Discussion: In summer, EM trapping layers occur more frequently over the Yellow Sea (35%), and over smaller regions in the center of the Sea of Japan and south of Japan (30%). Trapping in the Yellow Sea is associated with moderately strong (16 M-units)

1
DUCTING CONDITIONS AROUND THE KOREAN PENINSULA
Tracy
Haack and Stephen D. Burk Naval Research
Laboratory Monterey, CA 93943
haack_at_nrlmry.avy.mil [phone]
Grid 1 ?x36 km
SST 10-m Wind 16 Jan 2000 12 UTC
SST 10-m Wind 16 Jun 1999 12 UTC
Grid 2 ?x9 km
Russia
Grid 3 ?x3 km
China
Sea of Japan
Grid 2 ?x9 km
Korea
Japan
Yellow Sea
Pacific Ocean
East China Sea
Terrain ht (m) SST (K) 1 Jan 2000
Winter Ducting Conditions Monthly Average --
Jan 2000
12 M-units
1400 m
300 m
20
10
6
200
700
0
0
100
0
Duct Frequency
Duct Strength
Duct Base Height
Duct Thickness
Discussion In winter, EM trapping layers occur
more frequently (10-20) south of the Korean
Peninsula and Japan. Trapping is associated with
fairly weak elevated ducts. The ducting in this
region have the following monthly averaged
characteristics duct bases at 1 km, thicknesses
of 250 m, and strengths up to 8 M-units.
Anomalous propagation of EM energy is likely to
be more prevalent in the southern region owing to
substantially warmer SST, 8 K higher than along
the Russian coast. With warmer SST, saturation
vapor pressures are less providing a more moist
marine atmospheric boundary layer environment.
That coupled with dry, subsiding synoptic flow
aloft arriving from either the NW (post-cold
frontal passage) or from the NE (eastern return
branch of a high pressure cell), creates
conditions ripe for ducting 10-20 of the time in
January 2000.
Summer Ducting Conditions Monthly Average --
Jun 2000
26 M-units
400 m
350 m
40
20
13
200
200
0
50
0
0
Duct Frequency
Duct Strength
Duct Base Height
Duct Thickness
Discussion In summer, EM trapping layers occur
more frequently over the Yellow Sea (35), and
over smaller regions in the center of the Sea of
Japan and south of Japan (30). Trapping in the
Yellow Sea is associated with moderately strong
(16 M-units) elevated ducts, while trapping in
the Sea of Japan is more likely to be surface
based (average duct base height 50 m). The
ducting increases in strength, elevation and
thickness at the southern latitudes in response
to the warmer SST of the Kurishio Current.
Anomalous propagation of EM energy is likely to
be more prevalent in the southern region owing to
substantially warmer SST, 8 K higher than along
the Russian coast. With warmer SST, saturation
vapor pressures are less providing a more moist
marine atmospheric boundary layer environment.
That coupled with dry, subsiding synoptic flow
aloft arriving from either the NW (post-cold
frontal passage) or from the NE (eastern return
branch of a high pressure cell), creates
conditions ripe for ducting 10-20 of the time in
January 2000.