GLOSSARY AND DEFINITIONS:---------------------------------------------
ANALOG (NATURAL ANALOG) - A WEATHER MAP THAT RESEMBLES ANOTHER WEATHER MAP -
USUALLY FROM DIFFERENT YEARS BUT THE SAME SEASON IN THE HISTORICAL RECORD. THE
CRITERION FOR SELECTING AN ANALOG IS OFTEN THE PATTERN CORRELATION BETWEEN THE
MAPS. TWO MAPS WILL JUST BEGIN TO RESEMBLE EACH OTHER TO THE HUMAN EYE AT A
PATTERN CORRELATION OF ABOUT 40%. TO BE USEFUL - ANALOGS NEED TO HAVE MUCH
HIGHER CORRELATIONS TO THE ORIGINAL MAP THAN THAT - 80% OR MORE. ANALOGS ARE
INCREASINGLY DIFFICULT TO FIND AS THE GEOGRAPHIC REGION BEING COMPARED
INCREASES IN SIZE. PERFECT ANALOGS TO THE ENTIRE NORTHERN HEMISPHERE SIMPLY
DO NOT EXIST - FOR PRACTICAL PURPOSES. THIS IS WHY SIMPLE ANALOG FORECAST
METHODS DO NOT WORK VERY WELL.
ANNUAL CYCLE - AT MOST LOCATIONS THE CLIMATE STATE VARIABLES - T - P - SST-
WIND - AND OTHERS DISPLAY A REGULAR VARIATION WHICH FOLLOWS THAT OF THE
ELEVATION OF THE SUN IN THE SKY. A GRAPH OF THE 30 YEAR AVERAGE OF A
VARIABLE FOR EACH DAY OF THE YEAR VERSUS DATE SHOWS A WAVE-FORM WHICH -
FOR T AT DES MOINES FOR EXAMPLE - RANGES SMOOTHLY FROM LOWEST VALUES IN THE
WINTER TO HIGHEST VALUES IN THE SUMMER.
ANOMALY - THE ARITHMETIC DIFFERENCE BETWEEN THE VALUE OF A VARIABLE AT A GIVEN
PLACE AND TIME AND THE LONG-TERM AVERAGE (USUALLY 30 YEARS) FOR THE LOCATION
AND TIME OF YEAR.
AO - ARCTIC OSCILLATION - A MEASURE OF THE DIFFERENCE IN PRESSURE (AT SEA LEVEL)
OR 500-HPA HEIGHT (IN THE MIDDLE TROPOSPHERE) BETWEEN THE NORTHERN POLAR REGION
AND MIDDLE LATITUDES. WHEN PRESSURES AND HEIGHTS ARE ABOVE (BELOW) AVERAGE AT
HIGH LATITUDES AND BELOW (ABOVE) AVERAGE AT MIDDLE LATITUDES - THE AO IS DEFINED
AS NEGATIVE (POSITIVE) AND IS ASSOCIATED WITH BELOW (ABOVE) AVERAGE TEMPERATURES
OVER MIDDLE LATITUDES - INCLUDING THE CONUS.
CA - CONSTRUCTED ANALOG - A LINEAR COMBINATION OF PAST OBSERVED ANOMALY
PATTERNS SUCH THAT THE COMBINATION IS AS CLOSE AS DESIRED TO THE INITIAL
STATE. A FORECAST IS OBTAINED BY PERSISTING THE WEIGHTS ASSIGNED TO EACH
YEAR IN THE HISTORICAL RECORD AND LINEARLY COMBINING THE STATES FOLLOWING
THE INITIAL TIME IN THE HISTORICAL YEARS.
CAS - CONSTRUCTED ANALOG SOIL MOISTURE PREDICTION TECHNIQUE.
CCA - CANONICAL CORRELATION ANALYSIS - A TECHNIQUE WHICH PREDICTS THE STATUS OF
U.S. T AND P FOR SOME FUTURE TARGET SEASON USING THE MOST RECENT 4 NON-
OVERLAPPING SEASONAL OBSERVATIONS OF TROPICAL PACIFIC SST - CIRCULATION AND
U.S. T OR P TO CHARACTERIZE THE RECENT BEHAVIOR OF THE CLIMATE - AND PAST
OBSERVATIONS TO PLACE RECENT BEHAVIOR INTO A HISTORICAL CONTEXT.
