GOMD-derived indicators: methodology
Indicators computed by GOMD from provider data: inputs, computation and limitations
What is a derived indicator?
Most indicators in GOMD are identical to the value published by the source institution. Derived indicators are different: their values are not published by the source institution; GOMD computes them from the institution's open data with the method described below. These indicators are stored in the database with the quality flag "derived by GOMD" and are tracked in a separate counter on the home page.
- A derived value is not an official statistic of the source institution and should not be attributed to it; a citation should name both the source of the input data and GOMD.
- When the provider updates or revises the input data, derived values do not change by themselves; they have to be recomputed and reloaded. The period covered by each indicator is given below.
- The code of the computations is open: the replication packages of the related publications contain the input files and the computation scripts. Publications and open code →
- The limitations of each indicator are given in the "Limitation" column of the tables and should be read before the values are used.
64 derived indicators
14 method groups
125,603 observations (at load time)
Relative sea-level trends at tide-gauge stations (2)Satellite-altimetry sea-level trend off the port (1)Vertical land motion near the port (1)Relative sea-level trend at the port (composite estimate) (3)State of the Argo float fleet and design-area coverage (8)Annual maximum heat stress (DHW) in reef regions (2)Port dynamics: cargo per call, arrival irregularity, cargo bunching and common factors (10)Indicators derived from FAO capture data: reef-associated fish catch and ENSO sensitivity (2)Tropical cyclone exposure of ports and expected loss of port calls (7)Regional sea ice: monthly extent, Arctic open-water days and joint open days along routes (5)Completeness of animal species inventories in sea areas (Chao1) at successive cut-offs (4)Microplastic concentration in surface net tows: 10° cell summaries (3)Seafood trade, dependence on a single supplier and exporter collapses (10)Port-sector sulphur dioxide excess at European ports (6)
Relative sea-level trends at tide-gauge stations
The input is the PSMSL RLR (Revised Local Reference) monthly mean sea-level files. For each station GOMD computes the linear trend over 1993–2024 and its standard error adjusted for first-order autocorrelation. The provider does not publish station trends for this period; the values are GOMD computations.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Relative sea-level trend, 1993–2024 — RLR stations
psmsl_rsl_trend_1993_2024 |
mm/yr single value |
578 entities 2024 578 obs. |
Linear trend of relative sea level at the station over 1993–2024. The period field is recorded as 2024. Derived value computed by GOMD; not a product published by the provider. | RLR values are relative to each station's own local reference (about 7000 mm added); levels cannot be compared across stations, only changes. Relative sea level includes vertical land motion. Abrupt vertical motions such as earthquakes are mixed into the trend. |
Standard error of the relative sea-level trend, 1993–2024
psmsl_rsl_trend_1993_2024_se |
mm/yr single value |
578 entities 2024 578 obs. |
Standard error of the trend, adjusted for first-order autocorrelation. The period field is recorded as 2024. Derived value computed by GOMD; not a product published by the provider. | May be optimistic relative to long-memory noise models. |
Satellite-altimetry sea-level trend off the port
The input is the NOAA LSA satellite-altimetry sea-level trend grid. For each port GOMD averages the trend of the grid cells within 150 km. The value is geocentric sea level and excludes vertical land motion.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Sea-level trend off the port — satellite altimetry, 1993–2025
noaa_lsa_sl_trend_port |
mm/yr single value |
1,936 entities 2025 1,936 obs. |
Mean trend of altimetry grid cells within 150 km of the port (geocentric sea level). The period field is recorded as 2025. Derived value computed by GOMD; not a product published by the provider. | Altimetry is unreliable in cells very close to the coast; the value represents the open sea off the port and excludes vertical land motion. |
Vertical land motion near the port
The input is the MIDAS GNSS velocity file of the Nevada Geodetic Laboratory. For each port GOMD takes the median vertical velocity of the GNSS stations within 30 km; positive values are uplift and negative values subsidence.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Vertical land velocity near the port — GNSS (MIDAS)
ngl_midas_vlm_port |
mm/yr single value |
871 entities 2025 871 obs. |
Median vertical velocity of GNSS stations within 30 km of the port; positive is uplift, negative is subsidence. The period field is recorded as 2025. Derived value computed by GOMD; not a product published by the provider. | The GNSS station is not at the port itself; subsidence can vary over short distances and reclaimed port areas may move at a different rate. |
Relative sea-level trend at the port (composite estimate)
Three observation tiers are used. Tier 1: the 1993–2024 relative sea-level trend of the nearest PSMSL station within 100 km of the port. Tier 2: satellite-altimetry trend combined with GNSS vertical land motion. Tier 3: satellite altimetry only (no land motion). The composite indicator gives the value of the highest tier available for the port; the tier is stored as a separate indicator.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Relative sea-level trend at the port — nearest tide gauge (≤100 km), 1993–2024
gomd_port_rsl_trend_gauge |
mm/yr single value |
820 entities 2024 820 obs. |
1993–2024 relative sea-level trend of the nearest PSMSL station within 100 km of the port. The period field is recorded as 2024. Derived value computed by GOMD; not a product published by the provider. | The tide gauge is near, not at, the port; the port area may subside at a different rate. Tier 3 values exclude land motion and are a lower bound on subsiding coasts. |
Relative sea-level trend at the port — composite estimate (tide gauge / altimetry − GNSS / altimetry)
gomd_port_rsl_trend_composite |
mm/yr single value |
1,943 entities 2025 1,943 obs. |
Value from the highest available observation tier for the port. The period field is recorded as 2025. Derived value computed by GOMD; not a product published by the provider. | The tide gauge is near, not at, the port; the port area may subside at a different rate. Tier 3 values exclude land motion and are a lower bound on subsiding coasts. |
