DOI: 10.5061/dryad.79cnp5j26
title: Data from: Documenting the progressions of secondary eyewall formations

description: Intense tropical cyclones can form secondary eyewalls (SEs) that contract
 towards the storm center and eventually replace the inner eyewall, a
 process known as an eyewall replacement cycle (ERC). However, SE formation
 does not guarantee an eventual ERC, and often, SEs follow differing
 evolutionary pathways. This study documents SE evolution and progressions
 observed in numerous tropical cyclones, and results in two new datasets
 using passive microwave imagery: a global subjectively labeled dataset of
 SEs and eyes and their uncertainties from 72 storms between 2016–19, and a
 dataset of 87 SE progressions that highlights the broad convective
 organization preceding and following a SE formation. The results show two
 primary SE pathways exist, No Replacement, known as Path 1, and
 Replacement, known as the Classic Path. Most interestingly, 53% of the
 most certain SE formations result in an eyewall replacement. The Classic
 Path is associated with stronger column average meridional wind, a faster
 poleward component of storm motion, more intense storms, weaker vertical
 wind shear, greater relative humidity, a larger storm wind field, and
 stronger cold air advection. This study highlights a greater number of
 potential SE pathways exist than previously thought. The results of this
 study detail several observational features of SE evolution that raise
 questions regarding the physical processes driving SE formations. Most
 importantly, environmental conditions and storm metrics identified here
 provide guidance for predictors in artificial intelligence applications
 for future tropical cyclone SE detection algorithms.
description: The secondary eyewall (SE) labels and SE
 Progression datasets are collected using three 89–92 GHz passive microwave
 imagers (GMI, SSMIS, and AMSR2) with horizontal and vertical (H &
 V) polarization from the Tropical Cyclone PRecipitation, Infrared,
 Microwave, and Environmental Dataset (TC PRIMED; https://doi.org/10.25921/dmy1-0595).  <em>Image Preprocessing</em> The dual-polarization allows for the creation of a single polarization-corrected temperature image, which reduces the impact of low-emissivity surface features, allowing TC internal features, such as SEs, to appear more distinct. The images are storm-centered and interpolated from the final best-track TC centers. Next, we interpolate the microwave images to a polar grid with a grid spacing of 4 km in radius by 10° in azimuth. Since our dataset includes Northern and Southern Hemisphere storms, we orient the images relative to storm motion, which points to the top of the page. <em>Storm Selection</em> For the SE labels dataset, we randomly select seventy-two storms with a lifetime maximum intensity greater than or equal to hurricane intensity (33 m s-1) from the North Atlantic, eastern and western North Pacific, and Southern Hemisphere tropical cyclone basins between 2016–19. For the SE Progressions dataset, we select a subset of our storms from the SE labels dataset (32 of 72) with a storm lifetime maximum SE confidence level of three or greater, where confidence ranges from 1 to 5, with a value of 1 being most uncertain. <em>Secondary Eyewall and Eye Labeling</em> We define an eye as a circular area or ring of lower Tb near the storm center and an SE as an outer minimum that surrounds a defined eye with four or more octants (i.e., coverage ≥ 50%). The labels use a confidence-based system, where confidence values again range from 1 (least confident 'yes') to 5 (most confident 'yes') and –1 (least confident 'no') to –5 (most confident 'no'). The eye labels are labeled by only one expert. However, the SE labels are labeled subjectively by four experts. A first expert (Expert 1) independently labels the dataset of seventy-two storms. Next, a second expert (Expert 2) independently labels the SE for the same dataset of microwave imagery. The two SE labeled datasets are then placed into three groups: no secondary eyewall, low confidence SEs (i.e., 1, 2, 3), and high confidence SEs (i.e., 4 and 5). Any SE label discrepancies between Experts 1 and 2 that result in different groups are relabeled by two other independent experts (Experts 3 and 4). The resulting confidence level is then the average between Experts 2, 3, and 4. If Experts 1 and 2 agree that a label should result in a low-confidence 'yes', but disagree on the confidence level, the average value between Experts 1 and 2 is taken. However, if the average confidence level is 1.5, then the confidence from Expert 1 is taken. For discrepancies between Experts 1 and 2 within the high-confidence 'yes' group, the confidence of Expert 1 is taken. For the 'no' group, the confidence level is taken from Expert 1. The purpose of this multi-expert labeling system is to address the subjective nature of labeling SEs and the temporal shortcomings of microwave imagery. The most uncertain cases are denoted using low-confidence values in the SE labels dataset. <em>Secondary Eyewall Progressions Definitions and Stages</em> Using the SE labels dataset, we construct a subset of storms with a lifetime maximum SE confidence level of 3 or greater as the basis of our SE Progressions dataset. We define a progression as the evolution of a convective organization from one stage to the next stage. Next, we document the convective appearances before, during, and after a SE formation, which are defined using three stages (Entrance Stage, SE Stage, and Exit Stage). The Entrance Stage is between the time of the first microwave image appearance of an outer convective band and the time of SE formation. The SE stage is when an SE is present in the microwave imagery. Lastly, the Exit Stage is the time of the first microwave image when only one eyewall is clearly visible after the appearance of a SE.
