Journal of Astronomy and Space Sciences

The Korean Space Science Society (한국우주과학회)
권호 표지
DOI QR코드

DOI QR Code

The First Report on the Afternoon E-Region Plasma Density Irregularities in Middle Latitude

  • Yang, Tae-Yong (Korea Astronomy and Space Science Institute) ;
  • Kwak, Young-Sil (Korea Astronomy and Space Science Institute) ;
  • Lee, Jaewook (Korea Astronomy and Space Science Institute) ;
  • Park, Jaeheung (Korea Astronomy and Space Science Institute) ;
  • Choi, Seonghwan (Korea Astronomy and Space Science Institute)
  • Received : 2021.05.19
  • Accepted : 2021.06.04
  • Published : 2021.06.15
Download PDF
⟨ Previous Next ⟩

Abstract

We report, for the first time, the afternoon (i.e., from noon to sunset time) observations of the northern mid-latitude E-region field-aligned irregularities (FAIs) made by the very high frequency (VHF) coherent backscatter radar operated continuously since 29 December 2009 at Daejeon (36.18°N, 127.14°E, 26.7°N dip latitude) in South Korea. We present the statistical characteristics of the mid-latitude afternoon E-region FAIs based on the continuous radar observations. Echo signal-to-noise ratio (SNR) of the afternoon E-region FAIs is found to be as high as 35 dB, mostly occurring around 100-135 km altitudes. Most spectral widths of the afternoon echoes are close to zero, indicating that the irregularities during the afternoon time are not related to turbulent plasma motions. The occurrence of afternoon E-regional FAI is observed with significant seasonal variation, with a maximum in summer and a minimum in winter. Furthermore, to investigate the afternoon E-region FAIs-Sporadic E (Es) relationship, the FAIs have also been compared with Es parameters based on observations made from an ionosonde located at Icheon (37.14°N, 127.54°E, 27.7°N dip latitude), which is 100 km north of Daejeon. The virtual height of Es (h'Es) is mainly in the height range of 105 km to 110 km, which is 5 km to 10 km greater than the bottom of the FAI. There is no relationship between the FAI SNR and the highest frequencies (ftEs) (or blanket frequencies (fbEs)). SNR of FAIs, however, is found to be related well with (ftEs-fbEs).

