{"Bibliographic":{"Title":"Gulf Stream System landward surface edge statistics","Authors":"","Publication date":"1983","Publisher":""},"Administrative":{"Date created":"08-20-2023","Language":"English","Rights":"CC 0","Size":"0000041992"},"Pages":["H\nQC\n851\nOF COMMUNITY\nU6\nN5\nno.67\nNOAA Technical Memorandum NWS NMC 67\n*\n*\nwith\nAbsence\nSTATES\nOF\nGULF STREAM SYSTEM LANDWARD SURFACE EDGE STATISTICS\nWashington, D.C.\nOctober 1983\nU.S. DEPARTMENT OF\n/\nNational Oceanic and\n/\nNational Weather\nCOMMERCE\nAtmospheric Administration\nService","NOAA TECHNICAL MEMORANDUMS\nNational Meteorological Center\nNational Weather Service, National Meterological Center Series\nThe National Meteorological Center (NMC) of the National Weather Service (NWS) produces weather anal-\nyses and forecasts for the Northern Hemisphere. Areal coverage is being expanded to include the entire\nglobe. The Center conducts research and development to improve the accuracy of forecasts, to provide\ninformation in the most useful form, and to present data as automatically as practicable.\nNOAA Technical Memorandums in the NWS NMC series facilitate rapid dissemination of material of general\ninterest which may be preliminary in nature and which may be published formally elsewhere at a later\ndate. Publications 34 through 37 are in the former series, Weather Bureau Technical Notes (TN), Na-\ntional Meterological Center Technical Memoranda; publications 38 through 48 are in the former series\nESSA Technical Memoranda, Weather Bureau Technical Memoranda (WBTM). Beginning with 49, publications\nare now part of the series, NOAA Technical Memorandums NWS.\nPublications listed below are available from the National Technical Information Service (NTIS), U.S.\nDepartment of Commerce, Sills Bldg., 5285 Port Royal Road, Springfield, VA 22161. Prices vary for\npaper copies; $4.50 microfiche. Order by accession number, when given, in parentheses.\nWeather Bureau Technical Notes\nTN\n22\nNMC\n34 Tropospheric Heating and Cooling for Selected Days and Locations over the United States\nDuring Winter 1960 and Spring 1962. Philip F. Clapp and Francis J. Winninghoff, 1965,\n18 pp. (PB-170-584)\n30 NMC 35 Saturation Thickness Tables for the Dry Adiabatic, Pseudo-adiabatic, and Standard Atmo-\nTN\nspheres. Jerrold A. LaRue and Russell J. Younkin, January 1966, 18 pp. (PB-169-382)\nTN\n37\nNMC\n36 Summary of Verification of Numerical Operational Tropical Cyclone Forecast Tracks for\n1965. March 1966, 6 pp. (PB-170-410)\nNMC 37 Catalog of 5-Day Mean 700-mb. Height Anomaly Centers 1947-1963 and Suggested Applica-\nTN\n40\ntions. J. F. O'Connor, April 1966, 63 pp. (PB-170-376)\nESSA Technical Memoranda\nWBTM NMC 38 A Summary of the First-Guess Fields Used for Operational Analyses. J. E. McDonell, Feb-\nruary 1967, 17 pp. (AD-810-279)\nWBTM NMC 39 Objective Numerical Prediction Out to Six Days Using the Primitive Equation Model-A Test\nCase. A. J. Wagner, May 1967, 19 pp. (PB-174-920)\nWBTM NMC 40 A Snow Index. R. J. Younkin, June 1967, 7 pp. (PB-175-641)\nWBTM NMC 41 Detailed Sounding Analysis and Computer Forecasts of the Lifted Index. John D. Stackpole,\nAugust 1967, 8 pp. (PB-175-928)\nWBTM\nNMC 42 On Analysis and Initialization for the Primitive Forecast Equations. Takashi Nitta and\nJohn B. Hovermale, October 1967, 24 pp. (PB-176-510)\n43 The Air Pollution Potential Forecast Program. John D. Stackpole, November 1967, 8 pp.\nWBTM\nNMC\n(PB-176-949)\nWBTM\nNMC\n44\nNorthern Hemisphere Cloud Cover for Selected Late Fall Seasons Using TIROS Nephanalyses.\nPhilip F. Clapp, December 1968, 11 pp. (PB-186-392)\nWBTM\nNMC\n45 On a Certain Type of Integration Error in Numerical Weather Prediction Models. Hans\nOkland, September 1969, 23 pp. (PB-187-795)\nWBTM\nNMC\n46\nNoise Analysis of a Limited-Area Fine-Mesh Prediction Model. Joseph P. Gerrity, Jr., and\nRonald D. McPherson, February 1970, 81 pp. (PB-191-188)\nNMC 47 The National Air Pollution Potential Forecast Program. Edward Gross, May 1970, 28 pp.\nWBTM\n(PB-192-324)\n48 Recent Studies of Computational Stability. Joseph P. Gerrity, Jr., and Ronald D. McPher-\nWBTM\nNMC\nson, May 1970, 24 pp. (PB-192-979)\n(Continued on inside back cover)","H\nQC\n851\nU6 N5\nno. 67\nNOAA Technical Memorandum NWS NMC 67\nGULF STREAM SYSTEM LANDWARD SURFACE EDGE STATISTICS\nn\nStephen J. (Auer\nOctober 1983\nWashington, D.C.\nOctober 1983\nCENTRAL\nLIBRARY\nOCT 27 1983\nN.O.A.A.\nU. S. Dept. of Commerce\nDEPARTMENT AND ATMOSPHERIC\nUNITED STATES\nNational Oceanic and\nNational Weather Service\nNOAA\nINSTRUCTIONS\nAMOUNT\nDEPARTMENT OF COMMERCE\nAtmospheric Administration\nRichard E. Hallgren,\nMalcolm Baldrige, Secretary\nJohn V. Byrne, Administrator\nActing Assistant Administrator\nS\nOF","I/1508","CONTENTS\nPage\n1\n1.\nIntroduction\n1\n2. NWS/NESS Oceanographic Analysis\n4\n3. Gulf Stream Features Data File\n4. Statistical Analysis of Data File.\n5\n7\n5. Gulf Stream Statistics\n16\nComparison with Other Studies\n6.