1. Dra. María del Carmen Heras Sánchez
Sea-surface temperature spatiotemporal analysis for the Gulf of California, : regime change simulation
Dra. María del Carmen Heras Sánchez
Cd. Obregón, Sonora, a 25 de Junio de 2018

2. Mexico / Universidad de Sonora

3. The Gulf of California
Is a semi-closed marginal sea characterized by a series of basins with differing depths and the Great Islands region.
Was formed around 5.3 M years ago.
Is one of the five most diverse and productive seas in the world, inhabited by more tan 8,000 marine animal species.

4. Sea Surface Temperature
The Gulf of California has been typified as an evaporation basin with a temperature gradient incrementing toward the Gulf’s interior during summer and decreasing during winter, with a net salt and heat gain that is balanced by sea water flux towards the Pacific ocean.
The latter being the mechanism that significantly influences the SST’s variability.
The Gulf’s climate is characterized by two distinct seasons: a warm season with SST => 25°C, and a cold season with SST temperatures < 25°C.
Spatially-wise, the areas around the large islands and the head of the Gulf show the lowest SST temperatures and the lowest variability in any given year.
Interannual SST variability is related to ENSO events.
Oceanographic conditions at the mouth of the Gulf are more sensitive to these inter-annual events.

5. Sea Surface Temperature
Surface circulation exhibit a distinct North American Monsoon system influence.
A southward flow along the Sonora and Sinaloa coastline during winter-spring, causing important upwellings.
Reversing its direction during summer-autumn but having a lesser impact on the thermal stratification along the Baja California Peninsula.
Higgins y Shi (2000)

6. Study area
Area: 237,207 km2
The Gulf of California is on average 200 km wide and has a length of 1500 km. Its natural borders are the arid Mexican states of Sonora and Sinaloa on the east, and the equally arid Baja California Peninsula on the west.
Its southern edge directly inter-communicates with the Pacific Ocean, but for this study we considered a hypothetical boundary running from Cabo San Lucas, B.C.S., to Bahía de Banderas, Nayarit.

7. Data set Spatial resolution: 4 km aprox. SST: Time resolution: Monthly
Period: January/1998 – December/2015
Number of files: 216 by timeserie
Format: raster .NC (NetCDF), .RST
Software: Idrisi 18, TerrSet
SST:
NOAA/ERDDAP/AVHRR, 2015
Aqua Modis/Ocean Color Web, 2016
MEI:
NOAA/ESRL, 2016
X = 274
Y = 240
Z = 216

8. Spatiotemporal Analysis of SST
28 (± 2.6) °C
23.4 (± 5.7) °C
Average: 25.4 (± 1.4) °C.
SST of large islands < 22.4 (± 4.9) °C.
The Gulf of California’s oceanography has been characterized by the sea Surface temperature (SST) at different spatial and temporal scales with data gathered by remote sensors.

9. Linear trend: 1.38 °C timeserie, 0.076 °C annual, 0.0064 °C monthly
Linear trend of SST
Average = 25.4 (± 1.4) °C
Linear trend: 1.38 °C timeserie, °C annual, °C monthly
(Confidende level: 95 %)
More than 1.4 °C rise
°C rise

10. Linear trend of SSTA: 1.2 °C
Spatiotemporal Analysis of SSTA/MEI (-1)
r = 0.64 (p < 0.05, confidence level of 95 %)
r > 0.60
r ~ 0.50
Linear trend of SSTA: 1.2 °C
MEI:
Niños: 35 %
Niñas: 26 %
MEI < 0.5 °C = 39 %
SSTA:
Niños: 30 %
Niñas: 34 %
SSTA < 0.5 °C = 36 %

11. Seasonal trend analysis of SST
Seasonal trend amplitudes of SST, for the Gulf of California.
RGB image compo-site: R=amplitude 0 =annual mean; G=amplitude 1 =annual cycle; B=amplitude 2 = semiannual cycle
Theil-Sen estimator, allowed us to eliminate both high-frequency noise and low-frequency variability, such that El Niño or La Niña’s effects would be excluded.

12. Seasonal trend analysis of SST
Nov :0
May :00
Nov :00
May :00
15. 5 days
3.91 days
January
Observed (a) and fitted (b) seasonal curves with 25 °C threshold
Summer season’s lengthening and summer and winter intensification
A fast and shifted SST seasonal change must impact the distribution, abundance, and development of the different species dwelling in the Gulf.

13. Seasonal trend analysis of SST
Signal homogenization
Rising trend in amplitude apparently due to pronounced summer and winter seasons
Earlier manifestation of the SST midpoint with respect to the previous year
Implies a later onset of SST change during the year
Theil-Sen trend: 0.72 °C, 0.04 °C annual, °C monthly (confidence level of 95 %) ꜛ
0.72 °C

14. Seasonal climatology of the Gulf of California

15. Seasonal trend analysis of SST
Gulf of California, SST seasonal trend analysis, , spatial distribution of SST for annual winter and summer
Seasonal trend analysis of SST

16. Seasonal trend analysis of SST
For STA, the series was partitioned in two subperiods: , and
Averages for the monthly SST of the Gulf of California, with isotherms at 0.2°C of equidis-tance: (a) and (b)
10 % ꜛ
1.5 %
8.5 %
Temporal profiles for monthly SST of the Gulf of California, with Theil-Sen and Linear trends: (a) and (b)

17. January 18th, 2019

18. Thank you!
Dra. Carmen Heras