Ozone Data Fields
Ozone Concentration
The ozone concentration field and associated error are given in units of mol/m3. Multiply by \(6.02214076 \times 10^{17}\) to convert these fields to units of molecules/cm3.
- ozone_concentration:
Mole concentration of ozone in units of mol/m3. Only converged values in the retrieval range and above any cloud layer are reported.
The associated error in the retrieved ozone is given by:
- ozone_concentration_standard_error:
Standard uncertainty of the retrieved ozone concentration in units of mol/m3.
The vertical resolution is computed for every retrieved profile from the FWHM of the averaging kernel and is given by:
- vertical_resolution:
FWHM of the averaging kernel, with units of km.
Although not recommended for general use, the field _rtm_internal_ozone_concentration
may be useful in
investigating possible biases due to retrieval saturation or other similar effects. This
field includes altitudes affected by clouds and those that have not fully converged.
- _rtm_internal_ozone_concentration:
The full ozone concentration profile as used in the SASKTRAN radiative transfer model in units of mol/m3.
Clouds
The cloud altitudes retrieved during the aerosol extinction retrieval. Clouds are separated into two categories:
- cloud_top_altitude:
The altitude, in km, of the top of a cloud detected in this profile, NaN otherwise
- psc_altitude:
The altitude, in km, of a polar stratospheric cloud detected in this profile, NaN otherwise
Note
While the ozone concentration is reported in _rtm_internal_ozone_concentration
when clouds are flagged, it is
unlikely to be a reliable quantitative measure, as assumptions made in the retrieval are not consistent
with cloud microphysics.
Meteorology
A few meteorological fields are included in the data to aid in analysis.
- temperature:
Temperature taken from MERRA 2 and interpolated to the current geometrical altitude grid.
- pressure:
Pressure in hPa taken from MERRA 2 and interpolated to the current geometrical altitude grid.
- tropopause_altitude:
Tropopause in km based on WMO lapse-rate tropopause definition; the first parameter for the lowest tropopause.Calculated from MERRA 2 temperature profiles.
Geometry
For ease of use, each OSIRIS scan is assigned to a specific geographic location and time. This is not strictly true, as a scan takes approximately 90 seconds to complete and spans a few degrees latitude over this time. The geometric data fields are defined at the 30 km point of each scan.
- latitude:
latitude in degrees north
- longitude:
longitude in degrees east
- time:
days since 1900-01-01 00:00:00
- local_solar_time:
Local solar time in hours
In addition to the geographic location, three solar angles are provided that define the measurement geometry of the line of sight with respect to sun.
- ssa:
Solar scattering angle. The angle between the line of sight and the solar beam.
- sza:
Solar zenith angle. The angle between solar beam and the vertical direction at the tangent point.
- saa:
Solar azimuth angle. The angle between the horizontal projection of the solar beam and the line of sight.
Additional Fields
- albedo:
The retrieved albedo of the surface.
Retrieval
These fields provide information about the retrieved ozone concentration profiles. It should be noted that values below
retrieval_lowerbound
are truncated from ozone_concentration
. Profiles with poor convergence are also filtered
from this product.
- retrieval_lowerbound:
Lowest altitude in km that is valid for the ozone retrieval.
- convergence_ratio:
Convergence ratio of the ozone retrieval.
- chi_sq:
The \({\chi}\)2 value of the ozone retrieval.