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Office for Coastal Management, 2022: Tropical Cyclone Wind Exposure North Atlantic 1987-2016,

Item Identification

Title: Tropical Cyclone Wind Exposure North Atlantic 1987-2016
Status: Completed
Publication Date: 2018-10-31

These data represent modeled, historical exposure of U.S. offshore, coastal, and international waters to tropical cyclone activity within the North Atlantic Ocean basin (1987-2016). BOEM Outer Continental Shelf Lease Blocks and equivalent areas for coastal and international waters were used to construct the grid by which exposure was quantified. Exposure was quantified using intersecting storm tracks, overlapping wind intensity areas, and mathematical return intervals. Symbology is based on the modeled occurrence of tropical storm force (34-knot) or greater winds per grid cell. Due to the way winds were calculated differently over land and over water, the interpretation of wind exposure metrics within coastal areas should be interpreted carefully. Data represent past climatology only and do not suggest predicted future impacts or exposure.


To support ocean planning activities pursuant to the Executive Order Regarding the Ocean Policy to Advance the Economic, Security, and Environmental Interests of the United States, the Energy Policy Act, the National Environmental Policy Act, the Rivers and Harbors Act, and the Coastal Zone Management Act.


Theme Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Science Keywords
ISO 19115 Topic Category climatologyMeteorologyAtmosphere
ISO 19115 Topic Category environment
ISO 19115 Topic Category oceans
ISO 19115 Topic Category planningCadastre
None Atlantic
None coastal energy planning
None environment
None extratropical storm
None hurricane
None marine
None ocean energy planning
None oceans
None offshore energy planning
None outer continental shelf lease blocks
None protractions
None tropical cyclone
None tropical storm

Spatial Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Location Keywords
None East Coast
None Puerto Rico
None U.S. Virgin Islands
None United States

Physical Location

City: Charleston
State/Province: SC

Data Set Information

Data Set Scope Code: Data Set
Maintenance Frequency: As Needed
Distribution Liability:

Data Set Credit: Bureau of Ocean Energy Management, NOAA Office for Coastal Management

Support Roles

Point of Contact

CC ID: 1116923
Date Effective From: 2018-06
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202


Currentness Reference: Publication Date

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 1116939
W° Bound: -106.773028
E° Bound: 7.303844
N° Bound: 70.951611
S° Bound: 0

Access Information

Security Class: Unclassified
Data Use Constraints:

For coastal and ocean planning

Distribution Information

Distribution 1

CC ID: 1116927
Download URL:

Distribution 2

CC ID: 1116926
Download URL:
Description: Data Registry

Data Quality


The attributes in this dataset are believed to be accurate.

Horizontal Positional Accuracy:

Maximum scale of intended use is 1:80,000.

Completeness Report:

Spatial and attribute properties are believed to be complete, although attribute information has been simplified. Geometric thresholds from original data are preserved. No tests have been completed for exhaustiveness.

Conceptual Consistency:

These data are believed to be logically consistent. Geometry is topologically clean.



Extended Best Track (EBT)

CC ID: 1116933
Contact Name: NOAA National Environmental Satellite, Data, and Information Service (NESDIS)
Citation URL:
Citation URL Name: Source Online Linkage
Citation URL Description:

URL where the source data were originally accessed.

Source Contribution:

Provided Extended Best Track (EBT) storm points data used for calculating climatology buffers (MEWs).

International Best Track Archive for Climate Stewardship (IBTrACS)

CC ID: 1116932
Contact Name: NOAA National Centers for Environmental Information (NCEI)
Citation URL:
Citation URL Name: Source Online Linkage
Citation URL Description:

URL where the source data were originally accessed.

Source Contribution:

Provided tropical cyclone storm segments data.

Outer Continental Shelf Lease Blocks and Protraction Diagrams

CC ID: 1116931
Contact Name: Bureau of Ocean Energy Management (BOEM)
Citation URL:
Citation URL Name: Source Online Linkage
Citation URL Description:

URL where the source data were originally accessed.

Source Contribution:

Contributed lease block and protraction diagram data and information.

