To better understand the origin and evolution of the Milky Way bulge , we have conducted a survey of bulge red giant branch and clump stars using the HERMES spectrograph on the Anglo-Australian Telescope .
We targeted ARGOS survey stars with pre-determined bulge memberships , covering the full metallicity distribution function .
The spectra have signal-to-noise ratios comparable to , and were analysed using the same methods as the GALAH survey .
In this work we present the survey design , stellar parameters , distribution of metallicity and alpha-element abundances along the minor bulge axis at latitudes b = -10 ^ { \circ } , -7.5 ^ { \circ } and -5 ^ { \circ } .
Our analysis of ARGOS stars indicates that the centroids of ARGOS metallicity components should be located \approx 0.09 dex closer together .
The vertical distribution of \alpha -element abundances is consistent with the varying contributions of the different metallicity components .
Closer to the plane , alpha abundance ratios are lower as the metal-rich population dominates .
At higher latitudes , the alpha abundance ratios increase as the number of metal-poor stars increases .
However , we find that the trend of alpha-enrichment with respect to metallicity is independent of latitude .
Comparison of our results with those of GALAH DR2 revealed that for [ Fe/H ] \approx - 0.8 , the bulge shares the same abundance trend as the high- \alpha disk population .
However , the metal-poor bulge population ( [ Fe/H ] \lesssim - 0.8 ) show enhanced alpha abundance ratios compared to the disk/halo .
These observations point to fairly rapid chemical evolution in the bulge , and that the metal-poor bulge population does not share the same similarity with the disk as the more metal-rich populations .