patrickbdevaney/mia9 · Datasets at Hugging Face

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2.1. Remote Sensing
The dataset of the satellite observations, used in the study, includes Sea Surface
Temperature (SST), distributed by the E.U. Copernicus Marine Service (https://www.
copernicus.eu/, accessed on 5 August 2022), covering the entire study period from 1982 to
2021 (Table 1). The SST dataset is the Operational SST and Ice Analysis (OSTIA; [44]) global
SST reprocessed product at 0.05◦ horizontal grid resolution, using in situ and satellite data.
The satellite-derived data consist of the daily mean gap-free (L4) horizontal fields over the
South Florida region (Figure 1). The South Florida SST data were used to analyze the SST
Water 2022, 14, 3840 5 of 28
temporal and spatial variability, and to detect the MHWs. Extensive validation of the OSTIA
product, based on comparisons with ARGO and drifter data, confirmed the good quality
of the SST fields at the global scale (Quality Information Document (https://catalogue.
marine.copernicus.eu/documents/QUID/CMEMS-SST-QUID-010-011.pdf, accessed on
1 October 2022). The performance of the product was also tested in the South Florida
coastal region with the use of in situ measurements collected by the National Data Buoy
Center (NDBC; Section 2.2) and is discussed in Section 3.1.
2.2. Field Observations
Hourly measurements of SST were derived from three NDBC buoys (Figure 1; Table 1),
located south of Key West (Buoy SANF1), at a Key Largo coastal region (Buoy MLRF1), and
at the entrance of Biscayne Bay (Buoy FWYF1). The field observations of SST were used
to evaluate the performance of the satellite-derived SST fields over different periods and
coastal areas of South Florida. Air temperature hourly data were also collected at Buoy
FWYF1 to evaluate the relation between SST and atmospheric temperature anomalies in
Biscayne Bay and Miami Beach.
2.3. Meteorological Data
The meteorological conditions for the study domain and period were derived from
the ERA5 hourly data on single levels, distributed by the Copernicus Marine Service
(Table 1). The ERA5 dataset is a fifth-generation European Centre for Medium-Range
Weather Forecasts (ECMWF) reanalysis that combines model data with observations (data
assimilation), providing hourly estimates for a large number of atmospheric quantities.
Herein, we used the meridional and zonal components of the wind at a height of 10 m
above the sea surface to estimate the variability of the wind speed over the ocean waters of
South Florida (land values excluded) during the 1982–2021 period. In addition, we also
used the air temperature at 2 m above the surface, which is produced by the interpolation
between the lowest model level and the Earth’s surface, taking into account the atmospheric
conditions. The hourly surface net shortwave solar radiation (QS), the surface net longave
backcatter radiation (Qb), the surface sensible heat flux (Qh), and the surface latent heat
flux (Qe) were also collected by the ERA5 dataset to estimate the interannual variability of
the surface net heat flux (QT; Equation (1)) over the 1982–2021 period.
QT = QS + Qb + Qe + Qh (1)
where QS and Qb represent the radiative terms, while the Qh and Qe represent the turbulent
terms. The ERA5 radiation fields are suitable to evaluate the long-term interannual variability of the heat fluxes over regional basins [45]. The spatial resolution of the atmospheric
hourly fields is 0.25◦
.
2.4. Hydrodynamic Simulations
The hydrodynamic simulations are based on the Florida Straits, South Florida, and
Florida Keys Hybrid Coordinate Ocean Model (FKEYS-HYCOM; Kourafalou and Kang,
2012) and cover a 9-year period (2012–2020). HYCOM (http://hycom.org, accessed on
10 October 2022; [46–48]) is a state-of-the-art, three-dimensional hydrodynamic model
with advanced mixing schemes and employs a flexible (hybrid) vertical coordinate system
(isopycnal, Cartesian, and sigma discretizations) that is advantageous for the topographically complex study area (Figure 1). FKEYS-HYCOM employs 26 hybrid vertical layers and
significantly high horizontal resolution of 1/100◦
, or 900 m as compared to 1/25◦
, 3.6 km
in the GoM-HYCOM outer model that provides the boundary conditions [49]. The model
domain covers the area from 78.08◦ W to 84.528◦ W and 22.188◦ N to 27.58◦ N (Figure 1).
The topography was derived from a high-resolution (1/100◦
) regional Gulf of Mexico
bathymetry developed at the Florida State University/COAPS with a minimum depth of
1 m. The FKEYS-HYCOM vertical coordinates are maintained in isopycnic mode in the
“open sea” domain (e.g., Straits of Florida), they smoothly transform to bottom following
Water 2022, 14, 3840 6 of 28
(sigma) and/or Cartesian (fixed z-level) coordinates in the mixed layer, and in the coastal
and shelf areas (e.g., Florida shelves, northern Cuban coast and shallow banks). Atmospheric forcing is provided by the Navy Global Environmental Model (NAVGEM, [50]).
The FKEYS-HYCOM has been validated with satellite [26,27] and in situ [51] data, showing
additional skill in reproducing the circulation patterns and capturing the FC evolution in
the Straits of Florida. We used the model outputs to derive the FC location in the Straits of
Florida and evaluate its impact on the coastal SST variability.
2.5. Detection of Marine Heat Waves
The study adopts the definition proposed by Hobday et al. [1] to determine the
MHW events, based on abrupt SST increases above a “climatologic” value (the baseline
temperature) for a certain time period. This approach has been broadly used to evaluate the
MHW variability in both global ocean (i.e., [14,52]) and regional basins (i.e., [9,10,12,44,53]).
To define a baseline temperature, Hobday et al. [1] proposed a period of 30 years, which is
associated with the time scale variability of ocean drives (e.g., El Nino). Herein, we use a
longer dataset of 40 years with satellite-derived SST fields (see Section 2.1). According to
this definition, a MHW is defined as a discrete and prolonged anomalously warm oceanbased event. Hobday et al. [1] also pointed out that a MHW should be defined relative
to a baseline period and a particular time of the year from which the intensity, duration
and spatial extent of the MHW could be defined. This also means that a MHW is not just
limited to the warmer months, since for some biological applications the consideration of
heatwaves in colder months is essential. The term ‘discrete’ implies that the MHW is an
identifiable event with clear start and end dates; ‘prolonged’ means that it has a duration
of at least 5 days. Gaps, between events of two days or less with subsequent five days or
more, will be considered as a continuous event. ‘Anomalously warm’ means that the water
temperature is warm compared to the baseline temperature. The baseline temperature
used in the present study is defined by the seasonal (monthly) varying 90th percentile,
derived from the 1982–2021 SST data in the resolution (0.05◦
) of the South Florida domain.
Moreover, the duration (the time between the start and end dates; ≥5 days) was also
computed for all detected MHW events. The intensity of the MHWs was examined based
on the methodology introduced by Hobday et al. [2]. The goal is to set categories of MHWs
on multiples of the value represented by the local difference between the climatological
mean and the 90th percentile baseline, which is the threshold used to identify MHWs.
Multiples of this local difference will describe different categories of MHWs. Magnitude
of scale descriptors, defined as moderate (1–2× times, Category 1), strong (2–3× times,
Category 2), and severe (>3× times, Category 3), can be allocated at each point in space
and time of an MHW event.
3. Results
3.1. Evaluation of Satellite-Derived SST at Coastal Areas
The quality of the SST fields at coastal areas is tested, based on the comparison with

