Electron energy balance in the F region above Jicamarca

Abstract

Abstract. Incoherent scatter measurements from Jicamarca, Peru, show that current models and cross sections account quite well for the heating and cooling of F region electrons, in marked contrast to earlier similar studies at low and middle latitudes. The latter showed discrepancies of the order of a factor of 2 between the calculated energy input and loss rates. The equatorial F region ionosphere provides the simplest configuration for such studies because the horizontal magnetic field eliminates vertical photoelectron transport and thermal conduction. We based our estimates of electron heating on photoelectron energy spectra computed from recently developed solar flux models and new absorption and ionization cross sections and included the additional energy source clue to quenching of the 2D roetastable state of nitrogen. This extra source is sometimes significant. Electron and ion temperatures and densities measured with the Jicamarca incoherent scatter radar were used to complete the calculations of the heating and cooling rates. VVe present here data from 2 days, one xvith low solar activity and one with moderate activity, over the altitude range 220-325 kin. The heating/cooling rates ranged from about 500 to 6000 eV cm -3 s -1. Over this entire range the calculated heating and cooling rates differed by 10% or less when the data quality was good.

Comparison of the measured and modeled electron densities and temperatures in the ionosphere and plasmasphere during 14–16 May 1991

“…The di erence between the revised and outdated cooling rates of thermal electrons leads to the maximum di erence of 230 K between the calculated electron temperatures at the F2-peak altitude and to the increase of the calculated F-region main peak electron density by up to a factor of 1.13. Contrary to previous studies given by Richards (1986), Khazanov (1997), andAponte et al (1999), we found that the resulting e ect of N( 2 D) electron quenching included in thermal electron heating on the electron temperature at the F2 peak altitude is the very weak increase of the calculated electron temperature up to about 35 K. It is found that the e ect of including the N( 2 D) di usion results in a decrease in the calculated daytime N( 2 D) number density above about 290 km and in a decrease of the daytime integral intensity at 520 nm up to a factor of 1.11.…”

“…We calculate the electron temperature and density using the revised and previous values of cooling rate and examine for the ÿrst time the e ect of the di erence between the revised and previous cooling rates on an agreement between the measured and modeled electron temperatures and densities during 14 -16 May 1991 to highlight the importance of using the revised cooling rates in theoretical models of the ionosphere and plasmasphere. Richards (1986), Richards and Khazanov (1997), and Aponte et al (1999) have demonstrated that thermal electrons gain an additional heating by quenching of N( 2 D). Using the updated chemistry of N( 2 D) and taking into account the N( 2 D) di usion, we examine the role of N( 2 D) quenching as a source of an additional thermal electron heat.…”

Topside measurements at Jicamarca during solar minimum

“…The electron-ion temperature ratio in the bottomside was underestimated. This may be a consequence of neglecting the heating of electrons through the quenching of an excited state of nitrogen (N( 2 D)) -see review by Aponte et al (1999). More significantly, the model failed to reproduce the large electron-ion temperature ratio enhancement in the topside that occurs at sunrise.…”

SAMI2‐PE: A model of the ionosphere including multistream interhemispheric photoelectron transport

“…The factor of 1/2 is for an isotropic pitch angle distribution, and the second factor corrects for the energy mismatch between and the average energy of the newly promoted electrons. We estimate the density of N( 2 D) by assuming it is in local equilibrium and using the reactions from Aponte et al [1999]. This density directly depends on the neutral O and O 2 densities as well as the electron, NO + , and N 2 + densities produced by the model.…”