CDC - CLIMATE DIAGNOSTIC CENTER. A NOAA ENVIRONMENTAL RESEARCH AND DEVELOPMENT
FACILITY HTTP://WWW.CDC.NOAA.GOV
CLIMATOLOGY - THE 30-YEAR AVERAGE OF A VARIABLE - LIKE TEMPERATURE - AT A
GIVEN LOCATION AND TIME OF YEAR.
CONUS - CONTERMINOUS UNITED STATES
CONVECTION - A PROCESS WHEREBY AIR BECOMES BUOYANT RELATIVE TO ITS SURROUNDINGS
AND BEGINS TO RISE IN A CONCENTRATED COLUMN - WHILE THE SURROUNDINGS SUBSIDE
OVER A MUCH LARGER AREA. THE TERM IS OFTEN USED TO DESCRIBE THE OCCURENCE OF
DEEP CUMULUS CONVECTION IN THE TROPICAL OCEANS.
CPC - CLIMATE
PREDICTION CENTER. A NOAA FACILITY WHICH PRODUCES OPERATIONAL
PREDICTIONS FOR 6-10-, 8-14-DAYS, MONTHLY AND SEASONAL TIME FRAMES.
http://www.cpc.ncep.noaa.gov
DATELINE - A HYPOTHETICAL LINE APPROXIMATELY ALONG THE 180TH MERIDIAN DESIGNATED
AS THE PLACE WHERE EACH CALENDAR DAY BEGINS.
DYNAMICAL MODEL - A PREDICTION METHOD WHICH USES EQUATIONS DESCRIBING THE
PHYSICAL BEHAVIOR OF A SYSTEM AND A COMPREHENSIVE SET OF CURRENT OBSERVATIONS
OF THE VALUES OF THE VARIABLES DESCRIBING THE CURRENT STATE OF THE SYSTEM
(INITIAL CONDITIONS) TO PREDICT THE VALUES OF THOSE VARIABLES A SHORT TIME-STEP
IN THE FUTURE. THOSE VALUES ARE - IN TURN - USED AS THE INITIAL CONDITIONS FOR
A SUBSEQUENT PREDICTION - AND SO ON - UNTIL THE DESIRED FUTURE PREDICTION TIME
IS REACHED.
EASTERLY WIND - WIND BLOWING FROM EAST TO WEST.
EC - EQUAL CHANCES - THE PROBABILITY OF THE MOST LIKELY CATEGORY CANNOT BE
DETERMINED AND THE EXPECTED LIKELIHOODS OF ABOVE - NORMAL - AND BELOW DO NOT
DIFFER FROM THEIR CLIMATOLOGICAL ODDS OF 33 1/3% EACH. EC REPLACES CL.
EL NINO - THE WARM PHASE OF THE ENSO CYCLE
ENSO - EL NINO/SOUTHERN OSCILLATION
FORCED OR FORCING - GENERALLY REFERS TO WARM OCEAN SURFACE TEMPERATURES IN
THE TROPICAL OCEANS WHICH SUCCESSIVELY INFLUENCE THE STRENGTH OF TROPICAL
CUMULUS CONVECTION - THE TROPICAL LARGE-SCALE ATMOSPHERIC CIRCULATION - THE
JET STREAMS AND FINALLY - THE MIDDLE LATITUDE CIRCULATION.
GCM - GENERAL CIRCULATION MODEL - A GENERIC TERM APPLIED TO GLOBAL DYNAMICAL
MODELS.
IRI - INTERNATIONAL RESEARCH INSTITUTE FOR CLIMATE PREDICTION - A NOAA-FUNDED
NON-GOVERNMENTAL ORGANIZATION WHICH PREPARES INTERNATIONAL CLIMATE FORECASTS.
http://iri.columbia.edu
ITCZ - INTERTROPICAL CONVERGENCE ZONE - A LINE WHERE THE SOUTHEASTERLY AND
NORTHEASTERLY TRADE WINDS CONVERGE - CHARACTERIZED BY ENHANCED CONVECTION.