2.1. Remote Sensing

The dataset of the satellite observations, used in the study, includes Sea Surface

Temperature (SST), distributed by the E.U. Copernicus Marine Service (https://www.

copernicus.eu/, accessed on 5 August 2022), covering the entire study period from 1982 to

2021 (Table 1). The SST dataset is the Operational SST and Ice Analysis (OSTIA; [44]) global

SST reprocessed product at 0.05◦ horizontal grid resolution, using in situ and satellite data.

The satellite-derived data consist of the daily mean gap-free (L4) horizontal fields over the

South Florida region (Figure 1). The South Florida SST data were used to analyze the SST

Water 2022, 14, 3840 5 of 28

temporal and spatial variability, and to detect the MHWs. Extensive validation of the OSTIA

product, based on comparisons with ARGO and drifter data, confirmed the good quality

of the SST fields at the global scale (Quality Information Document (https://catalogue.

marine.copernicus.eu/documents/QUID/CMEMS-SST-QUID-010-011.pdf, accessed on

1 October 2022). The performance of the product was also tested in the South Florida

coastal region with the use of in situ measurements collected by the National Data Buoy

Center (NDBC; Section 2.2) and is discussed in Section 3.1.

2.2. Field Observations

Hourly measurements of SST were derived from three NDBC buoys (Figure 1; Table 1),

located south of Key West (Buoy SANF1), at a Key Largo coastal region (Buoy MLRF1), and

at the entrance of Biscayne Bay (Buoy FWYF1). The field observations of SST were used

to evaluate the performance of the satellite-derived SST fields over different periods and

coastal areas of South Florida. Air temperature hourly data were also collected at Buoy

FWYF1 to evaluate the relation between SST and atmospheric temperature anomalies in

Biscayne Bay and Miami Beach.

2.3. Meteorological Data

The meteorological conditions for the study domain and period were derived from

the ERA5 hourly data on single levels, distributed by the Copernicus Marine Service

(Table 1). The ERA5 dataset is a fifth-generation European Centre for Medium-Range

Weather Forecasts (ECMWF) reanalysis that combines model data with observations (data

assimilation), providing hourly estimates for a large number of atmospheric quantities.

