Microwave Limb Sounder (MLS) experiments measure naturally-occurring microwave thermal emission from the limb (edge) of Earth's atmosphere to remotely sense vertical profiles of atmospheric gases, temperature, pressure, and cloud ice. The overall objective of these experiments is to provide information that will help improve our understanding of Earth's atmosphere and global change.

Aura MLS Data

UPDATED - MLS "190 GHz" Observations Status

The MLS science team plans to "duty cycle" the 190-GHz observations (specifically of H2O, N2O, HCN, and upper stratospheric HNO3) to conserve remaining life for these measurements. The plan going forward is to reactivate the MLS 190-GHz subsystem for around six days each calendar month (plus a partial day for turn on and another for shutdown). As noted previously, depending on how the aging of the 190-GHz receiver progresses, we may lengthen or shorten each activation period by one or two days, but our aim will be to always have these measurements active around the middle of each calendar month. Substantial changes to this plan will be noted in future announcements.

The first of the reactivation periods (May 13-20, 2024) proceeded without issue, and we are on track to reactivate again on June 11, 2024, per the current duty cycle schedule.

In addition to H2O, N2O, HCN, and, for pressures less than 20 hPa, HNO3, which are not measured when the 190-GHz system is off, the MLS cloud products (Ice Water Content, IWC, and Ice Water Path, IWP) are also impacted and should not be used. Unfortunately, the effects on the IWC and IWP products are not properly flagged in the Level 2 data files, an issue that will be addressed in future versions of the MLS dataset.

Finally, note that MLS observations of other species (e.g., O3, HCl, ClO, CO, etc.) are unaffected by this issue.

UPDATED - Aura MLS v4 Production Ending in May 2024

The science team for the Microwave Limb Sounder (MLS) on NASA's Aura satellite is finalizing new “Version 6” (V6) data processing algorithms and software. We anticipate releasing V6 MLS data in summer 2024, once its quality has been assessed and documented. Reprocessing of the entire (19-year-to-date) MLS record with the V6 software will take approximately two years, completing in mid-2026. During that time, we will continue to process incoming MLS data with the current V5 algorithms and software, thus ensuring uninterrupted availability of a uniform MLS dataset encompassing the full mission lifetime. However, to maximize the computing resources available for V6 reprocessing, we will cease processing the incoming data with the older V4 algorithms and software. The last V4 data generated will be for May 31, 2024.

Recent Publications

  1. Zolghadrshojaee, M., S. Tegtmeier, S. Davis, and R.P. Kedzierski, "Variability and long-term changes in tropical cold-point temperature and water vapor," Atmos. Chem. Phys. 24, 12, 7405-7419, doi:10.5194/acp-24-7405-2024, 2024.
  2. Sonnabend, J., J. , F. Ploeger, L. Hoffmann, P. , B. Kern, and R. , "Lagrangian transport based on the winds of the icosahedral nonhydrostatic model ICON," Meteorol. Z., doi:10.1127/metz/2024/1207, 2024.
  3. Diouf, M., F. Lefevre, A. Hauchecorne, and J. Bertaux, "Three‐Dimensional Modeling of the O21∆ Dayglow: Dependence on Ozone and Temperatures," Journal of Geophysical Research: Atmospheres 129, 8, doi:10.1029/2023jd040159, 2024.
  4. Wang, Q., A. Duan, C. Zhang, Y. Peng, and C. Xiao, "A connection from Siberian snow cover to Arctic stratospheric ozone," Atmos. Res. 307, 107507, doi:10.1016/j.atmosres.2024.107507, 2024.
  5. Lee, W., I. Song, B. Song, and Y. Kim, "Quasi-10 d wave activity in the southern high-latitude mesosphere and lower thermosphere MLT region and its relation to large-scale instability and gravity wave drag," Atmos. Chem. Phys. 24, 6, 3559-3575, doi:10.5194/acp-24-3559-2024, 2024.