scholarly journals The bottomside parameters <i>B0</i>, <i>B1</i> obtained from incoherent scatter measurements during a solar maximum and their comparisons with the IRI-2001 model

2002 ◽  
Vol 20 (6) ◽  
pp. 817-822 ◽  
Author(s):  
N. K. Sethi ◽  
K. K. Mahajan
Keyword(s):  
Solar Maximum ◽  
Local Times ◽  
Iri Model ◽  
Density Profiles ◽  
Incoherent Scatter ◽  
Ionosphere Modeling ◽  
Resolution Electron ◽  
Maximum Period ◽  
Modeling And Forecasting ◽  
Electron Density Profiles

Abstract. High resolution electron density profiles (Ne) measured with the Arecibo (18.4 N, 66.7 W), Incoherent Scatter radar (I. S.) are used to obtain the bottomside shape parameters B0, B1 for a solar maximum period (1989–90). Median values of these parameters are compared with those obtained from the IRI-2001 model. It is observed that during summer, the IRI values agree fairly well with the Arecibo values, though the numbers are somewhat larger during the daytime. Discrepancies occur during winter and equinox, when the IRI underestimates B0 for the local times from about 12:00 LT to about 20:00 LT. Furthermore, the IRI model tends to generally overestimate B1 at all local times. At Arecibo, B0 increases by about 50%, and B1 decreases by about 30% from solar minimum to solar maximum.Key words. Ionosphere (equational ionosphere; modeling and forecasting)

scholarly journals Comparative study of electron density from incoherent scatter measurements at Arecibo with the IRI-95 model during solar maximum

2000 ◽  
Vol 18 (12) ◽  
pp. 1630-1634 ◽  
Author(s):  
N. K. Sethi ◽  
V. K. Pandey
Keyword(s):  
Electron Density ◽  
Solar Maximum ◽  
Iri Model ◽  
Bottom Part ◽  
Density Profiles ◽  
Incoherent Scatter ◽  
F Region ◽  
Electron Density Profiles ◽  
Thickness Parameter ◽  
Modelling And Forecasting

Abstract. Arecibo (18.4 N, 66.7 W) incoherent scatter (IS) observations of electron density N(h) are compared with the International Reference Ionosphere (IRI-95) during midday (10–14 h), for summer, winter and equinox, at solar maximum (1981). The N(h) profiles below the F2 peak, are normalized to the peak density NmF2 of the F region and are then compared with the IRI-95 model using both the standard B0 (old option) and the Gulyaeva-B0 thickness (new option). The thickness parameter B0 is obtained from the observed electron density profiles and compared with those obtained from the IRI-95 using both the options. Our studies indicate that during summer and equinox, in general, the values of electron densities at all the heights given by the IRI model (new option), are generally larger than those obtained from IS measurements. However, during winter, the agreement between the IRI and the observed values is reasonably good in the bottom part of the F2 layer but IRI underestimates electron density at F1 layer heights. The IRI profiles obtained with the old option gives much better results than those generated with the new option. Compared to the observations, the IRI profiles are found to be much thicker using Gulyaeva-B0 option than using standard B0.Key words: Ionosphere (modelling and forecasting)

scholarly journals Variations of topside ionospheric scale heights over Millstone Hill during the 30-day incoherent scatter radar experiment

2007 ◽  
Vol 25 (9) ◽  
pp. 2019-2027 ◽  
Author(s):  
L. Liu ◽  
W. Wan ◽  
M.-L. Zhang ◽  
B. Ning ◽  
S.-R. Zhang ◽  
...  
Keyword(s):  
Electron Density ◽  
Thermal Structure ◽  
Plasma Temperature ◽  
Scale Height ◽  
Incoherent Scatter Radar ◽  
Density Profiles ◽  
Incoherent Scatter ◽  
Scatter Radar ◽  
Vertical Scale ◽  
Electron Density Profiles

