Historical Eastern North Pacific Tropical Cyclone Tracks, 1949-2004

Frequently-anticipated questions:

• What does this data set describe?
  1. How should this data set be cited?
  2. What geographic area does the data set cover?
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
  5. What is the general form of this data set?
  6. How does the data set represent geographic features?
  7. How does the data set describe geographic features?
• Who produced the data set?
  1. Who are the originators of the data set?
  2. Who also contributed to the data set?
  3. To whom should users address questions about the data?
• Why was the data set created?
• How was the data set created?
  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
  3. What similar or related data should the user be aware of?
• How reliable are the data; what problems remain in the data set?
  1. How well have the observations been checked?
  2. How accurate are the geographic locations?
  3. How accurate are the heights or depths?
  4. Where are the gaps in the data? What is missing?
  5. How consistent are the relationships among the data, including topology?
• How can someone get a copy of the data set?
  1. Are there legal restrictions on access or use of the data?
  2. Who distributes the data?
  3. What's the catalog number I need to order this data set?
  4. What legal disclaimers am I supposed to read?
  5. How can I download or order the data?
• Who wrote the metadata?

What does this data set describe?

1. How should this data set be cited?

   National Oceanic and Atmospheri, Tropical Prediction Center/National Hurr, 200509, Historical Eastern North Pacific Tropical Cyclone Tracks, 1949-2004: National Atlas of the United States, Reston, VA.

   Online Links:

   • <http://nationalatlas.gov/atlasftp.html?openChapters=chpclim#chpclim>

2. What geographic area does the data set cover?

   West_Bounding_Coordinate: 129.5

   East_Bounding_Coordinate: -85.2

   North_Bounding_Coordinate: 54.0

   South_Bounding_Coordinate: 4.2

3. What does it look like?

4. Does the data set describe conditions during a particular time period?

   Beginning_Date: 19490611

   Ending_Date: 13-Oct-2004

   Currentness_Reference: Ground condition

5. What is the general form of this data set?

6. How does the data set represent geographic features?
   1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • String (19381)

   2. What coordinate system is used to represent geographic features?

      Horizontal positions are specified in geographic coordinates, that is, latitude and longitude. Latitudes are given to the nearest 0.1. Longitudes are given to the nearest 0.1. Latitude and longitude values are specified in Decimal degrees.

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is GRS1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222.
      

7. How does the data set describe geographic features?

   Subtropical and tropical cyclone tracks (described by phralll020.dbf)

   The path followed by the center of a tropical cyclone or related storm. A tropical cyclone is a warm-core, non-frontal low-pressure system that develops over tropical or subtropical waters, covering a large region and with organized convection (i.e. thunderstorm activity) and definite cyclonic (counter-clockwise circular) surface wind circulation. Related storms are those that develop into tropical cyclones or develop from them, such as tropical disturbances, lows, and extratropical storms. (Source: National Oceanic and Atmospheric Administration, Tropical Prediction Center/National Hurricane Center)

   Shape

   The representation of the entity in the data. (Source: National Atlas of the United States)

   Value	Definition
   PolyLine	1-dimensional element that may or may not surround a 2- dimensional element.

   Fnode#

   Internal sequence number of the from-node. (Source: National Atlas of the United States)

   Range of values
   Minimum:	0
   Maximum:	0

   Tnode#

   Internal sequence number of the to-node. (Source: National Atlas of the United States)

   Range of values
   Minimum:	0
   Maximum:	0

   Lpoly#

   Internal sequence number of the left polygon. (Source: National Atlas of the United States)

   Range of values
   Minimum:	0
   Maximum:	0

   Rpoly#

   Internal sequence number of the right polygon. (Source: National Atlas of the United States)

   Range of values
   Minimum:	0
   Maximum:	0

   Length

   Length of the line in coverage units. In the distributed file, coverage units represent decimal degrees. (Source: National Atlas of the United States)

   Range of values
   Minimum:	0.000
   Maximum:	6.096

   Phralll020

   Internal feature number. (Source: National Atlas of the United States)

   Range of values
   Minimum:	1
   Maximum:	19381

   Year

   The year of the storm advisory, in the format yyyy. Advisories are issued for storms that have attained at least tropical depression status, and are issued every six hours, at 0000, 0600, 1200, and 1800 hours. Tropical Prediction Center/National Hurricane Center advisories are discontinued once a storm makes landfall and all storm warnings are dropped, or when the wind speed drops below 30 knots or 35 mph. The records for each date are listed in order. (Source: National Oceanic and Atmospheric Administration, Tropical Prediction Center/National Hurricane Center)