description: # Data from: Documenting the progression of secondary eyewall formations
 [https://doi.org/10.5061/dryad.79cnp5j26](https://doi.org/10.5061/dryad.79cnp5j26) Two datasets are provided here: A Secondary Eyewall (SE) Labels Dataset and an SE Progressions Dataset. The datasets are labeled using passive microwave imagery (89–92 GHz) from the Tropical Cyclone PRecipitation, Infrared, Microwave, and Environmental Dataset (TC PRIMED; [https://doi.org/10.25921/dmy1-0595](https://doi.org/10.25921/dmy1-0595)). The results from this dataset are highlighted in greater detail in Cheung et al. (2023). ## Description of the data and file structure *Secondary Eyewall Labels Dataset* The Secondary Eyewall (SE) Labels Dataset is a subjectively labeled dataset of secondary eyewalls and eyes from seventy-two tropical cyclones between 2016–2019 from the North Atlantic, eastern and western North Pacific, and Southern Hemisphere basins. 2322 microwave imagery observations (dimension: 'obs') are recorded. We provide coordinates of 'time', 'storm\_latitude', and 'storm\_longitude' at the time of each microwave imagery overpass. Variables included in this dataset are: 'basin , 'cyclone\_number', 'season', 'platform\_name', 'instrument\_name', 'granule\_number', 'source\_filename', 'intensity', 'eye\_label', 'eye\_label\_qc', 'secondary\_eyewall\_label', 'secondary\_eyewall\_label\_qc'. dimensions: obs = 2322 ; variables: string basin(obs) ; basin:long\_name = "Tropical cyclone basin" ; basin:comment = "AL - North Atlantic basin, north of the Equator; SL - South Atlantic basin, south of the Equator; EP - North East Pacific basin, eastward of 140 degrees west longitude; CP - North Central Pacific basin, between the dateline and 140 degrees west longitude; WP - North West Pacific basin, westward of the dateline; IO - North Indian Ocean basin, north of the Equator between 40 and 100 degrees east longitude; SH - South Pacific Ocean basin and South Indian Ocean basin." ; basin:coverage\_content\_type = "thematicClassification" ; basin:coordinates = "time storm\_latitude storm\_longitude" ; byte cyclone\_number(obs) ; cyclone\_number:\_FillValue = -1b ; cyclone\_number:long\_name = "Tropical cyclone annual cyclone number" ; cyclone\_number:comment = "Assigned once a system develops into a tropical or subtropical cyclone" ; cyclone\_number:units = "1" ; cyclone\_number:valid\_range = 1b, 49b ; cyclone\_number:missing = -1b ; cyclone\_number:coverage\_content\_type = "thematicClassification" ; cyclone\_number:coordinates = "time storm\_latitude storm\_longitude" ; short season(obs) ; season:long\_name = "Tropical cyclone basin season" ; season:comment = "The calendar year for the Northern Hemisphere. For the Southern Hemisphere, the year begins July 1, with calendar year plus one." ; season:coverage\_content\_type = "thematicClassification" ; season:units = "1" ; season:valid\_range = 2016s, 2019s ; season:coordinates = "time storm\_latitude storm\_longitude" ; string platform\_name(obs) ; platform\_name:long\_name = "Satellite platform name" ; platform\_name:coverage\_content\_type = "auxiliaryInformation" ; platform\_name:coordinates = "time storm\_latitude storm\_longitude" ; string instrument\_name(obs) ; instrument\_name:long\_name = "Satellite instrument name" ; instrument\_name:coverage\_content\_type = "auxiliaryInformation" ; instrument\_name:coordinates = "time storm\_latitude storm\_longitude" ; string