Process Steps

Process Step 1

CC ID: 1116934

CREATE THE GRID 1. Within the North Atlantic ocean basin only (since the EPAC grid uses only lease blocks), generate gridded fishnets for state waters and waters outside the EEZ that are not covered by OCS lease blocks. Make gridded cells coincident with lease blocks, as explained below. (NOTE: lease blocks and fishnets will not line up with the irregular lease blocks in the old Texas and Louisiana protraction maps.) 2. Per UTM zone, determine extent (top, bottom, left, right) of fishnet, using X and Y values referenced from BOEM's Official Protraction Diagram Maps ( per region. Block size (cell width/height) in Gulf of Mexico is 15,840 feet, and 4,800 meters for the rest of the US. Note that the extent values for zones (fishnets) in the Gulf of Mexico and Atlantic will be different. Within the fishnet tool, set number of rows and columns to 0, uncheck the option to Create Label Points, and set output to POLYGON. 3. Define the fishnet's projection per respective UTM zone. Use projection BLM (US Feet) for Gulf of Mexico, and projection WGS84 (meters) for rest of US. 4. Project all UTM zones over the Gulf of Mexico (UTM 14, 15, 16, 17) into NAD27, and UTM zones over the rest of the North Atlantic basin into WGS84. Then project all UTM zones into NAD83. 5. Add a field (fishnetID) to each fishnet and populate it with the respective UTM zone name and a unique ID (number). For example "18N-112". 6. Merge UTM zones (fishnets) together. Where there is overlap between UTM zones (fishnets), priority should be given to the eastern UTM zone's grid cells. (NOTE: special attention was given to the regional area around the Florida Keys. Here, the OCS lease blocks are irregular, where blocks from the Atlantic and the Gulf of Mexico overlap. Furthermore, the UTM fishnets shift from feet to meters here, within UTM zone 17N). 7. Merge the Atlantic and Gulf of Mexico lease blocks together and give priority to Gulf of Mexico lease blocks where there is overlap with Atlantic lease blocks in UTM zone 17N. 8. Merge the North Atlantic composite fishnet and the composite lease blocks layer together, with overlap priority given to the lease blocks. 9. Remove all unnecessary fields and modify attributes as needed.

Process Date/Time: 2018-08-01 00:00:00

Process Step 2

CC ID: 1116935

MODELING EXPOSURE 29. Buffer each subset (Cat 1, Cat 2, etc.) based on the respective MEW calculations for both overland and overwater (76 data sets total). Set Side Type field to right or left, depending on the buffer being run. Merge respective wind speed buffers (34kt, 50kt, 64kt) and then dissolve by storm ID (Serial_Num), storm name (Name), and season (Season). 30. Perform Spatial Join of the composite grid and buffers (34kt, 50kt, 64kt) to generate wind threshold counts per grid cell. 31. Perform Spatial Join of the composite grid and IBTrACS storm segments to generate storm segment counts per block. 32. Join count values of all outputs (34kt, 50kt, 64kt, and segments) together, based on the gridID field. 33. Calculate an average "return interval" value (30 years / count) per grid cell for each wind threshold (34kt, 50kt, 64kt). 34. Remove all unnecessary fields and populate others according to data dictionary.

