Representation of solar tides in the stratosphere and lower mesosphere in state-of-the-art reanalyses and in satellite observations
Atmospheric solar tides in the stratosphere and the lower mesosphere are investigated using temperature data from five state-of-the-art reanalysis data sets (MERRA-2, MERRA, JRA-55, ERA-Interim, and CFSR) as well as TIMED SABER and Aura MLS satellite measurements. The main focus is on the period 200...
Gespeichert in:
Veröffentlicht in: | Atmospheric chemistry and physics 2018-02, Vol.18 (2), p.1437-1456 |
---|---|
Hauptverfasser: | , , |
Format: | Artikel |
Sprache: | eng |
Schlagworte: | |
Online-Zugang: | Volltext |
Tags: |
Tag hinzufügen
Keine Tags, Fügen Sie den ersten Tag hinzu!
|
Zusammenfassung: | Atmospheric solar tides in the stratosphere and the lower mesosphere
are investigated using temperature data from five state-of-the-art
reanalysis data sets (MERRA-2, MERRA, JRA-55, ERA-Interim, and CFSR)
as well as TIMED SABER and Aura MLS satellite
measurements. The main focus is on the period 2006–2012 during
which the satellite observations are available for direct comparison
with the reanalyses. Diurnal migrating tides, semidiurnal migrating
tides, and nonmigrating tides are diagnosed. Overall the reanalyses
agree reasonably well with each other and with the satellite
observations for both migrating and nonmigrating components,
including their vertical structure and the seasonality. However, the
agreement among reanalyses is more pronounced in the lower
stratosphere and relatively weaker in the upper stratosphere and
mesosphere. A systematic difference between SABER and the reanalyses is
found for diurnal migrating tides in the upper stratosphere and the
lower mesosphere; specifically, the amplitude of trapped modes
in reanalyses is significantly smaller than that in SABER, although
such difference is less clear between MLS and the reanalyses. The
interannual variability and the possibility of long-term changes in
migrating tides are also examined using the reanalyses during
1980–2012. All the reanalyses agree in exhibiting a clear quasi-biennial oscillation (QBO) in the tides, but the most significant
indications of long-term changes in the tides represented in the
reanalyses are most plausibly explained by the evolution of the
satellite observing systems during this period. The tides are also
compared in the full reanalyses produced by the Japan Meteorological
Agency (i.e., JRA-55) and in two parallel data sets from this agency:
one (JRA-55C) that repeats the reanalysis procedure but without any
satellite data assimilated and one (JRA-55AMIP) that is
a free-running integration of the model constrained only by observed
sea surface temperatures. Many aspects of the tides are closer in
JRA-55C and JRA-55AMIP than these are to the full reanalysis JRA-55,
demonstrating the importance of the assimilation of satellite data
in representing the diurnal variability of the middle atmosphere. In
contrast to the assimilated data sets, the free-running model has no
QBO in equatorial stratospheric mean circulation and our results
show that it displays no quasi-biennial variability in the tides. |
---|---|
ISSN: | 1680-7324 1680-7316 1680-7324 |
DOI: | 10.5194/acp-18-1437-2018 |