The relationship between the Arctic Oscillation (AO) and daily temperature variance of 150 Chinese stations are investigated in the present study for wintertime (1 No-vember through 31 March) in the period of 1954-200...The relationship between the Arctic Oscillation (AO) and daily temperature variance of 150 Chinese stations are investigated in the present study for wintertime (1 No-vember through 31 March) in the period of 1954-2001. Re-sults show that the temperature variance significantly de-creases during the high AO years, and increases in low AO cases. A key factor connecting them is the Siberian High, particularly the high-frequency fluctuations of the High. Within the seasonal time scale, the frequency of low-temperature extremes (daily temperature anomaly below 2σ,σ is the standard deviation of daily temperature for a given winter and a given station) displays an odd relation to the variance: a larger (smaller) variance is found to be asso-ciated with smaller (greater) frequency o low-temperature events. That is due to the non-normal distribution of the temperatures, and also influenced by the hhases of AO. Dur-ing the last 50 years or so, AO experiences a significant increasing trend, meanwhile the variance of daily sea level pressure (SLP) in the central region of Siberian High has decreased at a rate of 10.7%/10 a. These result in a signifi-cant weakening of the daily temperature variance in China with a trend of 4.1%/10 a, and a significant increaswe in the intra-seasonal low-temperature extremes at a rate of 0.16d/10 a.展开更多
文摘The relationship between the Arctic Oscillation (AO) and daily temperature variance of 150 Chinese stations are investigated in the present study for wintertime (1 No-vember through 31 March) in the period of 1954-2001. Re-sults show that the temperature variance significantly de-creases during the high AO years, and increases in low AO cases. A key factor connecting them is the Siberian High, particularly the high-frequency fluctuations of the High. Within the seasonal time scale, the frequency of low-temperature extremes (daily temperature anomaly below 2σ,σ is the standard deviation of daily temperature for a given winter and a given station) displays an odd relation to the variance: a larger (smaller) variance is found to be asso-ciated with smaller (greater) frequency o low-temperature events. That is due to the non-normal distribution of the temperatures, and also influenced by the hhases of AO. Dur-ing the last 50 years or so, AO experiences a significant increasing trend, meanwhile the variance of daily sea level pressure (SLP) in the central region of Siberian High has decreased at a rate of 10.7%/10 a. These result in a signifi-cant weakening of the daily temperature variance in China with a trend of 4.1%/10 a, and a significant increaswe in the intra-seasonal low-temperature extremes at a rate of 0.16d/10 a.
