https://yu-cheng.co/tags/siod/SIODHugoBlox Kit (https://hugoblox.com)en-usMon, 04 Jul 2016 17:07:00 +0000https://yu-cheng.co/media/icon_hu_87a968e0c4fc153c.pnghttps://yu-cheng.co/tags/siod/https://yu-cheng.co/blog/meeting_note_0629/Mon, 04 Jul 2016 17:07:00 +0000https://yu-cheng.co/blog/meeting_note_0629/<p> </p> <p><strong>What scientific questions are the authors addressing?</strong><br> How the phase of the SIOD and therefore the SST anomaly expression of the Indian Ocean, modulates the Southern Africa precipitation response to ENSO?</p> <p><strong>What methods do the authors use to address the questions?</strong></p> <ul> <li>SA Land area bound by the region 15S-35S; 12.5E-42.5E</li> <li>Observation: Global Precipitation Climatology Project version 2.2 (GPCP) 1979 to 2014, 2.5 x 2.5 deg resolution. Hadley-NOAA Optimum Interpolation dataset (OISST) 1.0x1.0 deg</li> <li>Three SST modes and their indices: ENSO (Nino3.4 &gt;0.5K, table 2), IOD, Subtropical-IOD (Fig. 1)</li> <li>Two experiments: (1) Forced by observed global SST (2) Forced by the leading pattern of glabal time-varying monthly SST anomaly added to the monthly climatology, to isolate the atmospheric response to ENSO. (EOF1, Fig. 4)</li> <li>Each experiment has two sets of ensembles from two different models:(1) 30 members of ECHAM5.4, 50 members of GFS2, on 1x1 deg horizonal grid.</li> <li>Test whether the SIOD modifies the relationship between SA precipitation and ENSO through an examination of SA precipitation as a function of SIOD phase in two forced simulations.</li> </ul> <p><strong>What are the authors&rsquo; main conclusions?</strong></p> <ul> <li>El Niño is associated with reduced precipitation in the Southern Africa, and La Niña tends to occur with abundant precipitation in the area. Both are further enhanced by out-of-phase SIOD, and disrupted by in-phase SIOD.</li> <li>For the in-phase SIOD and ENSO during December-March, SA precipitation is associated with an SST anomaly over the <em>Agulhas Current region.</em></li> <li>ENSO is related to an equivalent barotropic Rossby wave over Southern Africa, that modifies the regional mid-tropospheric vertical motions and precipitation.</li> <li>The EOF1 forced case, either phase of SIOD does not modulate the SA precipitation response to ENSO (indistinguishable Fig. 10 and 11)</li> </ul> <p><strong>What are the implications of the results?</strong></p> <p>ENSO has been an important parameter for rainy season SA precipitation prediction, as SST playing a critical role in the regional climate. The modulation relationship between SIOD and ENSO presented here can help to make more informed forecasts.</p> <p><strong>Why did you choose this paper?</strong> looking into papers about South African precipitation variability.</p> <p><strong>Who read this paper?</strong> Yu Cheng</p>