Sally Approaching SG601

Sally is currently approaching the Gulf Coast and is still expected to intensify over the next day https://www.nhc.noaa.gov/text/refresh/MIATCDAT4+shtml/132040.shtml? Currently glider SG601, a NOAA NDBC glider piloted by Kevin Martin at USM is heading southeastward toward the eye of the storm. SG601 is on track to enter  a warm and salty eddy that is within Sally’s projected path over the next 24 hours

Sea Surface Temeperature from the Navy Global Ocean Forecasting System (GOFS) 3.1

Sea Surface Salinity from the Navy GOFS model

Eddies like these can contain additional ocean heat that, if conditions are right, could be used as an energy source for the storm. We’ll be looking closely at SG601 data as it simultaneously enters the eddy, and starts to be influenced by the eye of the storm. Currently, profiles of temperature from SG601, show a warm surface layer over the upper 50 meters, that has not yet started to mix with underlying cooler waters.

Michael Gulf of Mexico SST anomaly and ocean response

Micahel is now making its way through the Carolinas and into the Northeastern part of the country. It looks like it had a truly devastating impact of the Florida panhandle region coming ashore as a category 4, a few miles per hour shy of a category 5. Some of the rapid intensification is likely due to warm sea surface temperatures in the Gulf of Mexico. Above is a plot of the 8-day composite sea surface temperature anomaly after removal of the 15 year average for the same time period. This product is generated by the University of Delaware Ocean Remote sensing and Biogeography (ORB) Lab. Above average temperatures are clearly visible in the northern portion of the Gulf where the storm intensified.

Additionally, this image shows a glider track in purple for the US Navy Glider NG288, which we’ve been following for the past few blog posts. The system collected data throughout the storm, transmitted it to shore where the Navy made it available to IOOS for public release.

In the time and depth slice from NG288 it’s clear that surface layer was very warm, exceeding 28 Celsius down to about 50 meters ahead of the storm.This thick warm surface layer provided an ample pool of heat to maintain and intensify Michael as it approached land. On October 10th, as the storm passed over the glider location there is rapid mixing and deepening of the surface mixed layer from 50 meters down to almost 100 meters, but with very limited ocean cooling. This is an exciting dataset that we’ll be using for years to come to understand rapid intensification of hurricanes in the Gulf of Mexico.

Hurricane Michael glider model comparisons for October 9th

According to the National Hurricane Center Michael has made landfall in Florida as a Category 4 Hurricane with winds just below Category 5 levels.

There’s an approximately 500 km wide swath of hurricane and tropical storm force winds across the eastern Gulf of Mexico.

Just prior to landfall, the storm’s eye passed within about 50 kilometers of Navy Glider NG288’s most recent reported location.

Above are Cross-sections of temperature from (top) Glider NG288, (middle) the Navy HYCOM Global Ocean Forecasting System 3.1, and (bottom) Navy HYCOM Global Ocean Forecasting System 3.0 run by the Navy Research Laboratory. The black contour shows the position of the 26 degrees Celsius isotherm, which is commonly used to calculate ocean heat content for hurricane intensity purposes.

At a glance the models have similar surface temperatures to the glider observations throughout the deployment, but the 26 degree Celsius isotherm in both GOFS 3.0 and 3.1 appear to be slightly shallower than the observed position.

Next we zoom in to the last days profile comparisons before Michaels passage. The lines and colors are defined as in the previous post, but now we’ve added a vertical line and red triangle indicating the 26 degree Celisus temperature its depth in the glider observations. The depth of the mixed layer at 50 meters is well represented by GOFS 3.1, while GOFS 3.0 does a better job of matching the observed temperature profiles below the mixed layer.

Navy Glider Model Comparisons for Hurricane Michael

The Atlantic Hurricane season is not over yet. Hurricane Michael has recently spun up in the Caribbean Sea and is making its way into the Gulf of Mexico. There are still a number of gliders in the east coast, Caribbean, and Gulf of Mexico picket line out there.  Navy Glider NG288 is positioned just to the right of Michael’s predicted track, where winds, waves, and ocean mixing are likely to be the highest. A plot of the NHC storm track and glider track (in black) is shown below from the MARACOOS Oceansmap Data Portal

Maria, our IOOS research analyst, has generated the usual glider data/model comparison profiles for the last day from Navy HYCOM GOFS 3.0 and 3.1.

In the left panel: individual glider data profiles are shown in green with the daily mean in black, GOFS 3.0 only archives daily and is plotted in magenta, and GOFS 3.1 profiles are every 3 hours and plotted in light blue with the daily average in dark blue. In the upper 30 meters both GOFS 3.0 and 3.1 are in good agreement with glider observations with temperatures all near 29 Celsius. Below 30 meters depth the models diverge, with GOFS 3.0 following the glider profiles closely throughout the water column. GOFS 3.1 remains a few degrees cooler than the glider and 3.0 until about 200 meters depth. The heat content, defined as the depth integrated heat above the 26 degree isotherm, for GOFS 3.1 is going to be lower than the glider or GOFS 3.0.

Both models are fresher than the observed salinity profiles throughout the water column, with GOFS 3.1 being closer to observations in the surface, and GOFS 3.0 closer near the salinity maximum at ~150 meters depth.

A snapshot of surface currents from Navy HYCOM in MARACOOS Oceansmap shows that a warm core loop current eddy is located just to the west of the storms predicted position at 1:00 PM CDT Tuesday October 9th. The glider is located in a frontal region near the storms predicted position at 1:00 AM CDT Wednesday October 10th, with slow currents to its east and fast northward currents to its west. The uncertainty in model data comparisons may be related to the placement of these features in the different models, and will require further investigation.

