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in the united states a not so silent

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spring marks the arrival of several

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billion birds migrating northward from

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central and south america

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but curiously enough the exact timing of

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this journey varies each year

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so why is that

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the key to this mystery may not lie in

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looking at the traditional flyways but

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instead in radar climate models and a

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little bit of math at the global

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modeling and assimilation office we

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routinely produce a comprehensive

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climate data set

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by combining observations and models and

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these are freely available to the public

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this data can be used to explain the

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characteristics of ecosystems like bird

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migration patterns

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in fact by using a network of 143 noaa

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radar stations across the continental

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united states the team analyzed 23 years

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of data to see if they could group

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stations that had similar year-to-year

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variability in the migration

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observations

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and this is different from the concept

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of flyways this is specifically looking

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at which radar stations across the

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united states

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in what regions have a similar

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variability in bird migration timing

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what they found is that the u.s can be

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divided into two regions east and west

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each with its own specific pattern of

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variability of migratory bird arrival

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times

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so

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now that we have divided the continental

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united states into two regions

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we can look at each region specifically

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and understand the climatic drivers of

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each region

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the team found that the behavior of

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rossby waves huge waves of high latitude

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westerly winds was a major influence for

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bird migrations in the east

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as raspy waves are triggered

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particularly those in the tropical

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pacific they influence climate patterns

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and bring warm temperatures to the

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eastern united states which in turn

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correlates with earlier arrivals of

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migratory birds in that region

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cold temperatures have the opposite

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effect

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variations in the west however seem to

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be linked to more regional climate

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conditions such as sea surface

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temperatures of adjacent waters

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in this study we try to highlight the

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fact that we can use our data for

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applications that would bridge climate

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science with other disciplines

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the team hopes that future research will

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build upon this study to help us better

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understand how changes in the climate