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[AHW21-P04] Atmosphericfronts of the rainy season in kyushu region using an objective method
Keywords:atmospheric fronts, surface weather chart, objective analysis
Torrential rainfall disasters induced by baiu fronts, which are stationary fronts appearing from May to July in Japan, occur frequently in kyushu region, western Japan. It is significant for society to examine variation of frontal rainfall associated with climate change. Atmospheric fronts depicted on a surface weather map published from Japan Meteorology Agency are estimated by forecasters[1]. We need to use an objective method for the detection of fronts in order to quantitative analysis.
Weather elements which defines atmospheric fronts are thermodynamical and dynamical variables[2]. The former is primary and used in TFP(Thermal Frontal Paramater)[2], which is common for an objective analysis[1][3]. The latter is secondary variables such as change of wind direction and employed for detection of fronts[4]. Another method using dimensionless number made of both variables is also proposed[5]. No method can detect all atmospheric fronts. We should investigate the feature of objective methods for frontal analysis and adopt an appropriate method.
In this research, we apply the method using thermodynamical and dynamical variables for analysis of atmospheric fronts, F diagnostic, subject to the rainy season in Japan. It is presented that fronts on surface weather chart exist succesively around the kyushu resion for many days in heavy rainfall events. In such a case, there are fronts detected by the objective method more frequently than usual.
[1] JMA, 2018, Quantitative Forecasting Technical Documents, 23, 84-103.
[2] Renard and Clarke, 1965, Mon. Weather Rev., 93, 547-556.
[3] Hewson, T. D., 1998, Meteorol. Appl., 5, 37-65.
[4] Simmonds et al., 2012, J. Clim., 25(6), 1945-1962
[5] Parfitt et al., 2017, Geophys. Res. Lett., 44, 4351-4358.
Weather elements which defines atmospheric fronts are thermodynamical and dynamical variables[2]. The former is primary and used in TFP(Thermal Frontal Paramater)[2], which is common for an objective analysis[1][3]. The latter is secondary variables such as change of wind direction and employed for detection of fronts[4]. Another method using dimensionless number made of both variables is also proposed[5]. No method can detect all atmospheric fronts. We should investigate the feature of objective methods for frontal analysis and adopt an appropriate method.
In this research, we apply the method using thermodynamical and dynamical variables for analysis of atmospheric fronts, F diagnostic, subject to the rainy season in Japan. It is presented that fronts on surface weather chart exist succesively around the kyushu resion for many days in heavy rainfall events. In such a case, there are fronts detected by the objective method more frequently than usual.
[1] JMA, 2018, Quantitative Forecasting Technical Documents, 23, 84-103.
[2] Renard and Clarke, 1965, Mon. Weather Rev., 93, 547-556.
[3] Hewson, T. D., 1998, Meteorol. Appl., 5, 37-65.
[4] Simmonds et al., 2012, J. Clim., 25(6), 1945-1962
[5] Parfitt et al., 2017, Geophys. Res. Lett., 44, 4351-4358.