I am writing a program to receive and interpret NMEA data from a GPS receiver. I am working with an Adafruit Ultimate GPS Receiver integrated with an Arduino.

The $GPRMC NMEA Sentence contains the Speed in Knots parameter, which I'm interested in. I want to convert this to a velocity vector, i.e. find speed in each direction (Vx, Vy, Vz). Is this possible by any mathematical calculation or through the NMEA Data?

The Adafruit library for the GPS also provides a function for getting the Speed value (in knots (same as above)).