We present updated stellar population models appropriate for old ages ( > 1 Gyr ) and covering a wide range in metallicities ( -1.5 \lesssim [ Fe/H ] \lesssim 0.3 ) .
These models predict the full spectral variation associated with individual element abundance variation as a function of metallicity and age .
The models span the optical-NIR wavelength range ( 0.37 - 2.4 \mu m ) , include a range of initial mass functions ( IMFs ) and contain the flexibility to vary 18 individual elements including C , N , O , Mg , Si , Ca , Ti , and Fe .
To test the fidelity of the models we fit them to integrated light optical spectra of 41 Galactic globular clusters ( GCs ) .
The value of testing models against GCs is that their ages , metallicities , and detailed abundance patterns have been derived from the HR diagram in combination with high resolution spectroscopy of individual stars .
We determine stellar population parameters from fits to all wavelengths simultaneously ( “ full spectrum fitting ” ) , and demonstrate explicitly with mock tests that this approach produces smaller uncertainties at fixed S/N ratio than fitting a standard set of 14 line indices .
Comparison of our integrated-light results to literature values reveals good agreement in metallicity , [ Fe/H ] .
When restricting to GCs without prominent blue horizontal branch populations we also find good agreement with literature values for ages , [ Mg/Fe ] , [ Si/Fe ] , and [ Ti/Fe ] .