IT MAY BE IN EITHER THE NORTHERN OR SOUTHERN HEMISPHERE - AND OCCASIONALLY
A DOUBLE ITCZ MAY BE SEEN IN BOTH HEMISPHERES NOT FAR FROM THE EQUATOR.
LA NINA - THE COLD PHASE OF THE ENSO CYCLE
MJO - MADDEN-JULIAN OSCILLATION - ALSO CALLED TROPICAL INTRA-SEASONAL OSCILLA-
TION - A DISTURBANCE IN TROPICAL CONVECTION - PRECIPITATION - WIND AND
PRESSURE. MJO PRECIPITATION AND CLOUDINESS ARE ENHANCED ONLY IN REGIONS WHERE
SSTS ARE VERY WARM - E.G. INDIAN OCEAN AND WEST PACIFIC. THE PRESSURE AND WIND
DISTURBANCE ASSOCIATED WITH MJO IS OBSERVED TO MOVE FROM WEST TO EAST
COMPLETELY AROUND THE GLOBAL TROPICS IN ABOUT 30 TO 60 DAYS.
NAO - NORTH ATLANTIC OSCILLATION TELECONNECTION PATTERN - WHICH MAY BE
CONSIDERED AS THE ATLANTIC HALF OF THE AO. NOTE THAT THE STATUS OF THE
AO/NAO AND OTHER SLOWLY VARYING CIRCULATION MODES - WHILE VERY IMPORTANT
IN DETERMINING THE TEMPERATURE AND PRECIPITATION REGIMES OVER THE U.S. - ARE
UNPREDICTABLE BEYOND A WEEK OR TWO AHEAD AT BEST BY CURRENT TECHNOLOGY AND ARE
NOT EXPLICITLY INCLUDED IN OUR FORECAST PROCESS AS RELIABLE PREDICTORS.
NORTHERLY WIND - WIND BLOWING FROM NORTH TO SOUTH.
OCN - OPTIMAL CLIMATE NORMALS - A FORECAST BASED ON PERSISTING THE AVERAGE
OF THE LAST 10 YEARS FOR TEMPERATURE AND THE LAST 15 YEARS FOR PRECIPITATION.
OLR - OUTGOING LONGWAVE RADIATION (HEAT) WHICH IS OBSERVED BY SATELLITE. IN
THE TROPICS - LOWER THAN AVERAGE OLR INDICATES ENHANCED DEEP CUMULUS CLOUDS
AND RAIN (SATELLITE IS SEEING COLD CLOUD TOPS) - WHILE HIGHER THAN AVERAGE OLR
INDICATES AN ABNORMAL ABSENCE OF CLOUDS AND RAIN (SATELLITE IS SEEING WARM
LOW LAYERS (SHALLOW CLOUDS) OF THE ATMOSPHERE OR THE SURFACE).
PNA - PACIFIC NORTH AMERICAN TELECONNECTION PATTERN.
QBO - QUASI-BIENNIAL OSCILLATION - AN OSCILLATION OF THE WIND IN THE LOWER
STRATOSPHERE BETWEEN EASTERLY AND WESTERLY WHICH REVERSES ON A NEARLY-
2 YEAR TIME SCALE. QBO IS ONE OF THE MOST REGULAR OSCILLATIONS KNOWN.
SIGNAL - THAT PART OF THE VARIATION OF THE ENVIRONMENT WHICH CORRESPONDS TO
A REAL - PHYSICAL PHENOMENON. WHEN THE SIGNAL IS LARGE - ITS SIGNATURE STANDS
OUT ABOVE THE REMAINDER TO THE VARIATION OF THE ENVIRONMENT - CALLED THE NOISE.
