I) What is IASCLIP?

IASCLIP is the Intra-Americas Studies of CLImate Processes, a new CLIVAR-VAMOS initiative for 2009-2014, endorsed by CLIVAR. The overarching goal of this program is to estimate and exploit potential predictability of warm-season weather and climate in the region (North America, Central America and Intra-Americas Seas), mainly on intraseasonal to interannual time scales, based on improved understanding and modeling of relevant physical and dynamical processes. IASCLIP will also seek to link research to societal applications in the region.

II) Why is the Intra-Americas Seas (IAS) of interest?

1. The IAS region is coincident with a majority of Atlantic tropical cyclone activity.

2. The IAS region and the surrounding continental regions are vulnerable to climate variability and change.

3. The interannual variations of the IAS offers hope of improving climate predictability in the boreal summer and fall season, a time of the year when our current climate models have the least forecast skill.

4. The IAS region hosts the second largest body of warm water (>28.5°C) in the world (the first being the warm pool of water in tropical western Pacific Ocean), and is therefore of scientific interest,(Fig. 2).

5. IAS region is one of the most poorly observed oceans of the world (Fig. 7).

6. Majority of the IPCC AR4 models showed very poor warm pool simulation (SST too cold in the IAS region), suggesting a pathological (or systemic) error in the way couple climate models work.

III) Why might the variability in the IAS engender climate predictability in climate models?

1. There is theoretical and observational evidence that the warm pool of water in the IAS region induces a Gill type response in the atmospheric circulation, with a cyclone in the lower troposphere and an anticyclone in the upper troposphere (Fig. 1).

2. Observations indicate that there is a robust interannual variation of the area of the warm pool (defined by the 28.5°C isotherm), which consequently modulates the SST gradients and the heat content raising the potential for either enhancing or inhibiting atmospheric convection (Fig. 2).

3. Observations indicate that the see-saw between the East Pacific Warm Pool (EPWP) and the Atlantic Warm Pool (AWP) has a bearing on the onset of the north American monsoon, tropical cyclone activity in the two basins, and other climate phenomena.

4. The variations of IAS have rather weak contemporaneous correlations with ENSO. Therefore IAS is seen as an alternative source of seasonal atmospheric predictability in boreal summer and fall season, when the IAS has peak interannual variations and the direct impacts of ENSO on climate are minimal.

5. The size of the summer warm pool is influenced by precursor climate patterns other than ENSO, such as the North Atlantic Oscillation and the Amazon convection, which enhance the potential predictability for Atlantic SST in the critical summer season.

IV) What are the perceived forced atmospheric variations from IAS variability?

1. Atlantic tropical cyclone activity (Fig. 3).

2. Caribbean Low Level Jet and associated moisture transports (Fig. 4).

3. Low level transport of water vapor across the Gulf coast that can potentially lead to Mid-West droughts and floods (Fig. 4).

4. Modulation of tornado activity in the tornado alley through its influence on low level vertical wind shear and moisture transport from the IAS.

5. Interannual summer season rainfall variability in the US Great Plains, Central America and the Caribbean region (Fig. 4).

6. North Atlantic Subtropical High (Fig. 4).

V) What are the objectives of the IASCLIP Forecast Forum 2010?

1.  To forecast the seasonal climate for August-September-October (ASO) 2010 for the IASCLIP region based on the forecasts from the 6 models.

2.  To highlight issues/errors of the operational climate prediction models over the IASCLIP region