Antarctic Peninsula warming and precipitation phase transition during atmospheric river events
Authors: Gorodetskaya Irina , Rowe Penny , Zou Xun , Chyhareva Anastasia , Krakovska Svitlana , Cordero Raul 
Published: December 2021

&lt;p&gt;&lt;span lang=&quot;en-US&quot;&gt;Polar amplification has been pronounced in the Arctic with near-surface air temperatures increasing at more than twice the global warming rate d&lt;/span&gt;uring the last several decades&lt;span lang=&quot;en-US&quot;&gt;. At the same time, over Antarctica temperature trends have exhibited a large regional variability. In particular, the &lt;/span&gt;Antarctic Peninsula (AP) &lt;span lang=&quot;en-US&quot;&gt;stands out as having a &lt;/span&gt;warming&lt;span lang=&quot;en-US&quot;&gt; rate much higher than&lt;/span&gt; the rest of the Antarctic ice sheet and other land areas in the Southern Hemisphere (SH)&lt;span lang=&quot;en-US&quot;&gt;.&lt;/span&gt; &lt;span lang=&quot;en-US&quot;&gt;F&lt;/span&gt;uture projections indicate that &lt;span lang=&quot;en-US&quot;&gt;warming and ice loss will intensify in both polar regions with important impacts&lt;/span&gt; globally. In addition to the warming amplification, there has been also an enhancement of the polar water cycle with increase&lt;span lang=&quot;en-US&quot;&gt;s&lt;/span&gt; &lt;span lang=&quot;en-US&quot;&gt;in &lt;/span&gt;poleward moisture transport and precipitation in both polar regions. An important process linking warming and precipitation enhancement is a shift towards more frequent rainfall compared to snowfall&lt;span lang=&quot;en-US&quot;&gt;. F&lt;/span&gt;uture projections show that the rain fraction will significantly increase in coastal Antarctica, especially in the AP. Atmospheric rivers (ARs), long corridors of intense moisture transport from subtropical and mid-latitude regions poleward, are known for &lt;span lang=&quot;en-US&quot;&gt;their &lt;/span&gt;prominent role in &lt;span lang=&quot;en-US&quot;&gt;both &lt;/span&gt;heat and moisture transport with impacts ranging from intense precipitation to temperature records and major melt events in Antarctica.&lt;span lang=&quot;en-US&quot;&gt; Limited observations have hampered process understanding and correct representation of these extreme events in models.&lt;/span&gt; &lt;span lang=&quot;en-US&quot;&gt;This presentation will give an overview of the &lt;/span&gt;enhanced observations targeting ARs in the A&lt;span lang=&quot;en-US&quot;&gt;P&lt;/span&gt; (&lt;span lang=&quot;en-US&quot;&gt;including &lt;/span&gt;surface meteorology, radiosonde, cloud and precipitation remote sensing, &lt;span lang=&quot;en-US&quot;&gt;and &lt;/span&gt;radiative fluxes) as part of the &lt;span lang=&quot;en-US&quot;&gt;Year of Polar Prediction (&lt;/span&gt;YOPP&lt;span lang=&quot;en-US&quot;&gt;)&lt;/span&gt;-SH international collaborative effort&lt;span lang=&quot;en-US&quot;&gt;. &lt;/span&gt;In-depth analysis of transport of heat and moisture, &lt;span lang=&quot;en-US&quot;&gt;atmospheric vertical structure, &lt;/span&gt;cloud properties&lt;span lang=&quot;en-US&quot;&gt; and precipitation phase transition from snowfall to rainfall &lt;/span&gt;during selected &lt;span lang=&quot;en-US&quot;&gt;AR &lt;/span&gt;case&lt;span lang=&quot;en-US&quot;&gt;s&lt;/span&gt; will be&lt;span lang=&quot;en-US&quot;&gt; presented and compared with ERA5 reanalysis and high-resolution Polar-WRF model simulations&lt;/span&gt;.&lt;span lang=&quot;en-US&quot;&gt; We will highlight three different local regimes around the AP: large-scale precipitation over the Southern Ocean north of the AP, orographic enhancement of precipitation in the western AP and the role of foehn, cloud/precipitation clearing and temperature increase in the northeastern AP. &lt;/span&gt;&lt;/p&gt;