EM 1110-2-1100 (Part II)
(Change 1) 31 July 2003
II-2-5. Definitions of Symbols
α
Equilibrium coefficient
γ
Peak enhancement factor used in the JONSWAP spectrum for fetch-limited seas
Air-sea temperature difference [deg EC]
∆T
Measured wind direction in standard meteorological terms (Equation II-2-14) [deg]
θmet
θvec
Measured wind direction in a Cartesian system with the zero angle wind blowing
toward the east (Equation II-2-14) [deg]
λ
Dimensionless constant in determining the height of the atmospheric boundary
layer (Equation II-2-12)
Dimensionless empirical coefficients used in empirical wave predictions
λ1-5
Mass density of air [force-time2/length4]
ρa
Mass density of water (salt water = 1,025 kg/m3 or 2.0 slugs/ft3; fresh water =
ρw
1,000kg/m3 or 1.94 slugs/ft3) [force-time2/length4]
σ
Dimensionless spectral width parameter
Wind stress [force/length2]
τ
n
Dimensionless universal function characterizing the effects of thermal stratification
Angular velocity of the earth (= 0.2625 rad/hr = 7.292x10-5 red/sec)
ω
A
Scaling parameter in the Holland wind model [length]
B
Dimensionless parameter that controls the peakedness of the wind speed
distribution in the Holland wind model
c
Particle velocity [length/time]
CD
Coefficient of drag for winds measured at 10-m [dimensionless]
CDz
Coefficient of drag for winds measured at level z [dimensionless]
e
Base of natural logarithms (= 2.718)
E(f)
Spectral energy density [length/hertz]
Coriolis parameter (= 2 ω sin φ = 1.458 x 10-4 sin φ), where φ is geographical
f
1
Period [sec]
Peak frequency of the spectral peak
fp
fu
Limiting frequency for a fully developed wave spectrum (Equation II-2-32)
g
h
Height of the boundary layer (Equation II-2-12) [length]
Meteorology and Wave Climate
II-2-69
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