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Multiple populations revealed in globular clusters (GCs) are importantwindows to the formation and evolution of these stellar systems. The metal-richGCs in the Galactic bulge are an indispensable part of this picture, but thehigh optical extinction in this region has prevented extensive research. Inthis work, we use the high resolution near-infrared (NIR) spectroscopic datafrom APOGEE to study the chemical abundances of NGC 6553, which is one of themost metal-rich bulge GCs. We identify ten red giants as cluster members usingtheir positions, radial velocities, iron abundances, and NIR photometry. Oursample stars show a mean radial velocity of $-0.14\pm5.47$ km s$^{-1}$, and amean [Fe/H] of $-0.15\pm 0.05$. We clearly separate two populations of stars inC and N in this GC for the first time. NGC 6553 is the most metal-rich GC wherethe multiple stellar population phenomenon is found until now. Substantialchemical variations are also found in Na, O, and Al. However, the twopopulations show similar Si, Ca, and iron-peak element abundances. Therefore,we infer that the CNO, NeNa, and MgAl cycles have been activated, but the MgAlcycle is too weak to show its effect on Mg. Type Ia and Type II supernovae donot seem to have significantly polluted the second generation stars. Comparingwith other GC studies, NGC 6553 shows similar chemical variations as otherrelatively metal-rich GCs. We also confront current GC formation theories withour results, and suggest possible avenues for improvement in the models.

Two Groups of Red Giants with Distinct Chemical Abundances in the Bulge Globular Cluster NGC 6553 Through the Eyes of APOGEE