Sea-level observation tier of the port (1: tide gauge; 2: altimetry + GNSS; 3: altimetry only)
gomd_port_rsl_tier |
tier single value |
1,943 entities 2025 1,943 obs. |
Observation tier used in the composite estimate. The period field is recorded as 2025. Derived value computed by GOMD; not a product published by the provider. | The tier reflects the availability of open data; national agencies may hold measurements that are not shared. |
State of the Argo float fleet and design-area coverage
The input is the Argo GDAC global profile index file (float identifier, date and position of every profile). From this index GOMD computes monthly counts of active floats and profiles, the age of the fleet and area-weighted coverage shares of the 3°×3° design cells. The random-placement expectation is a benchmark computed under the assumption that floats are placed independently with probability proportional to area.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Number of Argo floats reporting a profile in the month
argo_fleet_active_floats |
floats monthly |
1 entities 2000-01 – 2026-10 322 obs. |
Number of floats that reported at least one profile in the month (core, deep and biogeochemical missions together). Derived value computed by GOMD; not a product published by the provider. | Computed from the index file; definitions may differ from those in programme status reports. The technical state of floats and sensor quality are not considered. |
Number of Argo profiles per month
argo_fleet_profiles |
profiles monthly |
1 entities 2000-01 – 2026-10 322 obs. |
Number of profiles taken in the month. Derived value computed by GOMD; not a product published by the provider. | Computed from the index file; definitions may differ from those in programme status reports. The technical state of floats and sensor quality are not considered. |
Mean age of active Argo floats
argo_fleet_mean_age_yr |
years monthly |
1 entities 2000-01 – 2026-10 322 obs. |
Mean time since first profile of the floats reporting in the month. Derived value computed by GOMD; not a product published by the provider. | Computed from the index file; definitions may differ from those in programme status reports. The technical state of floats and sensor quality are not considered. |
Share of active Argo floats older than five years
argo_fleet_share_over5y_pct |
% monthly |
1 entities 2000-01 – 2026-10 322 obs. |
Share of floats reporting in the month whose first profile is more than five years old. Derived value computed by GOMD; not a product published by the provider. | Computed from the index file; definitions may differ from those in programme status reports. The technical state of floats and sensor quality are not considered. |
Snapshot coverage of the Argo design area (one position per float)
argo_design_snapshot_coverage_pct |
% monthly |
1 entities 2000-01 – 2026-10 322 obs. |
Area share of design cells containing at least one float when each float is assigned to a single 3°×3° cell by the position of its first profile in the month. Derived value computed by GOMD; not a product published by the provider. | Computed from the index file; definitions may differ from those in programme status reports. The technical state of floats and sensor quality are not considered. |
Monthly coverage of the Argo design area (≥1 profile in the month)
argo_design_monthly_coverage_pct |
% monthly |
1 entities 2000-01 – 2026-10 322 obs. |
Area share of design cells with at least one profile in the month. Derived value computed by GOMD; not a product published by the provider. | Computed from the index file; definitions may differ from those in programme status reports. The technical state of floats and sensor quality are not considered. |
Random-placement expectation of Argo design-area coverage
argo_design_random_expectation_pct |
% monthly |
1 entities 2000-01 – 2026-10 322 obs. |
Expected snapshot coverage if the floats in the design area were placed independently with probability proportional to area. Derived value computed by GOMD; not a product published by the provider. | Computed from the index file; definitions may differ from those in programme status reports. The technical state of floats and sensor quality are not considered. |
Number of Argo floats deployed per year
argo_fleet_deployments |
floats/year annual |
1 entities 2000 – 2025 26 obs. |
Number of floats whose first profile falls in the year. Derived value computed by GOMD; not a product published by the provider. | Computed from the index file; definitions may differ from those in programme status reports. The technical state of floats and sensor quality are not considered. The deployment year is approximated by the year of the first profile. |
Annual maximum heat stress (DHW) in reef regions
The input is the daily time-series files of the NOAA Coral Reef Watch regional virtual stations. For each station and calendar year GOMD takes the maximum of daily DHW (degree heating weeks). The country value is the mean of the annual maxima of the reef-region stations assigned to the country.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Annual maximum degree heating week (DHW) — reef region
crw_dhw_annual_max |
°C-weeks annual |
214 entities 1985 – 2025 8,774 obs. |
Calendar-year maximum of daily DHW at the regional virtual station. Derived value computed by GOMD; not a product published by the provider. | DHW is a satellite-based indicator of bleaching risk, not a measure of observed bleaching. The regional station value is based on the 90th percentile of the reef pixels in the region. |
Annual maximum degree heating week (DHW) — country mean
crw_dhw_annual_max_country |
°C-weeks annual |
103 entities 1985 – 2025 4,223 obs. |
Mean of the annual maximum DHW of the reef-region stations assigned to the country. Derived value computed by GOMD; not a product published by the provider. | DHW is a satellite-based indicator of bleaching risk, not a measure of observed bleaching. The regional station value is based on the 90th percentile of the reef pixels in the region. The country value may not represent all reefs of the country. |
Port dynamics: cargo per call, arrival irregularity, cargo bunching and common factors
The input is the IMF PortWatch daily port data (port calls and import and export tonnage; provider estimates based on AIS ship positions). GOMD computes the annual indicators from daily values at port and calendar-year level: cargo per call (total tonnage / total calls), the variance-to-mean ratio of daily calls and the coefficient of variation of daily cargo volume. Common factors are estimated by static principal components from year-on-year growth rates of the monthly call (or tonnage) series of ports; the port shares are the parts of each port's growth variance explained by the global factor and left as port-specific.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Port — cargo per call (annual)
