We have carried out ^ { 12 } CO ( J = 2–1 ) and ^ { 12 } CO ( J = 3–2 ) observations at spatial resolutions of 1.0–3.8 pc toward the entirety of loops 1 and 2 and part of loop 3 in the Galactic center with NANTEN2 and ASTE .
These new results revealed detailed distributions of the molecular gas and the line intensity ratio of the two transitions , R _ { 3 - 2 / 2 - 1 } .
In the three loops , the line intensity ratio R _ { 3 - 2 / 2 - 1 } is in a range from 0.1 to 2.5 with a peak at \sim 0.7 .
The ratio in the disk molecular gas is in a range from 0.1 to 1.2 with a peak at 0.4 , significantly smaller than that in the Galactic center .
This supports that the loops are more highly excited than the disk molecular gas .
An LVG analysis of three transitions , ^ { 12 } CO J = 3–2 and 2–1 and ^ { 13 } CO J = 2–1 , toward six positions in loops 1 and 2 shows density and temperature are in a range 10 ^ { 2.2 } – 10 ^ { 4.7 } cm ^ { -3 } and 15–100 K or higher , respectively .
Three regions extended by 50–100 pc in the loops tend to have higher excitation conditions as characterized by R _ { 3 - 2 / 2 - 1 } greater than 1.2 .
The highest ratio of 2.5 is found in the most developed foot points between loops 1 and 2 .
This is interpreted that the foot points indicate strongly shocked conditions as inferred from their large linewidths of 50–100 km s ^ { -1 } , confirming the suggestion by \citet kt2009b .
The other two regions outside the foot points suggest that the molecular gas is heated up by some additional heating mechanisms possibly including magnetic reconnection .
A detailed analysis of four foot points have shown a U shape , an L shape or a mirrored-L shape in the b - v distribution .
It is shown that a simple kinematical model which incorporates global rotation and expansion of the loops is able to explain these characteristic shapes .