\n19\n7. Summary\n20\nReferences\niii","Gulf Stream System Landward Surface Edge Statistics\nSteve Auer\nNOAA, NWS, National Meteorological Center\nWashington, DC 20233\n1. INTRODUCTION\nThis paper represents a statistical evaluation of the mean position,\nstandard deviation, and maximum northward and southward positions of the\nGulf Stream System landward surface edge. The surface edge is determined\nfor each 0.5° longitudinal transect from 91°-44°W measuring the course\nof the Gulf Stream System from the Yucatan Strait to the Grand Banks.\nThese statistics are derived from the initial year of the daily Oceano-\ngraphic Analysis (May 28, 1980 - May 29, 1981), which contains synoptic\nfrontal locations of the Gulf Stream System. The Oceanographic Analysis\nis a joint operational product of the National Meteorological Center\n(NMC) of the National Weather Service and the National Earth Satellite\nService (NESS) (now NESDIS). This operational product has several advan-\ntages as a statistical base of Gulf Stream System variability: 1. A\nsynoptically analyzed Gulf Stream System position is derived several\ntimes per week, 2. the primary data source is high resolution (1 km)\nsatellite imagery, 3. the analysis region covers a large extent of the\nGulf Stream System. NMC has begun to review this historical record to\ngenerate statistics on Gulf Stream System variability as a step towards\nits goal of forecasting the Gulf Stream System's position.\nThe Gulf Stream System can be subdivided into two major regions:\nThe Loop Current, located in the Gulf of Mexico, and the Gulf Stream,\nlocated in the Northwest Atlantic Ocean. The Gulf Stream System's edge\nis named a \"landward surface edge\" in this paper to signify that it is\nthe edge nearest to the North American continental landmass. This edge\nis predominantly detected by satellite imagery which measures the \"skin\"\n(the first millimeter) of the sea surface. This paper will describe the\ndaily Oceanographic Analysis, provide details on the Gulf Stream features\ndata file and statistics program, present the resultant NMC Gulf Stream\nSystem landward surface edge statistics, and compare these NMC statistics\nto those of two other surveys.\n2. NWS/NESS OCEANOGRAPHIC ANALYSIS\nThe NWS/NESS Oceanographic Analysis is a subjectively determined,\nreal-time, synoptic ocean feature analysis covering the Northwest Atlantic\nand Gulf of Mexico. This large analysis region is operationally divided\ninto two product sections, the (U.S.) Northeast Coast and the (U.S.) Southeast\nCoast. The analysis for the Northeast Coast (fig. 1), bounded by 35°-50°N\nand 44°-76°W, is produced each Monday, Wednesday, and Friday. The analysis\nfor the Southeast Coast (fig. 2), bounded by 18° °-36°1 - N and 65°-98°W, is\n1","8\n16\n7\n140°\n45\n3\n19\n8\n50°\n4\n- Oceanographic Analysis - - Northeast Coast from May 30, 1980\nshw\nSIW\n17\n4\nWE\n21\n9\n60°\nWE\n23\n3\nshw\n5\nSIW\n8\n21\n6\n12\nE\nWE\n22\nshw\nshw\nSAR\n20\n15.\nHydrog apher Canyon\nKey for Submerine Canyone\nWashington Canyon\nWilmington Canyon\nBalamore Canyan\nLydenia Canyon\nHudeon Canyon\nCorear Canyon\nAtlanta Canyon\nBlock Canyon\nFigure 1.\n26\nID\n70°\nOCEANOGRAPHIC IR'ALYSIS\nWe\nHy\nC\nMAY 30,1980\nNATIONAL EARTH SATELLITE SERVICE\n19\n22\nSEA SURFACE EMPERATURE (\")\nESTIMATED FRONTAL LOCATION\nDIRECTION OF FLOW NOT AXIS\nWE\nas\nNATIONAL WEATHER SERVICE\nFRONTAL LOCATION\nSARGASSC WATER\n15 500\n14 572\n13 55 4\n12 53 6\n11 518\n10 500\n0 482\n0 48 4\n44 6\n42 8\n5 410\nC F\n13\nGULF STRE 3\nSHEL WATER\nSLOPE WATER\nTEMPERATURE\nCONVERSIONS\nWARMEDO\nCOLDEDOY\nW\nICE EDGE\nB\nD127 Nas #587\nSYMBOL LEGEMO\nWe\n78 B\n770\n752\n734\n710\n00 8\nOPC\n17 62 d\n1 th 00 8\nso\n64\nDATE\nShw\nBAR\nXXX\nSNW\nos\nWE\nCE\n18\nC\n27\n20\n25\n24\n23\n2n\n21\n20\nIN\n2","27\n26\n25\n130°\nof\n27\n20\n22\n70°\nCA\n27\nSAR\nFigure 2. - - Oceanographic Analysis - - Southeast Coast from May 29, 1980\n24.\n24\n26\n26\ns\n0010\n26\n0.\nGS\no\n80°\n25\n28\nis 590\n536\n510\n500\n482\n44 6\n42 8\n410\n5.\n13 ss.\nas\nTEMPERATURE\nCONVERSIONS\nC\n14\n12\n11\n10\nD\n2:\n28\n80 6\n26 78 8\n25 770\n752\n734\n716\n69 8\n680\n19 66 2\n18 64 4\n17 62 0\n16 60 8\nC\n27\n24\n23\n22\n21\n20\n23\nSEA SURFACE TEMPERATURE (c)\nESTIMATED FRONTAL LOCATION\nDIRECTION OF FLOW NOT AXIS\nSUBTROPICAL CONVERGENCE\nZ.\nFRONTAL LOCATION\nSARGASSO WATER\nLOOP CURRENT\nGULF STREAM\nSHELF WATER\nSLOPE WATER\n200m\nWARM EDDY\nCO D FOOY\n27\nSYMBOL LEGEND\n90\nSnw\nSAR\nSM\nSTC\n28\nGS\nWE\nLC\nCE\n19\n21\nOCEANOG. RAPHIC ANALYSIS\nDATE MAY 29, 1980\nNATIONAL EARTH SATELLITE SERVICE\n26\n21\nNATIONAL WEATHER SERVICE\n26\nD127 N98 #587\n3","produced each Tuesday and Thursday. These products are disseminated by\nNWS facsimile, auto-telecopier, marine weather radio, and mail. Oceano-\ngraphic features depicted on the products include the Loop Current, the\nGulf Stream, anticyclonic eddies, cyclonic eddies, the shelf/slope\nfront, Sargasso water, and the Labrador Current.\nThe real-time data used in the Oceanographic Analysis includes NOAA\nsatellite imagery, expendable bathythermograph data (XBT), and sea surface\ntemperatures (SST) from data buoys, satellites, and ships. NOAA polar-\norbiting infrared satellite imagery, with a resolution of 1 km, is the\npredominant data source used to determine feature boundaries. Available\nXBT's also are used to determine the feature boundaries.