gomd_port_cargo_per_call_t |
metric tonnes/call annual |
1,539 entities 2019 – 2025 9,816 obs. |
Ratio of total import and export tonnage to the total number of port calls in the calendar year; ports with at least 100 calls in the year. Derived value computed by GOMD; not a product published by the provider. | Derived from AIS-based provider estimates; may be affected by missing signals and later revisions. Tonnage is not an official port throughput statistic. The indicator reflects ship size and load factor together. |
Port — variance-to-mean ratio of daily port calls (annual)
gomd_port_calls_dispersion |
ratio annual |
1,539 entities 2019 – 2025 9,816 obs. |
Ratio of the within-year variance to the mean of the daily number of port calls; equals 1 for Poisson arrivals. Ports with at least 100 calls in the year. Derived value computed by GOMD; not a product published by the provider. | Derived from AIS-based provider estimates; may be affected by missing signals and later revisions. Tonnage is not an official port throughput statistic. |
Port — coefficient of variation of daily cargo volume (annual)
gomd_port_daily_cargo_cv |
ratio annual |
1,264 entities 2019 – 2025 8,848 obs. |
Ratio of the within-year standard deviation to the mean of daily cargo volume; the 1,264 ports with at least 100 calls in every year of 2019–2025. Derived value computed by GOMD; not a product published by the provider. | Derived from AIS-based provider estimates; may be affected by missing signals and later revisions. Tonnage is not an official port throughput statistic. |
Port — share of the global factor in port-call growth (2020–2026)
gomd_port_global_factor_share_pct |
% single value |
1,361 entities 2026 1,361 obs. |
Share of the variance of year-on-year growth in the port's monthly calls explained by the global port factor (January 2020–October 2026). The period field is recorded as 2026. Derived value computed by GOMD; not a product published by the provider. | Derived from AIS-based provider estimates; may be affected by missing signals and later revisions. Tonnage is not an official port throughput statistic. Factors are estimated by static principal components; 1,361 ports. |
Port — share of the port-specific component in port-call growth (2020–2026)
gomd_port_specific_share_pct |
% single value |
1,361 entities 2026 1,361 obs. |
Variance share of the port-specific component remaining after the global, regional and country factors are removed (January 2020–October 2026). The period field is recorded as 2026. Derived value computed by GOMD; not a product published by the provider. | Derived from AIS-based provider estimates; may be affected by missing signals and later revisions. Tonnage is not an official port throughput statistic. Factors are estimated by static principal components; 1,361 ports. |
Global port factor (all calls)
gomd_port_global_factor |
standard units monthly |
1 entities 2020-01 – 2026-10 82 obs. |
First principal component of the year-on-year growth rates of monthly port calls at world ports (1,361 ports). Derived value computed by GOMD; not a product published by the provider. | Derived from AIS-based provider estimates; may be affected by missing signals and later revisions. Tonnage is not an official port throughput statistic. The sign and scale of a factor are arbitrary by construction; it is oriented to correlate positively with the growth of the sample total. |
Global container port-call factor
gomd_container_calls_global_factor |
standard units monthly |
1 entities 2020-01 – 2026-10 82 obs. |
First principal component of the year-on-year growth rates of container-ship calls (641 ports). Derived value computed by GOMD; not a product published by the provider. | Derived from AIS-based provider estimates; may be affected by missing signals and later revisions. Tonnage is not an official port throughput statistic. The sign and scale of a factor are arbitrary by construction; it is oriented to correlate positively with the growth of the sample total. |
Global container tonnage factor
gomd_container_tonnage_global_factor |
standard units monthly |
1 entities 2020-01 – 2026-10 82 obs. |
First principal component of the year-on-year growth rates of tonnage carried by container ships (831 ports). Derived value computed by GOMD; not a product published by the provider. | Derived from AIS-based provider estimates; may be affected by missing signals and later revisions. Tonnage is not an official port throughput statistic. The sign and scale of a factor are arbitrary by construction; it is oriented to correlate positively with the growth of the sample total. |
World container-ship port calls, year-on-year growth
gomd_world_container_calls_yoy_pct |
% monthly |
1 entities 2020-01 – 2026-10 82 obs. |
Symmetric growth rate of the monthly number of container-ship calls at world ports relative to the same month of the previous year. Derived value computed by GOMD; not a product published by the provider. | Derived from AIS-based provider estimates; may be affected by missing signals and later revisions. Tonnage is not an official port throughput statistic. The sign and scale of a factor are arbitrary by construction; it is oriented to correlate positively with the growth of the sample total. |
World container tonnage, year-on-year growth
gomd_world_container_tonnage_yoy_pct |
% monthly |
1 entities 2020-01 – 2026-10 82 obs. |
Symmetric growth rate of the monthly tonnage carried by container ships at world ports relative to the same month of the previous year. Derived value computed by GOMD; not a product published by the provider. | Derived from AIS-based provider estimates; may be affected by missing signals and later revisions. Tonnage is not an official port throughput statistic. The sign and scale of a factor are arbitrary by construction; it is oriented to correlate positively with the growth of the sample total. |
Indicators derived from FAO capture data: reef-associated fish catch and ENSO sensitivity
The input is the FAO global capture production database (marine catch reported by countries). Reef-associated fish catch is the country-year sum of the species items belonging to families associated with coral reefs. ENSO sensitivity is the contemporaneous response of the country's detrended log marine catch to the ENSO-year index (July–June mean ONI), estimated by a separate regression for each country.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Reef-associated fish catch (derived from FAO reported catch)
gomd_reef_fish_catch_t |
metric tonnes annual |
75 entities 1975 – 2024 2,747 obs. |