   Range of values
   Minimum:	1949
   Maximum:	2004

   Month

   The month of the storm advisory. Advisories are issued for storms that have attained at least tropical depression status, and are issued every six hours, at 0000, 0600, 1200, and 1800 hours. Tropical Prediction Center/National Hurricane Center advisories are discontinued once a storm makes landfall and all storm warnings are dropped, or when the wind speed drops below 30 knots or 35 mph. The records for each date are listed in order. (Source: National Oceanic and Atmospheric Administration, Tropical Prediction Center/National Hurricane Center)

   Range of values
   Minimum:	1
   Maximum:	12

   Day

   The day of the storm advisory. Advisories are issued for storms that have attained at least tropical depression status, and are issued every six hours, at 0000, 0600, 1200, and 1800 hours. Tropical Prediction Center/National Hurricane Center advisories are discontinued once a storm makes landfall and all storm warnings are dropped, or when the wind speed drops below 30 knots or 35 mph. The records for each date are listed in order. (Source: National Oceanic and Atmospheric Administration, Tropical Prediction Center/National Hurricane Center)

   Range of values
   Minimum:	1
   Maximum:	31

   Btid

   The unique event identifier. Identifiers are sequential, starting with 1 in June, 1949 and ending with 766 in October, 2003. (Source: National Oceanic and Atmospheric Administration, Tropical Prediction Center/National Hurricane Center)

   Range of values
   Minimum:	1
   Maximum:	779

   Name

   The given name of a storm. Storms are named if they are true tropical storms and attain a sustained wind speed of at least 39 mph. (Source: National Oceanic and Atmospheric Administration, Tropical Prediction Center/National Hurricane Center)

   Value	Definition
   NOT NAMED	There is no given name for the storm. Prior to 1950 storms were not named. Later storms that were not recognized as tropical storms or hurricanes at the time of their occurrence are also not named.

   Formal codeset
   Codeset Name:	World-Wide Tropical Cyclone Names
   Codeset Source:	World Meteorological Organization

   Long

   The longitude of the starting point of the storm track segment, in tenths of a degree. Storm center positions are collected every six hours, and each storm center position is represented by a longitude- latitude coordinate pair. When a storm stood still longer than the six-hour collection interval, the next location point was offset approximately 0.0001 degrees to retain relevant information. Any variation in longitude smaller than 0.1 degrees should be assumed to be an introduced offset from the originally recorded point. (Source: National Atlas of the United States)

   Range of values
   Minimum:	-180.0000000
   Maximum:	180.0000000

   Lat

   The latitude of the starting point of the storm track segment, in tenths of a degree. Storm center positions are collected every six hours, and each storm center position is represented by a longitude- latitude coordinate pair. When a storm stood still longer than the six-hour collection interval, the next location point was offset approximately 0.0001 degrees to retain relevant information. Any variation in longitude smaller than 0.1 degrees should be assumed to be an introduced offset from the originally recorded point. (Source: National Atlas of the United States)

   Range of values
   Minimum:	4.2000000
   Maximum:	54.0000000

   Wind_kts

   The measured or estimated wind speed at the time of the advisory, in whole knots. (Source: National Oceanic and Atmospheric Administration, Tropical Prediction Center/National Hurricane Center)

   Value	Definition
   0	The wind speed is unknown.

   Range of values
   Minimum:	10.0
   Maximum:	160.0

   Pressure

   The measured or estimated barometric pressure at the time of the advisory, in millibars. (Source: National Oceanic and Atmospheric Administration, Tropical Prediction Center/National Hurricane Center)

   Value	Definition
   0	The barometric pressure is unknown.

   Range of values
   Minimum:	98
   Maximum:	1018

   Wind_mph

   The measured or estimated wind speed at the time of the advisory, rounded to the nearest 5 miles per hour. (Source: National Oceanic and Atmospheric Administration, NOAA Coastal Services Center)

   Value	Definition
   0	The wind speed in unknown. The barometric pressure is unknown.

