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30 - MLH - Millstone Hill I.S. Radar
Instrument Type: Instrument > Radar > IncoherentScatterRadar
Observatory: None
Observation Site: MLH - Millstone Hill I.S. Radar
Operating Mode:

Instrument Page: MLH

The incoherent scatter transmitter station at Millstone Hill, Massachusetts (42.6N, 71.5W) has been in operation since 1960. The facility is part of and operated by the Massachusetts Institute of Technology. ISR data comes from the fixed zenith antenna, the steerable antenna, or both. The electron densities from the power profile were calibrated with an on-site ionosonde, where recently, this ionosonde has been the University of Massachusetts at Lowell digisonde. Since the Coast Guard uses some of the frequencies needed to properly scan the ionosphere, calibration can sometimes be difficult. The calibrated electron density is then corrected for Te and Ti effects, where Te and Ti come from auto-correlation fits. The calibration and auto-correlation fits now have the same height resolution, although in the past, the auto-correlation fits had lower height resolution. The ion composition changes from mostly O2+ and NO+ at lower altitudes, to mostly O+, and then to H+ and some He+ at higher altitudes. Above 400 km, the percent H+ is computed along with the major ion O+. At lower altitudes, the ratio of molecular ions to the total number of ions is modeled as specified by the FORTRAN code segment below. REAL FUNCTION PMF(Z) Z1=AMIN1(-(Z-120.)/40.,50.) H=10.-6.*EXP(Z1) Z2=AMIN1(-(Z-180.)/H, 50.)