\nData gaps - areas where feature positions are not known - frequently\noccur in the synoptic record of the Oceanographic Analysis. These are\nusually caused by cloudiness, obscuring satellite monitoring of the\nsea surface. The spatial and temporal span of these data gaps varies.\nIn an extreme case, cloud-related data gaps lasting several weeks have\noccurred in the Northeast Coast product area east of 55°W during wintertime.\nAnother cause of a data gap occurs when the intense seasonal heating of\nthe surface waters weakens the surface gradients creating a near-isother-\nmal condition. This condition can inhibit the analysis of ocean\nfeatures in regions south of 35°N, especially in the Gulf of Mexico.\nDuring the initial analysis year, the Loop Current was not observed from\nJuly to late October due to this seasonal heating effect. For more\ncomplete details on the NWS/NESS Oceanographic Analysis, the reader is\nreferred to Gemmill and Auer (1982).\n3. GULF STREAM FEATURES DATA FILE\nThe Gulf Stream features data file is a digital file of weekly\nsynoptic positions of the Stream's landward surface edge. The file also\ncontains locations and sizes of Gulf Stream eddies (eddy statistics are\nnot discussed in this paper). This weekly file is derived from the\ndaily Oceanographic Analysis and is objectively analyzed to yield the\nGulf Stream statistics. A weekly synoptic period of feature positions\nis chosen to reduce the occurrence of data gaps while still maintaining\ncontinuity in feature changes.\nTo determine the weekly Gulf Stream position, the five daily Oceano-\ngraphic Analyses for that week are reviewed and one \"complete as possible\"\nobserved weekly Gulf Stream edge position is determined. This weekly\nposition is time centered about 0000Z Thursday. For example, from the\nNortheast Coast product section of the analysis, the day order of pre-\nference for a weekly edge position is Wednesday, Friday, and Monday, in\nthat order. Similarly, from the Southeast Coast product section, Thursday\nis preferred over Tuesday. After reviewing the five daily analyses, any\ndata gaps remaining in the weekly edge are left blank. For instance, if\nthe landward edge is not seen east of 60°W during the week, no weekly\nedge is entered into the file for that area.\n4","The map grid scheme for entering Gulf Stream data into the Gulf\nStream features data file is composed of 0.5° longitudinal transects from\n91°-44°W. The weekly edge is determined on each transect to the nearest\n0.1° of latitude. In order to accurately describe the landward edge,\nthere is an allowance for one to three edge crossings on a transect.\nMultiple crossings are usually needed to describe the Loop Current, the\nGulf Stream at 80°W, and Gulf Stream meanders. Figure 3 shows the 0.5°\nlongitudinal transect grid overlaid with a typical weekly edge position.\nIn figure 3, two edge crossings are seen at 86.5°-88°W (in Loop Current)\nand at 80°W (Gulf Stream); three edge crossings are seen at 58.5°-60°W (Gulf\nStream meander). The majority of the longitudinal transects only have\none edge crossing.\nThe following explanation of these multiple edge crossings is given\nto avoid potential confusion in understanding the data file set-up. The\nmost intricate part of the file is for the Loop Current because it can\nassume a variety of spatial configurations and because it is not always\npresent at longitudes west of 86°W. To define the Loop, an imaginary\naxis of reference is chosen along the 86°W longitude. When the Loop is\npresent at a longitudinal transect west of 86°W, it always crosses the\ntransect twice. On the other hand, the Loop is always present at longi-\ntudes east of 86°W and can cross a transect one to three times depending\non the Loop configuration. In figure 3, the Loop is not present west of\n88°W, crosses transects 86.5°-88°W twice, and crosses transects east of\n86.5°W only once.\nThe Gulf Stream is always defined with two crossings at 80°W.\nAs the Stream flows along the Florida coast, the landward edge remains\nnear 80°W for about 550 km. The first edge crossing is determined where\nthe Stream edge first touches or crosses 80°W and the second edge is\ndetermined where the Stream edge last departs from 80°W. In figure 3,\nthe Stream initially crosses 80°W at 25°N and departs at 30.5°N.\nGulf Stream meanders sometimes require two to three edge crossings\non a longitudinal transect to accurately define their positions. One\nexample of such a case is seen in figure 3 for the meander at 58.5°-60°W.\nHowever, the meander downstream at 54°-57°W requires only one edge\ncrossing per transect.\n4. STATISTICAL ANALYSIS OF DATA FILE\nThe landward surface edge statistics of maximum northward and southward\npositions, mean edge position, and standard deviation are computed from the\nGulf Stream features data file along each 0.5 longitudinal transect. A\ntotal count of the number of observations (observed weekly edge positions)\nis provided for each transect. In addition, the total number of weeks\nthat the Loop Current is observed to be absent along transects 86.5°-91°W\nis provided.