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Request and download pressure time series at a given location

Source: R/geopressure_timeseries.R
geopressure_timeseries.Rd

This function returns the surface atmospheric pressure time series from ERA5 at any requested location.

If the location queried is over water, the location will be moved to the closest onshore location.

The ERA5 pressure time series of the response \(P_{ERA}\) will be provided on a hourly basis between start_time and end_time or the same as pressure$date if pressure is supplied.

If you supply the pressure of the geolocator \(P_{gl}\), the function will additionally return the altitude of the geolocator above sea level \(z_{gl}\) using the barometric equation, $$ z_{{gl}}(x)=z_{ERA5}(x) + \frac{T_{ERA5}(x)}{L_b} \left( \frac{P_{gl}}{P_{ERA5}(x)} \right)^{\frac{RL_b}{g M}-1},$$ where \(z_{ERA}\), \(T_{ERA}\), and \(P_{ERA}\) respectively correspond to the ground level elevation, temperature at 2m, and ground level pressure of ERA5, \(L_b\) is the standard temperature lapse rate, \(R\) is the universal gas constant, \(g\) is the gravity constant and \(M\) is the molar mass of air. See more information at the GeoPressureAPI documentation.

To be able to compare the temporal variation of the retrieved pressure of ERA5 \(P_{ERA}\) to the geolocator pressure \(P_{gl}\), the function also returns the ERA pressure normalized with the geolocator mean pressure measurement as surface_pressure_norm. $$ P_{ERA5,0}(\boldsymbol{x})[t] = \left( P_{ERA5}(\boldsymbol{x})[t]-P_{gl}[t]\right) - \left( \frac{1}{n}\sum_{i=1}^{n} P_{ERA5}(\boldsymbol{x})[i]-P_{gl}[i] \right).$$

Usage

geopressure_timeseries(
  lat,
  lon,
  pressure = NULL,
  start_time = NULL,
  end_time = NULL,
  timeout = 60 * 5,
  quiet = FALSE,
  debug = FALSE
)

Arguments

lat

Latitude to query (0° to 90°).

lon

Longitude to query (-180° to 180°).

pressure

A data.frame of pressure time series, containing at least a "date" and "value" column.

start_time

If pressure is not provided, start_time defines the start time of the time series as POSIXlt.

end_time

If pressure is not provided, end_time defines the end time of the time series as POSIXlt.

timeout

duration before the code is interrupted both for the request on GeoPressureAPI and on GEE (in seconds, see httr2::req_timeout()).

quiet

logical to hide messages about the progress

debug

logical to display additional information to debug a request

Value

A data.frame containing

  • date POSIXct date time

  • surface_pressure pressure (hPa)

  • lon same as input lon except if over water

  • lat same as input lat except if over water.

  • surface_pressure_norm only if pressure is provided as input

  • altitude only if pressure is provided as input

References

Nussbaumer, Raphaël, Mathieu Gravey, Martins Briedis, and Felix Liechti. 2023. Global Positioning with Animal‐borne Pressure Sensors. Methods in Ecology and Evolution, 14, 1118–1129 https://doi.org/10.1111/2041-210X.14043.

See also

Other pressurepath: plot_pressurepath(), pressurepath_create(), pressurepath_update()

Examples

# Request pressure at a given location
pressurepath <- geopressure_timeseries(
  lat = 46, lon = 6,
  start_time = "2017-01-01 00:00",
  end_time = "2017-01-02 00:00",
  quiet = TRUE
)

str(pressurepath)
#> 'data.frame':	25 obs. of  4 variables:
#>  $ date            : POSIXct, format: "2017-01-01 00:00:00" "2017-01-01 01:00:00" ...
#>  $ surface_pressure: num  969 969 968 968 967 ...
#>  $ lat             : num  46 46 46 46 46 46 46 46 46 46 ...
#>  $ lon             : num  6 6 6 6 6 6 6 6 6 6 ...

plot(pressurepath$date, pressurepath$surface_pressure,
  type = "b", ylab = "Pressure (hPa)", xlab = "Datetime"
)


# Retrieve the altitude of a bird being at this location adding random noise on the sensor.
pressurepath <- geopressure_timeseries(
  lat = 46, lon = 6,
  pressure = data.frame(
    data.frame(
      date = pressurepath$date,
      value = pressurepath$surface_pressure + rnorm(nrow(pressurepath))
    )
  ),
  quiet = TRUE
)

str(pressurepath)
#> 'data.frame':	25 obs. of  7 variables:
#>  $ date                 : POSIXct, format: "2017-01-01 00:00:00" "2017-01-01 01:00:00" ...
#>  $ pressure_tag         : num  969 968 969 967 967 ...
#>  $ surface_pressure     : num  969 969 968 968 967 ...
#>  $ altitude             : num  485 489 478 492 488 ...
#>  $ lat                  : num  46 46 46 46 46 46 46 46 46 46 ...
#>  $ lon                  : num  6 6 6 6 6 6 6 6 6 6 ...
#>  $ surface_pressure_norm: num  970 969 968 968 967 ...

plot(pressurepath$date, pressurepath$altitude,
  type = "b", ylab = "Altitude (m)", xlab = "Datetime"
)