Sum of the species items belonging to families associated with coral reefs (snappers, groupers, emperors, parrotfishes, surgeonfishes, rabbitfishes, etc.) in the catch reported by the country to FAO; countries with reef regions. Derived value computed by GOMD; not a product published by the provider. | The definition rests on reporting items at family level and may include non-reef catch. National reports under-represent small-scale and subsistence catch; some items are FAO estimates. |
ENSO sensitivity of national marine catch (1952–2024)
gomd_enso_catch_sensitivity_pct |
% per ONI unit single value |
146 entities 2024 146 obs. |
Contemporaneous response of the country's detrended log marine catch to a 1 °C increase in the ENSO-year index (July–June mean ONI), in per cent. The period field is recorded as 2024. Derived value computed by GOMD; not a product published by the provider. | Most coefficients cannot be distinguished from zero; only one of 146 countries survives control for multiple testing. Should not be used to rank countries. |
Tropical cyclone exposure of ports and expected loss of port calls
The inputs are IBTrACS version 4 storm tracks (1980–2025) and the locations and daily port calls of the 2,065 IMF PortWatch ports. Tracks are linearly interpolated to hourly steps; an encounter is any case in which the centre of a system with winds of at least 34 knots comes within 100 km (great-circle distance) of a port, classified by the maximum wind while within 100 km (tropical storm 34–63, hurricane 64–95, major hurricane ≥96 knots). The loss of port calls per event is estimated from 1,321 encounters in 2019–2026 as the sum of calls below the normal level (mean of days 56 to 8 before the event) from two days before to fourteen days after the passage. The expected annual loss is the port's encounter counts by class multiplied by these mean losses and divided by 46 years.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Port — tropical cyclone encounters per decade (≥34 kt, ≤100 km), 1980–2025
gomd_port_tc_encounters_per_decade |
encounters/decade single value |
2,065 entities 2025 2,065 obs. |
Decadal frequency over 1980–2025 of encounters in which a system with winds of at least 34 knots came within 100 km of the port. The period field is recorded as 2025; the value is 0 for ports with no encounter. Derived value computed by GOMD; not a product published by the provider. | The encounter definition rests on distance to the storm centre and ignores the size of the wind field, waves and storm surge. Track records of the 1980s are less reliable in some basins. |
Port — hurricane-force encounters per decade (≥64 kt, ≤100 km), 1980–2025
gomd_port_tc_hurricane_encounters_per_decade |
encounters/decade single value |
2,065 entities 2025 2,065 obs. |
Decadal frequency over 1980–2025 of encounters with winds of at least 64 knots while within 100 km. The period field is recorded as 2025. Derived value computed by GOMD; not a product published by the provider. | The encounter definition rests on distance to the storm centre and ignores the size of the wind field, waves and storm surge. Track records of the 1980s are less reliable in some basins. |
Port — expected annual loss of port calls from tropical cyclones
gomd_port_tc_expected_loss_days_yr |
port-days/yr single value |
2,065 entities 2025 2,065 obs. |
Computed from the port's 1980–2025 encounter counts multiplied, by intensity class (tropical storm, hurricane, major hurricane), by the mean net loss of port calls estimated from daily call data for 2019–2026 (0.66, 1.16 and 2.03 port-days) and divided by 46 years. One port-day is a loss equal to the port's calls on a normal day. The period field is recorded as 2025. Derived value computed by GOMD; not a product published by the provider. | The encounter definition rests on distance to the storm centre and ignores the size of the wind field, waves and storm surge. Track records of the 1980s are less reliable in some basins. The indicator rests on the port's own exposure and the average response of all ports, not on the port's own loss history; it excludes differences in resilience between ports and physical damage. The loss for the major-hurricane class is estimated from only 90 events. |
World ports — annual number of tropical cyclone encounters (≥34 kt)
gomd_world_port_tc_encounters |
encounters annual |
1 entities 1980 – 2025 46 obs. |
Total number of port–storm encounters (≥34 knots, ≤100 km) at the 2,065 ports in the calendar year. Derived value computed by GOMD; not a product published by the provider. | The encounter definition rests on distance to the storm centre and ignores the size of the wind field, waves and storm surge. Track records of the 1980s are less reliable in some basins. Port locations and weights are held fixed; the series does not reflect the growth of the port network. |
World ports — annual number of hurricane-force encounters (≥64 kt)
gomd_world_port_tc_encounters_hurricane |
encounters annual |
1 entities 1980 – 2025 46 obs. |
Annual number of encounters with winds of at least 64 knots while within 100 km. Derived value computed by GOMD; not a product published by the provider. | The encounter definition rests on distance to the storm centre and ignores the size of the wind field, waves and storm surge. Track records of the 1980s are less reliable in some basins. Port locations and weights are held fixed; the series does not reflect the growth of the port network. |
World ports — annual number of major-hurricane encounters (≥96 kt)
gomd_world_port_tc_encounters_major |
encounters annual |
1 entities 1980 – 2025 46 obs. |
Annual number of encounters with winds of at least 96 knots while within 100 km. Derived value computed by GOMD; not a product published by the provider. | The encounter definition rests on distance to the storm centre and ignores the size of the wind field, waves and storm surge. Track records of the 1980s are less reliable in some basins. Port locations and weights are held fixed; the series does not reflect the growth of the port network. |
World ports — cargo-weighted annual tropical cyclone exposure
gomd_world_port_tc_cargo_weighted_exposure |
encounters per port annual |
1 entities 1980 – 2025 46 obs. |
Mean number of encounters per port in the year, weighted by the ports' mean annual cargo volume in 2019–2025. Derived value computed by GOMD; not a product published by the provider. | The encounter definition rests on distance to the storm centre and ignores the size of the wind field, waves and storm surge. Track records of the 1980s are less reliable in some basins. Port locations and weights are held fixed; the series does not reflect the growth of the port network. |
Regional sea ice: monthly extent, Arctic open-water days and joint open days along routes
