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Mexico And The North ( Station 15 )

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lf of Mexico to the north (station 15) in Little Lake during 2010 (10 months) and 2011 (5
141 months) (Figure 1). Surface temperature and salinity were recorded in-situ using a handheld Yellow
142 Springs Instruments (YSI) multi-probe field meter. Water samples were stored in a cooler and brought
143 back to the laboratory on the same day. The samples were immediately filtered using pre-rinsed 0.2 μm
Remote Sens. 2015, 7 5
Nuclepore membrane filters (Whatman GmbH) and analyzed for optical 144 absorption. Meteorological
145 data (wind speed and wind direction) were acquired from NOAA 's National Data Buoy Center
146 (NDBC) at the Grand Isle station (GISL1, 20.265°N 89.958°W) for 2010 and 2011. River discharge
147 information was obtained …show more content…

The cuvette was rinsed twice with Milli-Q water (a Barnstead Nanopure® Model D-
158 50280 purification system with purity of 18.2 MΩ) and once with filtered seawater before each
159 measurement to avoid contamination by the previous sample. The absorption coefficients (aCDOM) were
160 calculated using the following equation, aCDOM (λ) = 2.304 × [A(λ)/L] (1)
161 where A(λ) is the absorbance at a wavelength λ, and L is the path length in meters. The absorption
162 spectra were corrected for scattering, temperature, and baseline drift by subtracting an average value of
163 absorption between 700 and 750 nm from each spectrum [40]. The exponential decay of the absorption
164 coefficient can be given by the following non-linear equation, ag(λ) = ag (λref) × exp [-S (λ - λref)] (2)
165 where ag(λ) is the amplitude of the CDOM absorption coefficient at any wavelength λ and λref is the
166 reference wavelength [41]. The absorption spectra generally represented by a non-linear equation (Eq.
167 2) was converted to a linear form by the logarithmic transformation of the dependent variable. Then,
168 least squares regression approach was applied to calculate spectral slope S between 275 nm and 295
169 nm, while the absorption coefficient at 355 nm (ag355) was used as a quantitative parameter of CDOM
170 [42].
171 2.4. Landsat Imagery
172 Landsat-5 TM data was used in this study due to the limitations of the

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