H21O-01
Recent potentially predictable droughts associated with the west Pacific warming mode and ENSO

Tuesday, 15 December 2015: 08:00
3011 (Moscone West)
Chris C Funk1,2, Andrew Hoell3, Shraddhanand Shukla4, Colin P Kelley5, Laura Harrison2 and Climate Hazards Group, (1)USGS, Santa Barbara, CA, United States, (2)University of California Santa Barbara, Geography, Santa Barbara, CA, United States, (3)NOAA Earth System Research Laboratory Physical Sciences Division, Boulder, CO, United States, (4)University of California Santa Barbara, Santa Barbara, CA, United States, (5)Organization Not Listed, Washington, DC, United States
Abstract:
The physicist John Archibald Wheeler suggested that “time is nature's way to keep everything from happening at once”. The analog in climate science may be multi-modal analysis, which can be used to identify characteristic space-time patterns associated with major frequency modes (e.g. ENSO, the MJO or the PDO). Under such a paradigm some SST variations, and SST increases, can be meaningfully associated with modes of atmosphere-ocean variability. Here, we build on a recently published work focused on the 'West Pacific Warming Mode' (WPWM) and several new studies examining ‘flavors of ENSO’. In this research, multi-modal analyses are applied to observations and to climate change simulations from coupled atmosphere-ocean general circulation models to help us explore interactions between these modes. Understanding these interactions and, by extension, their respective and combined influences on droughts may enable us to better identify drought prediction opportunities.

 This talk describes the thermodynamic structure of the WPWM, and suggests that warming in the Indo-Pacific warm pool is intensified by local increases in water vapor content. This observed warming has supported an enhanced west-to-central Pacific sea surface temperature gradient. This tendency appears to interact with ENSO variability, favoring La Niña-like conditions and associated teleconnections with East Africa. We examine potential WPWM contributions to drying in East Africa, and examine specific opportunities for regional drought prediction by comparing these boreal spring teleconnections with long-term (1900-2014) rainfall trends for southern Tanzania during boreal winter. While southern Tanzania has experienced substantial rainfall declines over the past 30 years, we suggest that these are mostly due to ENSO-related cooling in the Niño 3.4 region. In contrast, boreal spring declines appear to be strongly influenced by both the WPWM and Niño 4 SST. These analyses suggest that a multi-modal conception of change and variability may help us recognize and anticipate anomalous climate events and associated droughts.

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