Overview of 2012/2013 winter over South Korea E-hyung Park, Doo-hee Ryu, and Hyun-kyung Kim Climate Prediction Division Korea Meteorological Administration

Contents 1. Temp. & Precip. over East Asia 2. Temp. & Precip. over Korea 3. Notable Events & Season Monitoring 4. Summary

Temperature & Precipitation over EA November December January February

Temperature over South Korea Daily Mean Temperature anomaly (℃) Anomaly: -1.6℃ -3.2℃ -1.1℃ -0.4℃ Mean (-1.0℃) Above Normal Below Normal 12.1 12.11 12.21 1.1 1.11 1.21 2.1 2.11 2.21 December January February normal above below

Precipitation over South Korea Daily averaged amount of precipitation(㎜) Ratio to normal: 162% 261% 103% 149% Total (139.3mm) 12.1 12.11 12.21 1.1 1.11 1.21 2.1 2.11 2.21 December January February normal above below

Notable Events & Season Monitoring

Schematic illustration of Ural blocking DJF 1950~2000 Blocking Frequency Atmospheric blocking made frequently in Pacific and Atlantic Ocean. A quasi-stationary blocking high over the North Pacific, which may exert an influence on the East Asian trough and indirectly affect the cold surge pathways in East Asia (Cheung et al., 2012). The region around the Ural Mountains is the third preferred region for blocking occurrence A strong positive height anomaly over the Urals in winter is related to a colder surface temperature in East Asia (Li, 2004). The circulation pattern over the Uarls is one of the critical factors in winter seasonal prediction for East Asia (Li, 2004). Schematic illustration of Ural blocking

Long-lasting cold episode and cold surge 500hPa GPH anomaly (21 Nov. to 10 Dec.) Daily mean temperature anomaly (℃) November 3rd December January 1st -1.4℃ (-4.4℃) -0.3℃ (-1.6℃) -3.3℃ (-3.7℃) -5.8℃ (-5.1℃) 11/21 11/26 12/1 12/6 12/11 12/16 12/21 12/26 1/1 1/6 SAT anomaly (21 Nov. to 10 Dec.) From late November to early December, an blocking high occurred over the Bering Sea  Block the west to east progression of the upper level airflow  A cold upper level trough passed through over East Asia

Long-lasting cold episode and cold surge 500hPa GPH anomaly (11 Dec. to 10 Jan.) Daily mean temperature anomaly (℃) November 3rd December January 1st -1.4℃ (-4.4℃) -0.3℃ (-1.6℃) -3.3℃ (-3.7℃) -5.8℃ (-5.1℃) 11/21 11/26 12/1 12/6 12/11 12/16 12/21 12/26 1/1 1/6 From mid to late December, the blocking high occurred over the Ural Mountains  The enhanced northerly cold advection increases mass convergence in the upper troposphere over Siberia  The Siberian High was significantly developed  Cold air outbreak in East Asia In December, the monthly mean temperature anomaly over South Korea was -3.2°C. It was the coldest since 1973. The record-breaking minimum temperatures were recorded in 3 to 4 January 2013 over South Korea since record began.

Long-lasting cold episode and cold surge December January February NCEP Climatology 2012/2013 Daily variations of maximum pressure of SH (hPa) 80~120°E, 40~60°N MSLP anomaly (11 Dec. to 10 Jan.) SAT anomaly (11 Dec. to 10 Jan.)

Frequent snow and rain in winter Daily averaged amount of Precipitation(㎜) Siberian High December January February 261% 103% 149% 12.1 12.11 12.21 1.1 1.11 1.21 2.1 2.11 2.21 In December, the monthly total precipitation over South Korea was 60.4㎜. It was the 2nd wettest since 1973. The rainy days (days with more than 0.1㎜) was 11.2 days (6.6 days), which was ranked 1st since 1973. In early-February, the total precipitation was 45.0㎜. It was the 1st since 1973. The rainy days was 5.4 days (1.9 days), which was ranked 1st since 1973. The number of rainy days during in the wintertime was 25.5 days (19.8 days), which was ranked the 3rd largest since 1973. Warm & Humid Air Upper level Cold Air

Stratospheric Sudden Warming Mean (1991~2004) 2012/2013 Max & Min (1991~2004)

Summary 1. Wintertime(2012/2013) climate over Korea - Temperature: below normal (-1.6℃) - Precipitation: above normal (162%) - Rainy days: 25.5 days (3rd largest since 1973) 2. The long-lasting cold episode and cold surge is strongly associated with the blocking high over the North Pacific and Ural Mountains. Especially, the Ural blocking intensifies the Siberian high and triggers a cold air outbreak in East Asia. 3. Continuously warm and humid southwesterly flow collided frequently with cold and dry continental upper air over the Korean Peninsula which induced severe atmospheric instability.

____ ___ ___ ____ _________

Siberian High & SAT Daily mean temperature anomaly (℃) December January February NCEP Climatology 2012/2013 -3.2℃ -1.1℃ Above Normal Below Normal -0.4℃ 12.1 12.11 12.21 1.1 1.11 1.21 2.1 2.11 2.21 Daily variations of maximum pressure of SH (hPa) 80~120°E, 40~60°N

SAT anomaly 2009/2010 DJF 2010/2011 DJF 2011/2012 DJF 2012/2013 DJF

Regression map & Anomalous pattern Korea Precip. (DJF) & OLR(DJF): 1979/80~2011/12 OLR 2012D/13J Anomalous pattern (Clim: 1979-2011 DJF)

Velocity Potential and SST Anomaly December SST monthly Anomaly