The input is the regional daily sea-ice extent of the NSIDC Sea Ice Index version 4 (14 Arctic and 5 Antarctic regions). Monthly extent is the monthly mean of daily values (at least 10 days). For open-water days the daily extent of each region is divided by that region's 1981–2010 March mean; days on which this ratio is below the threshold (15% or 50%) are counted between 1 May and 31 December. Data that are every other day before 1987 are linearly filled over gaps of at most three days. The route indicator counts, for the Northern Sea Route (Kara, Laptev, East Siberian, Chukchi) and the Northwest Passage (Baffin, Canadian Arctic Archipelago, Beaufort, Chukchi), the days on which all four regions are below the threshold on the same day.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Regional sea-ice extent — monthly mean
nsidc_regional_sea_ice_extent_monthly_km2 |
sq. km monthly |
19 entities 1979-01 – 2026-10 10,887 obs. |
Monthly mean of daily sea-ice extent (area with at least 15% ice concentration) in the NSIDC region. Derived value computed by GOMD; not a product published by the provider. | The monthly mean is computed by GOMD from daily values and may differ slightly from the monthly product published by NSIDC. Recent months are preliminary. |
Arctic region — open-water days (extent below 15% of winter level)
gomd_arctic_open_water_days_15 |
days annual |
14 entities 1979 – 2025 658 obs. |
Number of days between 1 May and 31 December on which regional ice extent is below 15% of the region's 1981–2010 March mean. Derived value computed by GOMD; not a product published by the provider. | The indicator rests on total regional extent; it ignores ice thickness, the distribution of ice within the region and ship ice class. An open-water day is not a measure of navigability. |
Arctic region — open-water days (extent below 50% of winter level)
gomd_arctic_open_water_days_50 |
days annual |
14 entities 1979 – 2025 658 obs. |
Number of days between 1 May and 31 December on which regional ice extent is below 50% of the region's 1981–2010 March mean. Derived value computed by GOMD; not a product published by the provider. | The indicator rests on total regional extent; it ignores ice thickness, the distribution of ice within the region and ship ice class. An open-water day is not a measure of navigability. |
Arctic route — days on which all seas along the route are open (15% threshold)
gomd_arctic_route_joint_open_days_15 |
days annual |
2 entities 1979 – 2025 94 obs. |
Number of days (1 May–31 December) on which ice extent is below 15% of the winter level in all four regions along the route on the same day. Derived value computed by GOMD; not a product published by the provider. | The indicator rests on total regional extent; it ignores ice thickness, the distribution of ice within the region and ship ice class. An open-water day is not a measure of navigability. |
Arctic route — days on which all seas along the route are open (50% threshold)
gomd_arctic_route_joint_open_days_50 |
days annual |
2 entities 1979 – 2025 94 obs. |
Number of days (1 May–31 December) on which ice extent is below 50% of the winter level in all four regions along the route on the same day. Derived value computed by GOMD; not a product published by the provider. | The indicator rests on total regional extent; it ignores ice thickness, the distribution of ice within the region and ship ice class. An open-water day is not a measure of navigability. |
Completeness of animal species inventories in sea areas (Chao1) at successive cut-offs
The inputs are the OBIS checklists with the number of records per species for 66 large marine ecosystems and 101 IHO sea areas. Only records in the kingdom Animalia identified to species rank with an accepted name are used. For each cut-off (1999, 2009, 2019, 2026) the records collected up to the end of that year are taken; undated records are not included. With S recorded species and f1 and f2 species with one and two records, the bias-corrected Chao1 estimate is S + f1(f1−1)/(2(f2+1)); completeness is the ratio of S to this estimate. Chao1 and completeness are given only for cut-offs with at least 30 species.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Sea area — number of recorded animal species (OBIS, cumulative by collection date)
gomd_obis_species_recorded |
species irregular |
167 entities 1999 – 2026 668 obs. |
Number of animal species in OBIS records from the area collected up to the end of the stated year. Cut-offs: 1999, 2009, 2019, 2026. Derived value computed by GOMD; not a product published by the provider. | Chao1 is a lower-bound estimator and, in GOMD's back-test, the 1999 estimates had been exceeded by 2026 in three quarters of the areas; completeness should be read as an upper bound and used to rank areas. The number of records is a crude measure of sampling effort. Large marine ecosystems and IHO sea areas overlap geographically. |
Sea area — number of species-level records (OBIS, cumulative)
gomd_obis_species_records |
records irregular |
167 entities 1999 – 2026 668 obs. |
Number of animal records identified to species from the area collected up to the end of the stated year. Cut-offs: 1999, 2009, 2019, 2026. Derived value computed by GOMD; not a product published by the provider. | Chao1 is a lower-bound estimator and, in GOMD's back-test, the 1999 estimates had been exceeded by 2026 in three quarters of the areas; completeness should be read as an upper bound and used to rank areas. The number of records is a crude measure of sampling effort. Large marine ecosystems and IHO sea areas overlap geographically. |
Sea area — estimated number of animal species (Chao1)
gomd_obis_chao1_richness |
species irregular |
166 entities 1999 – 2026 663 obs. |
Bias-corrected Chao1 richness estimate computed from records collected up to the end of the stated year. Cut-offs: 1999, 2009, 2019, 2026. Derived value computed by GOMD; not a product published by the provider. | Chao1 is a lower-bound estimator and, in GOMD's back-test, the 1999 estimates had been exceeded by 2026 in three quarters of the areas; completeness should be read as an upper bound and used to rank areas. The number of records is a crude measure of sampling effort. Large marine ecosystems and IHO sea areas overlap geographically. |
Sea area — estimated inventory completeness (Chao1)
gomd_obis_inventory_completeness_pct |
% irregular |
166 entities 1999 – 2026 663 obs. |
Ratio of recorded species to the Chao1 estimate, in per cent. Cut-offs: 1999, 2009, 2019, 2026. Derived value computed by GOMD; not a product published by the provider. | Chao1 is a lower-bound estimator and, in GOMD's back-test, the 1999 estimates had been exceeded by 2026 in three quarters of the areas; completeness should be read as an upper bound and used to rank areas. The number of records is a crude measure of sampling effort. Large marine ecosystems and IHO sea areas overlap geographically. |