\nFor most of the Gulf Stream System, only one statistical edge deter-\nmination per transect is needed, but several transects do require multiple\ndeterminations. Two edge determinations are needed at 80°W since, as\n5","1980,\n26-30,\nsurface\nFigure\n6","mentioned, the Stream generally flows along this transect from about\n25.5°-30.5°N. Two edge determinations per transect are needed to define\nthe Loop Current west of 86°W. The first transect crossing is for the\ninitial flow from the Yucatan Strait west into the Gulf and the second\ntransect is for the return flow as the Loop turns and flows eastward\nacross the Gulf north of 25°N. Either one or three edge crossings per\ntransect is needed to define the Loop from 84°-85.5°W because the Loop\nexhibits two basic configurations here. For example, the Loop may have\na rounded Z-shape configuration across these transects, in which case,\nthree edge determinations per transect are needed. Or, the Loop may\nhave a simple, falling curve shape which requires only one edge determin-\nation per transect. The statistical values are computed for both cases.\nFor the data used in this study, over 70% of the observed weeks had only\none edge crossing per transect in this region. Therefore, only one\nstatistical edge position will be given in this paper.\nThe maximum northward and southward edge positions during the data\nperiod (one year in this study) are determined by comparing all the edge\ncrossings at each 0.5° longitudinal transect. The maximum northward\nedge is the northernmost latitude edge observed and the maximum southward\nedge is the southernmost latitude edge.\nThe mean landward edge is computed for each transect by summing up\nthe weekly edge observations and dividing by the number of observed\nweeks. However, only one edge position per transect per week is allowed\nin the summation. For a week when a transect has two to three edge\ncrossings, such as for a Stream meander, a weekly mean value is computed\nfrom the most northward and southward crossings. This value then becomes\nthe weekly edge value to be used in the computation of the mean. Of\ncourse, this multiple-edge procedure does not apply to the Loop Current\nfrom 86.5°-91°W and the Stream at 80°W.\nThe standard deviation about each calculated transect mean is determined\nby first squaring and summing the weekly edge crossings. However, only one\ntransect entry per week is allowed in the summation. For a week when a\ntransect has two to three edge crossings, except from 86.5°-91°W and at\n80°W, the weekly entry is the mean of the squares of the most northward\nand southward edge crossings. This mean weekly value is used to preserve\nthe variability. Finally, standard deviation is determined by computing\nthe square root of the absolute value of the total sum of the squares\ndivided by the number of observed weeks subtracted from the mean squared.\nA count of the number of weeks that the Loop is absent at longitudinal\ntransects 86.5°-91°W is also made. For each transect this count indicates\nthe number of weeks in which the Loop did not cross that transect. This\nvalue does not include weeks of no data, such as, during summertime\nsolar heating and cloudiness. This record of Loop occurance will show\nthe westward variability of the Loop Current.\n5.\nGULF STREAM STATISTICS\nTable 1 shows the westward variability of the Loop Current from the\nstudy data, May 28, 1980-May 29, 1981. However, as mentioned earlier,\nthere are no Loop data for much of July-October because of the seasonal\nheating effect. During the data period, the Loop was always present\n7","Table 1 . - Loop Current westward variability. Loop Current occurrence at\nlongitudinal transects 86.5°-91°W.\n% Time\nLoop\nLoop\nabsent\nLoop present\nLongitude\nObservations\npresent\n91.0\n38\n0\n38\n0.0\n38\n0.0\n90.5\n38\n0\n2.6\n90.0\n38\n1\n37\n89.5\n38\n4\n34\n10.5\n28\n26.3\n89.0\n38\n10\n11\n26\n29.7\n88.5\n37\n37\n23\n14\n62.2\n88.0\n25\n13\n65.8\n87.5\n38\n10\n73.7\n87.0\n38\n28\n37\n0\n100.0\n86.5\n37\n8","heating effect. During the data period, the Loop was always present\nalong 86.5°W, never present west of 90.0°W, and present less than 30% of\nthe time west of 88°W. For this reason, the mean curve of the Loop will\nbe arbitrarily placed no further west than 88°W.\nFigure 4 contains three weekly Gulf Stream landward edge data dis-\ntribution plots for the longitudinal transects along 86°W in the Loop\nCurrent, along 72°W just east of Cape Hatteras, and along 61°W in the\nGulf Stream meander region. The distribution curve at 72°W has the\nclosest resemblence to a normal \"Gaussian\" curve, while the curve at\n86°W appears flatter and more random. Because the sample size is small\n(<100), no conclusions will be made on the stationarity of the process\nand normality will be assumed.\nTable 2 contains the computed statistical values of mean, standard\ndeviation, and maximum northward and southward edges for each transect.\nAlso included in table 2 are the number of weekly observations and the\ndates of maximum northward and southward edge occurrence.