Aura MLS

Data Access

The EOS MLS data describe a piecewise linear representation of vertical profiles of gas phase chemical abundances, temperature, and cloud ice density.

The vertical coordinate is log10 (atmospheric pressure) with, typically, 6 breakpoints per decade pressure (. . ., 3.16, 2.15, 1.47, 1.00, 0.68, 0.46, 0.32 hPa, . . .).

The vertical range of usefulness depends upon the specific data product and the data version. Some of the MLS observations are "noisy" in nature, with the consequence that negative values are reported - these should not be masked or ignored, as failure to include them (in the averages that are required of these data) will lead to an artificial positive bias.

It is essential that users of MLS data understand and apply the data quality and status indicators available in the data files. These are described, for each released version of MLS data, by MLS Data Quality Documents. These documents also describe the expected precision, resolution, and known artifacts of each product for that data version - and improvement priorities for future data versions. They are available for MLS Version 5 (v5) data at the MLS Data Documentation page.

The MLS team very strongly encourages users to contact us with any questions on the data and if you find features that seem unreasonable. Although we have done our best to produce a reasonably sound data set within one year of becoming operational, we have no misconceptions that all the data artifacts have been identified.

Feedback from users is of great benefit for improving the quality of the next data version. We also welcome, and encourage, users to just inform us that you are using MLS data. By knowing who you are, we can contact you with new data issues as we find them (the MLS team inspects all daily data, and reviews the findings on a weekly basis). Contacts can be made via e-mail to or to the individual(s) listed in the table below.

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EOS MLS Version 5 Data

(Products with a * require significant averaging over most or all of their vertical range in order to obtain a useful signal-to-noise ratio.)

Useful Vertical Range / H Pa
MLS Contact
*BrO10 - 3.2Luis Millan Valle
*CH3Cl147 - 4.6Michelle Santee
*CH3CN46 - 1.0Michelle Santee
CH3OH147 - 100 (contact MLS science team before contemplating use)Michelle Santee
ClO147 - 1.0Michelle Santee
CO215 - 0.001troposhpere: Michael Schwartz stratosphere / mesosphere: Hugh Pumphrey
geopotential height261 - 0.00046Michael Schwartz
H2O316 - 0.001troposphere: Bill Read stratosphere / mesosphere: Alyn Lambert
HCl100 - 0.32Lucien Froidevaux
*HCN21 - 0.1Hugh Pumphrey
HNO3215 - 1.5 (1.0 under enhanced conditions)Michelle Santee
*HO222 - 0.046Luis Millan Valle
*HOCl10 - 2.2Lucien Froidevaux
Ice water content215 - 83Alyn Lambert
Ice water pathN/AAlyn Lambert
N2O100 - 0.46Alyn Lambert
O3261 - 0.001troposphere: Michael Schwartz stratosphere / mesosphere: Lucien Froidevaux
OH32 - 0.0032Luis Millan Valle
Relative Humidity316 - 0.001Bill Read
SO2215 - 10Bill Read
Temperature261 - 0.00046Michael Schwartz