Keywords

References

  1. Ecklund WL, Carter DA, Balsley BB, Gradient drift irregularities in mid-latitude sporadic E, J. Geophys. Res. 86, 858-862 (1981). https://doi.org/10.1029/JA086iA02p00858
  2. Fejer BG, Kelley MC, Ionospheric irregularities, Rev. Geophys. 18, 401-454, (1980). http://doi.org/10.1029/RG018i002p00401
  3. Fukao S, Oliver WL, Onishi Y, Takami T, Sato T, et al., F-region seasonal behavior as measured by the MU radar, J. Atmos. Terr. Phys. 53, 599-618, (1991). http://doi.org/10.1016/0021-9169(91)90088-O
  4. Fukao S, Sato T, Tsuda T, Kato S, Wakasugi K, et al., The MU radar with an active phased array system: 1. antenna and power amplifiers, Radio Sci. 20, 1155-1168 (1985a). https://doi.org/10.1029/RS020i006p01155
  5. Fukao S, Tsuda T, Sato T, Kato S, Wakasugi K, et al., The MU radar with an active phased array system: 2. in-house equipment, Radio Sci. 20, 1169-1176 (1985b). https://doi.org/10.1029/RS020i006p01169
  6. Fukao S, Yamamoto M, Tsunoda, RT, Hayakawa H, The SEEK (Sporadic-E Experiment over Kyushu) campaign, Geophys. Res. Lett. 25, 1761-1764 (1998). https://doi.org/10.1029/98GL00932
  7. Haldoupis C, A review of radio studies of auroral E region ionospheric irregularities, Ann. Geophys. 7, 239-258, (1989).
  8. Hussey GC, Schlegel K, Haldoupis C, Simultaneous 50-MHz coherent backscatter and digital ionosonde observations in the midlatitude E region, J. Geophys. Res. 103, 6991-7001 (1998). https://doi.org/10.1029/97JA03089
  9. Kwak YS, Yang TY, Kil H, Phanikumar DV, Heo BH, et al., Characteristics of the E- and F-region field-aligned irregularities in middle latitudes: initial results obtained from the Daejeon 40.8 MHz VHF radar in South Korea, J. Astron. Space Sci. 31, 15-23 (2014). https://doi.org/10.5140/JASS.2014.31.1.15
  10. Lee CC, Liu JY, Pan CJ, Igarashi K, The heights of sporadic-E layer simultaneously observed by the VHF radar and ionosondes in Chung-Li, Geophys. Res. Lett. 27, 641-644 (2000). https://doi.org/10.1029/1999GL003713
  11. Maruyama T, Saito S, Yamamoto M, Fukao S, Simultaneous observation of sporadic E with a rapid-run ionosonde and VHF coherent backscatter radar, Ann. Geophys. 24, 153-162 (2006). https://doi.org/10.5194/angeo-24-153-2006
  12. Ogawa T, Takahashi O, Otsuka Y, Nozaki K, Yamamoto M, et al., Simultaneous middle and upper atmosphere radar and ionospheric sounder observations of midlatitude E region irregularities and sporadic E layer, J. Geophys. Res. 107, SIA 3-1-SIA 3-13 (2002). https://doi.org/10.1029/2001JA900176
  13. Ogawa T, Yamamoto M, Fukao S, Middle and upper atmosphere radar observations of turbulence and movement of midlatitude sporadic E irregularities, J. Geophys. Res. 100, 12173-12188 (1995). https://doi.org/10.1029/95JA00261
  14. Otsuka Y, Onoma F, Shiokawa K, Ogawa T, Yamamoto M, et al., Simultaneous observations of nighttime medium-scale traveling ionospheric disturbances and E region field-aligned irregularities at midlatitude, J. Geophys. Res. 112, A06317 (2007). https://doi.org/10.1029/2005JA011548
  15. Patra AK, Rao PB, High-resolution radar measurements of turbulent structure in the low-latitude E region, J. Geophys. Res. 104, 24667-24673, (1999). http://doi.org/10.1029/1999JA900303
  16. Patra AK, Venkateswara Rao N, Phanikumar DV, Chandra H, Das U, et al., A study on the low-latitude daytime E region plasma irregularities using coordinated VHF radar, rocket-borne, and ionosonde observations, J. Geophys. Res. 114, A11301 (2009). https://doi.org/10.1029/2009JA014501
  17. Phanikumar DV, Patra AK, Devasia CV, Yellaiah G, Seasonal variation of low-latitude E-region plasma irregularities studied using Gadanki radar and ionosonde, Ann. Geophys. 26, 1865-1876 (2008). https://doi.org/10.5194/angeo-26-1865-2008
  18. Phanikumar DV, Patra AK, Kwak YS, Kim KH, Yellaiah G, Low latitude E-region irregularities studied using Gadanki radar, ionosonde and in situ measured electron density, Astrophys. Space Sci. 323, 225-233 (2009). https://doi.org/10.1007/s10509-009-0066-y
  19. Saito S, Yamamoto M, Fukao S, Marumoto M, Tsunoda RT, Radar observations of field-aligned plasma irregularities in the SEEK-2 campaign, Ann. Geophys. 23, 2307-2318 (2005). https://doi.org/10.5194/angeo-23-2307-2005
  20. Tsunoda RT, Fukao S, Yamamoto M, On the origin of quasiperiodic radar backscatter from midlatitude sporadic E, Radio Sci. 29, 349-365 (1994). https://doi.org/10.1029/93RS01511
  21. Tsunoda RT, Fukao S, Yamamoto M, Hamasaki T, First 24.5-MHz radar measurements of quasi-periodic backscatter from field-aligned irregularities in midlatitude sporadic E, Geophys. Res. Lett. 25, 1765-1768 (1998). https://doi.org/10.1029/98GL01086
  22. Whitehead JD, Recent work on mid-latitude and equatorial sporadic-E, J. Atmos. Terr. Phys. 51, 401-424 (1989). https://doi.org/10.1016/0021-9169(89)90122-0
  23. Woodman RF, Yamamoto M, Fukao S, Gravity wave modulation of gradient drift instabilities in mid-latitude sporadic E irregularities, Geophys. Res. Lett. 18, 1197-1200 (1991). https://doi.org/10.1029/91GL01159
  24. Yamamoto M, Fukao S, Ogawa T, Tsuda T, Kato S, A morphological study on mid-latitude E-region field-aligned irregularities observed with the MU radar, J. Atmos. Terr. Phys. 54, 769-777 (1992). https://doi.org/10.1016/0021-9169(92)90115-2
  25. Yamamoto M, Fukao S, Tsunoda RT, Pfaff RF, Hayakawa H, SEEK-2 (Sporadic-E Experiment over Kyushu 2)-project outline, and significance, Ann. Geophys. 23, 2295-2305 (2005). https://doi.org/10.5194/angeo-23-2295-2005
  26. Yamamoto M, Fukao S, Woodman RF, Ogawa T, Tsuda T, et al., Mid-latitude E region field-aligned irregularities observed with the MU radar, J. Geophys. Res. 96, 15943-15949 (1991). https://doi.org/10.1029/91JA01321
  27. Yamamoto M, Itsuki T, Kishimoto T, Tsunoda RT, Pfaff RF, et al., Comparison of E-region electric fields observed with a sounding rocket and a Doppler radar in the SEEK campaign, Geophys. Res. Lett. 25, 1773-1776 (1998). https://doi.org/10.1029/98GL01055
  28. Yamamoto M, Komoda N, Fukao S, Tsunoda RT, Ogawa T, et al., Spatial structure of the E region field-aligned irregularities revealed by the MU radar, Radio Sci. 29, 337-347 (1994). https://doi.org/10.1029/93RS01846
  29. Yang TY, Kwak YS, Kil H, Lee YS, Lee WK, et al., Occurrence climatology of F region field-aligned irregularities in middle latitudes as observed by a 40.8 MHz coherent scatter radar in Daejeon, South Korea, J. Geophys. Res. 120, 10107-10115 (2015). https://doi.org/10.1002/2015JA021885