| 英文摘要: | The research for this award would renew the support for the ongoing operations of the Southern Argentina Agile MEteor Radar (SAAMER) system but with diverse and significantly expanded research applications using data from two new correlative instruments to be installed by research colleagues from two other institutions (Boston University and Institute for Atmospheric Physics, Germany). SAAMER was installed on Tierra del Fuego (TdF) to observe the large-scale dynamics within the mesosphere and lower thermosphere (MLT) in the altitude range of 75 to 95 km. This height range is where the semidiurnal tide and various planetary waves have a range of diverse effects. This location is within a latitude band where these motions have large responses, but also where the existing MLT database of winds and temperatures is quite sparse. The SAAMER location on TdF was also motivated by the occurrence of the major 'hotspot' of gravity wave (GW) activity on Earth centered over the Southern Andes, Drake Passage, and Antarctic Peninsula. This hotspot is due to the major GW sources in this region, which include high mountains, strong jet streams, and the passage of vigorous frontal systems. These sources yield large GW events and significant MLT momentum fluxes (MF). Strong interactions of GW structures with the larger-scale motions in the MLT region are to be expected, and SAAMER results to date confirm expectations that the fluxes in this region would be very large. This work has also revealed an ability to characterize meteor head echoes, non-specular meteor trails, and meteor radiants observed in routine measurement modes. The new SAAMER studies would be more comprehensive than before due to correlative airglow imaging as well as new local Rayleigh lidar and multi-receiver radar measurements combined with the use of satellite observations by SABER on TIMED and CIPS on AIM for large- and small-scale dynamics studies. These multi-instrument studies will enable quantification of the important small-scale GWs (and MFs) having wavelengths ëh~20-100 km that are challenging to quantify without such correlative measurements. MLT dynamical studies, especially in regard to the quantification of GW dynamics, momentum transport and its deposition, are central needs in defining more accurate parameterizations of these dynamics in global research, weather prediction, and climate models addressing broad societal needs. Measurements of large-scale dynamics likewise serve to constrain models of these dynamics, especially at high southern latitudes. Meteoroid trajectory studies may provide clues to potential meteor impact risks. SAAMER is also an educational and training tool through various NSF programs devoted to promoting international collaborative activities between U.S. and S. American researchers and students, including extensive exchanges between the U.S., Argentina, and Brazil to date.
The research award to the PI would address MLT dynamics, meteors, and microphysics with focus upon the following questions:
1) Continued Large-scale dynamics studies of mean winds, tides, and PWs and their structure, interactions, and inter-hemispheric and inter-annual variability;
2) Further quantification of momentum fluxes by small-scale GWs employing SAAMER, the BU all-sky imager, and the IAP Rayleigh lidar, with exploration of GW sources and their propagation characteristics combined with the study of possible development of secondary GW generation, and influences by mean winds, tides, and PWs;
3) Further characterization of the meteoroid population, velocities, trajectories, diurnal, seasonal, and global variability of meteor rates, and the meteoric mass flux into the MLT; and
4) Routine measurements of meteor head echoes and non-specular trails and PMSE allowing studies addressing meteor ablation and PMSE microphysics. |