DOI QR코드

DOI QR Code

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

  • Kwak, Young-Sil ;
  • Yang, Tae-Yong ;
  • Kil, Hoysub ;
  • Phanikumar, Devulapalli Venkata ;
  • Heo, Bok-Haeng ;
  • Lee, Jae-Jin ;
  • Hwang, Junga ;
  • Choi, Seong-Hwan ;
  • Park, Young-Deuk ;
  • Choi, Ho-Seong
  • Received : 2014.01.27
  • Accepted : 2014.02.19
  • Published : 2014.03.15

Abstract

We present preliminary observations of the field-aligned-irregularities (FAIs) in the E and F regions during the solar minimum (2009 - 2010) using the 40.8 MHz coherent backscatter radar at Daejeon ($36.18^{\circ}N$, $127.14^{\circ}E$, $26.7^{\circ}N$ dip latitude) in South Korea. The radar, which consists of 24 Yagi antennas, observes the FAIs using a single beam with a peak power of 24 kW. The radar has been continuously operated since December 2009. Depending on the manner of occurrence of the backscatter echoes, the E-region echoes are largely divided into two types: quasi-periodic (QP) and continuous echoes. Our observations show that the QP echoes occur frequently above an altitude of 105 km in the post-sunset period and continuous echoes occur preferentially around an altitude of 105 km in the post-sunrise period. QP echoes appear as striated discrete echoes for a period of about 10 - 20 min. The QP-type echoes occur more frequently than the continuous-type echoes do and the echo intensity of the QP type is stronger than that of the continuous type. In the F region, the FAIs occur at night at an altitude interval of 250 - 450 km. As time proceeds, the occurrence height of the FAIs gradually increases until early in the morning and then decreases. The duration of the F-region FAIs is typically a few hours at night, although, in rare cases, FAIs persist throughout the night or appear even after sunrise. We discuss the similarities and differences of the FAIs observed by the Daejeon radar in comparison with other radar observations.