Microplastic concentration in surface net tows: 10° cell summaries
The input is the water-sample records of the NOAA NCEI Marine Microplastics archive. Only net tows (neuston, manta, AVANI and plankton nets) are used; bottle, bucket, pump and grab samples are excluded because they measure a different size range. Records are assigned to 10°×10° cells. The cell value is the geometric mean concentration (pieces/m³) of the non-zero tows; cells with at least 10 non-zero tows are given. The study-adjusted value is the cell effect from a regression of log10 concentration on cell and study fixed effects, expressed at the level of the study with the most records.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Microplastics — geometric mean concentration in net tows (10° cell, 1972–2022)
gomd_mp_net_tow_cell_gm |
pieces/m³ single value |
99 entities 2022 99 obs. |
Geometric mean concentration of the non-zero net tows in the cell. The period field is recorded as 2022. Derived value computed by GOMD; not a product published by the provider. | Sampling is opportunistic and very uneven across cells; more than half of the records come from a single programme. Two net tows at the same place and season differ by a median factor of 2.2; cell values based on few tows are uncertain. The value does not show change over time. |
Microplastics — net-tow concentration adjusted for study effects (10° cell)
gomd_mp_net_tow_cell_gm_study_adjusted |
pieces/m³ single value |
99 entities 2022 99 obs. |
Cell level from a linear model with cell and study fixed effects, expressed at the level of the study with the most records. The period field is recorded as 2022. Derived value computed by GOMD; not a product published by the provider. | Sampling is opportunistic and very uneven across cells; more than half of the records come from a single programme. Two net tows at the same place and season differ by a median factor of 2.2; cell values based on few tows are uncertain. The value does not show change over time. |
Microplastics — number of non-zero net tows in the cell
gomd_mp_net_tow_cell_samples |
tows single value |
99 entities 2022 99 obs. |
Number of non-zero net tows on which the cell mean is based. The period field is recorded as 2022. Derived value computed by GOMD; not a product published by the provider. | Sampling is opportunistic and very uneven across cells; more than half of the records come from a single programme. Two net tows at the same place and season differ by a median factor of 2.2; cell values based on few tows are uncertain. The value does not show change over time. |
Seafood trade, dependence on a single supplier and exporter collapses
The input is the bilateral trade flows of the CEPII BACI database in the HS 1992 nomenclature (version 202601): value (US dollars) and quantity (tonnes) by exporter, importer, six-digit product and year. Seafood comprises chapter 03, headings 1604, 1605 and 1504 and subheading 2301.20 (105 products); 2024 is not used because reporting was incomplete. Country totals are sums of these flows by importer and by exporter. For the dependence indicators the quantity share of the largest supplier country is computed in each importer–product–year market (at least 100 tonnes in the year); the country value is the import-value-weighted mean of this share and the share of import value in markets where it is at least 50%. An exporter collapse is a year in which an exporter's exports of a product fall to half or less of the mean of the three preceding years (at least 500 tonnes, positive in all three years) with no collapse of the same exporter and product in the three preceding years. The raw data are not hosted on GOMD; the replication package contains the seafood subset.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Seafood imports — value
gomd_seafood_imports_musd |
million US dollars annual |
226 entities 1995 – 2023 6,327 obs. |
Total import value of the country in the 105 seafood product codes (current US dollars). Derived value computed by GOMD; not a product published by the provider. | BACI is a reconciliation of exporter and importer declarations and may differ from national statistics. Re-exports are not separated. Quantities are product weight, not live-weight equivalent. Members of the Southern African Customs Union before 2000 and Belgium and Luxembourg before 1999 are not reported separately. |
Seafood exports — value
gomd_seafood_exports_musd |
million US dollars annual |
226 entities 1995 – 2023 6,179 obs. |
Total export value of the country in the 105 seafood product codes (current US dollars). Derived value computed by GOMD; not a product published by the provider. | BACI is a reconciliation of exporter and importer declarations and may differ from national statistics. Re-exports are not separated. Quantities are product weight, not live-weight equivalent. Members of the Southern African Customs Union before 2000 and Belgium and Luxembourg before 1999 are not reported separately. |
Seafood imports — quantity
gomd_seafood_imports_t |
tonnes annual |
226 entities 1995 – 2023 6,326 obs. |
Total import quantity of the country in the 105 seafood product codes (product weight). Derived value computed by GOMD; not a product published by the provider. | BACI is a reconciliation of exporter and importer declarations and may differ from national statistics. Re-exports are not separated. Quantities are product weight, not live-weight equivalent. Members of the Southern African Customs Union before 2000 and Belgium and Luxembourg before 1999 are not reported separately. |
Seafood exports — quantity
gomd_seafood_exports_t |
tonnes annual |
226 entities 1995 – 2023 6,172 obs. |
Total export quantity of the country in the 105 seafood product codes (product weight). Derived value computed by GOMD; not a product published by the provider. | BACI is a reconciliation of exporter and importer declarations and may differ from national statistics. Re-exports are not separated. Quantities are product weight, not live-weight equivalent. Members of the Southern African Customs Union before 2000 and Belgium and Luxembourg before 1999 are not reported separately. |
Seafood imports — mean share of the largest supplier
gomd_seafood_import_top_supplier_share_pct |
% annual |
224 entities 1995 – 2023 5,713 obs. |
