Abstract
Large-scale climate change is superimposed on interacting patterns of climate variability that fluctuate on numerous temporal and spatial scales—elements of which, such as seasonal timing, may have important impacts on local and regional ecosystem forcing. Lake Baikal in Siberia is not only the world's largest and most biologically diverse lake, but it has exceptionally strong seasonal structure in ecosystem dynamics that may be dramatically affected by fluctuations in seasonal timing. We applied time-frequency analysis to a near-continuous, 58-year record of water temperature from Lake Baikal to examine how seasonality in the lake has fluctuated over the past half century and to infer underlying mechanisms. On decadal scales, the timing of seasonal onset strongly corresponds with deviation in the zonal wind intensity as described by length of day (LOD); on shorter scales, these temperature patterns shift in concert with the El Nino-Southern Oscillation (ENSO). Importantly, the connection between ENSO and Lake Baikal is gated by the cool and warm periods of the Pacific Decadal Oscillation (PDO). Large-scale climatic phenomena affecting Siberia are apparent in Lake Baikal surface water temperature data, dynamics resulting from jet stream and storm track variability in central Asia and across the Northern Hemisphere.
Highlights
Shifts in both magnitude and timing of temperature, precipitation and other climate variables associated with climate change have affected ecosystems, independently and in concert
Using the Pacific Decadal Oscillation (PDO)’s warm and cool phase transitions to define segments of the El Nino Southern Oscillation (ENSO) and W(t,40) time series a priori, we found very strong cross-correlations (r) during PDO cool phases, with no cross-correlation coefficient magnitude smaller than 0.57, with the strongest relationships when ENSO is an average of 3.5 months ahead of W(t,40) (Fig. 4B)
The Lake Baikal surface temperature time series was shown to transduce ENSO – an index of sea surface temperature anomalies 10,000 km away–but only when the PDO was in its cool phase, and this teleconnection was deciphered in the short-term (n = 40) variability in annual seasonality
Summary
Shifts in both magnitude and timing of temperature, precipitation and other climate variables associated with climate change have affected ecosystems, independently and in concert. We discovered a significant relationship of the LOD anomaly with phase at the broadest scale, W(t,192), with a cross-correlation coefficient of 0.507 at a lag of zero months (p,0.0001; Fig. 3), for the period where both data sets are available (1962–1994).
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