The influence of atmospheric wave dynamics on interannual variation in the surface temperature of lakes in the English Lake District

Abstract

Surface water temperatures in four lakes of the English Lake District (TL) are shown to be sensitive to climate change and a large-scale atmospheric phenomenon known as tropospheric Rossby wave breaking (RWB). RWB occurs frequently near the English Lake District, bringing warm and moist air, or cool and dry air, from distant sources. RWB case examples and composites are used to show three dimensional circulations and anomalies of near-surface temperature and humidity associated with the two types of RWB (anticyclonic and cyclonic). Statistical models of lake surface temperature are developed for each season using objectively identified variability patterns of anticyclonic and cyclonic RWB, along with an index of Northern Hemisphere annual mean surface temperature (TNH) to account for climate change. The statistical models, depending on season, account for 54–69% of TL variance. RWB alone contributes significantly during each season, accounting for 37–52% of TL variance after the effect of TNH is removed. RWB is a key physical mechanism underlying the North Atlantic Oscillation (NAO), a regional-scale weather-pattern that is frequently related to coherent lake properties. RWB may therefore be a more fundamental driver than the NAO in controlling interannual variation in the properties of lakes such as ice duration, metabolic rates, phenology, species composition and, via effects on stratification, underwater light-climate, nutrient-cycling and oxygen-depletion. Variation in other meteorological features that are linked to RWB, such as precipitation, may have additional effects. RWB is also likely to influence terrestrial and marine environments.