Borehole temperatures reveal details of 20th century warming at Bruce Plateau, Antarctic Peninsula
Borehole temperatures reveal details of 20th century warming at Bruce Plateau, Antarctic Peninsula
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DOI：
10.5194/tc-6-675-2012
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发表时间：
2011-11
期刊：
影响因子：
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通讯作者：
V. Zagorodnov;O. Nagornov;T. Scambos;A. Muto;E. Mosley‐Thompson;E. Pettit;S. Tyuflin
中科院分区：
文献类型：
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作者：
V. Zagorodnov;O. Nagornov;T. Scambos;A. Muto;E. Mosley‐Thompson;E. Pettit;S. Tyuflin
2009年至2010年夏季，在布鲁斯高原一个名为Larissa Site Beta(S 66°02‘，西经°04’，海拔1975.5米)的地点钻了两个143.18米和447.73米(基岩)的冰芯钻孔。在钻井后不久，两个钻孔都用热敏电阻进行了记录。用一系列带有卫星上行链路的电阻温度计对浅井进行了4个月的测量。将由钻孔温度剖面反演得到的表面温度代理数据与位于南极半岛到南极洲西部的纬向横断面上的气象站和冰芯所提供的数十年记录进行比较。拉里萨站点的Beta剖面显示，温度从表面向下下降，穿过冰层的上部三分之一，然后变暖到海床。最近一年的平均气温为−14.78°C(在15米深处测量，缩写为T15)。在173m深度测得的最低温度为−15.8°C，基温为−10.2°C。在稳态条件下，年平均温度与测得温度剖面下部的梯度与积累率为1.9×103 kg m−2 a−1和基础热流密度(Q)分别为88 mW m−2。然而，中层温度变化表明，最近的温度变化很大。用一种反演法(Tikhonov和Samarskii，1990)计算了过去200年间重建的地表温度(T S=T15)。由此我们发现，从1920年到1940年，气温普遍较低(最低温度T S=−16.2°C)，然后在1995年左右逐渐升高到−14.2°C，然后在接下来的十年里变冷，最后几年变暖。最冷的时期之前是19世纪相对温暖的T 15≥−15°C。为了便于地区比较地表温度历史，我们使用我们的T 15数据和附近的气象站记录来改进对延迟率的估计(海拔，根据纬度调整：Γa(L))。Γa(L)在过去35年中具有良好的时空一致性，这意味着这里观测到的气候趋势是区域性的，并且在较大的海拔范围内是一致的。
Two ice core boreholes of 143.18 m and 447.73 m (bedrock) were drilled during the 2009–2010 austral summer on the Bruce Plateau at a location named LARISSA Site Beta (66°02' S, 64°04' W, 1975.5 m a.s.l.). Both boreholes were logged with thermistors shortly after drilling. The shallow borehole was instrumented for 4 months with a series of resistance thermometers with satellite uplink. Surface temperature proxy data derived from an inversion of the borehole temperature profiles are compared to available multi-decadal records from weather stations and ice cores located along a latitudinal transect of the Antarctic Peninsula to West Antarctica. The LARISSA Site Beta profiles show temperatures decreasing from the surface downward through the upper third of the ice, and warming thereafter to the bed. The average temperature for the most recent year is −14.78°C (measured at 15 m depth, abbreviated T 15 ). A minimum temperature of −15.8°C is measured at 173 m depth, and basal temperature is estimated to be −10.2°C. Current mean annual temperature and the gradient in the lower part of the measured temperature profile have a best fit with an accumulation rate of 1.9×10 3 kg m −2 a −1 and basal heat flux ( q ) of 88 mW m −2 , if steady-state conditions are assumed. However, the mid-level temperature variations show that recent temperature has varied significantly. Reconstructed surface temperatures ( T s = T 15 ) over the last 200 yr are derived by an inversion technique (Tikhonov and Samarskii, 1990). From this, we find that cold temperatures (minimum T s =−16.2°C) prevailed from ~1920 to ~1940, followed by a gradual rise of temperature to −14.2°C around 1995, then cooling over the following decade and warming in the last few years. The coldest period was preceded by a relatively warm 19th century at T 15 ≥−15°C. To facilitate regional comparisons of the surface temperature history, we use our T 15 data and nearby weather station records to refine estimates of lapse rates (altitudinal, adjusted for latitude: Γ a(l) ). Good temporal and spatial consistency of Γ a(l) over the last 35 yr are observed, implying that the climate trends observed here are regional and consistent over a broad altitude range.