The Aroon Oscillator measures the strength of a trend. It is constructed by subtracting Aroon Down from Aroon Up. The Aroon Oscillator oscillates between -100 and +100 with zero as the center line. It signals an uptrend if it is moving towards its upper limit and a downtrend when it is moving towards the lower limit. The closer the Aroon Oscillator value is to either extreme the stronger the trend is.
Chart courtesy of Prophet Financial Systems