stilt.observations.pressure_altitudes#

stilt.observations.pressure_altitudes(pressures, *, surface_pressure, surface_altitude, temperature=None, top=None)[source]#

Return the altitudes above sea level of a retrieval’s pressure levels.

Use the result as the altitudes of slant_points(), so the slant follows the retrieval’s own layers. The pressure levels are, for example, OCO-2’s pressure_levels or TROPOMI’s surface_pressure minus multiples of pressure_interval. Altitudes come from the hypsometric equation, integrated up from the surface.

Parameters:

  • pressures (TypeAliasType) – Pressure levels, in hPa, in any order.

  • surface_pressure (float) – The sounding’s surface pressure, in hPa. Levels at higher pressure are below the surface and are dropped.

  • surface_altitude (float) – The sounding’s surface altitude, in meters above sea level.

  • temperature (float | TypeAliasType | None) – Temperature in K. None uses the standard atmosphere lapse rate of 6.5 K/km from a surface temperature of 288.15 K minus 6.5 K/km times the surface altitude; this matches the U.S. Standard Atmosphere below 11 km. A single value assumes an isothermal atmosphere, with scale height R_d T / g (7.3 km at 250 K). One value per level integrates layer by layer with each layer’s mean temperature, and the layer between the surface and the first level takes the first level’s temperature. Use a profile when the retrieval or its prior gives one.

  • top (float | None) – Drop levels above this altitude, in meters above sea level, such as the top of the meteorology.

Returns:

Altitudes in meters above sea level, from the surface upward, so the first one anchors the slant at the sounding’s location.

Return type:

ndarray