Macquarie Island (54.50°S, 158.94°E) is an isolated island with modest orography in the midst of the Southern Ocean with precipitation records dating back to 1948. These records (referred to as MAC) are of particular interest because of the relatively large biases in the energy and water budgets commonly found in climate simulations and reanalysis products over the region. A basic climatology of the surface precipitation P is presented and compared with the ERA-Interim (ERA-I) reanalysis. The annual ERA-I precipitation (953 mm) is found to underestimate the annual MAC precipitation (1023 mm) by 6.8% from 1979 to 2011. The frequency of 3-h surface precipitation at MAC is 36.4% from 2003 to 2011. Light precipitation (0.066 ≤ P < 0.5 mm h−1) dominates this dataset (29.7%), and heavy precipitation (P ≥ 1.5 mm h−1) is rare (1.1%). Drizzle (0 < P < 0.066 mm h−1) is commonly produced by ERA-I (43.9%) but is weaker than the detectable threshold of MAC. Warm rain intensity and frequency from CloudSat products were compared with those from MAC. These CloudSat products also recorded considerable drizzle (16%–30%) but were not significantly different from MAC when P ≥ 0.5 mm h−1. Heavy precipitation events were, in general, more commonly associated with fronts and cyclonic lows. Some heavy precipitation events were found to arise from weaker fronts and lows that were not adequately represented in the reanalysis products. Yet other heavy precipitation events were observed at points/times not associated with either fronts or cyclonic lows. Two case studies are employed to further examine this finding.
The red color formation of Acer mandshuricum leaves is caused by the accumulation of anthocyanins primarily, but the molecular mechanism researches which underlie anthocyanin biosynthesis in A. mandshuricum were still lacking. Therefore, we combined the transcriptome and metabolome and analyzed the regulatory mechanism and accumulation pattern of anthocyanins in three different leaf color states. In our results, 26 anthocyanins were identified. Notably, the metabolite cyanidin 3-O-glucoside was found that significantly correlated with the color formation, was the predominant metabolite in anthocyanin biosynthesis of A. mandshuricum. By the way, two key structural genes ANS (Cluster-20561.86285) and BZ1 (Cluster-20561.99238) in anthocyanidin biosynthesis pathway were significantly up-regulated in RL, suggesting that they might enhance accumulation of cyanidin 3-O-glucoside which is their downstream metabolite, and contributed the red formation of A. mandshuricum leaves. Additionally, most TFs (e.g., MYBs, bZIPs and bHLHs) were detected differentially expressed in three leaf color stages that could participate in anthocyanin accumulation. This study sheds light on the anthocyanin molecular regulation of anthocyanidin biosynthesis and accumulation underlying the different leaf color change periods in A. mandshuricum, and it could provide basic theory and new insight for the leaf color related genetic improvement of A. mandshuricum.
The permafrost response to variations in Arctic vegetation remains controversial. We investigated the consequences of Arctic vegetation greenness variation over the past three decades using a coupled land-atmosphere model and found that it induces air temperature perturbation, which is further amplified by snow cover variation and eventually leaves a footprint on soil temperature. Compared to the atmospheric impacts of vegetation, local shading of vegetation canopy has relatively minor effects on soil temperature. Significant soil warming was observed along the summer snowline between the Low and High Arctic, indicating the direct impact of snow cover variation led by vegetation changes. In the Low Arctic, the winter snowpack insulates the soil from colder air, resulting in less permafrost. In the High Arctic, snow persists for more than 330 d per year and has a strong protection effect on the permafrost as it insulates soil from warmer summer air and reflects solar radiation.
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