Marine heatwave indices

Definition

Marine heatwave (MHW) indices have been defined to estimate sub-regional changes in MHW characteristics over the last four decades, as follows:

[MHW mean intensity]: annual mean of MHW intensity (above the mean)

[MHW maximum intensity]: annual maximum of MHW intensity (above the mean)

[MHW mean duration]: annual mean of MHW duration

[MHW frequency]: annual number of discrete events

[MHW total days]: annual total number of MHW days

Visualization

Every annual parameter is computed from the MHWs as detected using the Copernicus Marine Service satellite SST products. This section provides figures about:

Annual state in 2023 (2D map in the Mediterranean Sea)

Sub-regional interannual and decadal variability over the period 1982-2023 (time series and associated statistics)

Mean and linear trend over the period 1982-2023 (2D maps in the Mediterranean Sea).

MHW mean intensity

Annual state (last year): map of annual mean intensity in the Mediterranean Sea

Sub-regional interannual/decadal variability (from 1982 to 2023): timeseries of annual mean intensity (left) and associated statistics (right) in sub-regions

Mean and trend (1982-2023): maps of mean and linear trend of mean intensity in the Mediterranean Sea

MHW maximum intensity

Annual state (last year): map of annual maximum intensity in the Mediterranean Sea

Sub-regional interannual/decadal variability (from 1982 to 2023): timeseries of annual maximum intensity (left) and associated statistics (right) in sub-regions

Mean and trend (1982-2023): maps of mean and linear trend of maximum intensity in the Mediterranean Sea

MHW mean duration

Annual state (last year): map of annual mean duration in the Mediterranean Sea

Sub-regional interannual/decadal variability (from 1982 to 2023): timeseries of annual mean duration (left) and associated statistics (right) in sub-regions

Mean and trend (1982-2023): maps of mean and linear trend of mean duration in the Mediterranean Sea

MHW frequency

Annual state (last year): map of annual number of events in the Mediterranean Sea

Sub-regional interannual/decadal variability (from 1982 to 2023): timeseries of annual number of events (left) and associated statistics (right) in sub-regions

Mean and trend (1982-2023): maps of mean and linear trend of number of events in the Mediterranean Sea

MHW total days

Annual state (last year): map of annual total days in the Mediterranean Sea

Sub-regional interannual/decadal variability (from 1982 to 2023): timeseries of annual total days (left) and associated statistics (right) in sub-regions

Mean and trend (1982-2023): maps of mean and linear trend of MHW total days in the Mediterranean Sea