Mean, weighted by import value, of the share of the largest supplier country in import quantity across the country's seafood product markets (six-digit products). Derived value computed by GOMD; not a product published by the provider. | BACI is a reconciliation of exporter and importer declarations and may differ from national statistics. Re-exports are not separated. Quantities are product weight, not live-weight equivalent. Members of the Southern African Customs Union before 2000 and Belgium and Luxembourg before 1999 are not reported separately. The share is computed over product markets with imports of at least 100 tonnes in the year; for small importers it rests on few markets. Substitution between product codes is not taken into account. |
Seafood imports — share of markets dependent on a single supplier
gomd_seafood_import_value_single_supplier_dependent_pct |
% annual |
224 entities 1995 – 2023 5,713 obs. |
Share of the country's seafood import value in product markets that obtain at least half of their supply from a single supplier country. In GOMD's study (rp29), losses after a supplier collapse were largely replaced below this threshold and not above it. Derived value computed by GOMD; not a product published by the provider. | BACI is a reconciliation of exporter and importer declarations and may differ from national statistics. Re-exports are not separated. Quantities are product weight, not live-weight equivalent. Members of the Southern African Customs Union before 2000 and Belgium and Luxembourg before 1999 are not reported separately. The share is computed over product markets with imports of at least 100 tonnes in the year; for small importers it rests on few markets. Substitution between product codes is not taken into account. |
Seafood exports — number of products with an export collapse
gomd_seafood_export_collapse_events |
products annual |
180 entities 1998 – 2023 3,632 obs. |
Number of seafood product codes in which the country's exports fell in that year to half or less of the mean of the three preceding years (year of onset). The value is 0 in years without a collapse. Derived value computed by GOMD; not a product published by the provider. | A collapse is a fall of exports to half or less of the mean of the three preceding years (baseline of at least 500 tonnes; no collapse of the same exporter and product in the three preceding years). Conversion between HS revisions can produce artificial falls in some product codes; the count should be read as an upper bound. The cause of the collapse (stock, disease, policy, classification) is not identified. Countries whose code changed during the period (Belgium–Luxembourg, Southern African Customs Union, Serbia–Montenegro, Sudan, Netherlands Antilles) are not in the country-level series but are included in the world total. |
World seafood trade — annual number of exporter collapses
gomd_world_seafood_export_collapse_events |
events annual |
1 entities 1998 – 2023 26 obs. |
World total of exporter–product collapses beginning in the year. Derived value computed by GOMD; not a product published by the provider. | A collapse is a fall of exports to half or less of the mean of the three preceding years (baseline of at least 500 tonnes; no collapse of the same exporter and product in the three preceding years). Conversion between HS revisions can produce artificial falls in some product codes; the count should be read as an upper bound. The cause of the collapse (stock, disease, policy, classification) is not identified. Countries whose code changed during the period (Belgium–Luxembourg, Southern African Customs Union, Serbia–Montenegro, Sudan, Netherlands Antilles) are not in the country-level series but are included in the world total. |
World seafood trade — share of trade supplied by collapsing exporters
gomd_world_seafood_collapsed_supply_share_pct |
% annual |
1 entities 1998 – 2023 26 obs. |
Mean exports over the three years before the collapse of the exporter–product pairs collapsing in the year, as a share of world seafood trade (tonnes) in the preceding year. Derived value computed by GOMD; not a product published by the provider. | A collapse is a fall of exports to half or less of the mean of the three preceding years (baseline of at least 500 tonnes; no collapse of the same exporter and product in the three preceding years). Conversion between HS revisions can produce artificial falls in some product codes; the count should be read as an upper bound. The cause of the collapse (stock, disease, policy, classification) is not identified. Countries whose code changed during the period (Belgium–Luxembourg, Southern African Customs Union, Serbia–Montenegro, Sudan, Netherlands Antilles) are not in the country-level series but are included in the world total. |
World seafood trade — share of import markets dependent on a single supplier
gomd_world_seafood_markets_single_supplier_dependent_pct |
% annual |
1 entities 1995 – 2023 29 obs. |
Share (by number of markets) of importer–product markets with imports of at least 100 tonnes in the year that obtain at least half of their supply from a single supplier country. Derived value computed by GOMD; not a product published by the provider. | BACI is a reconciliation of exporter and importer declarations and may differ from national statistics. Re-exports are not separated. Quantities are product weight, not live-weight equivalent. Members of the Southern African Customs Union before 2000 and Belgium and Luxembourg before 1999 are not reported separately. The share is computed over product markets with imports of at least 100 tonnes in the year; for small importers it rests on few markets. Substitution between product codes is not taken into account. |
Port-sector sulphur dioxide excess at European ports
The inputs are hourly SO₂ measurements reported to the European Environment Agency (validated E1a flow 2016–2025, up-to-date E2a flow 2026), hourly wind observations of NOAA NCEI GHCNh and port locations from IMF PortWatch. Each sampling point is assigned to its nearest port; points within 5 km of a port and with a meteorological station within 40 km are used (330 points, 154 ports). The bearing from the point to the port is computed; an hour is assigned to the port sector if the wind direction is within 45° of that bearing and to the opposite sectors if it differs by 90° or more; hours with wind speed below 0.5 m/s are discarded. The point-month excess is mean SO₂ in port-sector hours minus the mean in opposite-sector hours (at least 24 hours in each). Port and regional values are annual means of point-month excesses; a port value requires at least 6 point-months in the year. Regions are defined by the sulphur limit of ship fuel: Mediterranean (0.50% since 2020, 0.10% since 1 May 2025), Atlantic coasts (0.50% since 2020), North Sea and Baltic (0.10% since 2015), Black Sea and Marmara (0.50% since 2020). The raw hourly data are not hosted on GOMD.
