Daily Satellite Observations of Hypochlorous Acid in the Stratosphere

MLS/Aura satellite data provides daily, near-global measurements of hypochlorous acid (HOCl) mixing ratios, a key chemical involved in ozone depletion. The dataset is binned into zonal and vertical grids, with recommended data from 10 to 2.15 hPa. It is produced by the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC) from the EOS Aura Microwave Limb Sounder instrument.

Use Cases

• Analyze seasonal and latitudinal variations in HOCl mixing ratios using the lat vs pressure zonal mean groups.
• Investigate diurnal cycles of chlorine chemistry by comparing daytime (SZA < 90) and nighttime (SZA > 110) profile groups.
• Study polar vortex dynamics and chemical processing using the equivalent latitude vs potential temperature and vortex average groups.
• Assess measurement uncertainty and variability for model validation using the std dev and rms data fields within each profile group.

Strengths

• Near-global spatial coverage from -82 to +82 degrees latitude.
• Vertical resolution of about 6 km within the useful range of 10 to 2.15 hPa.
• Data is subdivided by orbit type (ascending/descending) and solar illumination for detailed analysis.
• Files contain one year of binned daily data, facilitating long-term trend studies.

Limitations

• The useful vertical range is limited to 10-2.15 hPa, excluding higher and lower atmospheric layers.
• Spatial resolution is coarse at 4-degree latitude zonal increments.
• Data quality and interpretation require consulting the specific EOS MLS Level 2 Version 5 Quality Document.

Provenance

Source

NASA Goddard Earth Sciences Data and Information Services Center (GES DISC).

Collection Method

Derived from radiances measured by the 640 GHz radiometer on the EOS Aura Microwave Limb Sounder (MLS) satellite instrument.

Time Range

Data files contain one year of data; specific years are not stated.

Geography

Near-global, from -82 to +82 degrees latitude.