granule\_number(obs) ; granule\_number:long\_name = "Satellite granule number for the tropical cyclone overpass." ; granule\_number:comment = "A satellite granule begins and ends at the southernmost point of the satellite ground track during its orbit." ; granule\_number:coverage\_content\_type = "auxiliaryInformation" ; int64 time(obs) ; time:\_FillValue = -999LL ; time:long\_name = "time" ; time:standard\_name = "time" ; time:calendar = "standard" ; time:units = "seconds since 1970-01-01" ; time:coverage\_content\_type = "coordinate" ; time:axis = "T" ; time:missing = -999LL ; string source\_filename(obs) ; source\_filename:long\_name = "TC PRIMED source filename" ; source\_filename:comment = "Source of passive microwave imagery on native grid before applying the variational analysis technique" ; float storm\_latitude(obs) ; storm\_latitude:\_FillValue = -999.9f ; storm\_latitude:long\_name = "Tropical cyclone center latitude linearly interpolated from the best-track to the passive microwave observation time" ; storm\_latitude:standard\_name = "latitude" ; storm\_latitude:units = "degrees\_north" ; storm\_latitude:valid\_range = -90.f, 90.f ; storm\_latitude:coverage\_content\_type = "coordinate" ; storm\_latitude:axis = "Y" ; storm\_latitude:interpolation\_description = "linear" ; storm\_latitude:missing = -999.9f ; float storm\_longitude(obs) ; storm\_longitude:\_FillValue = -999.9f ; storm\_longitude:long\_name = "Tropical cyclone center longitude linearly interpolated from the best-track to the passive microwave observation time" ; storm\_longitude:standard\_name = "longitude" ; storm\_longitude:units = "degrees\_east" ; storm\_longitude:valid\_range = 0.f, 360.f ; storm\_longitude:coverage\_content\_type = "coordinate" ; storm\_longitude:axis = "X" ; storm\_longitude:interpolation\_description = "linear" ; storm\_longitude:missing = -999.9f ; short intensity(obs) ; intensity:\_FillValue = -1s ; intensity:long\_name = "Tropical cyclone intensity linearly interpolated from the best-track to the passive microwave observation time; maximum 1-min average sustained wind speed at 10 m" ; intensity:standard\_name = "tropical\_cyclone\_maximum\_sustained\_wind\_speed" ; intensity:units = "kt" ; intensity:valid\_range = 0s, 300s ; intensity:missing = -1s ; intensity:coverage\_content\_type = "physicalMeasurement" ; intensity:interpolation\_description = "linear" ; intensity:coordinates = "time storm\_latitude storm\_longitude" ; byte eye\_label(obs) ; eye\_label:\_FillValue = -1b ; eye\_label:long\_name = "The existence of an eye" ; eye\_label:standard\_name = "status\_flag" ; eye\_label:comment = "An eye is defined as a minima (ice scattering or ring) around the center of a 85 to 92 GHz microwave imagery. This image should be a signal image with a Gaussian filter." ; eye\_label:flag\_values = 0b, 1b ; eye\_label:flag\_meanings = "not\_present present" ; eye\_label:valid\_range = 0b, 1b ; eye\_label:missing = -1b ; eye\_label:ancillary\_variables = "eye\_label\_qc" ; eye\_label:coverage\_content\_type = "thematicClassification" ; eye\_label:coordinates = "time storm\_latitude storm\_longitude" ; byte eye\_label\_qc(obs) ; eye\_label\_qc:\_FillValue = -1b ; eye\_label\_qc:long\_name = "The confidence in existence of an eye quality flag" ; eye\_label\_qc:standard\_name = "status\_flag" ; eye\_label\_qc:flag\_values = 1b, 2b, 3b, 4b, 5b ; eye\_label\_qc:flag\_meanings = "very\_low low medium high very\_high" ; eye\_label\_qc:valid\_range = 1b, 5b ; eye\_label\_qc:missing = -1b ; eye\_label\_qc:coverage\_content\_type = "qualityInformation" ; eye\_label\_qc:coordinates = "time storm\_latitude storm\_longitude" ; byte secondary\_eyewall\_label(obs) ; secondary\_eyewall\_label:\_FillValue = -1b ; secondary\_eyewall\_label:long\_name = "The existence of a secondary eyewall" ; secondary\_eyewall\_label:standard\_name = "status\_flag" ; secondary\_eyewall\_label:comment = "A secondary eyewall is defined as an outer minima surrounding a defined eye with 4 or more octants using 85 to 92 GHz microwave imagery. This image should be a signal image with a Gaussian filter. Subjective to spiral rainband determination." ; secondary\_eyewall\_label:flag\_values = 0b, 1b ; secondary\_eyewall\_label:flag\_meanings = "not\_present present" ; secondary\_eyewall\_label:valid\_range = 0b, 1b ; secondary\_eyewall\_label:missing = -1b ; secondary\_eyewall\_label:ancillary\_variables = "secondary\_eyewall\_label\_qc" ; secondary\_eyewall\_label:coverage\_content\_type = "thematicClassification" ; secondary\_eyewall\_label:coordinates = "time storm\_latitude storm\_longitude" ; byte secondary\_eyewall\_label\_qc(obs) ; secondary\_eyewall\_label\_qc:\_FillValue = -1b ; secondary\_eyewall\_label\_qc:long\_name = "The confidence in existence of a secondary eyewall quality flag" ; secondary\_eyewall\_label\_qc:standard\_name = "status\_flag" ; secondary\_eyewall\_label\_qc:flag\_values = 1b, 2b, 3b, 4b, 5b ; secondary\_eyewall\_label\_qc:flag\_meanings = "very\_low low medium high very\_high" ; secondary\_eyewall\_label\_qc:valid\_range = 1b, 5b ; secondary\_eyewall\_label\_qc:missing = -1b ; secondary\_eyewall\_label\_qc:coverage\_content\_type = "qualityInformation" ; secondary\_eyewall\_label\_qc:coordinates = "time storm\_latitude storm\_longitude" ; global attributes: :title = "Microwave imagery based tropical cyclone secondary eyewall labels" ; :summary = "A global dataset of subjectively labeled dataset of tropical cyclone eyes and secondary eyewalls. Each label is associated with a subjective confidence value to provide some quality information. The subjective labels come from AMSR2, GMI, SSMIS imagery in the Tropical Cyclone Precipitation, Infrared, Microwave, and Environmental Dataset." ; :keywords = "EARTH SCIENCE &gt; ATMOSPHERE &gt; WEATHER EVENTS &gt; TROPICAL CYCLONES" ; :Conventions = "CF-1.8, ACDD-1.3" ; :id = "TCPRIMED\_secondary\_eyewall\_label\_dataset\_v1r0.nc" ; :naming\_authority = "gov.noaa.nesdis.star" ; :history = "Created 2023-07-21T19:30:47.710Z " ; :source = "Labels derived from Razin, M. N., C. J. Slocum, J. A. Knaff, and P. J. Brown, 2022: Tropical Cyclone Precipitation, Infrared, Microwave, and Environmental Dataset (TC PRIMED), v1.0, NOAA National Centers for Environmental Information. https://doi.org/10.25921/dmy1-0595." ; :processing\_level = "NOAA Level 4" ; :comment = "Passive microwave imagery from TC PRIMED that was used for labelling was passed through a variational analysis technique with half-power filter wavelengths of 32 km in radius and 90 degrees in azimuth to reduce impact of instrument resolution differences." ; :acknowledgment = "Supported by the National Oceanic and Atmospheric Administration and National Science Foundation under grant AGS-1950172. The scientific results and conclusions, as well as any views or opinions expressed herein, are those of the author(s) and do not necessarily reflect those of NOAA or