Twentieth Century Winter Changes in Southern Hemisphere Synoptic Weather Modes

Table 1

Periods 𝑇^𝑑𝑟 and growth rates 𝜔^𝑑𝑖 of selected modes for the 1949–68 NCEP/NCAR basic state with standard parameterizations (𝐾^𝑑=2.338×10¹⁶ m⁴ s⁻¹, 𝑄^𝑑𝐹=1500K, 𝐶^𝑑𝐹=5×10⁻⁴K m⁻¹), their mode number, and class of mode. Also shown are the largest pattern correlations 𝐴_𝑐 between a given mode and the modes for the 1975–94 NCEP/NCAR basic state with standard parameterizations and the 1975–94 mode for which the pattern correlation is largest as well as the change in the growth rate Δ𝜔^𝑑𝑖.

Class	Mode	𝑇^𝑑𝑟	𝜔^𝑑𝑖	𝑇^𝑑𝑟	𝜔^𝑑𝑖	𝐴𝑐	Mode	Δ𝜔^𝑑𝑖
	1949–68	(days)	(day^−1)	(days)	(day^−1)		1975–94
SH cyclogenesis	1	1.20	0.4250	1.30	0.2824	0.9148	9	−33.5%
ML blocking	30	6.11	0.2566	6.25	0.2279	0.4597	21	−11.2%
HL blocking	8	7.40	0.3495	8.02	0.3317	0.8342	4	−5.1%
HL blocking	11	5.22	0.3184	5.08	0.3101	0.8468	6	−2.6%
NWCB	43	8.01	0.2100	8.19	0.2624	0.8036	12	+24.9%
Antarctic	6	13.08	0.3624	17.48	0.3606	0.9416	3	−0.5%
Antarctic	26	52.1	0.2746	121.3	0.2700	0.8542	11	−1.7%
ISO	57	59.0	0.1444	41.85	0.1858	0.8506	35	+28.7%
African EW	22	4.14	0.2881	3.83	0.3071	0.7959	7	+6.6%