The Bible teaches us about the sendings of the Persons of God. In Latin, the word sending translates missio, and so divine missions or divine sendings are the same things.
The Bible teaches that the Father visibly sends the Son into the world to take to himself human flesh in the Incarnation (John 1:14; 3:13, 17).
Scripture also teaches that the Father and Son send the Holy Spirit at Pentecost visibly as winds, tongues of fire, and as the enabler of tongues (Acts 2). These are called the visible missions (sendings) of the Son and Spirit because they are visible.
Humans can see Jesus because he has a human body; and at Pentecost, the tongues of fire particularly and visibly show the Spirit sent to the church.
Subsequent to the two visible sendings of the Son and Spirit, two invisible missions follow.
Since Jesus lived by the Holy Spirit (Acts 10), the Spirit united the Word to the flesh (Lk 1), & the Spirit mutually indwells the 1 divine nature of the Son, then Jesus can be said to give the Spirit without measure (John 3:34) b/c he has the Spirit from his fullness (John 1).
This invisible mission of the Spirit to thus indwell the hearts of the Church unites us by grace to the Son of God, who in turn in his invisible mission dwells in our hearts by faith. These two invisible sendings or indwellings follow the two visible missions.
In this sense, we can see a pattern in Scripture that works like this: the Father visibly sends the Son, and the Father and Son visibly send the Spirit.
Although I’d give my argument, I basically conclude that the triune God—amazingly—terminates his mission in created effects—the human body of Christ or visible signs at Pentecost. I also say that the missions of God extend the processions of God into time and place.
The coherence of the missions of God reveals the truthfulness and coherency of the doctrine of divine processions. The processions reveal the inner logic of the missions, and the missions confirm by means of tracing an effect (missions) to their cause (processions).