Engineering topics

Kai, K.

Publications and source records attributed to Kai, K..

8 records

NASA NTRS1986

Radio evidence for a delayed acceleration process in solar flares

Observations of six delayed solar radio bursts at dm and mm frequencies are analyzed. The events included five Type II bursts. The data comprise 17 GHz interferometer data and ISEE-3 and SMM hard X-ray spectrometry data which peaked 0.5-1.0 hr after the main radio bursts. The data indicate the electrons with energies in the MeV range continue to be excited for tens of minutes after the impulsive phase acceleration. The continuing acceleration occurs in a large magnetic structure extending to at least 200,000 km altitude. The radio signals arise from a columnar source, the microwave signals being emitted near a leg or legs and meterwave emissions originating from the top of the magnetic structure.

Kai, K.↗

NASA NTRS1986

Position measurements of rapidly fluctuating microwave bursts

It was investigated whether microwave source positions change while the total fluxes of hard X-rays and microwaves show remarkable rapid fluctuations of the order of seconds. The position measurements were made in one dimension (east-west direction) with the 17 GHz interferometer at Nobeyama. Position changes greater than a few arc seconds can be detected. The result shows that significant position changes are found for five of seven bursts but that no position changes greater than 3 arc seconds are found for the remaining two bursts.

Kai, K.↗

NASA NTRS1986

The HESP (High Energy Solar Physics) project

A project for space observations of solar flares for the coming solar maximum phase is briefly described. The main objective is to make a comprehensive study of high energy phenomena of flares through simultaneous imagings in both hard and soft X-rays. The project will be performed with collaboration from US scientists. The HESP (High Energy Solar Physics) WG of ISAS (Institute of Space and Astronautical Sciences) has extensively discussed future aspects of space observations of high energy phenomena of solar flares based on successful results of the Hinotori mission, and proposed a comprehensive research program for the next solar maximum, called the HESP (SOLAR-A) project. The objective of the HESP project is to make a comprehensive study of both high energy phenomena of flares and quiet structures including pre-flare states, which have been left uncovered by SMM and Hinotori. For such a study simultaneous imagings with better resolutions in space and time in a wide range of energy will be extremely important.

Kai, K.↗

NASA NTRS1985

Estimation of Regional Evapotranspiration Using Remotely Sensed Land Surface Temperature. Part 1: Measurement of Evapotranspiration at the Environmental Research Center and Determination of Priestley-taylor Parameter

In order to study the distribution of evapotranspiration in the humid region using remote sensing technology, the parameter (alpha) in the Priestley-Taylor model was determined. The daily means of the parameter alpha = 1.14 can be available from summer to autumn and alpha = to approximately 2.0 in winter. The results of the satellite and the airborne sensing done on 21st and 22nd January, 1983, are described. Using the vegetation distribution in the Tsukuba Academic New Town, as well as the radiation temperature obtained by remote sensing and the radiation data observed at the ground surface, the evapotranspiration was calculated for each vegetation type by the Priestley-Taylor method. The daily mean evapotranspiration on 22nd January, 1983, was approximately 0.4 mm/day. The differences in evapotranspiration between the vegetation types were not detectable, because the magnitude of evapotranspiration is very little in winter.

Kotada, K.↗

NASA NTRS1985

Estimation of Regional Evapotranspiration Using Remotely Sensed Land Surface Temperature. Part 2: Application of Equilibrium Evaporation Model to Estimate Evapotranspiration by Remote Sensing Technique

In a humid region like Japan, it seems that the radiation term in the energy balance equation plays a more important role for evapotranspiration then does the vapor pressure difference between the surface and lower atmospheric boundary layer. A Priestley-Taylor type equation (equilibrium evaporation model) is used to estimate evapotranspiration. Net radiation, soil heat flux, and surface temperature data are obtained. Only temperature data obtained by remotely sensed techniques are used.

Kotoda, K.↗

NASA NTRS1985

Microwave and X-ray observations of delayed brightenings at sites remote from the primary flare locations

Five examples of solar flares observed with the 17-GHz interferometer at Nobeyama in which a secondary microwave burst occurred at a distance of 100,000 km to 1,000,000 km from the primary flare site are presented. The secondary microwave burst in all five cases had a similar time profile to the primary burst with a delay of 2 to 25 s. The velocity of a triggering agent inferred from this delay and spatial separation is 10,000 km to 100,000 km/s. The intensity of the secondary burst was a factor of 3 to 25 smaller than that of the primary burst in all events except for one case in which it was a factor of 2 larger. The polarization degree of the secondary burst at 17 GHz was 35 percent, significantly higher than the average value for typical impulsive bursts. Two of the events were accompanied by meterwave type III/V bursts located high in the corona between the primary and secondary sites. For two of the other events, X-ray images of the secondary source were obtained with the hard-X-ray imaging spectrometer on the Solar Maximum Mission. These observations strongly suggest that the distant microwave bursts were produced by electrons with energies of 10 keV to 100 keV which were channeled along a huge loop from the main flare site to the remote location.

Nakajima, H.↗

NASA NTRS1984

Microwave and X-ray observations of delayed brightenings at sites remote from the primary flare locations

Five examples of solar flares observed with the 17-GHz interferometer at Nobeyama in which a secondary microwave burst occurred at a distance of 100,000 km to 1,000,000 km from the primary flare site are presented. The secondary microwave burst in all five cases had a similar time profile to the primary burst with a delay of 2 to 25 s. The velocity of a triggering agent inferred from this delay and spatial separation is 10,000 km to 100,000 km/s. The intensity of the secondary burst was a factor of 3 to 25 smaller than that of the primary burst in all events except for one case in which it was a factor of 2 larger. The polarization degree of the secondary burst at 17 GHz was 35%, significantly higher than the average value for typical impulsive bursts. Two of the events were accompanied by meterwave type III/V bursts located high in the corona between the primary and secondary sites. For two of the other events, X-ray images of he secondary source were obtained with the hard-X-ray imaging spectrometer on the Solar Maximum Mission. These observations strongly suggest that the distant microwave bursts were produced by electrons with energies of 10 keV to 100 keV which were channeled along a huge loop from the main flare site to the remote location.

Nakajima, H.↗

NASA NTRS1983

Acceleration and confinement of energetic particles in the 1980 June 7 solar flare

Pulsations with large amplitude and duration have been observed during the hard X-ray and microwave radio bursts associated with the 1980 June 7 solar flare. The high time resolution measurements of 20-800 keV X-rays were made with the X-ray spectrometers aboard the ISEE 3 and P78-1 spacecraft. The radio measurements, covering metric to microwave wavelengths, were made at the Nobeyama and Toyokawa observatories in Japan. The temporal evolution of the X-ray and radio spectra and the polarization and spatial structure of the microwave source have been examined. The following interpretation is found to be consistent with the observations: (1) the variations in the electron acceleration/injection spectrum are responsible for the observed variations in the hard X-ray and microwave emissions; (2) the locations of the hard X-ray and microwave sources are probably different, the X-ray source being located at a lower altitude.

Kane, S. R.↗