Herein, we used the meridional and zonal components of the wind at a height of 10 m

above the sea surface to estimate the variability of the wind speed over the ocean waters of

South Florida (land values excluded) during the 1982–2021 period. In addition, we also

used the air temperature at 2 m above the surface, which is produced by the interpolation

between the lowest model level and the Earth’s surface, taking into account the atmospheric

conditions. The hourly surface net shortwave solar radiation (QS), the surface net longave

backcatter radiation (Qb), the surface sensible heat flux (Qh), and the surface latent heat

flux (Qe) were also collected by the ERA5 dataset to estimate the interannual variability of

the surface net heat flux (QT; Equation (1)) over the 1982–2021 period.

QT = QS + Qb + Qe + Qh (1)

where QS and Qb represent the radiative terms, while the Qh and Qe represent the turbulent

terms. The ERA5 radiation fields are suitable to evaluate the long-term interannual variability of the heat fluxes over regional basins [45]. The spatial resolution of the atmospheric

hourly fields is 0.25◦

.

2.4. Hydrodynamic Simulations

The hydrodynamic simulations are based on the Florida Straits, South Florida, and

Florida Keys Hybrid Coordinate Ocean Model (FKEYS-HYCOM; Kourafalou and Kang,

2012) and cover a 9-year period (2012–2020). HYCOM (http://hycom.org, accessed on

10 October 2022; [46–48]) is a state-of-the-art, three-dimensional hydrodynamic model

with advanced mixing schemes and employs a flexible (hybrid) vertical coordinate system

(isopycnal, Cartesian, and sigma discretizations) that is advantageous for the topographically complex study area (Figure 1). FKEYS-HYCOM employs 26 hybrid vertical layers and

significantly high horizontal resolution of 1/100◦

, or 900 m as compared to 1/25◦

, 3.6 km

in the GoM-HYCOM outer model that provides the boundary conditions [49]. The model

domain covers the area from 78.08◦ W to 84.528◦ W and 22.188◦ N to 27.58◦ N (Figure 1).

The topography was derived from a high-resolution (1/100◦

) regional Gulf of Mexico

bathymetry developed at the Florida State University/COAPS with a minimum depth of

1 m. The FKEYS-HYCOM vertical coordinates are maintained in isopycnic mode in the

“open sea” domain (e.g., Straits of Florida), they smoothly transform to bottom following

Water 2022, 14, 3840 6 of 28

(sigma) and/or Cartesian (fixed z-level) coordinates in the mixed layer, and in the coastal

and shelf areas (e.g., Florida shelves, northern Cuban coast and shallow banks). Atmospheric forcing is provided by the Navy Global Environmental Model (NAVGEM, [50]).

The FKEYS-HYCOM has been validated with satellite [26,27] and in situ [51] data, showing

additional skill in reproducing the circulation patterns and capturing the FC evolution in

the Straits of Florida. We used the model outputs to derive the FC location in the Straits of

Florida and evaluate its impact on the coastal SST variability.

2.5. Detection of Marine Heat Waves

The study adopts the definition proposed by Hobday et al. [1] to determine the

MHW events, based on abrupt SST increases above a “climatologic” value (the baseline

temperature) for a certain time period. This approach has been broadly used to evaluate the

MHW variability in both global ocean (i.e., [14,52]) and regional basins (i.e., [9,10,12,44,53]).

To define a baseline temperature, Hobday et al. [1] proposed a period of 30 years, which is

associated with the time scale variability of ocean drives (e.g., El Nino). Herein, we use a

longer dataset of 40 years with satellite-derived SST fields (see Section 2.1). According to

this definition, a MHW is defined as a discrete and prolonged anomalously warm oceanbased event. Hobday et al. [1] also pointed out that a MHW should be defined relative

to a baseline period and a particular time of the year from which the intensity, duration

and spatial extent of the MHW could be defined. This also means that a MHW is not just

limited to the warmer months, since for some biological applications the consideration of

heatwaves in colder months is essential. The term ‘discrete’ implies that the MHW is an

identifiable event with clear start and end dates; ‘prolonged’ means that it has a duration

of at least 5 days. Gaps, between events of two days or less with subsequent five days or

more, will be considered as a continuous event. ‘Anomalously warm’ means that the water

temperature is warm compared to the baseline temperature. The baseline temperature

used in the present study is defined by the seasonal (monthly) varying 90th percentile,

derived from the 1982–2021 SST data in the resolution (0.05◦

) of the South Florida domain.

Moreover, the duration (the time between the start and end dates; ≥5 days) was also

computed for all detected MHW events. The intensity of the MHWs was examined based

on the methodology introduced by Hobday et al. [2]. The goal is to set categories of MHWs

on multiples of the value represented by the local difference between the climatological

mean and the 90th percentile baseline, which is the threshold used to identify MHWs.

Multiples of this local difference will describe different categories of MHWs. Magnitude

of scale descriptors, defined as moderate (1–2× times, Category 1), strong (2–3× times,

Category 2), and severe (>3× times, Category 3), can be allocated at each point in space

and time of an MHW event.

3. Results

3.1. Evaluation of Satellite-Derived SST at Coastal Areas

The quality of the SST fields at coastal areas is tested, based on the comparison with