\nThe number of weekly edge observations along longitudinal transects\neast of 86°W ranges from a low of 26 at 44°W to the possible maximum of\n53 from 75°-71°W. Those transects with fewer than 53 observations reflect\nthe number of weeks of no data, either due to cloudiness or the seasonal\nheating effect. For longitudinal transects 86.5°-91°W, the smaller\nnumber of observations is also in part due to the westward migration\ncharacteristic of the Loop, as illustrated in table 1.\nFigure 5 shows the statistical curves. The maximum northward and\nsouthward edge curves (dashed lines) indicate that the Loop Current has a\nnorthward intrusion range from 24°-28°N and a westward intrusion range from\n86.5°-90°W. The Gulf Stream's latitudinal range (i.e., between the maximum\ncurves) increases downstream in what appears to be four distinct growth\nzones. The range is small in the Florida Straits (83°-80°W). The smallest\nrange value is 67 km at both 81.5°W and 80.5°W. The range exhibits a\nslight increase along the Carolinas (80°-75°W), probably a result of the\nsmall amplitude waves which normally propagate downstream from 78°W.\nThe Stream range increases again between 75°-70°W. This increase is due,\nin part, to the presence of small amplitude meanders which translate\nthrough the region. The range is largest east of 70°W, a result of the\nlarge amplitude meanders found translating downstream in this region.\nThe maximum range value is 745 km at 48°W. These maximum curves must be\nused with caution because the data represents only one year, and further\ninput of data will probably increase the ranges of most, if not all, of\nthese transects.\nThe mean curve in figure 5 (solid line) is arbitrarily cut off west\nof 88°W in the Loop Current as mentioned previously. To show continuity\nin the Gulf Stream System's flow, the mean curve line is drawn along 88°W\nconnecting the two defined mean points. A similar adjustment is also\ndone at 80°W, because the small east-west movement of the Gulf Stream edge\nas it flows north along 80°W is not accounted for by the 0.5° longitudinal\ntransect grid scheme. A small dip is seen in the mean northern Loop\nedge curve at 86.5°W. This may be interpreted as a result of the Loop\nCurrent's intrusion pattern, where the Loop intrudes westward as well as\n9","Number of\nObservations\n5\n4\n86.0°W\n3\n2\nn = 35\n1\n24°N\n25°N\n26°N\n27°N\n28°N\n29°N\nLatitude\nNumber of\nObservations\n7\n6\n5\n72.0°W\n4\n3\na = 53\n2\n1\n36°N\n37°N\n38°V\n39°N\nLatitude\nNumber of\nObservations\n6\n5\n61.0 W\n4\n3\nn = 49\n2\nI\n37°N\n38°V\n39°N\n40°N\n41°N\n42°N\nLatitude\nFigure 4. --Gulf Stream landward surface edge data distribution curves at\nthree selected longitudes\n10","Standard\nDeviation\nTable 2. - NMC Gulf Stream Landward surface edge statistical values listed by longitude (note 86.5°-91°W\n0.50\n0.70\n0.40\n0.78\n0.89\n0.63\n0.53\n0.61\n0.84\n1.03\n0.85\n1.02\n0.97\n0.86\n0.36\n0.23\n0.22\n0.19\n0.18\n0.17\n0.32\n0.23\n0.20\n0.18\n0.23\n0.28\n0.29\n0.32\n0.35\n0.0\n25.60\n24.28\n23.99\n24.20\n31.86\n33.96\n25.00\n24.85\n24.93\n24.64\n23.44\n21.80\n23.99\n24.21\n22.90\n26.00\n25.40\n25.04\n24.61\n24.05\n24.40\n24.74\n25.45\n30.57\n31.45\n32.10\n32.26\n32.50\n32.86\n33.31\nMean\nObservations\nNumber\n0.\n0.\n1.\n4.\n10.\n11.\n21.\n22.\n25.\n32.\n35.\n35.\n34.\n33.\n32.\n32.\n32.\n32.\n32.\n32.\n32.\n32.\n37.\n51.\n51.\n51.\n51.\n50.\n49.\n49.\n50.\n50.\nRange\n0.0\n1.1\n1.2\n0.9\n0.8\n0.6\n2.7\n2.8\n2.7\n2.1\n2.5\n3.2\n4.1\n3.5\n3.9\n4.1\n3.3\n2.5\n0.7\n0.6\n1.3\n1.3\n1.2\n1.0\n0.9\n1.0\n1.5\n1.2\n1.3\n1.4\n100880\n61180\n61180\n120380\n81380\n122480\n12180\n100880\nDate\n81380\n61180\n53080\n120380\n123180\n123180\n123180\n12181\n32581\n22781\n121080\n52081\n50681\n12181\n21381\n42981\n21381\n32581\n52081\n21381\n22781\n22781\nNO OBSERVATIONS AT THIS LONCITUDE\nNO OBSERVATIONS AT THIS LONGITUDE\nMaximum\n20.8\n23.7\nSouth\n25.0\n24.3\n23.9\n23.5\n23.0\n22.2\n21.8\n24.2\n23.5\n23.1\n23.1\n23.2\n23.2\n23.3\n23.5\n23.9\n24.0\n24.4\n30.0\n24.7\n30.6\n31.4\n31.6\n31.7\n31.8\n32.2\n33.2\n32.7\n62580\n100280\n62580\n122480\n111280\n122480\n91180\n61880\nDate\n81380\n123180\n11581\n12181\n81380\n20481\n32081\n111980\n112680\n112680\n21881\n30481\n52081\n40181\n11581\n41581\n42081\n41581\n41581\n32081\n50681\n50681\nhas two listings).\nMaximum\nNorth\n31.3\n24.3\n26.9\n25.0\n25.0\n25.4\n26.6\n26.3\n24.0\n27.0\n25.7\n24.3\n28.3\n26.5\n25.7\n24.5\n24.4\n24.5\n24.5\n24.7\n26.0\n31.8\n32.4\n32.5\n32.7\n33.3\n33.4\n34.0\n34.6\n27.1\nLongitude\n76.0\n83.0\n82.5\n91.0\n90.5\n90.0\n89.5\n89.0\n88.5\n88.0\n87.5\n87.0\n86.5\n86.0\n85.5\n85.0\n84.5\n84.0\n83.5\n82.0\n81.5\n81.0\n80.5\n80.0\n80.0\n79.5\n79.0\n78.5\n78.0\n77.5\n77.0\n76.5","Standard\nDeviation\n0.47\n0.42\n0.62\n0.75\n0.80\n0.90\n0.29\n0.24\n0.24\n0.41\n0.46\n0.70\n0.95\n0.96\n0.88\n0.91\n0.78\n0.77\n0.21\n0.28\n0.35\n0.37\n0.36\n0.39\n0.39\n0.40\n0.42\n0.44\n0.42\n0.51\n0.71\n0.66\n35.96\n37.32\n37.97\n37.93\n38.30\n38.45\n38.75\n34.54\n35.08\n37.94\n38.04\n38.16\n38.26\n38.35\n38.57\n38.90\n39.01\n39.05\n39.09\n39.15\n39.35\n35.61\n36.26\n36.53\n36.78\n36.95\n37.19\n37.46\n37.68\n38.05\n37.91\n38.04\nMean\nObservations\nNumber\n51.\n51.\n51.\n51.\n51.\n50.\n51.\n51.\n51.\n51.\n51.\n51.\n51.\n50.\n49.\n49.\n49.\n48.\n53.\n53.\n53.\n53.\n52.\n51.\n51.\n51.\n51.\n53.\n53.\n53.\n53.\n53.