Sargassum.jl

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Units and Time API ​

These are the full docstrings for the units and time functionality of Sargassum.jl.

Index ​

Sargassum.UNITS Constant
julia
const UNITS

A dictionary mapping dimension names to the Unitful.Unitlike that measures it.

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Sargassum.T_REF Constant
julia
T_REF

The time to which all times are referred, default January 1, 2000.

This is a Ref, access or modify the actual value with T_REF.x.

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Sargassum.datetime2time Method
julia
datetime2time(dt)

Convert dt::DateTime to the amount of time since T_REF expressed in the units of UNITS["time"].

This inverts time2datetime.

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Sargassum.months2time Method
julia
months2time(months::Integer)

Calculate the date in (year, month) format after months months have elapsed since T_REF.

Example

julia
months2time(219)
(2018, 4)

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Sargassum.time2datetime Method
julia
time2datetime(time)

Convert the amount of time since T_REF expressed in the units of UNITS["time"] to a DateTime.

By convention, time is rounded down to the nearest second.

This inverts datetime2time.

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Sargassum.time2months Method
julia
time2months(yr::Integer, mnth::Integer)

Calculate the number of months since T_REF of the date with year yr and month mnth.

time2months(yearmonth::Tuple{Integer, Integer})

Compute time2months(yearmonth[1], yearmonth[2]).

time2months(time::DateTime)

Compute time2months(year(time), month(time)).

Example

julia
time2months(2018, 4)
219

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Sargassum.time2ymw Method
julia
time2ymw(time)

Convert the time measured in days since T_REF to the corresponding to the year y, month m and week w.

The days of the four weeks per month are defined as the 7th, 14th, 21nd and 28th.

This is the inverse of ymw2time.

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Sargassum.ymw2time Method
julia
ymw2time(y, m, w)

Convert the time corresponding to the year y, month m and week w indicated into a single time measured in days since T_REF.

The days of the four weeks per month are defined as the 7th, 14th, 21nd and 28th.

Can be applied as ymw2time((y, m , w)).

This is the inverse of time2ymw.

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Sargassum.ymwplusweek Method
julia
ymwplusweek(ymw, n_week)

Calculate the (year, month, week) after n_week weeks have passed since ymw.

Example

ymwplusweek((2018, 10, 2), 12) == (2019, 1, 2)

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Sargassum.ymwspan2weekspan Method
julia
ymwspan2weekspan(ymw1, ymw2)

Return a vector list of all (year, month, week) tuples between ym1 = (year1, month1, week1) and ym2 = (year2, month2, week2) inclusive.

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Sargassum.EARTH_RADIUS Constant
julia
const EARTH_RADIUS

The radius of the Earth, equal to 6371 km.

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Sargassum.EQR Constant
julia
const EQR

The EquirectangularReference used during all conversions. This is a Ref, use EQR.x to acess the actual EquirectangularReference.

Defaults

  • lon0: -75.0 degrees

  • lat0: 10.0 degrees

  • R: 6731 km

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Sargassum.EquirectangularReference Type
julia
EquirectangularReference{U}

A container for the reference longitude and latitude of an equirectangular projection.

Fields

  • lon0: The standard longitude degrees (East/West).

  • lat0: The standard latitude degrees (North/South).

  • R: The radius of the Earth. The units of this quantity are the units of the equirectangular coordinates.

Constructor

EquirectangularReference(; lon0 = -75.0, lat0 = 10.0, units = UNITS["distance"])

Example

To measure distances in meters,

julia
eqr = EquirectangularReference(units = u"m")

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Sargassum.sph2xy Method
julia
sph2xy(lon, lat; eqr = EQR.x)

Compute planar coordinates [x, y] from spherical coordinates (lon, lat) [deg E/W, deg N/S] using EquirectangularReference, eqr, default EQR.

The units of x and y the same as eqr.R.

Further Methods

sph2xy(lon_range, lat_range; eqr = EQR)

where lon_range and lat_range are AbstractRange. Returns (x_range, y_range).

sph2xy(lon_lat; eqr = EQR)

where lon_lat is a 2 x N `Matrix. Returns a result in the same shape as the input.

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Sargassum.xy2sph Method
julia
xy2sph(x, y, eqr = EQR.x)

Compute spherical coordinates [lon, lat] [deg] from rectilinear coordinates (x, y) using EquirectangularReference eqr, default EQR.

The units of x and y should be the same as eqr.R.

Further Methods

xy2sph(x_range, y_range)

where x_range and y_range are AbstractRange. Returns (lon_range, lat_range).

xy2sph(xy)

where xy is a 2 x N Matrix.

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Sargassum.γ_sphere Method
julia
γ_sphere(y; eqr = EQR.x, geometry = true)

Calculate the geometric correction factor sec(lat_0) * cos(lat), converting y to lat automatically using EquirectangularReference eqr, default EQR.

If geometry == false, γ_sphere is always equal to 1.0.

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Sargassum.τ_sphere Method
julia
τ_sphere(y; eqr = EQR.x, geometry = true)

Calculate the geometric correction factor τ = tan(lat)/R converting y to lat automatically using EquirectangularReference eqr, default EQR.

If geometry == false, τ_sphere is always equal to 0.0.

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