Precise measurement of neutral wind in daytime thermosphere by rocket-released Lithium vapor

研究热层对了解全球大气（如全球变暖）具有重要意义，但对热层的观测是困难的。稀薄大气中只有不到1%被太阳紫外线电离，因此可以被雷达观测到，而99%以上的中性大气太难观测，阻碍了我们的理解。由于火箭发射的TMA （Try-Methyl-Aluminum）对人工照明云的光学跟踪，已经建立了160公里以下夜间热层中性风的测量，但在白天的测量从未建立过。利用火箭释放的锂离子及其在阳光下的共振散射，建立了白天中性风的测量方法。2013年7月，日美两国达成协议。进行了合作火箭实验，成功地对火箭释放的锂进行了20分钟的观测，从而建立了困难的测量。

To study the thermosphere is important for understanding global atmosphere (e.g. global warming), however, observation of thermosphere is difficult. Less than 1% of the rarefied atmosphere is ionized by solar ultra-violet, thus it can be observed by radars, whereas, more than 99% of the neutral atmosphere is too difficult to observe, preventing from our understanding. Due to optical tracking of artificially illuminating clouds by rocket-released TMA (Try-Methyl-Aluminum), it has been established neutral wind measurement in nighttime thermosphere below about 160 km, however, the measurement in daytime has never been established before. We use rocket-released Lithium and its resonance-scattering by sunlight in order to establish the neutral wind measurement in daytime. In July 2013, Japan-U.S. collaborating rocket experiment was carried out and the rocket-released Lithium was successfully observed for 20 minutes, resulting on establishment of the difficult measurement.