Refractivity in the Coastal Atmospheric Boundary Layer
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Refractivity in the Coastal Atmospheric Boundary Layer Stephen Burk and Tracy Haack Naval Research Laboratory Monterey, CA
description
Refractivity in the Coastal Atmospheric Boundary Layer. Stephen Burk and Tracy Haack Naval Research Laboratory Monterey, CA. Strength ( M). Height. top. Thickness (= top-base). base. Modified Refractivity, M. Refractivity in the Coastal Atmospheric Boundary Layer. . Q. Height. - PowerPoint PPT Presentation
Transcript of Refractivity in the Coastal Atmospheric Boundary Layer
Refractivity in the Coastal Atmospheric Boundary Layer
Stephen Burk and Tracy HaackNaval Research Laboratory
Monterey, CA
Refractivity in the Coastal Atmospheric Boundary Layer
Hei
ght
Q
base
top
Strength (M)
Thickness (= top-base)
Modified Refractivity, M
Hei
ght
Potential Temperature &Specific Humidity
COAMPSTM 27km grid
Cook & Burk, 1992, BLM, 58, 151-159.Burk & Thompson, 1997, JAM, 36, 22-31.Haack & Burk, 2001, JAM, 40, 673-687.Burk, Haack, Rogers, & Wagner, 2003, JAM, 349-367.
INDIA
SAUDIARABIA
Wallops 2000EM PropagationField Experiment
from NSWCDD/TR-01/132
COAMPSTM Wallops Island
DTG: 10-12 Apr 2000 Triple nest: 27-9-3 km Vertical: 40 levels
10-m Winds/SLPSST/SLP
DMDZ/THETA
Hei
ght (
m)
x = 3 km
x = 27 km
April 10, 20001200 UTC
April 11, 20001200 UTC
April 12, 20001200 UTC
EDH(m)
RH(%)
T(0C)
U(m/s)
Dots = COAMPSTM forecast values
Ta
IR
Obs from Davidson, NPS
3 am LT10 Apr 2000
Norfolk*
Wallops
COAMPSTM SST and Ground Temperature
*284
297
COAMPSTM Sensible Heat Flux (W/m2);near surface streamlines
11 Apr 2000
3 am LT 3 pm LT
0
0
0
60
20
-20
400
20
60
40
20
0
0
0
0
20
-20
COAMPSTM Evaporation Duct Height (m)11 Apr 2000
3 am LT 3 pm LT
4
6 10
12
24
2
4
8
28
base
top
Strength (M)
Modified Refractivity, M
Hei
ght
hourly fields from 00 UTC 11 Apr-2300 UTC 12 Apr 2000
Animation of two 24h COAMPSTM forecasts of:40m(shaded); 50m streamlines; & dM/dz = 0 isosurface (white)
Horizontal: Evaporation Duct Height (shaded) & StreamlinesVertical: Potential Temperature (shaded & contoured)“Clouds”: Trapping Layer (DMDZ=0 isosurface)
0
1 km
North South
M Crossection
(a)
M CrossectionShaded with dM/dz
(b)
1800 UTC 12 Apr 2000 COAMPSTM
Looking toward SE across Tidewater PeninsulaRed Isosurface dM/dz = 157 M-units/km subrefractionWhite isosurface dM/dz = 0 M-units/km trapping layer
(c)
Mixing Ratio (g/kg), Shaded;Potential Temperature (K),contoured
1800 UTC 12 Apr 2000 COAMPSTM
Duct parameters from COAMPSTM
1800 UTC 12 Apr 2000Wallops Island
Duct Base Height (m) Duct Thickness (m) Duct Strength (M-units)
0
100
200
300
400
500
0
100
200
300
0
3
6
9
12
15
18
Summary
• COAMPSTM forecasts both evaporation ducts and elevated and/or surface based ducts
• To date, most modeling studies of refractivity/propagation have focused on subsidence dominated, strongly capped BL’s (e.g., CA coast in summer; Persian Gulf)
• Intensive Observation Periods of the Wallops-2000 propagation field experiment are addressed here using COAMPSTM at high resolution. Model refractivity will be inserted into propagation codes for comparison with prop measurements.
• New insights into refractivity structure in frontal regions are emerging
• Accurate forecasting of major synoptic features (e.g., frontal boundaries) can be of greater importance than extremely high model resolution in defining local refractive structure/ EM propagation conditions. Mesoscale ensembles may be very useful in this context.