\nRange\n2.4\n2.4\n2.9\n1.2\n1.7\n1.7\n1.5\n1.8\n1.8\n3.2\n3.0\n2.4\n2.3\n2.7\n4.1\n5.2\n5.3\n4.7\n4.6\n4.2\n3.9\n3.9\n3.8\n3.6\n3.8\n3.6\n4.0\n1.1\n1.2\n1.3\n1.3\n1.5\n100880\n90480\n121780\n111980\n90480\n91180\n100880\n62580\nDate\n111980\n90480\n91880\n32581\n100880\n20481\n52081\n52781\n111980\n111980\n52081\n52081\n52781\n52781\n122480\n20481\n20481\n20481\n20481\n21881\n22781\n22781\n12181\n32581\nMaximum\nSouth\n36.0\n36.4\n33.8\n33.9\n35.2\n35.5\n36.0\n36.0\n35.7\n36.5\n36.4\n36.4\n36.3\n36.7\n37.3\n37.1\n36.1\n36.2\n36.9\n36.9\n36.6\n36.7\n37.3\n37.2\n37.3\n37.2\n37.1\n37.1\n37.2\n36.9\n37.0\n37.2\n53080\n82180\n12180\n100280\n100280\n100280\n100280\n100280\n100880\n101580\n72380\n72380\n72380\n72380\n72380\n72380\n72380\n72380\n22781\n73080\n72380\n72380\n61180\nDate\n71680\n82880\n73080\n90480\n30481\n32081\n32081\n32081\n52781\nMaximum\nNorth\n41.0\n35.0\n35.6\n37.0\n37.3\n36.3\n36.7\n37.5\n37.7\n38.0\n38.2\n38.2\n39.5\n39.7\n39.7\n39.4\n38.8\n38.5\n41.5\n39.1\n39.6\n41.8\n42.0\n42.0\n41.8\n41.1\n41.0\n40.9\n40.8\n40.7\n40.6\n41.2\nTable -Continued\nLongitude\n66.0\n61.0\n72.0\n70.0\n68.0\n67.0\n65.0\n64.0\n75.5\n75.0\n74.0\n73.0\n74.5\n73.5\n72.5\n71.5\n71.0\n70.5\n69.5\n69.0\n68.5\n67.5\n66.5\n65.5\n64.5\n63.5\n63.0\n62.5\n62.0\n61.5\n60.5\n60.0","Standard\nDeviation\n0.79\n0.86\n1.00\n0.92\n0.80\n0.60\n0.94\n0.97\n1.02\n0.99\n0.79\n0.75\n0.74\n0.91\n0.82\n0.93\n0.86\n0.69\n0.66\n0.64\n0.64\n0.82\n1.03\n1.24\n1.36\n1.47\n1.41\n1.17\n39.50\n39.43\n39.47\n39.45\n39.51\n39.43\n39.47\n39.94\n39.70\n40.11\n39.62\n39.64\n39.75\n39.64\n39.78\n39.86\n40.06\n39.61\n39.99\n39.95\n39.49\n39.97\n40.23\n40.54\n40.93\n41.26\n42.00\n41.59\nMean\nObservations\nNumber\n48.\n48.\n47.\n47.\n47.\n47.\n47.\n47.\n47.\n47.\n45.\n44.\n44.\n44.\n42.\n41.\n40.\n40.\n40.\n40.\n39.\n39.\n38.\n38.\n37.\n37.\n36.\n36.\n3.2\n3.0\nRange\n4.0\n3.5\n3.6\n2.7\n2.6\n2.6\n3.0\n4.1\n4.3\n3.9\n4.0\n3.9\n4.1\n3.6\n3.4\n3.6\n4.0\n3.1\n3.3\n3.9\n5.5\n6.7\n6.0\n6.4\n5.4\n4.4\n72380\n61180\n60480\nDate\n52781\n52781\n32581\n32581\n72380\n61180\n32081\n32081\n21881\n42981\n52781\n42981\n42981\n40881\n41581\n32081\n50681\n50681\n50681\n42981\n42981\n50681\n50681\n50681\n12181\nMaximum\nSouth\n38.0\n38.0\n38.0\n38.2\n37.3\n37.2\n37.4\n37.9\n37.8\n37.8\n37.9\n37.3\n37.8\n37.8\n37.9\n37.5\n37.2\n38.2\n38.4\n38.2\n38.3\n38.5\n38.0\n38.0\n39.0\n40.0\n38.7\n39.5\n111280\n70980\n70980\n70980\n91880\n102280\n111280\n111280\n110680\n110680\n102280\nDate\n53080\n91180\n91180\n91180\n91180\n91180\n100280\n101580\n92380\n102280\n102280\n51381\n52081\n52081\n51381\n70280\n21381\nMaximum\nNorth\n41.4\n45.1\n41.8\n41.8\n41.2\n41.0\n41.0\n40.7\n41.3\n41.3\n41.7\n40.8\n41.3\n41.3\n41.8\n42.1\n45.0\n43.5\n44.7\n44.9\n44.4\n41.7\n41.4\n41.4\n41.4\n41.3\n41.1\n41.2\nTable 2 - Continued\nLongitude\n55.0\n53.0\n51.0\n59.0\n58.0\n57.0\n49.0\n48.0\n52.5\n52.0\n51.5\n50.5\n50.0\n49.5\n48.5\n47.5\n47.0\n46.0\n46.5\n59.5\n58.5\n57.5\n56.5\n56.0\n55.5\n54.5\n54.0\n53.5","Standard\nDeviation\n1.20\n1.44\n1.26\n1.28\n0.49\n0.45\n0.49\n1.75\n0.93\n0.84\n1.23\n0.0\n42.56\n25.80\n42.91\n42.91\n26.00\n26.54\n26.69\n26.36\n26.67\n26.48\n25.66\n42.41\nMean\nObservations\nNumber\n36.\n35.\n29.\n26.\n0.\n0.\n1.\n4.\n10.\n10.\n22.\n23.\n26.\n36.\n0.0\nRange\n4.4\n6.4\n5.6\n5.9\n1.4\n1.4\n1.8\n4.4\n4.3\n4.9\n7.0\n53080\n53080\n61180\n120380\n61180\nDate\n53080\n53080\n81380\n22781\n32581\n22781\n50681\nNO OBSERVATIONS AT THIS LONGITUDE\nNO OBSERVATIONS AT THIS LONGITUDE\nMaximum\nSouth\n40.0\n39.7\n26.0\n39.7\n39.7\n25.1\n25.9\n25.8\n23.3\n23.6\n23.0\n21.0\n81380\n123180\n80680\n123180\nDate\n102280\n111280\n81380\n10781\n52781\n52781\n10781\n21881\nMaximum\nNorth\n26.5\n44.4\n46.1\n45.3\n45.6\n26.0\n27.3\n27.6\n27.7\n27.9\n27.9\n28.0\nTable 2. - Concluded\nLongitude\n89.5\n86.5\n45.0\n44.0\n45.5\n44.5\n91.0\n90.5\n90.0\n89.0\n88.5\n88.0\n87.5\n87.0","40°\n35°\n30°\n25°\n20\n50°\n45°\n50°\nFigure 5. . -- NMC Gulf Stream landward surface edge statistical curves\n60\n70°\n80°\nStandard Deviation\n90°\nMaximum\nLEGEND\nMean","northward into the Gulf of Mexico. At 86.5°W, because the Loop is always\npresent, the mean value includes the smallest as well as the largest\nLoop intrusions indicated by the maximum extent values. In contrast,\nthe mean Loop values west of 86.5°W, where the Loop is present less than\n80 percent of the time, are biased toward the maximum northward intrusions.\nThus, one would expect the mean Loop values west of 86.5° to be greater\nthan those to the east. The mean maximum northward intrusion of the\nLoop is 26.7°N at 87.5°W.\nIn the Gulf Stream, the influence of the \"Charleston Bump\" bathy-\nmetry feature near 32°N 78°W, which deflects the Gulf Stream seaward of\nthe continental slope (Legeckis, R., 1975), is confirmed through the\nmean curve. The mean curve of the Gulf Stream east of Cape Hatteras is\ndirected roughly east-northeastward from 75°-49°W and then more northeast-\nward from 49°-44°W. The length of the data record and the weekly sampling\nintervals are, apparently, enough to smooth out the individual Gulf Stream\nmeanders. However, the \"bump\" in the mean curve at 55°W is curious. Is\nthis an artifact of data for one year or is it a real feature, implying\nthat more Gulf Stream meanders are present at this location? More years\nof data are required to answer this question.