Table 2.

Summary of the data recorded by the drifters and units (UTC = Coordinated Universal Time; WGS = World Geodetic System; NED = North-East-Down system).

Column	Variables		Units
Microcontroller
1	Time		ms
GNSS
2	Time		ms
3	UTC Time		ms
4	Nano UTC time		ns
5	Latitude (WGS84)		10−7 degrees
6	Longitude (WGS84)		10−7 degrees
7	Height above ellipsoid		mm
8	Horizontal accuracy		mm
9	Ground speed		mm/s
10	NED north velocity		mm/s
11	NED east velocity		mm/s
12	NED down velocity		mm/s
13	Number of satellites		-
14	Heading		10−5 degrees
IMU
15	Quaternions	w	-
16		y	-
17		x	-
18		z	-
19	Acceleration	x	m/s2
20		y	m/s2
21		z	m/s2
22	Magnetic field	x	µT
23		y	µT
24		z	µT
25	Gyroscope	x	rad/s
26		y	rad/s
27		z	rad/s
28	Calibration of gyroscope		-
29	Calibration of accelerometer		-
30	Calibration of magnetometer		-