The Indian Pulsar Timing Array (InPTA) collaboration has recently made its
first official data release (DR1) for a sample of 14 pulsars using 3.5 years of
uGMRT observations. We present the results of single-pulsar noise analysis for
each of these 14 pulsars using the InPTA DR1. For this purpose, we consider
white noise, achromatic red noise, dispersion measure (DM) variations, and
scattering variations in our analysis. We apply Bayesian model selection to
obtain the preferred noise models among these for each pulsar. For PSR
J1600−3053, we find no evidence of DM and scattering variations, while for
PSR J1909−3744, we find no significant scattering variations. Properties vary
dramatically among pulsars. For example, we find a strong chromatic noise with
chromatic index ∼ 2.9 for PSR J1939+2134, indicating the possibility of a
scattering index that doesn't agree with that expected for a Kolmogorov
scattering medium consistent with similar results for millisecond pulsars in
past studies. Despite the relatively short time baseline, the noise models
broadly agree with the other PTAs and provide, at the same time,
well-constrained DM and scattering variations.Comment: Accepted for publication in PRD, 30 pages, 17 figures, 4 table