Altimetry Help

[Team Karma]

I have searched around the internet a fair amount in an attempt to find a good explanation of exactly what an altimetry image is showing me. I know it is supposed to show you areas of upwelling and down welling but beyond that I am lost. How do read the charts/images? What is a good thing to see on an altimetry image and how should I use it in conjunction with SST and chlorophyll images? I use terrafin and buoyweather. Is there another site that provides better information for the entire Pacific Coast from Mexico to Panama?

I have not found anything that explains it thoroughly enough for me to completely understand how to confidently use Altimetry information.

Thank you in advance to anyone willing to share any info.

[tunabite]

hiltons realtime navigator

[tunabite]

go to demo then tutorial on altimetry, you can do this without signing up i believe......

[Team Karma]

Thank you tunabite. You should get a commission for signing me up.

[blueoceaneyez]

Upwelling - nutrient rich water moving UP
Downwellings - nutrient poor / warm water moving DOWN
You don't wanna fish centers of high or low, you wanna look for neutral or slightly positive zones (green, yellow), or pinched zones between a high and low.

Having a MLD, thermocline shot helps too, imo.

I use SeaView Altimetry.

[Free_Jumper]

I have searched around the internet a fair amount in an attempt to find a good explanation of exactly what an altimetry image is showing me. I know it is supposed to show you areas of upwelling and down welling but beyond that I am lost. How do read the charts/images? What is a good thing to see on an altimetry image and how should I use it in conjunction with SST and chlorophyll images? I use terrafin and buoyweather. Is there another site that provides better information for the entire Pacific Coast from Mexico to Panama?

I have not found anything that explains it thoroughly enough for me to completely understand how to confidently use Altimetry information.

Thank you in advance to anyone willing to share any info.

Strong gradients (rapid changes) between features (highs and lows) equals good places to fish. Chlorophyll will generally be concentrated as a proxy for currents and frontal boundaries - algae going for a ride. Rapid changes in sea surface temperature can be a proxy for upwelling - temperature breaks may indicate productivity. However concentrations of bait don't always stack up on remote sensed isotherms - find the bait find the predators...

http://earth.eo.esa.int/brat/html/ap...welcome_en.htm

The ocean is the surface studied by the majority of altimetry applications, and some missions are even optimised for it. Ultimate applications include oceanography itself, as well as the implications of ocean movements on climate (and vice-versa, the effects of climate change on the ocean).

Ocean currents can raise sea surface height by up to a metre higher than the surrounding area. Currents can therefore be mapped by measuring height variations. Satellite altimetry, supplying continuous worldwide observations, has been increasing our knowledge of ocean circulation since the 1978 Seasat mission. The ocean is also a turbulent environment -- especially so in the major current areas--, where 'mesoscale' eddies (i.e. eddies measuring about 50-500 km across) are generated and move. The goal of operational oceanography is to describe in real-time and to forecast such ocean dynamics, with altimetry supplying the most important data for assimilation.

The tides, another ocean phenomenon seen by altimetry, can now be gauged to within 2 cm, thanks largely to altimetry. This has helped to improve our understanding of Earth-Moon interactions such as the Moon's impact on the length of the day on Earth, and has given some insight into one of the driving forces of the Earth's climate system.

Last, but not least, by tracking changes in sea level, altimetry helps us to monitor mean sea level, its time variations and geographical patterns. Many studies are ongoing, in the context of research into the greenhouse effect.

http://oceanmotion.org/html/backgrou...ophic-flow.htm

Bottom line, assuming geostrophic balance in the northern hemisphere draw a line from high sea surface height to low and currents deflect to the right about the high.

http://oceanworld.tamu.edu/resources...apter10_03.htm


http://www.tos.org/oceanography/issu...cobs_et_al.pdf


Sea level changes observed by satellite altimeter instruments have long been recognized as a vital source or information on open ocean circulation. In a simplified manner, the ocean may be viewed as layers of fluids within which different dynamic processes dominate. Near the ocean surface (within about 30 m, though at times much deeper), fluxes of momentum from wind stress and heat are strong contributors to environmental variations.

Aside from the mixed layer, the open ocean may be generally viewed as a warm water mass overlying a colder relatively denser water mass.

Ocean variations are primarily controlled by changes in the depth of the thermocline, which is the boundary that separates the two water masses. There is a strong correlation between thermocline depth and sea level, which produces a pressure anomaly throughout the water column (see Fox et al., this issue). For example, a relatively high sea level indicates high pressure, and this pushes the thermocline downward.

Open ocean dynamics generating the sea level changes are mainly mesoscale eddies and current meanders.

http://www.aoml.noaa.gov/phod/altimetry/about.php

NOAA/AOML Altimetry Products
NOAA/AOML distributes on its web server several products derived from altimetric sea height anomaly fields, for weather and climate studies. These products are validated using data from a variety of platforms, such as XBTs, drifters, moorings, and profiling floats:
The global surface currents, a project of the NOAA CoastWatch Caribbean Node that is housed at NOAA/AOML, are produced on a daily basis using altimeter-blended data obtained from NRL.



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[Team Karma]

Upwelling - nutrient rich water moving UP
Downwellings - nutrient poor / warm water moving DOWN
You don't wanna fish centers of high or low, you wanna look for neutral or slightly positive zones (green, yellow), or pinched zones between a high and low.

Having a MLD, thermocline shot helps too, imo.

I use SeaView Altimetry.

Why do you want to fish slightly positive zones? I understand pinched zones and avoiding centers but don't grasp why slightly positive would be better than slightly negative.

[Free_Jumper]

This won't answer your question directly and has more regionally specific information - but may help build some insight over predators and ocean variability.

http://www.tos.org/oceanography/issu....2_letters.pdf