the Department of Commerce." ; :license = "Creative Commons Zero (CC0)" ; :date\_created = "2023-07-21T19:30:47.710Z" ; :creator\_name = "Alex Alvin Cheung" ; :creator\_email = "a98alvin@umd.edu" ; :creator\_url = "https://aosc.umd.edu/people/alvin-cheung" ; :creator\_type = "person" ; :creator\_institution = "MD/ATMOS &gt; Department of Atmospheric & Oceanic Science, University of Maryland" ; :creator\_country = "USA" ; :creator\_sector = "academic" ; :contributor\_name = "Christopher J. Slocum, John A. Knaff; Muhammad Naufal Razin" ; :contributor\_email = "Christopher.Slocum@noaa.gov, John.Knaff@noaa.gov; Naufal.Razin@colostate.edu" ; :contributor\_url = "https://www.star.nesdis.noaa.gov/" ; :contributor\_type = "person" ; :contributor\_institution = "DOC/NOAA/NESDIS/STAR/RAMMB &gt; Regional And Mesoscale Meteorology Branch, Center for Satellite Applications and Research, NESDIS, NOAA, U.S. Department of Commerce; COLOSTATE/CIRA &gt; Cooperative Institute for Research in the Atmosphere, Colorado State University" ; :contributor\_country = "USA" ; :contributor\_sector = "gov\_federal; academic" ; :institution = "DOC/NOAA/NESDIS/STAR/RAMMB &gt; Regional And Mesoscale Meteorology Branch, Center for Satellite Applications and Research, NESDIS, NOAA, U.S. Department of Commerce" ; :project = "TC PRIMED &gt; Tropical Cyclone Precipitation, Infrared, Microwave, and Environmental Dataset" ; :product\_version = "1.0" ; :geospatial\_lat\_units = "degrees\_north" ; :geospatial\_lat\_min = -37.8 ; :geospatial\_lat\_max = 53.2 ; :geospatial\_lon\_units = "degrees\_east" ; :geospatial\_lon\_min = 32. ; :geospatial\_lon\_max = 343.1 ; :time\_coverage\_start = "2016-02-09T18:46:09.000Z" ; :time\_coverage\_end = "2019-12-05T17:55:05.000Z" ; :time\_coverage\_duration = "P1345DT23H8M56S" ; :uuid = "17f36c96-27fd-11ee-a62e-ac1f6b482136" ; :keyword\_vocabulary = "GCMD:Global Change Master Directory (GCMD) Keywords v9.1.5" ; :standard\_name\_vocabulary = "CF Standard Name Table v77" ; :platform = "GCOMW1 GPM F17 F18 F19" ; :instrument = "AMSR2 GMI SSMIS" ; :ncei\_template\_version = "NCEI\_NetCDF\_Point\_Template\_v2.0" ; :cdm\_data\_type = "Point" ; :featureType = "point" ; :date\_issued = "2023-03-15T18:00:00.000Z" ; :date\_metadata\_modified = "2023-06-21T18:00:00.000Z" ; :references = "Cheung, A. A., C. J. Slocum, J. A. Knaff, and M. N. Razin, 2023: Documenting the Progressions of Secondary Eyewall Formations. Weather Forecasting. Submitted." ; :date\_modified = "2023-07-21T19:30:47.710Z" ; *Secondary Eyewall Progressions Dataset* The SE Progressions dataset is recorded using a subset of 32 storms from the SE Labels dataset with a lifetime maximum SE confidence level of 3 or greater. 87 SE progressions are recorded (dimension: 'index\_of\_progression'), each with three associated SE stages: Entrance, SE, and Exit (dimension: 'Stage\_of\_Progression'). Coordinates included are: 'storm\_latitude', 'storm\_longitude', and 'time'. Variables provided are: 'label\_threshold', 'season', 'basin', 'cyclone\_number', 'designation', 'time\_length', and 'source\_filename'. The 'storm\_latitude', 'storm\_longitude', and 'time' are based on values from the nearest overpass time. The 'label\_threshold' represents the lifetime maximum threshold met by the storm of the corresponding progression. A 'label\_threshold' of three indicates that the progression's storm meets the label\_threshold of 3, but not 4. However, a label\_threshold' of