The explosive eruption of the Hunga‐Tonga volcano in the southwest Pacific at 0415UT on 15 January 2022 triggered gigantic atmospheric disturbances with surface air pressure waves propagating around the globe in Lamb mode. In space, concentric traveling ionosphere disturbances (CTIDs) are also observed as a manifestation of air pressure waves in New Zealand ∼0500UT and Australia ∼0630UT. As soon as the air pressure waves reached central Australia ∼0800UT, conjugate CTIDs appeared almost simultaneously in the northern hemispheres through interhemispheric coupling, much earlier than the arrival of the surface air pressure waves to Japan after 1100UT. Combining observations over Australia and Japan between 0800 and 1000UT, both direct and conjugate CTIDs show similar horizontal phase velocities of 320–390 m/s, matching with the dispersion relation of Lamb mode. The arrival of atmospheric Lamb wave to Japan later created in situ CTIDs showing the same Lamb mode characteristics as the earlier conjugate CTIDs.

[1] Using the Global Positioning System radio occultation (GPSRO) technique, the observation of the global ionosphere becomes possible. The irregularity in the ionospheric sporadic-E (Es) layer, which is probably caused by wind shear, can be investigated by analyzing the signal-to-noise ratio (SNR) of RO signal. In this study, the relation between the amplitude of RO signals and the electron density profiles of the ionosphere is simulated, and RO data recorded in the time period from mid-2008 to mid-2011 are used for the analysis. Based on the simulation results, the multiple-layer-type (MLT) and the single-layer-type (SLT) Es layers which are defined by the shape of SNR, are used to analyze the global distribution of Es layer. The seasonal MLT Es layer is compared with the seasonal wind shear, which is obtained from the Horizontal Wind Model (HWM07). Furthermore, the seasonal MLT Es layer is compared with the SLT Es layer, and the global altitude distributions of MLT and SLT Es layers are similar while the magnitude distributions are different. Unlike the MLT Es layer, the global distribution of the SLT Es layer is similar to the distribution of E region peak electron density (N m E), which is related to the solar zenith angle.

AB STRACTMulti-chan nel Global Po si tion Sys tem (GPS) car rier phase sig nals re ceived by the FormoSat-3 (FS3)/COS MIC pro gram's six low Earth or bit ing (LEO) sat el lites were used to un der take ac tive limb sound ing of the Earth's at mo sphere and ion o sphere via ra dio occultation (RO). In this study, the ef fects of large-scale hor i zon tal gra di ents and/or inhomogeneous ion o spheric elec tron densities (n e ) were con sid ered by de vel op ing an it er a tive scheme to de ter mine "com pen sated" to tal elec tron con tent (TEC) val ues through nearby occultation ob ser va tions. Us ing an it er a tive Abel in ver sion through "com pen sated" TEC val ues, more than one-hun dred and eighty thou sand ver ti cal ion o spheric n e pro files were col lected dur ing the in tense ob ser va tion pe riod (IOP) of 20 June -27 Sep tem ber (day num ber 171 to 270) 2006. Coincidences of GPS RO ob ser va tions to ion o spheric n e ionosonde data from forty-nine world wide sta tions have been ex am ined. It is found that the it er a tive scheme gives im proved re triev als over the stan dard Abel in ver sion. From sev eral thou sand matches within the IOP ex per i ment, the root mean square (rms) foF2 dif fer ences be tween the ionosonde mea sure ments and the FS3/COS MIC re triev als are im proved from 1.67 to 1.07 MHz. The re sults also show im prove ment in the over es ti mates (un der es ti mates) on low (high) re trieved foF2s, while the ob tained hmF2s give better agreement with ionosonde observations. Ocean. Sci., 20, 181-191, doi: 10.3319/TAO.2007.12.19.01(F3C) IN TRO DUC TIONRa dio occultations (RO) have long been used in the remote sens ing of plan e tary at mo spheres (Fjeldbo et al. 1969). Re ceiv ing multi-chan nel Global Po si tion ing Sys tem (GPS) car rier phase sig nals from a low Earth or bit ing (LEO) sat ellite and prob ing Earth's at mo sphere and ion o sphere via occultation was pro posed by the Jet Pro pul sion Lab o ra tory in 1988. How ever, it was first im ple mented by the Uni ver sity Cor po ra tion for At mo spheric Re search (UCAR) (Zou et al. 1995;Ware et al. 1996;Kursinski et al. 1997;Rocken et al. 1997) as the GPS/Me te o rol ogy (GPS/MET) pro gram. The main ob jec tives of this GPS-LEO occultation mis sion were nu mer i cal weather pre dic tion and long-term mon i tor ing of Earth's cli mate. Af ter the GPS/MET mis sion, fur ther missions flown with GPS occultation re ceiv ers onboard include the Dan ish Ørsted, the Ger man CHAMP, the Ar gentin ean SAC-C, the Amer i can-Ger man GRACE, the South Af ri can SUNSAT, and the Ion o sphere Occultation Ex per iment (IOX) onboard the PICOSAT sat el lite.The Tai wan FS3/Con stel la tion Ob serv ing Sys tem for Me te o rol ogy, Ion o sphere, and Cli mate (COS MIC) sat el lites were suc cess fully launched on 15 April 2006. In re la tion to the GPS/MET, CHAMP, and SAC-C mis sions, the FS3/ COS MIC pro ject's goal was to place six mi cro-sat el lites into six dif fer ent or bits at ~700 -800 km al ti tudes. Each mi crosat el lite is eq...

We report in this paper a new MRI contrast agent based on magnetic nanodiamonds fabricated by Fe ion implantation. The Fe atoms that are implanted into the nanodiamonds are not in direct contact with the outside world, enabling this new contrast agent to be free from cell toxicity. The image enhancement was shown clearly through T2 weighted images. The concentration dependence of the T2 relaxation time gives a relaxivity value that is about seven times that of the regular non-magnetic nanodiamonds. Cell viability study has also been performed. It was shown that they were nearly free from cytotoxicity independent of the particle concentration used. The imaging capability demonstrated here adds a new dimension to the medical application of nanodiamonds. In the future one will be able to combine this capability of magnetic nanodiamonds with other functions through surface modifications to perform drug delivery, targeted therapy, localized thermal treatment and diagnostic imaging at the same time.

[1] A numerical and phenomenological model of global ionospheric electron density (N e ) is investigated. The three-dimensional N e model has been named the Taiwan Ionospheric Model (TWIM) and constructed from monthly weighted and hourly vertical N e profiles retrieved from FormoSat3/COSMIC GPS radio occultation measurements. The TWIM exhibits vertically fitted Chapman layers, with distinct F2, F1, E, and D layers, and surface spherical harmonics approaches for the fitted Chapman layer parameters including peak density, peak density height, and scale height. These results are useful in investigation of near-Earth space and large-scale N e distribution with diurnal and seasonal variations, along with geographic features such as the equatorial anomaly (EA). This paper also investigates the diurnal and seasonal variations of EAwithin different ionospheric layers and specifically attempts to account for the latitudinal and longitudinal structures caused by atmospheric tides.