SAGE II¶
Variables¶
As far as possible the original SAGE II variable names used in the IDL scripts and documentation have been adopted. If xarray is chosen as the output format revision and creation date information is not included in the output structure.
Altitude Range for Species¶
| Species | Range (km) |
|---|---|
| Ozone | 5-60 |
| NO2 | 15-60 |
| Aerosol | 1-45 |
| Water Vapor | MSL-40 |
Revision Info¶
| Field | Description |
|---|---|
| Num_Prof | Number of profiles (records) in file |
| Met_Rev_Date | LaRC Met Model Rev Date (yyyymmdd) |
| Driver_Rev | LaRC Driver version (eg. 6.20) |
| Transmission_Rev | LaRC Transmission version |
| Inversion_Rev | LaRC Inversion version |
| Spectroscopy_Rev | LaRC Inversion version |
| Eph_File_Name | Ephemeris file name |
| Met_File_Name | Met file name |
| Ref_File_Name | Refraction file name |
| Trans_File_Name | Transmission file name |
| Spec_File_Name | Species profile file name |
| FillVal | Fill value |
Altitude grid and range info¶
| Grid_Size | Altitude Grid spacing |
|---|---|
| Alt_Grid | Geometric Alt |
| Alt_Mid_Atm | Geometric Alt for Dens_Mid_Atm |
| Range_Trans | Transmission Min & Max alt |
| Range_O3 | Ozone Density Min & Max alt |
| Range_NO2 | NO2 Density Min & Max alt |
| Range_H2O | H2O Density Min & Max alt |
| Range_Ext | Extinction Min & Max alt |
| Range_Density | Density Min & Max alt |
| Range_Surface | Surface Area Min & Max alt |
Event Specific Info¶
| YYYYMMDD | Event Date (yyyymmdd) at 30 km |
| event_num | The event number |
| HHMMSS | Event Time (hhmmss) at 30 km |
| Day_Frac | Time of Year (ddd.fraction) |
| Lat | Sub-tangent Lat at 30km |
| Lon | Sub-tangent Lon at 30km |
| Beta | Spacecraft Beta angle (degree |
| Duration | Duration of event (seconds) |
| Type_Sat | Instrument Event Type, 0=sr, 1=ss) |
| Type_Tan | Event Type, Local (0=sr,1=ss) |
Process Tracking Flag info¶
| Processing Success | |
| Dropped | Value is non-zero if event is dropped |
| InfVec | 32 bits describing the event processing |
| Ephemeris | |
| Eph_Cre_Date | Record creation date (yyyymmdd) |
| Eph_Cre_Time | Record creation time (hhmmss) |
| Met | |
| Met_Cre_Date | Record creation date (yyyymmdd) |
| Met_Cre_Time | Record creation time (hhmmss) |
| Refraction | |
| Ref_Cre_Date | Record creation date (yyyymmdd) |
| Ref_Cre_Time | Record creation time (hhmmss) |
| Transmission | |
| TRANS_Cre_Date | Record creation date (yyyymmdd) |
| TRANS_Cre_Time | Record creation time (hhmmss) |
| Inversion | |
| SPECIES_Cre_Date | Record creation date (yyyymmdd) |
| SPECIES_Cre_Time | Record creation time (hhmmss) |
Species File Contents¶
Field Type Description
| Tan_Alt | Center-of-Sun Tangent Alt (km) |
| Tan_Lat | Center-of-Sun Lat (deg) |
| Tan_Lon | Center-of-Sun Lon (deg) |
| NMC_Pres | Pressure (mb) (0.5-70km) |
| NMC_Temp | Temperature (K), (0.5-70km) |
| NMC_Dens | Density (molecules/cm3) (.5-70km) |
| NMC_Dens_Err | Density Uncertainty(%x100) |
| Trop_Height | Tropopause height in km |
| Wavelength | Channel wavelengths |
| O3 | O3 number density (cm-3) |
| NO2 | NO2 number density (cm-3) |
| H2O | H2O number density (ppp) |
| Ext386 | 386 nm aerosol extinction (1/km) |
| Ext452 | 452 nm aerosol extinction (1/km) |
| Ext525 | 525 nm aerosol extinction (1/km) |
| Ext1020 | 1020 nm aerosol extinction (1/km) |
| Density | Molecular density (1/cm^3) |
| SurfDen | Aerosol surface area density (micrometer^2/cm^3) |
| Radius | Aerosol effective radius (micrometer) |
| Dens_Mid_Atm | Middle atmosphere retrieved density(1/cm^3) |
| O3_Err | o3 number density uncertainty (%x100) |
| NO2_Err | NO2 number density uncertainty (%x100) |
| H2O_Err | H2O number density uncertainty (%x100) |
| Ext386_Err | 386 nm aerosol ext. uncertainty (%x100) |
| Ext452_Err | 452 nm aerosol ext. uncertainty (%x100) |
| Ext525_Err | 525 nm aerosol ext. uncertainty (%x100) |
| Ext1020_Err | 1020 nm aerosol ext. uncertainty (%x100) |
| Density_Err | Density uncertainty (%x100) |
| SurfDen_Err | Aerosol surface area density uncertainty(%x100) |
| Radius_Err | Aerosol effective radius uncertainty (%x100) |
| Dens_Mid_Atm_Err | Middle atmosphere density uncertainty (%x100) |
| InfVec | Bit-wise quality flags |
Quality Flags¶
SAGE II data returns both event (index) flags as well as species flags. These are 32 bit integers contained in the InfVec and ProfileInfVec variables respectively. However, for easier use the flags can be expanded to show each bit separately.
from pysagereader.sage_ii_reader import SAGEIILoaderV700
sage = SAGEIILoaderV700(data_folder=r'path\to\sage\data', enumerate_flags=True)
data = sage.load_data('2000-1-1', '2003-12-31', -10, 10)
The flags can also be returned in a separate array for convenience.
from pysagereader.sage_ii_reader import SAGEIILoaderV700
sage = SAGEIILoaderV700(data_folder=r'path\to\sage\data', return_separate_flags=True)
data, flags = sage.load_data('2000-1-1', '2003-12-31', -10, 10)
Data Filtering¶
Ozone¶
It is recommend that only a subset of the ozone data be used for scientific analysis, based on
filtering recommendations from the release notes.
Ozone results that meet these criteria can be determined from the ozone_filter variable in the returned
dataset. A value of 0 indicates ozone should not be used. The following criteria are used as the filters:
- Exclusion of all data points with an uncertainty estimate of 300% or greater
- Exclusion of all profiles with an uncertainty greater than 10% between 30 and 50 km
- Exclusion of all data points at altitude and below the occurrence of an aerosol extinction value of greater than 0.006 km-1
- Exclusion of all data points at altitude and below the occurrence of both the 525nm aerosol extinction value exceeding 0.001 km-1 and the 525/1020 extinction ratio falling below 1.4
- Exclusion of all data points below 35km an 200% or larger uncertainty estimate
Aerosol¶
To remove cloud contamination from the aerosol data flags Cloud_Bit_1 and Cloud_Bit_2 are used to
compute the cloud_filter. A value of 1 indicates there is a cloud present at or above that altitude.