The diurnal and semidiurnal tidal wind field variations in the altitudes between 80 and 100 km of the earth's atmosphere over a mid-latitude station are studied by means of the phases of the zonal and meridional w...The diurnal and semidiurnal tidal wind field variations in the altitudes between 80 and 100 km of the earth's atmosphere over a mid-latitude station are studied by means of the phases of the zonal and meridional wind measurements made at Atlanta (34 ° N, 84 ° W). The rotation of diurnal tidal wind vector is seen to be clockwise at lower heights (80-86 km), swinging between clockwise and anti-clockwise at intermediate heights (88-96 km) and anti-clockwise at higher heights (96-100 km). The senses of rotation of diurnal and semidiurnal tidal wind vectors are compared between the stations located in the same and opposite hemispheres. The results are consistent with the tidal theory in the case of Atlanta and Adelaide (35°S, 139 ° E) whereas in the case of other stations considered in the present study, they showed marked variations.展开更多
This work presents a modified formula for the fractal box counting dimension.The method is based on the utilisation of the probability distribution formula in the fractal box count.The purpose of this method is to use...This work presents a modified formula for the fractal box counting dimension.The method is based on the utilisation of the probability distribution formula in the fractal box count.The purpose of this method is to use it for the discrimination of oil spill areas from the surrounding features,e.g.sea surface and look-alikes,using RADARSAT-1 SAR Wide beam mode(W1),Standard beam mode(S2)and Standard beam mode(S1)data acquisition under different wind speeds.The results show that the new formula is able to discriminate between oil spills and look-alike areas.The results also illustrate that the new fractal formula identifies well the deficiency of oil spills in pairs of S2 data.Further,there are no significant differences between fractal values of look-alikes,low wind zone,and current shear features in different beam modes for acquisition of RADARSAT-1 SAR data.The W1 mode data,however,show an error standard deviation of 0.002,thus performing a better discrimination of oil spills than the S1 and S2 mode data.展开更多
文摘The diurnal and semidiurnal tidal wind field variations in the altitudes between 80 and 100 km of the earth's atmosphere over a mid-latitude station are studied by means of the phases of the zonal and meridional wind measurements made at Atlanta (34 ° N, 84 ° W). The rotation of diurnal tidal wind vector is seen to be clockwise at lower heights (80-86 km), swinging between clockwise and anti-clockwise at intermediate heights (88-96 km) and anti-clockwise at higher heights (96-100 km). The senses of rotation of diurnal and semidiurnal tidal wind vectors are compared between the stations located in the same and opposite hemispheres. The results are consistent with the tidal theory in the case of Atlanta and Adelaide (35°S, 139 ° E) whereas in the case of other stations considered in the present study, they showed marked variations.
文摘This work presents a modified formula for the fractal box counting dimension.The method is based on the utilisation of the probability distribution formula in the fractal box count.The purpose of this method is to use it for the discrimination of oil spill areas from the surrounding features,e.g.sea surface and look-alikes,using RADARSAT-1 SAR Wide beam mode(W1),Standard beam mode(S2)and Standard beam mode(S1)data acquisition under different wind speeds.The results show that the new formula is able to discriminate between oil spills and look-alike areas.The results also illustrate that the new fractal formula identifies well the deficiency of oil spills in pairs of S2 data.Further,there are no significant differences between fractal values of look-alikes,low wind zone,and current shear features in different beam modes for acquisition of RADARSAT-1 SAR data.The W1 mode data,however,show an error standard deviation of 0.002,thus performing a better discrimination of oil spills than the S1 and S2 mode data.