four indicates that the progression's storm meets the label\_threshold of both 3 and 4. The 'designation' represents the designated rainband appearance for a stage of SE progression. The 'source\_filename' represents the list of files used between the beginning of the Entrance Stage and the end of the Exit Stage. netcdf TCPRIMED\_secondary\_eyewall\_progression\_dataset\_v1r0 { dimensions: Index\_of\_Progression = 87 ; Stage\_of\_Progression = 3 ; Number\_of\_Files = 28 ; variables: byte label\_threshold(Index\_of\_Progression) ; label\_threshold:long\_name = "The storm maximum lifetime SE label confidence threshold met." ; label\_threshold:standard\_name = "status\_flag" ; label\_threshold:comment = "If the threshold is 4, then the storm maximum lifetime SE label confidence is 4 or greater. If the threshold is 3 then the storm maximum lifetime SE label confidence is 3, but does not meet the 4 threshold." ; label\_threshold:flag\_values = 3b, 4b ; label\_threshold:flag\_meanings = "3\_threshold 4\_threshold" ; label\_threshold:valid\_range = 3b, 4b ; label\_threshold:missing = -1b ; label\_threshold:ancillary\_variables = "label\_threshold" ; label\_threshold:coverage\_content\_type = "thematicClassification" ; short season(Index\_of\_Progression) ; season:long\_name = "Tropical cyclone basin season" ; season:comment = "The calendar year for the Northern Hemisphere. For the Southern Hemisphere, the year begins July 1, with calendar year plus one." ; season:coverage\_content\_type = "thematicClassification" ; season:units = "1" ; season:valid\_range = 2016s, 2019s ; string basin(Index\_of\_Progression) ; basin:long\_name = "Tropical cyclone basin" ; basin:comment = "AL - North Atlantic basin, north of the Equator; SL - South Atlantic basin, south of the Equator; EP - North East Pacific basin, eastward of 140 degrees west longitude; CP - North Central Pacific basin, between the dateline and 140 degrees west longitude; WP - North West Pacific basin, westward of the dateline; IO - North Indian Ocean basin, north of the Equator between 40 and 100 degrees east longitude; SH - South Pacific Ocean basin and South Indian Ocean basin." ; basin:coverage\_content\_type = "thematicClassification" ; byte cyclone\_number(Index\_of\_Progression) ; cyclone\_number:long\_name = "Tropical cyclone annual cyclone number" ; cyclone\_number:comment = "Assigned once a system develops into a tropical or subtropical cyclone" ; cyclone\_number:units = "1" ; cyclone\_number:valid\_range = 1b, 49b ; cyclone\_number:missing = -1b ; cyclone\_number:coverage\_content\_type = "thematicClassification" ; byte designation(Index\_of\_Progression, Stage\_of\_Progression) ; designation:long\_name = "Progression designation" ; designation:standard\_name = "status\_flag" ; designation:flag\_values = 1b, 2b, 3b, 4b, 5b, 6b, 7b, 8b, 9b, 10b ; designation:flag\_meanings = "Inner\_to\_Outer Outer\_to\_Inner HC FC SE\_Fade SE\_Spiral SE\_Merge Replacement TC\_Weakening Unknown" ; designation:valid\_range = 1b, 10b ; designation:missing = -1b ; designation:coverage\_content\_type = "qualityInformation" ; designation:coordinates = "storm\_latitude time storm\_longitude" ; byte time\_length(Index\_of\_Progression, Stage\_of\_Progression) ; time\_length:long\_name = "The time length of the stage. Note that the exit stage has a time length of zero, since by definition the start of the exit should no longer have an SE. This is rounded to 6 hour