\nThe standard deviation curves (dotted lines) are one standard devi-\nation about the mean curve. Statistically this envelope can be expected\nto contain about 67 percent of all the mean positions of the Gulf Stream,\nwith the assumption that the data are normally distributed. If one were\nto visualize a doubling of the standard deviation about the mean, this\nenvelope statistically would then be expected to contain 95 percent of\nall the mean Stream positions. Thus one can speculate on the validity\nof the maximum curves. Note that at 67.5°W the maximum curve is less\nthan two standard deviations from the mean, while at 65°W the maximum\nis more than five standard deviations from the mean.\nLooking at the standard deviation envelope along the Gulf Stream\nSystem, there is large variability in the Loop Current and small varia-\nbility from the Florida Straits to 75°W. The variability then appears\nto exhibit a linear increase from Cape Hatteras to 44°W, except from 53°\n-50°W where the variability decreases slightly. This pinching of the\nGulf Stream landward edge domain at 53°-50°W is also seen in the maximum\nnorthward and southward curves at this location. This curious feature\nmay be an artifact of the data set, or it may imply a constraining\ninfluence by the Labrador Current, which is generally located to the\nnorth of this region.\n6. COMPARISON WITH OTHER STUDIES\nThe NMC landward surface edge mean is compared to the provisional\nGulf Stream climatology of Baig, Gaby, and Wilder (1981) in figure 6.\nThis climatology determined the monthly surface edge position of the\nGulf Stream System from 90°-75°W. The Gaby curve shown in figure 6 is a\nmean of the 12 monthly mean curves. These monthly mean curves were subjec-\ntively determined from 4 years (November 1976-October 1980) of Gulf Stream\nsurface edge positions. The edge positions were taken from the Gulf\n16","NMC\n75\n36\n35\n10\nline)\n29\n34)\n28\n(solid\n77\n33\nmean\n26\nline)\n24\n25\n(dashed\n78\n\"\n2)\n30\nYe\n29\n28\n26\nMIA\ncan.\n81\nHMC\nGaby,\n82\n30\nBaig,\n83\n87\n6\nFigure\n29\n28\n27\n22\n23\n25\n26\n24","30N\nSON\n45\n40\n35\n40W\n45\nmean (solid lines) with the same by Fisher (1977) (dashed lines).\n50\nFigure 7. - Comparison of NMC Gulf Stream landward surface edge maximum and\nSOUTHERN LIMIT\n55\n60\n65\n70\n75\nBOW","Stream System Flow Chart, a regional operational product of the Miami\nSatellite Field Service Station of NESS. The NMC and Gaby mean curves\nshow good agreement 83°-75°W, but only a fair agreement for the Loop\nCurrent. The Loop Current differences may be a result of several fac-\ntors, including different years of data, different time lengths of data,\nand subjective versus objective mean determinations.\nThe NMC mean and maximum northward and southward curves are compared\nto the Fisher (1977) statistical curves in figure 7. The Fisher curves\nwere determined from a historical bathythermograph data file using the\nwidely accepted Gulf Stream edge convention of 15°C at 200 m depth. The\nNMC mean curve is smoother, but shows good agreement with the Fisher mean\ncurve (+ 0.5°1atitude). Note however that the \"bump\" in the NMC curve at\n55°W is a reverse bump in the Fisher curve. The NMC mean and maximum\ncurves appear to be generally located slightly south of the Fisher curves.\nThis is an unexpected relationship because one expects that the surface\nedge of the Stream would be located north of the 200 m edge. The reason\nfor this apparent contradiction may be because the conventional 200 m\ndetermination used by Fisher can not distinguish Gulf Stream water from\nanticyclonic eddy water as this study does. Thus, a slight northward\nbias could be expected in his curves since anticyclonic eddies occur\nnorth of the Stream.\n7. SUMMARY\nThe NMC Gulf Stream System landward surface edge statistical curves\nrepresent an initial approximation of Gulf Stream variability determined\nfrom the daily, operational NWS/NESS Oceanographic Analysis. The opera-\ntional set up of this product provides, within the limits of present-day\nsynoptic ocean monitoring, a good temporal and spatial record of synoptic\nGulf Stream surface edge locations, except for the Loop Current during\nthe summertime. The future plans of this project include the addition\nof subsequent weekly data into the Gulf Stream Features data file and\nthe recalculation of the statistical curves. A longer data record will\nhopefully yield higher confidence levels in the curves. Other plans\nfor the project include analyzing speed and direction and formation and\nabsorption locations of Gulf Stream eddies, the translation speed and\ngrowth rate of Gulf Stream meanders, and seasonal trends in Gulf Stream\nfeatures. This information will be a valuable step toward NMC's desire\nto eventually forecast the position of the Gulf Stream System.\n19","REFERENCES\nBaig, S., Gaby, D., Wilder, J., 1981. A Provisional Gulf Stream System\nClimatology. Mariners Weather Log 25:5:323-347. (4-year mean\ncurve sent separately by Gaby.)\nFisher, A., , Jr., 1977. Historical limits of Northern Edge of the Gulf\nStream. Gulfstream. 3:7:6-7.