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STATUS:
11.11.2020
Instrument Status:
The spacecraft continues to perform nominally.
SOFIE
SOFIE
SOFIE is currently collecting sunset science observations, and housekeeping parameters all indicate a stable and healthy instrument. SOFIE V1.3 data are available online.
An 8‐year record of SOFIE and SABER observations were recently used to evaluate the roles of vertical and oblique gravity wave (GW) propagation in the polar summer mesosphere [Thurairajah et al., 2020]. Obliquely propagating waves are of interest because they are presumed to be generated by the summer monsoons. In the high‐latitude upper mesosphere, the correlation coefficient between the time series of polar mesospheric cloud (PMC) ice water content (IWC) and GW amplitude is 0.48, indicating that the observed GWs enhance PMCs. For vertically propagating waves, the correlation coefficient between IWC and stratospheric/lower mesospheric (20–70 km) GW amplitude at the same high latitudes becomes more negative with increasing altitude. This change in correlation from negative in the lower mesosphere to positive at PMC altitudes suggests the presence of another GW source. The positive correlation between time series of IWC and GW amplitude from 0–50°N (20–90 km) shows a slanted structure suggesting oblique propagation (see Figure below). This pattern is more robust in some seasons than others. This interannual variability may be due to the latitudinal gradient of the mesospheric easterly jet where steeper gradients allow for low‐latitude tropospheric GWs to be refracted to the high‐latitude mesosphere more efficiently. Gravity‐Wave Regional or Global Ray Tracer (GROGRAT) ray tracing simulations show that GWs that reach PMC altitudes are more often propagated obliquely from low latitudes, than vertically (from below). For obliquely propagating waves, GROGRAT indicates that non-orographic tropospheric GWs with faster phase speed (>20 m/s) and longer horizontal wavelength (>400 km) have a higher probability of reaching the polar summer mesosphere.
Thurairajah, B., Cullens, C. Y., Siskind, D. E., Hervig, M. E., & Bailey, S. M. (2020). The role of vertically and obliquely propagating gravity waves in influencing the polar summer mesosphere. Journal of Geophysical Research: Atmospheres, 125, e2020JD032495. https://doi.org/10.1029/2020JD032495 (article)
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The correlation between time series of IWC (averaged over ~60–85°N latitude; ~84 km altitude) and GW amplitude at a range of latitudes (0–50°N) , ~25–95 km). The results are shown as the correlation coefficient as color contours corresponding to the GW latitude and height.
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