intervals." ; time\_length:standard\_name = "Stage\_Time\_Length" ; time\_length:units = "s" ; time\_length:coordinates = "storm\_latitude time storm\_longitude" ; string source\_filename(Index\_of\_Progression, Number\_of\_Files) ; source\_filename:long\_name = "TC PRIMED source filename" ; source\_filename:comment = "List of source files used for examination this progression. Source of passive microwave imagery on native grid before applying the variational analysis technique." ; double storm\_latitude(Index\_of\_Progression, Stage\_of\_Progression) ; storm\_latitude:\_FillValue = -999.9 ; storm\_latitude:long\_name = "Latitude based on nearest passive microwave observation time. The tropical cyclone center latitude is linearly interpolated from the best-track to the passive microwave observation time." ; storm\_latitude:standard\_name = "latitude" ; storm\_latitude:units = "degrees\_north" ; storm\_latitude:valid\_range = -90.f, 90.f ; storm\_latitude:coverage\_content\_type = "coordinate" ; storm\_latitude:axis = "Y" ; storm\_latitude:interpolation\_description = "linear" ; storm\_latitude:missing = -999.9 ; double storm\_longitude(Index\_of\_Progression, Stage\_of\_Progression) ; storm\_longitude:\_FillValue = -999.9 ; storm\_longitude:long\_name = "Longitude based on nearest passive microwave observation time. The tropical cyclone center longitude is linearly interpolated from the best-track to the passive microwave observation time." ; storm\_longitude:standard\_name = "longitude" ; storm\_longitude:units = "degrees\_east" ; storm\_longitude:valid\_range = 0.f, 360.f ; storm\_longitude:coverage\_content\_type = "coordinate" ; storm\_longitude:axis = "X" ; storm\_longitude:interpolation\_description = "linear" ; storm\_longitude:missing = -999.9 ; int64 time(Index\_of\_Progression, Stage\_of\_Progression) ; time:long\_name = "The time at each progression. The entrance time stamp represents the approximate end time of the entrance stage. The SE time stamp represents the approximate start time of the SE stage. The exit time stamp represents the approximate first time where no SE exists anymore." ; time:standard\_name = "progression\_time" ; time:coverage\_content\_type = "coordinate" ; time:axis = "T" ; time:missing = -999.9 ; time:units = "seconds since 1970-01-01 00:00:00" ; global attributes: :title = "Secondary Eyewall Progressions Dataset" ; :summary = "Secondary Eyewall Progressions dataset. Label threshold represents the maximum threshold met for storms with at least one lifetime maximum yes SE label. For example, if label\_threshold = 3, this indicates that this progression only meets the 3 threshold. If label\_threshold = 4, then this progression meets both the 3 and 4 label threshold." ; :keywords = "EARTH SCIENCE &gt; ATMOSPHERE &gt; WEATHER EVENTS &gt; TROPICAL CYCLONES" ; :Conventions = "CF-1.8, ACDD-1.3" ; :id = "TCPRIMED\_secondary\_eyewall\_progression\_dataset\_v1r0.nc" ; :naming\_authority = "gov.noaa.nesdis.star" ; :history = "Created 2023-07-21T19:30:47.710Z " ; :source = "Secondary eyewall progressions derived from Razin, M. N., C. J. Slocum, J. A. Knaff, and P. J. Brown, 2022: Tropical Cyclone Precipitation, Infrared, Microwave, and Environmental Dataset (TC PRIMED), v1.0, NOAA National Centers for Environmental Information. https://doi.org/10.25921/dmy1-0595." ; :processing\_level = "NOAA Level 4" ; :comment = "Passive microwave imagery from TC PRIMED that was used for labelling was passed