Japan Geoscience Union Meeting 2019

Presentation information

[E] Poster

A (Atmospheric and Hydrospheric Sciences ) » A-OS Ocean Sciences & Ocean Environment

[A-OS07] Climate variability and predictability on subseasonal to decadal timescales

Thu. May 30, 2019 10:45 AM - 12:15 PM Poster Hall (International Exhibition Hall8, Makuhari Messe)

convener:Takashi Mochizuki(Japan Agency for Marine-Earth Science and Technology), V Ramaswamy(NOAA GFDL), Doug Smith(Met Office), Yushi Morioka(Japan Agency for Marine-Earth Science and Technology)

[AOS07-P08] Exploring synoptic-scale drivers of interannual rainfall variability over Africa

*Piotr Wolski1, Chris Jack1, Waarith Abrahams1, Stefaan Conradie1 (1.University of Cape Town)

Keywords:rainfall variability, statistical climatology, Africa, self organizing maps

Variability in local climate is a result of an interplay of multi-scale drivers – processes and feedbacks - intertwined within dependency or conditioning chain across spatial scales: from global to synoptic to meso- to local. Resolving these drivers and dependencies can be framed through the following questions: where does a deterministic signal at a particular time scale arise, how does it propagate through space and scales, and how can we maximize our ability to capture it? Here, we report on an exploratory study focusing on the synoptic-scale forcing underlying rainfall variability at the interannual time scale over Africa. In that, we systematically map, over the continent, variables and spatial scales which provide the strongest explanatory power of interannual rainfall variability. In addition, we constrast the explanatory power of mean state of synoptic fields with that of their variance, and of frequency of individual (daily) states. The analyses utilize multiple regression and CCA performed on mean de-orthogonalized fields of q,t,u,v,z at various pressure levels, with daily states of synoptic variables classified using self-organizing maps (SOM). The results are interpreted from the process perspective in terms of their agreement with the current understanding of the role of process chains affecting rainfall over various regions of the contient, and in terms of their implications to statistical downscaling of climate projections and seasonal forecasts.