   Range of values
   Minimum:	10.0
   Maximum:	185.0

   Category

   The intensity classification of the storm. Hurricanes are classified according to the Saffir-Simpson Hurricane Scale. (Source: National Oceanic and Atmospheric Administration, Tropical Prediction Center/National Hurricane Center)

   Value	Definition
   E	The storm was classified as Extratropical at the time of the advisory. Extratropical is a term used in advisories and tropical summaries to indicate that a cyclone has lost its tropical characteristics. The term implies both that the cyclone has moved out of the tropics and that the energy source driving the storm has changed. While tropical cyclones derive their energy from the convection of warm, moist air, extratropical storms derive their energy from the temperature contrast between warm and cold air masses. It is important to note that cyclones can become extratropical and still retain winds of hurricane or tropical storm force.
   h3	The storm was classified as a Category 1 hurricane at the time of the advisory. A Category 1 hurricane is a tropical cyclone with maximum sustained surface (10 meter) winds of 64 knots/74 mph to 82 knots/95 mph, inclusive.
   H2	The storm was classified as a Category 2 hurricane at the time of the advisory . A Category 2 hurricane is a tropical cyclone with maximum sustained surface (10 meter) winds of 83 knots/96 mph to 95 knots/110 mph, inclusive.
   H3	The storm was classified as a Category 3 hurricane at the time of the advisory. A Category 3 hurricane is a tropical cyclone with maximum sustained surface (10 meter) winds of 96 knots/111 mph to 113 knots/130 mph, inclusive.
   H4	The storm was classified as a Category 4 hurricane at the time of the advisory. A Category 4 hurricane is a tropical cyclone with maximum sustained surface (10 meter) winds of 114 knots/131 mph to 135 knots/155 mph, inclusive.
   H5	The storm was classified as a Category 5 hurricane at the time of the advisory. A Category 5 hurricane is a tropical cyclone with maximum sustained surface (10 meter) winds greater than 135 knots/155 mph.
   L	The storm was classified as a tropical low at the time of the advisory. A tropical low indicates low pressure at the surface, but no other characteristics of a tropical cyclone are present.
   TD	The storm was classified as a tropical depression at the time of the advisory. A tropical depression is a tropical cyclone with maximum sustained surface (10 meter) winds of less than 34 knots/ 39 mph.
   TS	The storm was classified as a tropical storm at the time of the advisory. A tropical storm is a tropical cyclone with maximum sustained surface (10 meter) winds of 34 knots/39 mph to 64 knots/73 mph, inclusive.

Who produced the data set?

1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
   • National Oceanic and Atmospheric Administration, Tropical Prediction Center/National Hurricane Center

2. Who also contributed to the data set?

3. To whom should users address questions about the data?
   NOAA Coastal Services Center
   Clearinghouse Manager
   2234 South Hobson Avenue
   Charleston, SC 29405-2413
   USA
   

   843-740-1200 (voice)
   843-740-1315 (FAX)
   [email protected]
   

   Hours_of_Service: Monday - Friday 8:00 AM - 5:00 PM Eastern Time

Why was the data set created?

These data are intended for geographic display and analysis at the national level, and for large regional areas. The data should be displayed and analyzed at scales appropriate for 1:2,000,000-scale data. No responsibility is assumed by the National Oceanic and Atmospheric Administration or the National Atlas of the United States in the use of these data.

How was the data set created?

1. From what previous works were the data drawn?

   EPA_2004 (source 1 of 1)

   National Oceanic and Atmospheri, Tropical Prediction Center/National Hurr, 200503, Eastern North Pacific Tracks File 1949-2004: NOAA National Hurricane Center, Miami, FL.

   Online Links:

   • <http://www.nhc.noaa.gov/pastall.shtml>

   Type_of_Source_Media: Online

   Source_Contribution: Spatial and attribute information.

2. How were the data generated, processed, and modified?

   Date: Aug-2005 (process 1 of 1)

   Historical track information was downloaded from the National Hurricane Center's Web site. The ASCII text file was formatted into an Arc/INFO table using AML. The INFO table was then processed into a generate file and an attribute table that were converted into an attributed cover.

   Location points are recorded every six hours. Each recorded point was associated with a unique line that extends from that point to the next recorded point. Small line segments, approximately 0.0001 degree long, were added to the end of each storm track to retain the final collection point's information. In the source data, tracks that crossed the 180-degree longitude line had negative longitude values even in the eastern hemisphere. The line segments were broken at the 180-degree longitude line and the negative longitude values for the eastern hemisphere were converted to the corresponding positive longitude values. This means that each track segment that crosses the 180-degree longitude line is now composed of two line segments which have the same descriptive information for the tropical storm.

