Jesus ascended, returned to The Father and The Holy Spirit before He could send the Holy Spirit. This is how things got intensely personal. Before the Ascension, Jesus could be in one place at one time. If he was in Galilee he couldn't be anywhere else. After the Ascension, Jesus sent the Holy Spirit, God's presence and Third Person of the Trinity who is not limited by being Incarnate. God is everywhere at all times. The Ascension of Jesus prepares the way for God to be personally present to us in the person of the Holy Spirit.
The Ascension is also a celebration that we get to participate in. I'll be reflecting on all of this on Sunday. -Fr. Ed