Abstract. A 30-day incoherent scatter radar (ISR) experiment was conducted at Millstone Hill (288.5° E, 42.6° N) from 4 October to 4 November 2002. The altitude profiles of electron density Ne, ion and electron temperature (Ti and Te), and line-of-sight velocity during this experiment were processed to deduce the topside plasma scale height Hp, vertical scale height VSH, Chapman scale height Hm, ion velocity, and the relative altitude gradient of plasma temperature (dTp/dh)/Tp, as well as the F2 layer electron density (NmF2) and height (hmF2). These data are analyzed to explore the variations of the ionosphere over Millstone Hill under geomagnetically quiet and disturbed conditions. Results show that ionospheric parameters generally follow their median behavior under geomagnetically quiet conditions, while the main feature of the scale heights, as well as other parameters, deviated significantly from their median behaviors under disturbed conditions. The enhanced variability of ionospheric scale heights during the storm-times suggests that the geomagnetic activity has a major impact on the behavior of ionospheric scale heights, as well as the shape of the topside electron density profiles. Over Millstone Hill, the diurnal behaviors of the median VSH and Hm are very similar to each other and are not so tightly correlated with that of the plasma scale height Hp or the plasma temperature. The present study confirms the sensitivity of the ionospheric scale heights over Millstone Hill to thermal structure and dynamics. The values of VSH/Hp tend to decrease as (dTp/dh)/Tp becomes larger or the dynamic processes become enhanced.

scholarly journals A comparison of EISCAT and Dynasonde measurements of the auroral ionosphere

1996 ◽  
Vol 14 (12) ◽  
pp. 1403-1412 ◽  
Author(s):  
K. J. F. Sedgemore ◽  
P. J. S. Williams ◽  
G. O. L. Jones ◽  
J. W. Wright
Keyword(s):  
Auroral Ionosphere ◽  
Incoherent Scatter Radar ◽  
Density Profiles ◽  
Incoherent Scatter ◽  
Scatter Radar ◽  
Complementary Techniques ◽  
Electron Density Profiles ◽  
Ionospheric Sounding ◽  
Over Time ◽  
Good Agreement

Abstract. Incoherent-scatter radar and ionospheric sounding are powerful and complementary techniques in the study of the Earth's ionosphere. The work presented here involves the use of the Tromsø Dynasonde as a correlative diagnostic with the EISCAT incoherent-scatter radar. A comparison of electron-density profiles shows how a Dynasonde can be used to calibrate an incoherent-scatter radar and to monitor changes in the system. Skymaps of the direction of Dynasonde echoes are compared with EISCAT-derived density profiles to illustrate how a Dynasonde can be used to measure the drift velocity of auroral features. Vector velocities fitted to Dynasonde echoes are compared with EISCAT-derived plasma velocities. The results show good agreement when the data are taken during quiet to moderately active conditions and averaged over time scales of 30 min or more.

Day-to-day changes in experimental electron density profiles and their implications to IRI model

2004 ◽  
Vol 34 (9) ◽  
pp. 1878-1886 ◽  
Author(s):  
G. Miró Amarante ◽  
M. Cueto Santamaría ◽  
M. Mosert de González ◽  
S.M. Radicella ◽  
R. Ezquer
Keyword(s):  
Electron Density ◽  
Iri Model ◽  
Density Profiles ◽  
Electron Density Profiles ◽  
Experimental Electron Density

scholarly journals Validation of COSMIC ionospheric peak parameters by the measurements of an ionosonde chain in China

2014 ◽  
Vol 32 (10) ◽  
pp. 1311-1319 ◽  
Author(s):  
L. Hu ◽  
B. Ning ◽  
L. Liu ◽  
B. Zhao ◽  
G. Li ◽  
...  
Keyword(s):  
Electron Density ◽  
Solar Maximum ◽  
Correlation Coefficients ◽  
Peak Height ◽  
Retrieval Algorithm ◽  
The North ◽  
F Region ◽  
Maximum Period ◽  
Electron Density Profiles ◽  
Mean Square Errors

Abstract. Although the electron density profiles (EDPs) from Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) measurement have been validated by ionosonde data at a number of locations during the solar minimum period, the performance of COSMIC measurements at different latitudes has not been well evaluated, particularly during the solar maximum period. In this paper the COSMIC ionospheric peak parameters (peak electron density of the F region – NmF2; peak height of the F region – hmF2) are validated by the ionosonde data from an observation chain in China during the solar maximum period of 2011–2013. The validations show that the COSMIC measurement generally agrees well with the ionosonde observation. The error in NmF2 from COSMIC and ionosonde measurements varies with latitude. At midlatitude stations, the differences between COSMIC NmF2s and those of ionosondes are very slight. However, COSMIC NmF2 overestimates (underestimates) that of the ionosonde at the north (south) of the equatorial ionization anomaly (EIA) crest. The relative errors of hmF2s are much lower than those of NmF2s at all stations, which indicates the EDP retrieval algorithm of the COSMIC measurement has a better performance in determining the ionospheric peak height. The root mean square errors (RMSEs) of NmF2s (hmF2s) are higher (lower) during the daytime than during the nighttime at all stations. Correlation analysis shows that the correlations for both NmF2s and hmF2s are comparably good (correlation coefficients > 0.9) at midlatitude stations, while correlations of NmF2 (correlation coefficients > 0.9) are higher than those of hmF2 (correlation coefficients > 0.8) at low-latitude stations.