SAB & MAB Stratification in GOFS 3.1

We use the Non-dimensional Potential Energy Anomaly, what we call the Stratification Factor, to represent the stratification structure on the continental shelf with one number so we can plot it as a map.

This first plot says that according to GOFS 3.1, the MAB shelf is highly stratified and the SAB shelf is much less stratified.

You can even see the very high stratification in the PEACH area just north of Cape Hatteras.

The first slide is the derivation of the Stratification Factor, and the second slide shows the current conditions in 3.1

Thanks.

Scott

OOI Gliders in the Glider DAC

Here are 3 maps people may find useful for their daily briefs.

First image is the IOOS Glider DAC showing the entire North Atlantic fleet.

The change from yesterday is the NSF OOI gliders are back in. Yesterday afternoon Mike Crowley worked on resolving the metadata issues and John Kerfoot was able to get the OOI Pioneer Array gliders back into the DAC.  So now this NSF OOI data is also going to the DAC and onto the GTS and into the models.

This image is an unprecendented combination of NOAA, Navy, NSF and Industry (TWR’s glider SILBO in Helene) supported gliders all collaborating through the IOOS Glider DAC to support our Weather-Ready Nation’s efforts to be better prepared for hurricanes.

Its inspiring, but with my own memories of Sandy, still difficult knowing what is in store for the southeast.

Second image zooms into the East Coast picket line, where you can now see the individual OOI gliders that were added to the mix last night.

The line up from south to north is

Catherine Edwards PELIGIA deployed for SECOORA.

Catherine Edwards deployed UNC RAMSES for NSF PEACH.

NOAA Spray

Travis Miles RU33

Wendell Brown UMass BLUE.

NSF OOI.

I know this is a glider distribution list, but there is a similar level of involvement in the IOOS HF Radar community.

Third image is from the MARACOOS OceansMap were we have taken the IOOS Glider DAC gliders, added the NHC Florence forecast cone, and also turned on the IOOS National HF Radar network 6 km grid (as you see in the menu on the left).

In the MAB, it was the combination of the gliders, the HFR, the satellites, and the 30-year time series of NDBC buoy data that made possible the scientific analysis and essential ocean process discovery that led to the science papers that provided the scientific basis for the change in approach that we see active today.

Thanks to the long list of people that worked with increasing intensity for months so that this array can be in place.

We will be looking at more gliders in the model data comparisons today. If anyone needs something special, let me know, and we will jump it in the queue.

Thanks all.  Stay safe.

Scott

Pelagia & GOFS and Copernicus Mercator

Here is a first look at what the European global ocean model is saying for Pelagia.

SST for Copernicus and GOFS 3.1 (the data assimilative initial condition for RTOFS) both have about the same surface temp.

That would be expected because they are both assimilating the similar global SST products.

Subsurface varies quite a bit between the models.  All colder than the models.

GOFS 3.0 is closest to the glider, but likely for the wrong reason, the lower spatial resolution of GOFS 3.0 in shallow water tends to produce isothermal layers in shallow water that then adjust the surface temperature to match the satellite SST.

GOFS 3.1 and Copernicus clearly have the resolution to produce stratified continental shelves.

RTOFS is coming in closer to the glider.  It takes a bit of time for the data flow to go through the system from the glider control center to the glider dac to ndbc to gts, so the PELAGIA profiles are probably just starting to appear in the NCEP tanks.

So these model profiles likely have very little data other than SST contributing to the assimilation.

This is what we hope to modify with the glider data and the GOFS 3.1 assimilation scheme.

As before – sending this out as fast as Maria is producing them so we can get this to Debra and Catherine for their briefs.

Thanks Maria.  Thanks all.

Scott

PELAGIA data-model comparison

Sending these along quickly to get them to partners at SECOORA and Skidaway University as fast as possible for the briefs they are giving.

They are of Glider PELAGIA deployed yesterday by Catherine Edwards for SECOORA.

Today’s plot is especially interesting, the mirror image of the issues in the Mid Atlantic.

In this case the glider data is nearly isothermal, very warm, like 28.5 C.

But here the operational models have a two-layer structure with warmer surface temperatures and colder bottom temperatures.

There still is a lot to discover on how the operational ocean models respond compared to the real ocean observed by the glider.

And we need to remember that this is a global model, designed more for deepwater –

But it is a seamless ocean boundary condition for HWRF that runs from deepwater across the shelf – just like a hurricane.

We have the published evidence that the MAB shelf can impact the hurricane intensity, and now we will see in real time how the SAB shelf responds and possibly see if it has an impact on intensity.

We are making great progress and continuing to learn how to improve our forecast models.

Good luck to our friends in the South Atlantic Bight.

Scott

Some USVI Glider Data ahead of Isaac

Another couple of images.

First is the location plot for the 3 USVI gliders from the GOC via Doug Wilson.

Second is the comparison of NG300 with GOFS 3.1 and 3.0 via Maria Aristizabal.

Also Ben Lacour and John Kerfoot have been looking at the data flow and are seeing the Navy gliders show up in the NCEP data tanks.

More to come tomorrow.

Scott

Hurricane Helene and Silbo in the eastern Atlantic

Just wanted to share these images of Helene and Silbo while we were working on the model-data comparisons for ramses and a Navy glider in the Caribbean.