through a variational analysis technique with half-power filter wavelengths of 32 km in radius and 90 degrees in azimuth to reduce impact of instrument resolution differences." ; :acknowledgment = "Supported by the National Oceanic and Atmospheric Administration and National Science Foundation under grant AGS-1950172. The scientific results and conclusions, as well as any views or opinions expressed herein, are those of the author(s) and do not necessarily reflect those of NOAA or the Department of Commerce." ; :license = "Creative Commons Zero (CC0)" ; :date\_created = "2023-07-21T19:30:47.710Z" ; :creator\_name = "Alex Alvin Cheung" ; :creator\_email = "a98alvin@umd.edu" ; :creator\_url = "https://aosc.umd.edu/people/alvin-cheung" ; :creator\_type = "person" ; :creator\_institution = "MD/ATMOS &gt; Department of Atmospheric & Oceanic Science, University of Maryland" ; :creator\_country = "USA" ; :creator\_sector = "academic" ; :contributor\_name = "Christopher J. Slocum, John A. Knaff; Muhammad Naufal Razin" ; :contributor\_email = "Christopher.Slocum@noaa.gov, John.Knaff@noaa.gov; Naufal.Razin@colostate.edu" ; :contributor\_url = "https://www.star.nesdis.noaa.gov/" ; :contributor\_type = "person" ; :contributor\_institution = "DOC/NOAA/NESDIS/STAR/RAMMB &gt; Regional And Mesoscale Meteorology Branch, Center for Satellite Applications and Research, NESDIS, NOAA, U.S. Department of Commerce; COLOSTATE/CIRA &gt; Cooperative Institute for Research in the Atmosphere, Colorado State University" ; :contributor\_country = "USA" ; :contributor\_sector = "gov\_federal; academic" ; :institution = "DOC/NOAA/NESDIS/STAR/RAMMB &gt; Regional And Mesoscale Meteorology Branch, Center for Satellite Applications and Research, NESDIS, NOAA, U.S. Department of Commerce" ; :project = "TC PRIMED &gt; Tropical Cyclone Precipitation, Infrared, Microwave, and Environmental Dataset" ; :product\_version = "1.0" ; :geospatial\_lat\_units = "degrees\_north" ; :geospatial\_lat\_min = -37.8 ; :geospatial\_lat\_max = 53.2 ; :geospatial\_lon\_units = "degrees\_east" ; :geospatial\_lon\_min = 32. ; :geospatial\_lon\_max = 343.1 ; :time\_coverage\_start = "2016-02-09T18:46:09.000Z" ; :time\_coverage\_end = "2019-12-05T17:55:05.000Z" ; :time\_coverage\_duration = "P1345DT23H8M56S" ; :uuid = "17f36c96-27fd-11ee-a62e-ac1f6b482136" ; :keyword\_vocabulary = "GCMD:Global Change Master Directory (GCMD) Keywords v9.1.5" ; :standard\_name\_vocabulary = "CF Standard Name Table v77" ; :platform = "GCOMW1 GPM F17 F18 F19" ; :instrument = "AMSR2 GMI SSMIS" ; :ncei\_template\_version = "NCEI\_NetCDF\_Point\_Template\_v2.0" ; :cdm\_data\_type = "Point" ; :featureType = "point" ; :date\_issued = "2023-03-15T18:00:00.000Z" ; :date\_metadata\_modified = "2023-06-21T18:00:00.000Z" ; :references = "Cheung, A. A., C. J. Slocum, J. A. Knaff, and M. N. Razin, 2023: Documenting the Progressions of Secondary Eyewall Formations. Weather Forecasting. In Revisions." ; :date\_modified = "2023-07-21T19:30:47.710Z" ; } ## Sharing/Access information Data was derived from the following sources: * The Tropical Cyclone PRecipitation, Infrared, Microwave, and Environmental Dataset (TC PRIMED) is available from the NOAA National Centers for Environmental Information (Razin et al. 2022). TC PRIMED is also on the NOAA Open Data Dissemination (NODD) program: [https://noaa-nesdis-tcprimed-pds.s3.amazonaws.com/index.html](https://noaa-nesdis-tcprimed-pds.s3.amazonaws.com/index.html).