Process Date/Time: 2018-09-01 00:00:00

Process Step 3

CC ID: 1116936

CLIMATOLOGY STEPS (MEW calculations) 10. Using the Extended Best Track (EBT) dataset, calculate the Maximum Extent of Winds (MEW) values following these steps. MEW are wind radii distances per standard wind threshold (34kt, 50kt, 64kt). 11. From, right-click and save the EBT data (1988-2016) as a text file and open in Excel, setting custom fixed-width columns within the import wizard. Insert missing column breaks where necessary and set the width carefully, capturing the appropriate characters per column. Save file. 12. Assign each column a field name based on metadata here: ( 13. Remove all EBT features in which storm type equals L, W, or D. (NOTE: No storm type values of 'D' were noted in the EBT data, even though the designation is stated within the metadata.) 14. Remove -99 values within fields. 15. Remove features if wind radii values in all four quadrants are zero. Per feature, even if only one of the four quadrants (per wind threshold) has a value above zero, retain the zero values in the other three cells for that wind threshold. 16. Remove all features with maximum wind values below 34 knots. (By definition, no wind radii values exist for EBT features with maximum winds below 34 knots, so these features are not relevant for MEW calculations.) 17. Modify the "longitudeWest" column by converting the values to negative values, so that features will plot appropriately (i.e. in the eastern hemisphere). Where necessary, convert longitude values within the eastern hemisphere by subtracting the value from 360. 18. Add the modified EBT data to ArcMap and export table as feature class. 19. Perform Select By Location, where all EBT points occurring over land (using a global countries layer) are selected. Include a 150nm buffer of the countries layer (with small islands removed) to select those EBT points occurring over land. (This is based on tropical cyclone literature, from Kruk 2010.) Export these selected features as a new feature class. These features will be used to calculate the average MEW values (buffer distances) for overland storm track segments. Switch the selection to select those features over water only. Export these selected features as a new feature class. These features will be used to calculate the average MEW values (buffer distances) for overwater storm track segments. If any overwater points exist over the Pacific Ocean basin, remove these. 20. For the overwater feature class, generate (storm) "category" values in a new field, based on wind speed values (see Due to the low sample of Cat 5 storms (1988-2016 = 28 points), combine these storms' (EBT points) wind radii values with the Cat 4 points when calculating MEW. 21. For the overland feature class, generate (storm) "category" values in a new field, based on wind speed values (see Due to the low sample of Cat 5 storms (1988-2016 = 24 points), combine these storms' (EBT points) wind radii values with the Cat 4 points when calculating MEWs. 22. Calculate MEW values per category for the overwater and overland features (separately) and record in a table. Compute averages for right (northeast, southeast) and left (northwest, southwest) quadrants. 23. Multiply all values by 0.67 to compute buffers for Eastern Pacific (EPAC) storms. This calculation is based on literature that has compared tropical cyclone sizes across global basins. This literature notes that wind swaths of EPAC tropical storms are approximately 33% smaller than North Atlantic tropical storms. (NOTE: size proportions between the North Atlantic and Eastern Pacific storms are variable within the literature.)

Process Date/Time: 2018-08-01 00:00:00

Process Step 4

CC ID: 1116937

STORM TRACKS STEPS 24. Extract those features in the IBTrACS data that are: 1) attributed to the North Atlantic (NA) basin; 2) occur in or after 1987; and 3) have maximum wind values above 33 knots. 25. Extract those features that are attributed as extratropical (ET), subtropical (SS), or tropical (TS). 26. Create a (storm) "Category" field. For features that are tropical storms ('TS'), modify the field value to the appropriate category, based on wind speed (see Also designate features as 'ET', 'SS', or 'TS' accordingly. 27. Separate the overland and overwater storm segments into separate feature classes. Do this by extracting all segments "completely contained" within the "land + 150nm buffer" layer. (NOTE: This was only done for the North Atlantic segments. The vast majority of Eastern Pacific segments (about 99%) within BOEM's Pacific lease blocks do not occur over land. Additionally, the MEW values for segments that do intersect land (i.e. Hawaiian Islands) compared to MEW values over water would be very minimal.) 28. For the overwater feature class, separate IBTrACS data by the seven categories (SS, ET, TS, 1, 2, 3, 4/5) into separate layers. Do the same for the overland feature class. (NOTE: For the ET, SS, and TS subsets, make additional subsets of these for the following segments: a) segments =34-49kt; b) segments =50-63kt; and c) segments >=64kt. This is required since not every ET, SS, and TS segment has winds greater than 50kt or 64kt, like Cat 1-Cat 5 segments do by definition.)

Process Date/Time: 2018-08-01 00:00:00

Child Items

Rubric scores updated every 15m

Rubric Score Type Title
Entity Tropical Cyclone Wind Exposure (North Atlantic, 1987-2016)

Catalog Details

Catalog Item ID: 66201
GUID: gov.noaa.nmfs.inport:66201
Metadata Record Created By: Brianna Key
Metadata Record Created: 2021-12-22 05:46+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2022-08-09 17:11+0000
Metadata Record Published: 2021-12-22
Owner Org: OCM
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2021-12-22
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2022-12-22