The investigators will upgrade and rebuild optical instruments at the Millstone Hill Observatory in Massachusetts. The instruments include a new patrol Fabry-Perot interferometer (FPI), an all-sky Doppler imager (ASDI), and a spectrometer. The observations will be used to systematically address a number of issues in mesospheric and thermospheric physics. Research will include the study of mid-latitude mesosphere and lower thermosphere (MLT) tides using the combined FPI mesospheric and thermospheric Doppler winds and all-sky images from hydroxyl and oxygen emissions and incoherent scatter radar observations. The semidiurnal tide usually has a large vertical wavelength so the combined observations will provide a large vertical altitude coverage during both the day and night, and will allow for a better characterization of the vertical tidal structure. Also, the all-sky imager at Millstone Hill will record the hydroxyl, sodium, and oxygen nightglow emissions for gravity wave activity and the investigators will use the FPI neutral winds from the same emissions to calculate the intrinsic gravity wave parameters. From the intrinsic parameters, they will deduce the propagation modes of the waves and several important wave parameters including quantitative measurements of vertical scale-sizes, estimates of the vertical fluxes of horizontal wave momentum and energy, and the amount of wave flux divergence between the airglow layers, the hydroxyl and oxygen layers, in particular. The FPI neutral wind and temperature measurements will be used to study the long-term trends in the mesosphere and thermosphere in connection with the solar cycles, and small-scale thermosphere temperature and neutral wind variations will be studied using the all sky Doppler imager. The regional cluster of optical instruments in conjunction with the Millstone Hill Incoherent Scatter radar will provide comprehensive coverage from the mesosphere to the thermosphere. They will provide a unique data set for studies of MLT dynamics and ionosphere/thermosphere interaction in the sub-auroral region. Multi-institute participation will foster more collaboration between different research groups. The Millstone Hill optical instruments will also be the test bed for the future distributed instrument projects.
As part of its Space Weather monitoring program, Scientific Solutions, Inc., deployed two interferometers to observe neutral oxygen emissions at wavelengths of 557 nm and 630 nm at the Millstone Hill Observatory in Westford, Massachusetts. Oxygen is the most abundant atom between 250 and 500 km altitude, and contributes significantly to Space Weather, the dynamic conditions in the upper atmosphere which greatly affect the operation of satellites serving a wide variety of ground activities, including cell phone communication and GPS operation. The analysis of oxygen emission spectra from the atmosphere is vital to the effort to fully understand and model Space Weather, and mitigate its deleterious effects on everyday activities. These interferometers are cable of very high spectral resolutions. They measure the winds and temperatures at two different altitudes within the near space environment. The lowers altitude of 97Km is near the altitude that green aurora forms. The higher altitude 250Km is where the space shuttle orbits. These measurements are needed to help understand and predict the behavior of the aurora and the atmosphere during solar events and magnetic storms. As part of the upgrade SSI developed a fully automated observations and data analysis system that automatically makes the observations, sends the data to an "airglow server" over the internet. The server analysis the data and publishes the winds and temperatures daily at the website www.neutralwinds.com. This upgrade resulted in improving the sensitivity of the 630nm interferometer by a factor of 40 and installing a second interferometer that makes lower altitude measurements. These measurements are now made continuously >200 nights/year and several joint radar optical measurement cycles have been completed. The unprecedented sensitivity and automation have resulted in the advancement of space science. Upper atmospheric climatology: By continuing these observations a 40 year database has been constructed that will allow for a systemic study of long term change in the near space environment. For the first time coupling between a stratospheric event, sudden stratospheric warming (SSW) and the earth’s thermosphere has been detected. Temperature data collected during this year’s SSW event shows a clear cooling trend in the thermosphere. The unprecedented sensitivity of this instrument has allowed the detection of a phenomenon called the Midnight Temperature Maximum (MTM), previously thought to exist only at the equator. This discovery helps to constrains computer models of the atmosphere and helps determine the probable cause of the MTM.
