IEEE Robotics & Automation Magazine - June 2013 - 29

1,200 Nautical Mi of Open Ocean
Phytoplankton Blooms
One of the more exciting discoveries made by the PacX
Wave Gliders occurred in mid-June of 2012. Between
Hawaii and the first NOAA Tropical Atmosphere Ocean
moored buoy, the two Australia-bound Wave Gliders, Papa
Mau and Benjamin, traveled through a phytoplankton
bloom-six days and 1,200 nautical mi in expanse (Figures
8 and 9). These blooms indicate proliferation of phytoplankton that is fundamental to ocean life and climate regulation.
Although typically monitored through satellite imagery,
direct validation of chlorophyll blooms at this resolution
provides a groundbreaking link between scientific modeling
and in situ measurement of the Pacific Ocean.
The PacX data discovered by Papa Mau and Benjamin was
independently validated by NASA's ocean color radiometer
(MODIS). Biological and physical properties within this distinct water mass were highly correlated. Papa Mau was the first
to encounter the feature, with Benjamin measuring remarkably similar results in chlorophyll-A, salinity, and temperature
when it reached the phytoplankton bloom six days later.
Receiving data from the center of the phytoplankton
bloom was intriguing for scientists because very little is
known regarding the cause of this oceanic phenomenon. The
data collected could help scientists discover if the ocean conditions made the phytoplankton bloom possible or if the phytoplankton bloom itself helped shape the ocean conditions.
The diurnal signal is due to photoinhibition. The phytoplankton adjusts their position in the water column near midday to limit sun exposure.

Becoming a Shellback-Crossing the Equator
On 12 July 2012, Papa Mau became the first Wave Glider to
become a shellback! As the Naval tradition of crossing the line
(crossing the equator) dictates, those who cross the equator
for the first time change from an undesirable Pollywag to a
trusted shellback. Everyone who successfully achieves this status is awarded a citation of under the Domain of Neptune
Rex. Indeed, Papa Mau's certification was awarded five days
after his historic crossing (Figure 10).
Surfing Through Cyclone Freda
On 26 December, Tropical Cyclone Freda and Benjamin met.
When Freda was peaking at a Category 4 Cyclone, Benjamin

Figure 10. Papa Mau's certification for becoming a shellback after
crossing the equator for the first time.

At Time of Minimum Distance (26 nmi), Wave Glider
and Satellite-Based Wind Speed Readings Converge

Wind Speed
120
100

knots

80
60
40
20

12
/1
2/
20
12
12
/1
0
7/
20 :00
12
12
/2
0
2/
20 :00
12
12
/2
0
7/
20 :00
1
1/
1/ 2 0
20 :0
13 0
1/
0
6/
20 :00
1
3
1/
0:
11
00
/2
01
3
0:
00

Wind Gust
Wind Speed
Satellite Wind Speed

Legend
Wind Speed (kts)
1-10
11-25
26-50
New Caledonia
51-75
76-100
101-125
Storm Track
0 40 80

320
160 240 32

Nautical Miles

Figure 11. Nine uninterrupted channels of MetOcean data while traversing through Category 3 and 4 Tropical Cyclone Freda,
26 December 2012. Wave Glider and satellite-based wind speed readings converge.

june 2013

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