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MODIS Images Catalog of Ceara Solitons Located Offshore of the Amazon River Delta in the Equatorial Atlantic Ocean

(2013)

By

Edwin Alfonso-Sosa, Ph. D.

Ocean Physics Education, Inc.

15-FEB-2014

Overview

Recently, 250-m resolution MODIS images acquired by the Earth Observing System Terra and Aqua

Satellites during sunglint conditions allowed us to survey high-frequency nonlinear internal solitary wave

occurrences on a near-global scale (Christopher Jackson, 2007). It is possible to detect internal solitons

packets leaving the generation area during fortuitous conditions: minimum cloud cover, near-specular

reflectance pattern of sunlight off the ocean surface (sunglint) and strong oceanic stratification.

On year 2013 we acquired MODIS Aqua/Terra images from the Western Equatorial Atlantic Ocean

during fortuitous conditions. A total of 8 images show clear surface patterns associated with internal

solitary waves departing just east from the Amazon Platform’s shelf break. This area is subject to strong

semidiurnal barotropic tides (M2). The images KML files in Google Earth™ allowed us to measure and

characterize the internal solitons. The ratio between the distance separating the solitons and the

semidiurnal M2 period (12.42 hrs= 44712 s) allowed us to estimate their speeds (Christopher Jackson,

2007). The image catalog shows the following information below each image. It includes: image date,

original image file name, soliton separation distance in kilometers, soliton wave front name with suffix,

distance from Ceará Ridge in kilometers, time period between images in seconds and the speed

expressed in meters per seconds . The suffix corresponds to the image day. An arbitrary origin point for

our distance measurements was selected at Ceará Ridge, the origin coordinates were: 5° 00’ 00” N, 44°

00’ 00” W. Positive distances values indicate that solitons were located west of the Ridge and negative

values that were located east of the Ridge. A large positive distance value means the soliton is located

near the shelf break. On the contrary, a small negative value means that the soliton is located near the

east side of the Ridge. It was not practical to select a particular origin position at the shelf break because

there were numerous generation points along the 145 km (90 miles) stretch.

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We acknowledge the use of Worldview. This tool from NASA's EOSDIS provides the capability to

interactively browse global, full-resolution satellite imagery and then download the underlying data.

Worldview uses the Global Imagery Browse Services (GIBS) to rapidly retrieve its imagery for an

interactive browsing experience.

References

Alfonso-Sosa, E., 2013. First MODIS Images Catalog of Aves Ridge Solitons in the Caribbean Sea (2008-

2013) 32 pp. 8.92 MB PDF.

Alfonso-Sosa, E., 2012. Estimated Speed of Aves Ridge Solitons Packets by Analysis of Sequential Images

from the Moderate Resolution Imaging Spectroradiometer (MODIS) 11 pp. 2.55 MB PDF.

Christopher Jackson, 2007. Internal wave detection using the Moderate Resolution Imaging

Spectroradiometer (MODIS). JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 112, C11012,

doi:10.1029/2007JC004220.

https://earthdata.nasa.gov/about-eosdis

https://earthdata.nasa.gov/gibs

http://oceanphysics.weebly.com/uploads/1/1/9/5/11950137/first_images_catalog_of_aves_ridge_soliton_2008-2013.pdf

http://seichecostero.weebly.com/uploads/1/1/9/5/11950137/estimated_speed_of_aves_ridge_solitons_packets.pdf

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6/24/2013 MODIS_Terra_CorrectedReflectance_TrueColor Ceará Ridge, Equatorial Atlantic Ocean

JUN-24-2013. Solitons departing from the shelf break to the Ceará Ridge, a 500 km travel distance.

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JUN-24-2013. Zoom view of the Amazon Platform’s Shelf Break and soliton’s origin approximate

positions (SOAP’s).

The initial soliton wave fronts (white lines) were generated just east of the Amazon Platform’s shelf

break. Soliton’s origin approximate positions (SOAP’s) identified for each image date.

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Numerous generation points at the shelf break and location of the Ceará Ridge reference point. The

distances were measured from the ridge reference point. Positive distances values are for solitons

located west of the Ridge and negative values for solitons located east of the Ridge. A large positive

distance value means the soliton is located near the shelf break. On the contrary, a small negative value

means the soliton is located near the east side of the Ridge.

Soliton Separation Distance

(km) Wave packet name

Distance from Ceará Ridge (km)

Direction of Propagation

Time Interval

between solitons (s)

Soliton Celerity

(m/s)

109.18 wavefront1_24JUN2013 -95.32 17.80 44712 2.44

136.95 wavefront2_24JUN2013 13.86 18.44 44712 3.06

122.03 wavefront3_24JUN2013 150.81 31.76 44712 2.73

89.79 wavefront4_24JUN2013 272.84 31.30 44712 2.01

122.34 wavefront5_24JUN2013 362.63 29.76 44712 2.74

wavefront6_24JUN2013 484.97 32.98

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9/5/2013 MODIS_Aqua_CorrectedReflectance_TrueColor Ceará Ridge, Equatorial Atlantic Ocean






Time Interval


Soliton Celerity

(m/s)

137.32 wavefront1_7SEP2013 103.14 34.99 44712 3.07

113.58 wavefront2_7SEP2013 240.46 34.99 44712 2.54

wavefront3_7SEP2013 354.04 34.99

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Time Interval


Soliton Celerity

(m/s)

168.99 wavefront1_9SEP2013 -182.18 63.05 44712 3.78

144.16 wavefront2_9SEP2013 -13.19 63.05 44712 3.22

wavefront3_9SEP2013 130.97 42.74

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Time Interval


Soliton Celerity

(m/s)

150.07 wavefront1_23SEP2013 -44.67 37.07 44712 3.36

144.60 wavefront2_23SEP2013 105.40 37.07 44712 3.23

wavefront3_23SEP2013 250.00 37.07

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Time Interval


Soliton Celerity

(m/s)

135.49 wavefront1_7OCT2013 -118.80 50.67 44712 3.03

125.56 wavefront2_7OCT2013 16.69 43.42 44712 2.81

133.32 wavefront3_7OCT2013 142.25 39.25 44712 2.98

wavefront4_7OCT2013 275.57 36.61

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