Original HRS subband 1 spectrum of the H₂O 1₁₀–1₀₁ line at 556.936 GHz observed on UT 8.78 August (upper panel), and several low and high frequency components of the spectrum determined using the EMD analysis (four lower panels) with labels indicating the mode number. The vertical axis is the calibrated main beam brightness temperature. The lower horizontal axis is the upper sideband frequency, while the upper axis shows the velocity with respect to the nucleus’s rest frame.