Hole-doping into K–TCNQ (TCNQ = 7,7,8,8-tetracyanoquinodimethane) crystals with segregated TCNQ anion radical columns with dimeric deformation (Peierls state) has been performed by a contact doping method using F4TCNQ (F4TCNQ = 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) crystals or powder. The sheet resistance of the K–TCNQ surface has been found to decrease by the F4TCNQ contact. Formation of K–F4TCNQ nanocrystals at the contact interface has been observed, but conductive AFM images indicate that current paths form along the hole-doped K–TCNQ surface. Interestingly, hole-doping into K–TCNQ suppresses the phase transition to the high-temperature phase (Mott insulator). This is considered to result from the energy gain by the delocalization of the doped carriers.
Abstract Typhoons cause significant damage and casualties worldwide, making accurate intensity estimation essential for risk mitigation. However, analyzing typhoons—particularly their size, cloud formations, and development rate—is challenging due to their unpredictable nature and various environmental influences. Cloud morphology, particularly the cloud-top altitude difference between the eyewall and the eye, is a key indicator of typhoon intensity, as suggested by the Dvorak technique. Traditionally, this data is derived from thermal infrared (TIR) measurements, but these are often unreliable due to atmospheric temperature inconsistencies. In this research, we developed a method using stereo-photogrammetry to analyze typhoons through aircraftcaptured images of the typhoon eye. We reconstructed a 3D model of 2018 Typhoon Trami’s eye, achieving a high resolution of 6.08 meters per pixel with a minimal projection error of 2.37 pixels. This model surpasses the resolution of satellite and radar sensors traditionally used for typhoon analysis. The model revealed a stair-step cloud structure likely associated with an eyewall replacement cycle occurring at that time. This technique allows for precise cloud-top height measurement, crucial for estimating typhoon intensity. Our findings were validated by comparing three cross-sections of the 3D model with TIR data from the Himawari-8 satellite and dropsonde measurements.
<p>Typhoon is a tropical cyclone in the western North Pacific and the South China Sea. It is the most devastating weather system in East Asia. Strong winds and heavy rainfalls associated with a typhoon often cause severe disasters in these regions. There are many cases of typhoon disasters even in the recent decades in these regions. Furthermore, future projections of typhoon activity in the western North Pacific show that its maximum intensity will increase with the climate change. However, the historical data of typhoon (best track data) include large uncertainty after the US aircraft reconnaissance of typhoon was terminated in 1987. Another problem is that prediction of typhoon intensity has not been improved for the last few decades. To improve these problems, in situ observations of typhoon using an aircraft are indispensable. The T-PARCII (Tropical cyclone-Pacific Asian Research Campaign for Improvement of Intensity estimations/forecasts) project is aiming to improve estimations and forecasts of typhoon intensity as well as storm track forecasts.</p><p>In 2017, the T-PARCII team performed dropsonde observations of intense Typhoon Lan in collaboration with Taiwan DOTSTAR, which was the most intense typhoon in 2017 and caused huge disaster over the central Japan. It was categorized as a supertyphoon by JTWC and as a very intense and huge typhoon by JMA. Typhoon Lan moved northeastward to the east of the Okinawa main island and it was located around 23 N on 21 and 28 N on 22 October. In these two days, we made dropsonde observations at the center of the eye and in the surrounding area of the eyewall. The observations showed that the central pressure of Lan slightly increases from 926 hPa on 21 to 928 hPa on 22 October with the northward movement. On the other hand, The JMA best track data indicate that the central pressure decreases from 935 hPa on 21 to 915 hPa on 22 October. The observations also showed a significant double warm core structure in the eye and the maximum wind speed along the eyewall. The dropsonde data were used for forecast experiments. The result shows an improvement of typhoon track prediction.</p><p>The T-PARCII team also made aircraft observations of Typhoon Trami during the period from 25 to 28 September 2018 in collaboration with the SATREPS ULAT group and DOTSTAR. Trami was almost stationary during the period to the south of the Okinawa main island. Then, it moved northward and finally made a landfall over the central part of Japan. This also caused a big disaster and electricity was shut down for several days in the central part of Japan. Typhoon Trami showed a drastic change of intensity from 25 to 26 September with a large change of eye size from about a diameter of 60 km to 200 km. Dropsonde observations showed the change of central pressure and maximum wind speed as well as the thermodynamic structure of the eye.</p>