   A limit in the processing software will not allow duplicate points, so where a storm stood still longer than the six-hour collection interval, the next location point was offset approximately 0.0001 degrees to retain relevant information.

   The cover was converted into a shapefile and an SDTS-formatted file.

   Data sources used in this process:

   • EPA_2004

3. What similar or related data should the user be aware of?

   National Oceanic and Atmospheri, Tropical Prediction Center/National Hurr, 200509, Historical North Atlantic Hurricane Tracks - Major Storms with Landfall in the United States, 1851-2004: National Atlas of the United States, Reston, VA.

   Online Links:

   • <http://nationalatlas.gov/atlasftp.html?openChapters=chpclim#chpclim>

   National Oceanic and Atmospheri, Tropical Prediction Center/National Hurr, 200509, Historical North Atlantic Tropical Cyclone Tracks, 1851-2004: National Atlas of the United States, Reston, VA.

   Online Links:

   • <http://nationalatlas.gov/atlasftp.html?openChapters=chpclim#chpclim>

How reliable are the data; what problems remain in the data set?

1. How well have the observations been checked?

   Specific accuracy information can be found in Neumann, C.J., B.R. Jarvinen, C.J. McAdie and G.R. Hammer, 1999: Tropical Cyclones of the North Atlantic Ocean, 1871-1999 (fifth revision). NCDC/NHC Historical Climatology Series 6-2, pp.11-14. Similar standards and techniques were applied to the post-1999 data.

2. How accurate are the geographic locations?

   Over-water portions of storm tracks before 1944 are subject to considerable uncertainties. Aircraft reconnaissance of storms near critical areas was introduced in 1944, and continuous weather satellite surveillance was introduced in the mid-1960s. These two developments allow a high degree of probability that more recent storm center locations were determined with a reasonable degree of accuracy.

3. How accurate are the heights or depths?

4. Where are the gaps in the data? What is missing?

   This map layer includes all known eastern North Pacific and central North Pacific tropical cyclones between 1949 and 2004. The term tropical cyclone as used here refers to subtropical depressions and storms, tropical depressions and storms, and all categories of hurricanes from Category 1 to Category 5. This dataset also includes hybrid systems such as tropical lows, waves, and disturbances, as well as extratropical storms.

5. How consistent are the relationships among the observations, including topology?

   Over-water portions of storm tracks before 1944 are subject to considerable uncertainties. Aircraft reconnaissance of storms near critical areas was introduced in 1944, and continuous weather satellite surveillance was introduced in the mid-1960s. These two developments mean that more recent storm records have a higher degree of accuracy than those prior to 1944. No tests for logical consistency have been performed on this map layer.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access_Constraints: None

Use_Constraints:

None. Acknowledgement of the National Oceanic and Atmospheric Administration, Tropical Prediction Center/National Hurricane Center, the NOAA Coastal Services Center and (or) the National Atlas of the United States of America would be appreciated in products derived from these data.

1. Who distributes the data set? (Distributor 1 of 1)
   Earth Science Information Center, U.S. Geological Survey
   507 National Center
   Reston, VA 20192
   

   1-888-ASK-USGS (1-888-275-8747) (voice)
   

   Contact_Instructions:

   In addition to the address above there are other ESIC offices throughout the country. A full list of these offices is at <http://ask.usgs.gov/esic_index.html>.

2. What's the catalog number I need to order this data set?

3. What legal disclaimers am I supposed to read?

   Although these data have been processed successfully on a computer system at the U.S. Geological Survey, no warranty expressed or implied is made by the U.S. Geological Survey or the National Oceanic and Atmospheric Administration regarding the utility of the data on any other system, nor shall the act of distribution constitute any such warranty. No responsibility is assumed by the U.S. Geological Survey or the National Oceanic and Atmospheric Administration in the use of these data.

4. How can I download or order the data?
   • Availability in digital form:

     Data format:	ESRI Shapefile
     Network links:	<http://nationalatlas.gov/atlasftp.html?openChapters=chpclim#chpclim>

     Data format:	SDTS
     Network links:	<http://nationalatlas.gov/atlasftp.html?openChapters=chpclim#chpclim>

   • Cost to order the data: There is no charge for the map layer.

Who wrote the metadata?

Dates:

Last modified: 19-Jun-2006

Metadata author:

Peg Rawson
National Atlas of the United States
12201 Sunrise Valley Dr
Reston, VA 20192

703-648-4183 (voice)
[email protected]

Metadata standard:

FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)