Keywords

VHF coherent backscatter radar;ionospheric irregularities;mid-latitude

References

  1. Behnke RA, F-layer height bands in the nocturnal ionosphere over Arecibo, JGR, 84, 974-978 (1979). http://dx.doi.org/10.1029/JA084iA03p00974 https://doi.org/10.1029/JA084iA03p00974
  2. Fukao S, McClure JP, Ito A, Sato T, Kimura I, et al., First VHF radar observation of mid-latitude F-region field-aligned irregularities, GRL, 15, 768-771 (1988). http://dx.doi.org/10.1029/GL015i008p00768 https://doi.org/10.1029/GL015i008p00768
  3. Choudary RK, Mahajan KK, Singh S, Kumar K, Anandan VK, First VHF radar observations of tropical latitude E-region field-aligned irregularities, GRL, 23, 3683-3686 (1996). http://dx.doi.org/10.1029/96GL02625 https://doi.org/10.1029/96GL02625
  4. Ecklund WL, Carter DA, Balsley BB, Gradient drift irregularities in mid-latitude sporadic E, JGR, 86, 858-862 (1981). http://dx.doi.org/10.1029/JA086iA02p00858 https://doi.org/10.1029/JA086iA02p00858
  5. Fukao S, Kelley MC, Shirakawa T, Takami T, Yamamoto M, et al., Turbulent upwelling of the mid-latitude ionosphere: 1. Observational results by the MU radar, JGR, 96, 3725-3746 (1991). http://dx.doi.org/10.1029/90JA02253 https://doi.org/10.1029/90JA02253
  6. 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, 1158-1168 (1985a). http://dx.doi.org/10.1029/RS020i006p01155 https://doi.org/10.1029/RS020i006p01155
  7. 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). http://dx.doi.org/10.1029/RS020i006p01169 https://doi.org/10.1029/RS020i006p01169
  8. Fukao S, Yamamoto, M, Tsunoda, RT, Hayakawa, H, The SEEK (Sporadic E Experiment over Kyushu) Campaign, GRL, 25, 1761-1764 (1998). http://dx.doi.org/10.1029/98GL00932 https://doi.org/10.1029/98GL00932
  9. Haldoupis C, Koehler J, Sofko G, Danskin D, McKibben M, Andre D, Preferential phase velocities for type 4 Irregularities in the auroral E-region plasma, JGR, 98, 6173-6179 (1993). http://dx.doi.org/10.1029/92JA02652 https://doi.org/10.1029/92JA02652
  10. Ogawa T, Yamamoto M, Fukao S, Middle and upper atmosphere radar observations of turbulence and movement of mid-latitude sporadic E irregularities, JGR, 100, 12173-12188 (1995). http://dx.doi.org/10.1029/95JA00261 https://doi.org/10.1029/95JA00261
  11. Kelley MC, Fukao S, Turbulent upwelling of the mid-latitude ionosphere: 2. Theoretical framework, JGR, 96, 3725-3746 (1991). http://dx.doi.org/10.1029/90JA02252 https://doi.org/10.1029/90JA02252
  12. Miller CA, Swartz WE, Kelley MC, Mendillo M, Nottingham D, Scali J, Reinisch B, Electrodynamics of midlatitude spread F: 1. Observations of unstable, gravity wave-induced ionospheric electric fields at tropical latitudes, JGR, 102, 11521-11532 (1997). http://dx.doi.org/10.1029/96JA03839 https://doi.org/10.1029/96JA03839
  13. 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, JGR, 107, SIA 3-1-SIA3-13 (2002). http://dx.doi.org/10.1029/2001JA900176 https://doi.org/10.1029/2001JA900176
  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 mid latitude, JGR, 112, A06317 (2007). http://dx.doi.org/10.1029/2005JA011548 https://doi.org/10.1029/2005JA011548
  15. Otsuka Y, Shiokawa K, Ogawa T, Yokoyama T, Yamamoto M, Spatial relationship of nighttime medium-scale traveling ionospheric disturbances and F-region field-aligned irregularities observed with two spaced all-sky airglow imagers and the middle and upper atmosphere radar, JGR, 114, A05302 (2009). http://dx.doi.org/10.1029/2008JA013902 https://doi.org/10.1029/2008JA013902
  16. Pan CJ, Liu CH, Rottger J, Su SY, A three dimensional study of E-region irregularity patches in the equatorial anomaly region using the Chung-Li VHF radar, GRL, 21, 1763-1766 (1994). http://dx.doi.org/10.1029/94GL01195 https://doi.org/10.1029/94GL01195
  17. Ragharavao R, Patra AK, Sripathi S, Equatorial E-region irregularities: A review of recent observations, JASTP, 64, 1435-1443 (2002). http://dx.doi.org/10.1016/S1364-6826(02)00107-4 https://doi.org/10.1016/S1364-6826(02)00107-4
  18. Pan CJ, Tsunoda RT, Quasi-periodic echoes observed with the Chung-Li VHF radar during the SEEK campaign, GRL, 25, 1809-1812 (1998). http://dx.doi.org/10.1029/98GL00302 https://doi.org/10.1029/98GL00302
