G-d ascends through teruah, G-d ascends through the sounds of the shofar.
Tehillim, Psalm 47
G-d's motivation in creating the world is the pleasure he receives from our fulfillment of the Torah and mitzvot. G-d's desire for our service, then, is the foundation on which the world is built. Remove the desire for our service, and there is nothing to sustain creation.
Kabbalah explains that this removal of desire occurs annually. Every Rosh Hashanah eve,
G-d's interest or desire in creation temporarily ceases. When we then recommit ourselves to
G-d's service to realigning our lives with the dictates of the Torah, G-d's desire is reignited. He once again commits to sustaining the world for the coming year.
The climax of this re-dedication is the sounding of the shofar, before which we recite Psalm 47, for this psalm conveys the meaning and power of the shofar and how it reawakens
G-d's desire in creation:
G-d (Elokim) ascends through teruah, G-d
(Y-H-V-H) through the sound of the shofar.
This verse mentions two Divine names: Elokim and Y-H-V-H. It also refers to two sounds of the shofar: the teruah and the tekiah (referred to in the verse as the "sound of the shofar").
Elokim is related to strength and judgment. When G-d acts as king of the universe and actively concerns Himself with sustaining it, He is called by this name. This is because it requires strength for a transcendent G-d to relate to a finite world, the strength to conceal Himself so that the world can be validated. Conversely, the loftier name Y-H-V-H, whose true pronunciation we avoid, represents G-d's essence, his inherent transcendence from creation.
Why does the psalmist juxtapose these Divine names with the two sounds of the shofar?
The teruah is a series of broken blasts. These fragmented blasts are the sound of our struggle to ascend from materialistic bondage to spiritual freedom. The tekiah, by contrast, a single, sustained blast, represents a G-dly flow of energy, uninterrupted and consistent.
As explained, it is through our re-dedication that G-d assumes the role of King each year.
This occurs as follows:
First, Elokim ascends--G-d retreats deep within Himself to rejuvenate His desire in creation. This is inspired by our teruah, our effort to draw closer to Him. Hence: Elokim ascends through teruah.
What follows is: Y-H-V-H through the sound of the shofar--a new, replenished flow of energy is drawn from G-d's Essence. G-d is reinstated as King and continues to sustain creation.
(Rabbi Dovber of Lubavitch)