsMapSlantRange(slantRange, altitude=None, elevation=None)

Calculate the ground scatter mapped slant range. See Bristow et al. [1994] for more details.

INPUTS:

• slantRange: normal slant range [km]
• altitude: altitude [km] (defaults to 300 km)
• elevation: elevation angle [degree]

OUTPUT:

• gsSlantRange: ground scatter mapped slant range [km] (typically slightly less than 0.5*slantRange. Will return -1 if (slantRange**2/4. - altitude**2 >= 0). This occurs when the scatter is too close and this model breaks down.

pydarn.radar.radFov.slantRange(frang, rsep, recrise, range_gate, center=True)

Calculate slant range

INPUTS:

• frang: first range gate position [km]
• rsep: range gate separation [km]
• recrise: receiver rise time [us]
• range_gate: range gate number(s)
• center: wether or not to compute the slant range in the center of the gate rather than at the edge

OUTPUT:

• srang: slant range [km]

pydarn.radar.radFov

alias of pydarn.radar.radFov