  19. Patra AK, Sripathi S, Kumar VS, Rao PB, Evidence of kilometer-scale waves in the lower E region from high resolution VHF radar observations over Gadanki, GRL, 29, 137-1-137-4 (2002). http://dx.doi.org/10.1029/2001GL013340 https://doi.org/10.1029/2001GL013340
  20. Perkins FW, Spread F and ionospheric currents, JGR, 78, 218-226 (1973). http://dx.doi.org/10.1029/JA078i001p00218 https://doi.org/10.1029/JA078i001p00218
  21. Saito A, Iyemori T, Blomberg LG, Yamamoto M, Takeda M, Conjugate observations of the mid-latitude electric field fluctuations with the MU radar and the Freja satellite, JASTP, 60, 129-140 (1998). http://dx.doi.org/10.1016/S1364-6826(97)00094-1 https://doi.org/10.1016/S1364-6826(97)00094-1
  22. Saito A, Nishimura M, Yamamoto M, Fukao S, Tsugawa T, et al., Observations of traveling ionospheric disturbances and 3-m scale irregularities in the nighttime F-region ionosphere with the MU radar and a GPS network, EPS, 54, 31-44 (2002).
  23. 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). http://dx.doi.org/10.5194/angeo-23-2307-2005 https://doi.org/10.5194/angeo-23-2307-2005
  24. Saito S, Yamamoto M, Hashiguchi H, Imaging observations of nighttime mid-latitude F-region field-aligned irregularities by an MU radar ultra-multi-channel system, Ann. Geophys., 26, 2345-2352 (2008). http://dx.doi.org/10.5194/angeo-26-2345-2008 https://doi.org/10.5194/angeo-26-2345-2008
  25. Tsunoda RT, Fukao S, Yamamoto M, On the origin of quasi-periodic radar backscatter from mid-latitude sporadic E, Radio Sci., 29, 349-365 (1994). http://dx.doi.org/10.1029/93RS01511 https://doi.org/10.1029/93RS01511
  26. Schlegel K, Coherent backscatter from ionospheric E-region plasma irregularities, JATP, 58, 933-941 (1996). http://dx.doi.org/10.1016/0021-9169(95)00124-7 https://doi.org/10.1016/0021-9169(95)00124-7
  27. Swartz WE, Kelley MC, Makela JJ, Collins SC, Kudeki E, et al., Coherent and incoherent scatter radar observations during intense mid-latitude spread F, GRL, 27, 2829-2832 (2000). http://dx.doi.org/10.1029/2000GL000021 https://doi.org/10.1029/2000GL000021
  28. Tanaka T, Venkateswaran SV, Characteristics of field-aligned E-region irregularities over Iioka ($36^{\circ}N$), Japan, I, JATP, 44, 381-393 (1982). http://dx.doi.org/10.1016/0021-9169(82)90045-9 https://doi.org/10.1016/0021-9169(82)90045-9
  29. Tsunoda RT, Fukao S, Yamamoto M, Hamasaki T, First 24.5-MHz radar measurements of quasi-periodic backscatter from field-aligned irregularities in mid-latitude sporadic E, GRL, 25, 1765-1768 (1998). http://dx.doi.org/10.1029/98GL01086 https://doi.org/10.1029/98GL01086
  30. Woodman RF, Yamamoto M, Fukao S, Gravity wave modulation of gradient drift instabilities in mid-latitude sporadic E irregularities, GRL, 18, 1197-1200 (1991). http://dx.doi.org/10.1029/91GL01159 https://doi.org/10.1029/91GL01159
  31. Yamamoto M, Fukao S, Ogawa T, Tsuda T, Kato S, A morphological study on mid-latitude E-region fieldaligned irregularities observed with the MU radar, JATP, 54, 769-777 (1992). http://dx.doi.org/10.1016/0021-9169(92)90115-2 https://doi.org/10.1016/0021-9169(92)90115-2
  32. Yamamoto M, Fukao S, Tsunoda RT, Pfaff RF, Hayakawa H, SEEK-2 (Sporadic-E Experiment over Kyushu 2)-Project Outline, and Signature, Ann. Geophys., 23, 2295-2305 (2005). http://dx.doi.org/10.5194/angeo-23-2295-2005 https://doi.org/10.5194/angeo-23-2295-2005
  33. Yamamoto M, Fukao S, Woodman RF, Ogawa T, Tsuda T, et al., Mid-latitude E-region field-aligned irregularities observed with the MU radar, JGR, 96, 15943-15949 (1991). http://dx.doi.org/10.1029/91JA01321 https://doi.org/10.1029/91JA01321
  34. Yamamoto M, Itsuya 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, GRL, 25, 1773-1776 (1998). http://dx.doi.org/10.1029/98GL01055 https://doi.org/10.1029/98GL01055
  35. 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). http://dx.doi.org/10.1029/93RS01846 https://doi.org/10.1029/93RS01846

Cited by

  1. Occurrence climatology ofFregion field-aligned irregularities in middle latitudes as observed by a 40.8 MHz coherent scatter radar in Daejeon, South Korea vol.120, pp.11, 2015, https://doi.org/10.1002/2015JA021885
  2. Effectiveness Criteria for Methods of Identifying Ionospheric Earthquake Precursors by Parameters of a Sporadic E Layer and Regular F2 Layer vol.32, pp.2, 2015, https://doi.org/10.5140/JASS.2015.32.2.137