K

K

Kelvins, a unit of absolute temperature

KE

Kinetic Energy

k

von Karman constant (=0.4)
grid index
rate constant

km

kilometers, a unit of length

kPa

kiloPascals, a pressure unit

L

L

length
latent heat
Obukhov length

LAER

Lowest Achievable Emission Rate

LCD

Local Climatological Data

LCL

Lifting Condensation Level

LEL

Lower Explosive Limit

LFC

level of free convection

LFM

limited-area fine-mesh

LI

Lifted Index

l

liter, a unit of volume

ln

natural logarithm (base e)

log

common logarithm (base 10)

M

M

wind speed

M_BL

Boundary layer wind speed

MACT

Maximum Achievable Control Technology

MB

megabyte
millibars

MCE

Mixed Cellulose Ester

METAR

meteorological observation code

MIPS

millions of (computer) instructions per second

ML

Mixed layer

MKS

metric system (SI) of units. Literally :
M=meters, K=kilograms, S=seconds

MOS

Model Output Statistics

MRF

Medium-range forecast

MSL

Mean sea level

m

mass

m

meters, a length unit

mb

millibars, a pressure unit

min

minutes, a unit of time

mm Hg

millimeters of mercury, a pressure unit

mph

miles per hour

N

N

Newton's, a unit of force
North

N

Number of data points

NAAQS

National Ambient Air Quality Standards

NCDC

national Climatic Data Center

NCEP

National Centers for Environmental Prediction

NESHAPs

National Emission Standards for Hazardous Air Pollutants

NEXRAD

NEXt generation of weather RADar

NGM

nested-grid model

NMC

National Meteorological Center

NOAA

National Oceanographic and Atmospheric Administration

NSPS

New Source Performance Standards

NSR

New Source Review

NSSL

National Severe Storms Laboratory

NWP

Numerical weather prediction

NWS

National Weather Service

n

number density
number of grid points being averaged

O

OFA

Overfire Air

OFM

operational numberical weather forecast model

OTAG

Ozone Transport Assessment group

OTC

Ozone Transport Commission

P

P

Pressure

P_o

sea-level pressure = 101.325 kPa

P_a

Pascal, a pressure unit

P_STP

Standard sea-level pressure = 101.325 kPa

PAN

Peroxyacyl Nitrates

PG

Pasquill-Gifford

PPM

Perfect prog method

PSD

Prevention of Significant Deterioration

PW

Precipital Weather

ppb

Parts per billion

ppm

parts per million

Q

Q

amount
source emission rate of pollutant

Q_A

cummulative heating or cooling

Q_ak

cumulative heating or cooling in kinematic units

QA/QC

Quality Assurance/Quality Control

R

R

distance
radius

°R

Rankine

RADM

Regional Acid Deposition Model

RAOB

Radiosonde observation

RAP

Reclaimed Asphalt Pavement

RASS

radio acoustic sounding system

RH

Relative humidity

RL

Residual layer

RTO

Regenerative Thermal Oxidizer

RUC

Rapid Update Cycle

RxL

Radix layer

r

water mixing ratio, a form of humidity

r_s

saturation mixing ratio

r_sat

saturation mixing ratio

r_T

total water mixing ratio

rad

radians

S

S

South
solar constant = 1368 +/- 7 W*m^-2

SBL

Stable Boundary Layer

SBLI

Lifted index calculated using surface based parcel

SCF

Standard Cubic Feet

SCFM

Standard Cubic Feet per Minute

SIP

State Implementation Plan

SL

Surface Layer

SO₂

sulfur dioxide

STP

Standard Temperature and Pressure

s

horizontal distance
seconds, a time unit

sin

sine

T

T

temperature

T_d

dew point temperature

T_e

temperature of environment

T_kat

temperature of katabatic layer

T_p

temperature of parcel

T_RL

residual layer temperature

T_r

reference temperature

T_STP

standard sea-level temperature = 15 degrees C = 288 K

T_s

surface temperature

T_v

virtual temperature

T_w

wet bulb temperature

TEQ

Toxic Equivalency Quotient

TH

thickness

TIROS

Television and Infrared Operational (satellite) System

TT

Total Totals

Torr

a unit of measure of pressure

t

time

t_d

length of day

t_L

Lagrangian time scale

t_UTC

Coordinated Universal Time

tke

Turbulent Kinetic Energy

U

U

wind component toward east

U_g

geostrophic wind component toward the east

U_jet

jet stream velocity

U_r

gradient wind component toward the east

URL

universal resource locator (internet web address)

U.S. EPA

United States Environmental Protection Agency

UTC

coordinated universal time

u*

friction velocity

V

V

wind component toward north
volume

V_g

geostrophic wind component toward the north

V_r

gradient wind component toward the North

VOC

Volatile Organic Compound

VT

Vertical Totals

W

W

upward wind component
width

W

watt, a power unit
West

W_mid

vertical velocity across 50 kPa surface

WMO

World Meteorological Organization

WX

weather

w_b

buoyancy velocity scale

X

X

cloud diameter or depth

x

distance toward east
distance from ceterline
path length
travel distance
distance downwind
distance from front

Y

Y

dimensionless crosswind distance of receptor from plume centerline

y

year

y

distance toward north

yr

year

Z

Z

dimensionless receptor height

Z_T

depth of troposphere (=11km)

z

vertical distance
depth
height

z_CL

plume centerline height

z_o

aerodynamic roughness length

z_T

depth of troposphere (=11 km)
height of topography

z_Trop

depth of troposphere (=11 km)