| Indicator | Unit · frequency | Coverage | Computation | Limitation |
|---|---|---|---|---|
Port — port-sector SO₂ excess
gomd_port_so2_port_sector_excess |
µg/m³ annual |
153 entities 2016 – 2026 1,298 obs. |
Difference between mean SO₂ measured with the wind from the port and with the wind from the opposite sectors at sampling points within 5 km of the port; annual mean of point-month values (at least 6 point-months in the year). Derived value computed by GOMD; not a product published by the provider. | The excess includes the contribution of industrial plants lying in the direction of the port as well as ships; it is not ship-related SO₂ alone. Wind is taken from a meteorological station a median of 8 km from the sampling point and may not represent the flow inside the port. Measured concentrations are close to instrument detection limits; the annual value of a single port is uncertain and small year-to-year differences should not be interpreted. The 2026 value rests on January–October and on data that are not finally validated. The port is represented by a single point. |
Port — mean SO₂ with the wind from the port sector
gomd_port_so2_port_sector_mean |
µg/m³ annual |
153 entities 2016 – 2026 1,298 obs. |
Mean SO₂ in hours with the wind from within 45° of the bearing to the port at sampling points within 5 km of the port; annual mean of point-month values. Derived value computed by GOMD; not a product published by the provider. | The excess includes the contribution of industrial plants lying in the direction of the port as well as ships; it is not ship-related SO₂ alone. Wind is taken from a meteorological station a median of 8 km from the sampling point and may not represent the flow inside the port. Measured concentrations are close to instrument detection limits; the annual value of a single port is uncertain and small year-to-year differences should not be interpreted. The 2026 value rests on January–October and on data that are not finally validated. The port is represented by a single point. |
Port — mean SO₂ with the wind from the opposite sectors
gomd_port_so2_opposite_sector_mean |
µg/m³ annual |
153 entities 2016 – 2026 1,298 obs. |
Mean SO₂ in hours with the wind from 90° or more away from the bearing to the port at sampling points within 5 km of the port; annual mean of point-month values. Derived value computed by GOMD; not a product published by the provider. | The excess includes the contribution of industrial plants lying in the direction of the port as well as ships; it is not ship-related SO₂ alone. Wind is taken from a meteorological station a median of 8 km from the sampling point and may not represent the flow inside the port. Measured concentrations are close to instrument detection limits; the annual value of a single port is uncertain and small year-to-year differences should not be interpreted. The 2026 value rests on January–October and on data that are not finally validated. The port is represented by a single point. |
Port — number of sampling points behind the SO₂ excess
gomd_port_so2_sampling_points |
points annual |
153 entities 2016 – 2026 1,298 obs. |
Number of SO₂ sampling points within 5 km of the port that enter the port's annual value. Derived value computed by GOMD; not a product published by the provider. | The excess includes the contribution of industrial plants lying in the direction of the port as well as ships; it is not ship-related SO₂ alone. Wind is taken from a meteorological station a median of 8 km from the sampling point and may not represent the flow inside the port. Measured concentrations are close to instrument detection limits; the annual value of a single port is uncertain and small year-to-year differences should not be interpreted. The 2026 value rests on January–October and on data that are not finally validated. The port is represented by a single point. |
Sea region — port-sector SO₂ excess at ports
gomd_region_so2_port_sector_excess |
µg/m³ annual |
4 entities 2016 – 2026 44 obs. |
Annual mean over point-month values of the port-sector SO₂ excess at sampling points within 5 km of the ports of the region. Derived value computed by GOMD; not a product published by the provider. | The excess includes the contribution of industrial plants lying in the direction of the port as well as ships; it is not ship-related SO₂ alone. Wind is taken from a meteorological station a median of 8 km from the sampling point and may not represent the flow inside the port. Measured concentrations are close to instrument detection limits; the annual value of a single port is uncertain and small year-to-year differences should not be interpreted. The 2026 value rests on January–October and on data that are not finally validated. The port is represented by a single point. The number of points entering the regional mean changes from year to year; the Black Sea and Marmara group has very few points after 2025. The decline at North Sea and Baltic ports cannot be explained by ship fuel and shows that the indicator also reflects non-ship sources. |
Sea region — number of sampling points behind the SO₂ excess
gomd_region_so2_sampling_points |
points annual |
4 entities 2016 – 2026 44 obs. |
Number of sampling points entering the regional mean. Derived value computed by GOMD; not a product published by the provider. | The excess includes the contribution of industrial plants lying in the direction of the port as well as ships; it is not ship-related SO₂ alone. Wind is taken from a meteorological station a median of 8 km from the sampling point and may not represent the flow inside the port. Measured concentrations are close to instrument detection limits; the annual value of a single port is uncertain and small year-to-year differences should not be interpreted. The 2026 value rests on January–October and on data that are not finally validated. The port is represented by a single point. The number of points entering the regional mean changes from year to year; the Black Sea and Marmara group has very few points after 2025. The decline at North Sea and Baltic ports cannot be explained by ship fuel and shows that the indicator also reflects non-ship sources. |