Datasets from PWS FE 2009

Work continues...

All collected data will be wrapped up and packaged on a couple project pages where you will always will be able to grab this information as needed in the future. This will include whatever is currently in the archive for 2004 and 2007.

DATASETS

The ftp accounts will remain OPEN. Please let data management know if you are making changes or updates to the data you have provided from the field. Your help is appreciated. This will help keep the 'packaged set' up to date.

RESOURCES

Please let us know if certain instrumentation or model runs will stop operations in the near or far future. If something gets turned "off" please drop us a line so we can save a few CPU cycles.

FOLLOW UP

Please feel free to contact us anytime about how we can improve data management services. A survey has already been distributed and will capture some of the suggestions and comments. If you think of one or two items later, it is never too late to send them along. We are also willing to restructure datasets, as needed, if the daily directory structure doesn't make sense.

PURPOSE:

To assess the reproducibility of estimating biomechanical parameters of abdominal aortic aneurysms (AAA) based on finite element (FE) computations derived from a commercially available, semiautomatic vascular analyzer that reconstructs computed tomographic angiography (CTA) data into FE models.
METHODS:

The CTA data from 10 consecutive male patients (mean age 74 years, range 63-87) with a fusiform infrarenal AAA >5 cm in diameter were used for this study, along with the CTA scans from 4 individuals without aortic disease. Three different observers used semiautomatic reconstruction software to create deformable contour models from axial CT scans. These 3-dimensional FE models captured the aortic wall and thrombus tissue using isotropic finite strain constitutive modeling. Geometric (maximum diameter and volume measurements based on an anatomical centerline) and biomechanical determinants [aneurysm peak wall stress (PWS) and the peak wall rupture risk (PWRR) index] were then calculated from the FE models. The determinations were made 5 times for each anonymized dataset presented for analysis in random order (5-fold measurements for 14 datasets produced 210 measurements from the 3 observers). Inter- and intraobserver variability were assessed by calculating the coefficient of variation of these repeated measures. The methodological variations were expressed with the intraclass correlation coefficient (ICC) and Bland-Altman plots.
RESULTS:

The median segmentation time was < 1 hour (mean 39.2 minutes, range 25-48) for datasets from the AAA patients; for the healthy individuals, segmentation times were considerably shorter (median 8.7 minutes, range 4-15). Intraobserver reproducibility was high, as represented by a CV <3% for the diameter measurement and < 5.5% for volume, PWS, and the PWRR index. The ICC was 0.97 (range 0.95-0.98) for diameter and 0.98 (range 0.97-0.99) for volume; for PWS and the PWRR index, the ICCs were equal at 0.98 (range 0.97-0.99).
CONCLUSION:

The reproducibility of volume and maximum diameter measurements in infrarenal AAAs with FE analysis is high. With the model used in this semiautomatic reconstruction software, wall stress analysis can be achieved with high agreement among observers and in serial measurements by a single observer

Data report for Aug 3rd 2009 @ 4 PM AKDT

Data report for Aug 3rd 2009 @ 4 PM AKDT

Data and system status:
* A HF Radar node has been turned off essentially ending the HF Radar service for the experiment. The last total is August 3rd @ 1800 GMT. Automatic processing has been turned off.
* The WRF, ROMS and SWAN forecast runs are continuing at present.

Data seen on Aug 2nd via FTP:
* Update for Naked Island (yet to be processed)
* Slocum glider (RU21)
* CTD: 8/2

Data seen on Aug 3rd via FTP (and other means) as of 4 PM AKDT:
* Remus
* SVP(10m): 8/2
* Argosphere(0m): 8/2
* Thermosalinograph: 8/2

Optimal window around 4pm today to release the 10-m drifter: a legacy of the 2009 FE?

Over the past few days, we have discussed to release a 10-m drifter (with more battery life and possibility of drifting for a long time after the FE is over) towards the end of the FE. The strong inflow from both HE and MS (at least the east side) made such a plan difficult.

However, the wind switched from easterlies two days ago to westerlies today. This provides a favorable condition for the cyclonic eddy (seen by both HF radar and ROMS), and outflow condition at HE. There is a very strong tidal current at the HE, see the above images, the tidal current at HE can be as large as 50 cm/s within six hours (associated with the 12 hourly M2 tides). The tidal current is very weak right now, 12pm Sunday. However, both the wind-driven and tidal-driven current are in phase later this afternoon. Based on all the information I have, this afternoon around 4pm (+/- 1 hour window) is predicted as the optimal window to release a 10-m drifter, slightly northwest of the HE. Both the surface (0-meter) and the 10-meter current are coherent, see attached image.

I don't know this plan is feasible, but it is worth some discussions. In case people on the boat don't access emails, I am wondering whether someone can call Scott or others on the boat. I will email the group, and contact Carter in the next hour.

It would be great if we can try to release one or more drifters today, so that we can continue to watch their trajectories after the FE is over.

Agreement between HF radar & ROMS surface current

The most recent HF radar data at 14 GMT or 6am AKDT this morning show a very strong outflow at HE. Good agreement is found between the HF radar observation and ROMS forecast. This should give us confidence using the ROMS forecast to guide drifter deployment, see next blog entry. The outflow at HE is over 50 cm/sec.

Data Report for August 1st, 2009

As of 12:30 AM 8/2, new data at the FTP site:

* Slocum glider
* SVP (10m)
* Argosphere (0m)
* CTD: 8/1 + other updates
* Thermosalinograph: 7/31, 8/1
* HF Radar: radials, no totals

SLDMBS update: 20090801_1644

For those accessing the SLDMBS drifter data via AOOS, a SLDMBS update was just passed along and processed (SLDMBS_20090801_1644). Thanks, LT Mike Glinski and Paul Webb!

WRF and ROMS forecast summary for July 31

7/31/2009 - A fast-moving low pressure system passed through the south central Alaska yesterday evening. This system passage caused a tightening of the pressure gradients in the region of PWS, resulting in winds strengthening to 15-20 knots and becoming more northeasterly. Today and through the weekend the ridge is forecast to build back, and depending on the location of the ridge axis, a tendency towards lighter, more southwesterly winds should be seen. The central Sound eddy, as revealed by HF radar observations, weakened overnight, perhaps in response to the stronger atmospheric wind forcing that developed. ROMS nowcast/forecast surface currents also show a weakening in the eddy circulation in the mean surface currents from the first 24 hours of today's ROMS forecast. Interestingly, the mean from the second 24 hours of the forecast shows a return of the eddy circulation. The tidal range will increase slightly over the next 48 hours. At Valdez, the tidal range will be around 10 feet. High water (5feet) will be at 20AKDT, and low water (-5 feet) at 5AKDT. There were no signficant operational issues today.