Analysis of deforestation in the Matahuayo-Tahuayo sector (Loreto) using images from TM, ETM+and OLI sensors during the period 2007-2015
DOI:
https://doi.org/10.15381/rif.v27i2.28263Keywords:
Chlorophyll-a, surface temperature, linear trend, wavelet transform, interannual variabilityAbstract
The concentration of chlorophyll-a in the oceans is a reliable indicator of phytoplankton biomass that
plays an important role in controlling the marine ecosystem. Here, we investigate the interannual
variability and trends of sea surface temperature (SST) and chlorophyll a (Chl-a) concentration in the
region bounded by the 1 mg m−3 isobath of Chlorophyll-a between northern and central Peru (latitudes 5°-16°S) of the Peruvian Sea, are studied from 2003 to 2021 using daily values from the MODIS
sensor database on board the Aqua satellite. In this region between 11°–16°S there is a statistically
significant moderate to intense cooling (≈-0.08°C decade−1) while for Chl -a there is a statistically
significant moderate cooling (≈0.4 mg m−3 decade−1) throughout the entire study region . Based on
the Mann-Kendall test, the pixels of statistically significant trends (95% confidence interval) of the
interannual anomalies of Chl-a and SST are highlighted, these pixels are averaged in time series where
the results indicated that produced similar negative trends, where Chl-a showed a trend of -0.076 mg
m−3 decade−1 on average and SST showed a trend of -0.047 °C decade−1 on average over 2003–2021.
The integrated wavelet spectra of the PC1 principal components of the Chl-a and SST anomalies
present significant variation on interannual time scales, centered on approximately 4.4 and 3.5 years
respectively. Our results show that a substantial fraction of the interannual variability of Chl-a in the
study area can be described by the first two EOF modes that explain 29.4% and 23.4% of the variance,
and SST can be described by only an EOF mode that explains 93.9% of the variance respectively. The
integrated wavelet spectra of the PC1(Chl-a) and PC1(TSM) records exhibit significant variation on
interannual time scales, centered on approximately 3.5 years respectively. The wavelet cross-correlation
between the Chl-a and SST time series is evident with a period T ≈ 3.5 years and a phase shift or
opposite phase of 180° between 2017-2019. In 2007-2011 there was a high correlation between periods
of 3 and 4 years, despite not being in phase.
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Copyright (c) 2024 Michel Choccña, Dante Espinoza, Joel Rojas, Jhon Guerrero, Rolando Badaracco
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