Climatological study of the ion temperature in the ionosphere as recorded by Millstone Hill incoherent scatter radar and comparison with the IRI model

Ion temperature data recorded by Millstone Hill incoherent scatter radar (42.61° N, 288.51° E) over four full solar cycles (from 1970 to 2018) are analyzed depict its climatological behavior in the range of altitudes between 100 and 550 km. The ion dependencies on altitude, local time, month year, activity level studied through a analysis based binning boxplot representation statistical values. Binned observations compared with International Reference Ionosphere (IRI) modeled values (IRI-2016 version). This comparison reveals several shortcomings IRI modeling at ionosphere altitudes, particular for altitudinal, diurnal, seasonal, description. main finding this study is that overall overestimation can be probably ascribed long-term cooling. Moreover, suggests model needs implement seasonal dependence, introduce more refined diurnal description allow multiple maxima seen observations. anchor point 430 km investigated detail show how also better altitude dependence desirable purposes. Some hints clues finally given improve model.