Warning: This writeup was done to help organize
my thoughts prior to the presentation.
The actual presentation may have been quite different!
The field program envisioned within this document, includes short termed process studies (such as EPIC2001), embedded within enhanced monitoring, built on the ENSO observing system. The part I've been involved in is the enhanced monitoring built on the TAO array.
As part of the EPIC enhanced monitoring, we enhanced the easternmost TAO line at 95W with 3 extra moorings -- 3.5N to better resolve the northern edge of the cold tongue, and 10N and 12N to extend the line across the ITCZ and into the NE Pac WP.
BP has 1 hour resolution. All other measurements have 10 minute or better. Daily averages of nearly all measurements are telemetered to shore via Service Argo and made available through the WWB (hit the Data Delivery Button). Realtime data of standard TAO measurements and of BP from all 10 EPIC buoys are also made available through the GTS. So for example, these BP data are ingested into most numerical prediction models. High res data are stored internally and therefore are made available only after the mooring is recovered. For example, the 10N mooring is scheduled to be recovered next week and that data will become available probably by no later than June though some might come earlier and some -- like salinity -- might be a little slower.
The shortwave radiometer allows us to compute the first term.
SST and downwelling longwave radiometer allows us to directly measure the 2nd term.
And Sensible and Latent Heat flux are computed using the COARE bulk algorithm with wind speed (and ocean current at 10 m depth), relative humidity, air temperature, and SST. With the radiation data we can also apply a model of the diurnal warm layer so that we can extrapolate the bulk SST to be a skin temperature.
Furthermore, with first deployments in November 1999 and final recoveries in Fall 2003, we will have this section enhanced for 3-4 years and be able to analyze diurnal-to-interannual variability in the CT/ITCZ structure.
At least that is our intent.
Consequently, there are some buoys like 2N and 0, that have been almost on a 6-monthly schedule. 3.5N right now is telemetering from Colombia. The end result is that 1) the data are gappy and 2) the costs are higher than anticipated. I have a proposal into the OAR Asst. Administrator's discretionary funds to help pay for the final two cruises. Without the increased funding, I will have to begin decommisioning these enhancements earlier than planned. Your support and endorsement will help determine the future of this observing system.
The frontal region associated with the northern edge of the cold tongue shows up in nearly all variables. Skipping down to the middle panel here we see that Air T and SST are almost identical at 2S and the equator, so that the air is relatively stable. Relative humidity is also high and latent heat flux (as well as sensible heat flux) have minimums on the equator. Just two degrees north, the air is must more unstable. Latent heat loss is 150 W/m2 larger. Winds are higher and the air is much drier.
There are a couple of other things that I would like to bring to your attention...
Although the magnitude of the winds' unit vector is twice as large as the 10 m current vector, we can see that the currents are a non-negligible fraction of the wind magnitude. Also, they are not necessarily in the same direction. This means that we need to be careful when computing the fluxes -- winds must be relative to the ocean currents. Further, the wind stress, may not be in the same direction as the 4 m winds, and indeed the winds may have a slight turning to them induced by the oblique currents.
Also, note that while the maximum rainfall is where we expect it at 8N, the freshest waters are south, at 3.5N. Could there be a landbased source of freshwater here? Also, what is the dynamical effect of this buoyancy gradient?
SWR was within a few Watts of its climatology over the record length. However, what I find remarkable is just how dark some days can get. For example on Sep 27, as tropical storm Juliette was spinning up to hurricane force, the 24-hour average SWR was less than 5 W/m2.
Finally, what is controlling this seasonal variability in the thermocline? Is it 1-d forcing? or 3-d? How does this variability relate to the evolution of the Costa Rica dome and local wind stress curl? These are a sampling of some questions I hope to address with this data set.
Meghan F. Cronin
Pacific Marine Environmental Laboratory
7600 Sand Point Way NE
Seattle, WA 98115 USA
Meghan Cronin's Home Page
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