scholarly journals Vertical electron density and topside effective scale height (<I>H</I><sub>T</sub>) variations over the Indian equatorial and low latitude stations

2011 ◽  
Vol 29 (10) ◽  
pp. 1861-1872 ◽  
Author(s):  
K. Venkatesh ◽  
P. V. S. Rama Rao ◽  
P. L. Saranya ◽  
D. S. V. V. D. Prasad ◽  
K. Niranjan
Keyword(s):  
Diurnal Variation ◽  
Electron Density ◽  
Scale Height ◽  
Electron Content ◽  
Iri Model ◽  
Night Time ◽  
Low Latitude ◽  
Density Profiles ◽  
Gps Tec ◽  
Electron Density Profiles

Abstract. Understanding the vertical electron density profile, which is the altitudinal variation of ionospheric electron density distribution is an important aspect for the ionospheric investigations. In this paper, the bottom-side electron density profiles derived from ground based ionosonde data and the ROCSAT-1 in-situ electron density data were used to determine the estimates of the topside electron density profiles using α-Chapman function over an equatorial station Trivandrum (8.47° N, 76.91° E) and a low latitude station Waltair (17.7° N, 83.3° E) in the Indian region. The reconstructed electron density profiles are compared with IRI (2007) model derived vertical electron density profiles which resulted in significant deviations between the two different profiles. Both the reconstructed electron density profiles and the IRI model derived profiles are integrated independently to derive the Total Electron Content (TEC) values which are compared with GPS derived TEC values. TEC values derived from the reconstructed electron density profiles give better estimates with the GPS-TEC compared to those of IRI model derived TEC values. Compared to the GPS-TEC, the IRI model is underestimating the TEC values during day-time and is overestimating during night-time at both the stations. The percentage deviations of IRI derived TEC from GPS-TEC are larger compared to those between reconstructed profile derived TEC and GPS-TEC. F2-layer peak electron density, peak height and electron density at ROCSAT altitudes (≈600 km) are used to derive the effective scale heights (HT) of the topside ionosphere during the period from July 2003 to June 2004. The diurnal and seasonal variations of HT and E×B drift velocities are presented in this paper. The diurnal variation of the effective scale height (HT) shows peak values around noon hours with higher values during day-time and lower values during night-time both at Trivandrum and Waltair. The E×B drift velocities at both the places also have shown a clear diurnal variation with a negative peak around 04:00 LT and maximum during day-time hours. The higher and lower values of HT seem to be associated with positive and negative phases of the E×B drift velocities, respectively.

scholarly journals The IRI topside parameters

2005 ◽  
Vol 2 ◽  
pp. 249-251 ◽  
Author(s):  
P. Coïsson ◽  
S. M. Radicella
Keyword(s):  
Electron Density ◽  
Wide Spectrum ◽  
Critical Conditions ◽  
High Solar Activity ◽  
Constitutive Parameter ◽  
Iri Model ◽  
Density Profiles ◽  
Electron Density Profiles ◽  
Very High

Abstract. The IRI electron density topside has been constructed on the basis of the data available about thirty years ago. Recently a large amount of data from old topside sounders have been processed to get electron density profiles. These profiles allow to test IRI model under a wide spectrum of different conditions and to understand the behavior of the modeled topside. A set of 12 000 topside profiles have been chosen from the ISIS2 database, selecting those with the better quality of the inverted profile. An analysis of each IRI topside constitutive parameter has been done for all the experimental cases allowing to find some critical conditions under which the IRI topside could become completely unrealistic. In particular for very high solar activity at high latitudes it has been found that some IRI parameters could reach values that change drastically the shape of IRI topside. A proposal to control their range of variability is formulated in order to avoid the occurrence of such cases.

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