TY - CONF

T1 - Parameters of sudden stratospheric warmings from the reanalysis database JRA-55

AU - Ефимов, Матвей Максимович

AU - Гаврилов, Николай Михайлович

N1 - Conference code: 15

PY - 2024/4

Y1 - 2024/4

N2 - The purpose of the study and classify parameters of sudden stratospheric warmings (SSW) using an automated method for determining the characteristics of SSW for the period from 1958 to 2017 according to Japanese reanalysis of meteorological information JRA-55. The times of start and end of the SSW are determined using the moments of the maximum rate of temperature change and the average zonal speed at an altitude of 30 km and latitudes above 60º N. Algorithms and programs have been developed in [1,2] to search for zero values ​​of the second derivative of temperature and zonal velocity with respect to time, which corresponds to extreme values ​​of the rate of change of these parameters. In this study, this method is used to search and determine the characteristics of SSW at an altitude of 30 km for the period from 1958 to 2017 using the JRA-55 database of the Japanese meteorological reanalysis. Based on the data from an automated search for SSW dates, an attempt was made to modify the generally accepted classification of SSW events based on the presence or absence of a reversal of the mean zonal wind and the magnitude of the temperature increment relative to its median at an altitude of 30 km. A search for early-winter, mid-winter and final stratospheric warmings was performed. A total of 148 winter-average SSW were detected, with an average of 2.5 events per year. The moments of maximum rates of change in temperature and zonal wind differ by no more than two days. Criteria for determining strong and moderate SSW, which can be considered as analogues of major and minor warming in the international classification of SSW, are described. The proposed method is highly sensitive and has made it possible to identify an additional class of weak SSWs. Early winter stratospheric warming occurring in late autumn or early winter (November-December) is considered separately. The final warming is also analyzed, for which there is no return of the average zonal wind to the west within 30 days after its reversal to the east, which occurs during the spring restructuring of the circulation of the middle atmosphere. A total of 63 strong warmings were detected at an altitude of 30 km. On average, strong warming occurs once a year.

AB - The purpose of the study and classify parameters of sudden stratospheric warmings (SSW) using an automated method for determining the characteristics of SSW for the period from 1958 to 2017 according to Japanese reanalysis of meteorological information JRA-55. The times of start and end of the SSW are determined using the moments of the maximum rate of temperature change and the average zonal speed at an altitude of 30 km and latitudes above 60º N. Algorithms and programs have been developed in [1,2] to search for zero values ​​of the second derivative of temperature and zonal velocity with respect to time, which corresponds to extreme values ​​of the rate of change of these parameters. In this study, this method is used to search and determine the characteristics of SSW at an altitude of 30 km for the period from 1958 to 2017 using the JRA-55 database of the Japanese meteorological reanalysis. Based on the data from an automated search for SSW dates, an attempt was made to modify the generally accepted classification of SSW events based on the presence or absence of a reversal of the mean zonal wind and the magnitude of the temperature increment relative to its median at an altitude of 30 km. A search for early-winter, mid-winter and final stratospheric warmings was performed. A total of 148 winter-average SSW were detected, with an average of 2.5 events per year. The moments of maximum rates of change in temperature and zonal wind differ by no more than two days. Criteria for determining strong and moderate SSW, which can be considered as analogues of major and minor warming in the international classification of SSW, are described. The proposed method is highly sensitive and has made it possible to identify an additional class of weak SSWs. Early winter stratospheric warming occurring in late autumn or early winter (November-December) is considered separately. The final warming is also analyzed, for which there is no return of the average zonal wind to the west within 30 days after its reversal to the east, which occurs during the spring restructuring of the circulation of the middle atmosphere. A total of 63 strong warmings were detected at an altitude of 30 km. On average, strong warming occurs once a year.

KW - sudden stratospheric warming

KW - Climatology

M3 - Abstract

SP - GC2024-OLD004

Y2 - 22 April 2024 through 26 April 2024

ER -