\nGemmill, W. H., Auer, S. J., 1982. Operational Regional Scale Surface\nTemperature and Ocean Feature Analyses. First Inter. Conf. on\nMeteorology and Air/Sea Interaction of the Coastal Zone. p. 290-295.\nLegeckis, R., 1975. Applications of Synchronous Meteorological Satellite\nData to the Study of Time Dependent Sea Surface Temperature Changes\nAlong the Boundary of the Gulf Stream. Geophys. Res. Lett. 2:435-438.\n20","(Continued from inside front cover)\nNOAA Technical Memorandums\nNWS NMC 49\nA Study of Non-Linear Computational Instability for a Two-Dimensional Model. Paul D.\nPolger, February 1971, 22 pp. (COM-71-00246)\nNWS NMC 50\nRecent Research in Numerical Methods at the National Meteorological Center. Ronald D.\nMcPherson, April 1971, 35 pp. (COM-71-00595)\nNWS NMC 51\nUpdating Asynoptic Data for Use in Objective Analysis. Armand J. Desmarais, December\n1972, 19 pp. (COM-73-10078)\nNWS NMC 52\nToward Developing a Quality Control System for Rawinsonde Reports. Frederick G. Finger\nand Arthur R. Thomas, February 1973, 28 pp. (COM-73-10673)\nNWS NMC 53\nA Semi-Implicit Version of the Shuman-Hovermale Model. Joseph P. Gerrity, Jr., Ronald D.\nMcPherson, and Stephen Scolnik, July 1973, 44 pp. (COM-73-11323)\nNWS NMC 54\nStatus Report on a Semi-Implicit Version of the Shuman-Hovermale Model. Kenneth Campana,\nMarch 1974, 22 pp. (COM-74-11096/AS)\nNWS NMC 55\nAn Evaluation of the National Meteorological Center's Experimental Boundary Layer model.\nPaul D. Polger, December 1974, 16 pp. (COM-75-10267/AS)\nNWS NMC 56\nTheoretical and Experimental Comparison of Selected Time Integration Methods Applied to\nFour-Dimensional Data Assimilation. Ronald D. McPherson and Robert E. Kistler, April\n1975, 62 pp. (COM-75-10882/AS)\nNWS NMC 57\nA Test of the Impact of NOAA-2 VTPR Soundings on Operational Analyses and Forecasts.\nWilliam D. Bonner, Paul L. Lemar, Robert J. Van Haaren, Armand J. Desmarais, and Hugh M.\nO'Neil, February 1976, 43 pp. (PB-256-075)\nNWS NMC 58\nOperational-Type Analyses Derived Without Radiosonde Data from NIMBUS 5 and NOAA 2 Temp-\nerature Soundings. William D. Bonner, Robert van Haaren, and Christopher M. Hayden, March\n1976, 17 pp. (PB-256-099)\nNWS NMC 59\nDecomposition of a Wind Field on the Sphere. Clifford H. Dey and John A. Brown, Jr.\nApril 1976, 13 pp. (PB-265-422)\nNWS NMC 60\nThe LFM Model 1976: A Documentation. Joseph P. Gerrity, Jr., December 1977, 68 pp. (PB-\n279-419)\nNWS NMC 61\nSemi-Implicit Higher Order Version of the Shuman-Hovermale Model. Kenneth A. Campana,\nApril 1978, 55 pp. (PB-286-012)\nNWS NMC 62\nAddition of Orography to the Semi-Implicit Version of the Shuman-Hovermale Model. Kenneth\nA. Campana, April 1978, 17 pp. (PB-286-009)\nNWS NMC 63\nDay-Night Differences in Radiosonde Observations in the Stratosphere and Troposphere.\nRaymond M. McInturff, Frederick G. Finger, Keith W. Johnson, and James D. Laver, September\n1979, 54 pp. (PB80 117989)\nNWS NMC 64\nThe Use of Drifting Buoy Data at NMC. David Wright, June 1980, 23 pp. (PB80 220791)\nNWS NMC 65\nEvaluation of TIROS-N Data, January-June 1979. David Wright, June 1980, 21 pp. (PB80\n220494)\nNWS NMC 66\nThe LFM II Model--1980. John E. Newell and Dennis G. Deaven, August 1981, 20 pp. (PB82\n156845)","NOAA CENTRAL LIBRARY\nCIRC QC851.U6 N5 no.67\nAuer, Stephe Gulf Stream System landwar\n8398 0004 2635 7\nNOAA SCIENTIFIC AND TECHNICAL PUBLICATIONS\nThe National Oceanic and Atmospheric Administration was established as part of the Department of\nCommerce on October 3, 1970. The mission responsibilities of NOAA are to assess the socioeconomic impact\nof natural and technological changes in the environment and to monitor and predict the state of the solid\nEarth, the oceans and their living resources, the atmosphere, and the space environment of the Earth.\nThe major components of NOAA regularly produce various types of scientific and technical informa-\ntion in the following kinds of publications:\nPROFESSIONAL PAPERS-Important defini-\nTECHNICAL SERVICE PUBLICATIONS-Re-\ntive research results, major techniques, and special\nports containing data, observations, instructions,\netc. A partial listing includes data serials; predic-\ninvestigations.\ntion and outlook periodicals; technical manuals.\nCONTRACT AND GRANT REPORTS- - Reports\ntraining papers, planning reports, and information\nprepared by contractors or grantees under NOAA\nserials; and miscellaneous technical publications.\nsponsorship.\nTECHNICAL REPORTS-Journal quality with\nextensive details, mathematical developments, or\nATLAS-Presentation of analyzed data generally\ndata listings.\nin the form of maps showing distribution of rain-\nfall. chemical and physical conditions of oceans and\nTECHNICAL MEMORANDUMS-Reports of\natmosphere, distribution of fishes and marine\npreliminary, partial, or negative research or tech-\nmammals, ionospheric conditions, etc.\nnology results, interim instructions, and the like.\nAND\nNOAA\nInformation on availability of NOAA publications can be obtained from:\nPUBLICATION SERVICES BRANCH (E/AI13)\nNATIONAL ENVIRONMENTAL SATELLITE, DATA, AND INFORMATION SERVICE\nNATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION\nU.S. DEPARTMENT OF COMMERCE\nWashington, DC 20235\nNOAA--S/T 83-159\n1943 8808 35\n06/04/97\nMAB"]}