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We have carried out ground-based NIRAS (Near-InfraRed Aurora and airglow Spectrograph) observations at Syowa station, Antarctic (   $$69.0^{\circ }\text {S}$$  69 . 0 ∘ S ,    $$39.6^{\circ }\text {E}$$  39 . 6 ∘ E ) and Kiruna (   $$67.8^{\circ }\text {N}$$  67 . 8 ∘ N ,    $$20.4^{\circ }\text {E}$$  20 . 4 ∘ E ), Sweden for continuous measurements of hydroxyl (OH) rotational temperatures and a precise evaluation of auroral contaminations to OH Meinel (3,1) band. A total of 368-nights observations succeeded for 2 winter seasons, and 3 cases in which    $$\text {N}_2^+$$  N 2 + Meinel (1,2) band around    $$1.5\,\mu \text {m}$$  1.5 μ m was significant were identified. Focusing on two specific cases, detailed spectral characteristics with high temporal resolutions of 30 s are presented. Intensities of    $$\text {N}_2^+$$  N 2 + band were estimated to be 228 kR and 217 kR just at the moment of the aurora breakup and arc intensification during pseudo breakup, respectively. At a wavelength of    $$\text {P}_1(2)$$  P 1 ( 2 ) line (   $$\sim 1523 \,\text {nm}$$  ∼ 1523 nm ),    $$\text {N}_2^+$$  N 2 + emissions were almost equal to or greater than the OH line intensity. On the other hand, at a wavelength of    $$\text {P}_1(4)$$  P 1 ( 4 ) line (   $$\sim 1542 \,\text {nm}$$  ∼ 1542 nm ), the OH line was not seriously contaminated and still dominant to    $$\text {N}_2^+$$  N 2 + emissions. Furthermore, we evaluated    $$\text {N}_2^+$$  N 2 + (1,2) band effects on OH rotational temperature estimations quantitatively for the first time. Auroral contaminations from    $$\text {N}_2^+$$  N 2 + (1,2) band basically lead negative bias in OH rotational temperature estimated by line-pair-ratio method with    $$\text {P}_1(2)$$  P 1 ( 2 ) and    $$\text {P}_1(4)$$  P 1 ( 4 ) lines in OH (3,1) band. They possibly cause underestimations of OH rotational temperatures up to 40 K. In addition,    $$\text {N}_2^+$$  N 2 + (1,2) band contaminations were temporally limited to a moment around the aurora breakup. This is consistent with proceeding studies reporting that enhancements of    $$\text {N}_2^+$$  N 2 + (1,2) band were observed associated with International Brightness Coefficient 2–3 auroras. It is also suggested that the contaminations would be neglected in the polar cap and the sub-auroral zone, where strong aurora intensification is less observed. Further spectroscopic investigations at these wavelengths are needed especially for more precise evaluations of    $$\text {N}_2^+$$  N 2 + (1,2) band contaminations. For example, simultaneous 2-D imaging observation and spectroscopic measurement with high spectral resolutions for airglow in OH (3,1) band will make great advances in more robust temperature estimations in the auroral zone.

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Temporal evolutions of $$\text {N}_2^+$$ Meinel (1,2) band near $$1.5.\,\upmu \text {m}$$ associated with aurora breakup and their effects on mesopause temperature estimations from OH Meinel (3,1) band