Based on synthetic flux spectra calculated from theoretical atmospheric models, a calibration of temperature and metallicity for the dwarfs observed in the Beijing-Arizona-Taiwan-Connecticut multicolor photometric system is presented in this paper. According to this calibration, stellar effective temperatures can be obtained from some temperature-sensitive color indexes. The sample stars have colors and magnitudes in the ranges 0.1 5 kpc, it could not be interpreted according to the different contributions from the three components because of the large uncertainty. So it is possible that there is little or no gradient for z > 5 kpc. The overall distribution shows a metallicity gradient d[Fe/H]/dz = -0.17 ± 0.04 dex kpc-1 for z < 15 kpc.
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