in the Korean peninsula over last 20 years BJ Sohn School of Earth and Environmental Sciences Seoul National University N S 1000 mb 100 Hong 1992 Numerical experiments for heavy rain over Korea ID: 930735
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Slide1
1
Polarizing
rain types linked to June drought
in the Korean peninsula over last 20
years
B.J. Sohn
School of Earth and Environmental Sciences
Seoul National University
Slide2N
S
1000
(
mb
)
100
Hong
(1992): Numerical experiments forheavy rain over Korea
July 29, 2007 (Joonang Daily)
Heavy rainfall mechanism
over Korea
500
Heavy rain event over Seoul
Slide3CFADs of PR reflectivity classified by rain
rate (
94070 )
Korea
Rapidly increasing
Ze
:
fast growing rain drops and associated heavy rainfall
Total samples
= 94,070(summers of (2002–2011)
Sohn et al. (2013, MWR)
Slide4US - Oklahoma
Vertically aligned reflectivity profile
Total samples
= 40,830
Slide5Slide6CFADs summary for 20
< RR
PR
<
40 mm/
hr
Warm type
Cold type
Slide7L: Mean PR reflectivity for 20
< RR
PR
<
40 mm/
hr
R: Possible growing process for warm rain
Song, H.-J., B. J. Sohn, S.-Y. Hong, and T.
Hashino
, 2017: Idealized numerical experiments on the microphysical evolution of warm-type heavy rainfall.
J. Geophys. Res. Atmos., 122, 1685-1699, doi:10.1002/2016JD025637.
Slide8(a) ASOS 60 stations
(b)
June
Precipitation
−70.55
mm
decade
-1
How are rain patterns changed in recent years, particularly in relation to the recent June drought over the Korean peninsula?
1998-2017
Slide9(a) Mean (mm)
(b)
Mean
(10
-3
g
m
-2
s
-1)(c) Trend (mm decade
-1)
(d) Trend (10
-3
g
m
-2
s
-1
decade
-1
)
Precipitation
Moisture Flux Convergence
June trend
(1998–2017)
Slide10(a) Mean
(b) Trend
PDF distribution of rainfall
averaged
over 60 stations
and 20-year trend (1998-2017)
Slide11Radar Reflectivity
(Rain Rate < 10 mm h
-1
)
(a) Mean
(d) Trend
(b) Mean
(e) Trend
(c) Mean
(f) Trend
Storm Height
Radar Reflectivity
(Rain
R
ate > 10 mm h
-1
)
Slide12(Rain Rate < 10 mm h
-1
)
July
August
(Rain
R
ate > 10 mm h
-1
)
Slide13Conclusions
Two
types
of heavy rainfall emerged as the most important rain processes over East Asia:
Type 1 (cold-type)
characterized by high storm height and abundant ice
water under
convectively unstable conditions, developing mostly over inland China; and
Type 2 (warm-type)
associated with a lower storm height and lower ice water content, developing mostly over the ocean.
It was suggested that
deep convection may not always be necessary to produce heavy rainfall in very humid environment if water vapor convergence is prevalent with a continuous supply of water vapor into the region in interest
.
Warm/cold type experiments using WRF model
: lower
storm height, earlier onset of precipitation, and heavier
precipitation, collision-coalescence process.
Polarizing rain types
: dominant
warm-type heavy rain with a medium storm height tends to be less frequent while cold-type heavy rains characterized by taller storm and ice abundant clouds become more frequent
in
last 20 years.
13
Slide14Flight Speed: 7.3 km/sec
PR :
Precipitation
Radar (13 GHz)
TMI: TRMM Microwave
Imager
(
10.65, 19.35, 37.0,
85.5 GHz)
VIRS: Visible/IR Scanner
Tropical Rainfall Measuring Mission (TRMM) (~ 1997 onwards)
TMI TB85V