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<p>In this paper, we exploit the first 10-year data record (2008–2017) of nitric acid (<span class="inline-formula">HNO₃</span>) total columns measured by the IASI-A/MetOp infrared sounder, characterized by an exceptional daily sampling and a good vertical sensitivity in the lower-to-mid stratosphere (around 50 <span class="inline-formula">hPa</span>), to monitor the relationship between the temperature decrease and the observed <span class="inline-formula">HNO₃</span> loss that occurs each year in the Antarctic stratosphere during the polar night. Since the <span class="inline-formula">HNO₃</span> depletion results from the formation of polar stratospheric clouds (PSCs), which trigger the development of the ozone (<span class="inline-formula">O₃</span>) hole, its continuous monitoring is of high importance. We verify here, from the 10-year time evolution of HNO<span class="inline-formula">₃</span> together with temperature (taken from reanalysis at 50 <span class="inline-formula">hPa</span>), the recurrence of specific regimes in the annual cycle of IASI <span class="inline-formula">HNO₃</span> and identify (for each year) the day and the 50 <span class="inline-formula">hPa</span> temperature (“drop temperature”) corresponding to the onset of strong <span class="inline-formula">HNO₃</span> depletion in the Antarctic winter. Although the measured <span class="inline-formula">HNO₃</span> total column does not allow for the uptake of <span class="inline-formula">HNO₃</span> by different types of PSC particles along the vertical profile to be differentiated, an average drop temperature of 194.2 <span class="inline-formula">±</span> 3.8 <span class="inline-formula">K</span>, close to the nitric acid trihydrate (NAT) existence threshold (<span class="inline-formula">∼</span> 195 <span class="inline-formula">K</span> at 50 <span class="inline-formula">hPa</span>), is found in the region of potential vorticity lower than <span class="inline-formula">−</span>10 <span class="inline-formula">×</span> 10<span class="inline-formula">⁻⁵</span> <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M21" display="inline" overflow="scroll" dspmath="mathml"><mrow class="unit"><mi mathvariant="normal">K</mi><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">m</mi><mn mathvariant="normal">2</mn></msup><mspace linebreak="nobreak" width="0.125em"/><msup><mi mathvariant="normal">kg</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup><mspace width="0.125em" linebreak="nobreak"/><msup><mi mathvariant="normal">s</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="65pt" height="15pt" class="svg-formula" dspmath="mathimg" md5hash="878a2aac9f17b3dfc7235690d977fb50"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-22-10993-2022-ie00001.svg" width="65pt" height="15pt" src="acp-22-10993-2022-ie00001.png"/></svg:svg></span></span> (similar to the 70–90<span class="inline-formula">^∘</span> S equivalent latitude region during winter). The spatial distribution and interannual variability of the drop temperature are investigated and discussed. This paper highlights the capability of the IASI sounder to monitor the evolution of polar stratospheric <span class="inline-formula">HNO₃</span>, a key player in the processes involved in the depletion of stratospheric <span class="inline-formula">O₃</span>.</p>