CHIDONG ZHANG: Next lightning talk is given by Andy Chiodi on S2S data source.

ANDY CHIODI: Thank you, Chidong, and thank you all for just being here. For this project, we performed data and modeling studies to identify or better understand patterns of the air-sea interaction that have societally relevant influence on weather conditions over land. Where feasible, we work to take what we've learned and make it translated to info that is useful to other agencies or resource [INAUDIBLE]. 

Our opportunism leads us to working on a variety of different projects. Some highlights over the past few years include taking a fresh look at El Niño and [INAUDIBLE] seasonal weather impacts using [INAUDIBLE] radiation information in a young, but productive collaboration with the Forest Service. First, why longwave radiation for El Niño? 

In the tropics, the top of the clouds are cold. The surface is warm, and the satellite measuring longwave radiation can easily distinguish between the two. This makes the longwave radiation measurements a useful proxy for tropical atmospheric convection. The basin scale eastward spread of tropical convection over the Pacific is thought to be key to the dynamical pathway by which El Niño-type conditions can influence weather over North America. 

But El Niño years are most commonly defined based on surface temperature conditions, which over the tropical Pacific are distributed differently than the longwave radiation conditions. All of these years are commonly identified as El Niño years based on surface temperature, but only a handful of them have consistent weather anomaly patterns that average to produce a robust composite with the familiar El Niño-type patterns. 

The others average together to produce something that's not statistically different from zero. We published an index that distinguishes the useful subset of El Niño years from the others, and it does this before winter, which is when the El Niño influence on US weather is strongest. So using longwave radiation to monitor for basic scale shifts and convection over the Pacific, it lets us know when we can have high confidence in seeing an El Niño-type weather pattern over North America. 

And instead, we should be focused on other sources of potential predictability, such as the MJO, which here Chidong, Mike, and Billy talk about. We've also published a different, but similarly useful index for La Niña weather associations. In this case, the index keys are on synaptic scale breaks and convection over the Western Tropical Pacific, which are linked to increases in the strength of the underlying easterly trade winds. 

These surges in the trades bring cool, dry air under the convection. They also drive surface temperature cooling to their east. Taken together, this has offered a new way of thinking about La Niña development. The index, in this case, identified as a subset of a commonly identified La Niña years that has robust association to seasonal weather anomalies over North America. 

A particularly useful one regionally is an increase, a robust increase in [INAUDIBLE] snow depth over the Washington Cascades, which when it occurred, [INAUDIBLE] municipal water supplies. So the skills we picked up working with the large atmospheric data sets has helped foster collaboration with the Forest Service aimed at understanding and predicting weather limitations on prescribed burning. This is an essential management tool applied for a number of goals, including ecosystem health and reducing the level of hazardous fuels. But to be both safe and effective, the fire has to be applied within a precise set of weather conditions. And finding those weather windows for burning is known as the main hurdle to reaching the desired level of treatment. 

So what we've done is work with the Forest Service and regional burners to create a climatology of the weather opportunity for prescribed burning over the Southeast, which is where 70% of the US burns take place. Even so, they want to burn more. Green is for more open, red for more closed window. These results have been received as a useful planning tool, for example, as recently have been shown, that most of the burning in this region is done in the Spring. 

Our results identified and showed that the fall is, at least, as open as Spring in terms of the weather opportunity for burning. This has motivated ongoing discussion, including planned workshops, to bring managers and burners together to figure out how to take better advantage of the identified opportunity for burning in fall in order to maximize acres burned given limited resources available to do so. We also analyzed the variability about this climatology for sources of predictability from the tropics, and we found potentially useful linkage to the longwave radiation based in the seasonal La Niña and El Niño that I just described. Michelle hasn't given me enough time to go into that in detail. 

So I just want to end by saying that, over the Northwest, where we have now only recently experienced a series of extremely active wildfire seasons, this has increased the motivation of a number of agencies, including the Forest Service, to do more prescribed burns to reduce hazardous levels of fuel, and thereby, mitigate the threat of extreme wildfire. We're currently working with them to do a similar project over the Northwest, where, again, our part of the deal is to mine the historical weather knowledge to help them meet [INAUDIBLE]. Thank you.

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