Subject: Re: March 30, 2002 Modulated Noise on WBD From: "Nicole Cornilleau-Wehrlin" Date: Wed, 2 Oct 2002 17:42:22 +0200 To: "Jolene Pickett" Dear Jolene, Sorry for the demlay to answer to your mail. First in what concerns the March 30, 2002 eveent. We made some analysis/plot that I enclose bspectro is an enlarge view of the dynamic spectra for the entire event for SC 4 in the Magnetic field aligned reference frame (MFA). Do you see a modulation for the same whole time interval or for a differet one? It shows that the polarisation is perpendicular to B field. Bpolar gives the waves polarisation, in the same MFA reference frame. It shows that the waves are linear, giving a mixture of right and left anded waves bspectra is an amplitude versus frewquency which clearly show a peak atround 1.5 Hz, consiotant with the modulatin you observe. The ULF waves are clearly a kind of Pc1-pearl event. The event you show rather fals in the cathegory of the so-called periodic emissions (2 -4s), thought to be linked to back and forth movement of elctrons along the field line or to two-hop whistlers I don't know if there has been successfull studies on the linkk with Pc1. The quasi period emission I was thinking about, are modulated by PC3 - field line resonances, by a compressional wave in the equatorial region. I give you the reference you ask: TIXIER M., CORNILLEAU-WEHRLIN N. How are the VLF quasi-periodic emissions controlled by harmonics of field line oscillations ? The results of a comparison between ground and GEOS satellites measurements J. Geophys. Res., 91 (A6), 6899-6919, 1986 Kind regards Nicole Nicole Cornilleau-Wehrlin tel: 33 (0)1 39 25 48 98 CETP/CNRS/UVSQ fax: 33 (0)1 39 25 48 72 10-12 Av. de l'Europe nicole.cornilleau at cetp.ipsl.fr 78140 Vélizy France ----- Message d'origine ----- De : "Jolene Pickett" À : ; "Jolene Pickett" Envoyé : lundi 23 septembre 2002 19:28 Objet : March 30, 2002 Modulated Noise on WBD > > Dear Nicole, > > > > I have looked at your STAFF-SC spectrogram on your web site, as > > you suggested, for March 30, 2002. This spectrogram appears to > > show a wave at around 1.8 Hz, which is the frequency with which > > we are seeing the noise bursts on WBD when the spacecraft are > > within 2 degrees of the magnetic equator. The bursts continue > > for 10 minutes or more, although it seems at these later times > > we are not seeing all of the modulated bursts. I have attached > > a spectrogram from WBD showing the noise bursts around 0800 UT. > > Could you give me your opinion as to whether or not this is the > > same phenomenon of which you spoke to me about at the Workshop. > > I think you said the results were from GEOS? Also, could you > > give me the citation of that work. > > > > I have the IMAGE data from this pass, and it appears as if > > the Cluster spacecraft are in a plamaspheric notch or trough > > at this magnetic local time of around 22.3. > > > > I trust you had a safe journey home. > > > > Best regards, > > > > Jolene bspectro_300301.ps Content-Type: application/postscript Content-Encoding: quoted-printable bspectra_300301.ps Content-Type: application/postscript Content-Encoding: quoted-printable bpolar_300301.ps Content-Type: application/postscript Content-Encoding: quoted-printable