SIGNAL IS SOMETIMES PREDICTABLE. NOISE IS NOT. THE RELATIONSHIP BETWEEN
SIGNAL AND NOISE IS EXPRESSED AS A NUMBER - CALLED THE SIGNAL-TO-NOISE RATIO
OR S/N. WHEN S/N IS GREATER THAN 1 - SIGNAL IS LARGER THAN NOISE - AND THE
SIGNATURE OF THE DISTURBANCE CAUSING THE SIGNAL CAN BE SEEN. WHEN S/N IS
LESS THAN 1 WE HAVE NO HOPE OF SEEING OR PREDICTING THE DISTURBANCE.
SMLR - SCREENING MULTIPLE LINEAR REGRESSION - A TECHNIQUE WHICH SELECTS THE BEST
SET OF PREDICTORS - FITTING THEM TO THE OBSERVATIONS TO CREATE EQUATIONS WHICH
CAN BE USED TO MAKE PREDICTIONS.
SOUTHERLY WIND - WIND BLOWING FROM SOUTH TO NORTH.
SPREAD - A MEASURE OF THE VARIATION - OR AGREEMENT AMONG MODEL FORECASTS WHICH
ARE VALID AT THE SAME TIME. LARGE SPREAD INDICATES POOR AGREEMENT. SMALL
SPREAD GENERALLY INDICATES GOOD AGREEMENT AMONG FORECASTS.
SST - SEA SURFACE TEMPERATURE
STATISTICAL PREDICTIONS - PREDICTIONS BASED MAINLY ON LARGE OBSERVATIONAL DATA
SETS. CCA - OCN - SMLR - CAS - CA ARE EXAMPLES OF THESE.
TAO - TROPICAL OCEAN-ATMOSPHERE PROJECT. A SOURCE OF REAL-TIME OBSERVATIONS OF
THE STATUS OF THE TROPICAL PACIFIC. DEVELOPED AND MAINTAINED BY THE PACIFIC
MARINE ENVIRONMENTAL LABORATORY (PMEL) - A NOAA FACILITY.
http://www.pmel.noaa.gov
TELECONNECTIONS - THESE GIVE THE HISTORICAL RELATIONSHIP BETWEEN A GIVEN POINT
AND ALL OTHER POINTS OVER A LARGE AREA - LIKE THE NORTHERN HEMISPHERE - FOR A
GIVEN TIME OF THE YEAR. THE POINTS ON THE MAP USUALLY CONSIST OF A SET OF
MORE OR LESS EVENLY SPACED LOCATIONS CALLED GRID POINTS.
TREND - AT A GIVEN LOCATION AND TIME OF YEAR - THE DIFFERENCE BETWEEN THE
AVERAGE OF THE MOST RECENT 10 (15) YEARS OF OBSERVATIONS OF T (P) AND THE
CLIMATOLOGY.
UPPER AIR HEIGHT PATTERN - A PATTERN FORMED BY THE CONTOURS WHICH MAP THE
TOPOGRAPHY OF THE HEIGHT ABOVE SEA LEVEL OF A SURFACE ALONG WHICH THE PRESSURE
IS EVERYWHERE THE SAME. THE LINES ON THIS MAP FORM A SERIES OF UNDULATING BUT
MORE OR LESS CIRCULAR SHAPES WHICH ARE CONCENTRIC ABOUT THE POLES AND WHICH
RESEMBLE A CROSS SECTION OF AN ONION. WELL ABOVE THE GROUND THE WIND BLOWS
PARALLEL TO THE CONTOURS WITH LOW PRESSURE TO THE NORTH (SOUTH) IN THE
NORTHERN (SOUTHERN) HEMISPHERE - GENERALLY FROM WEST TO EAST - WITH SPEED
PROPORTIONAL TO THE SLOPE OF THE SURFACE. THE CLOSER (FARTHER APART) THE
CONTOURS ARE TOGETHER (THE STEEPER (SHALLOWER) THE SLOPE) THE FASTER (SLOWER)
THE WIND SPEED.
WESTERLY WIND - WIND BLOWING FROM WEST TO EAST.
ZONAL FLOW PATTERN - OCCURS WHEN 500-HPA CONTOURS LIE IN AN EAST-WEST DIRECTION
PARALLEL TO LATITUDE CIRCLES WITH NEARLY PURE WEST-TO-EAST FLOW.
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