A Three-Year Climatology of the Wind Field Structure at Cape Baranova (Severnaya Zemlya, Siberia) from SODAR Observations and High-Resolution Regional Climate Model Simulations during YOPP
A Three-Year Climatology of the Wind Field Structure at Cape Baranova (Severnaya Zemlya, Siberia) from SODAR Observations and High-Resolution Regional Climate Model Simulations during YOPP
复制标题
根据 YOPP 期间的 SODAR 观测和高分辨率区域气候模型模拟得出的巴拉诺瓦角（西伯利亚北地岛）风场结构的三年气候学
作者：
G. Heinemann;C. Drüe;A. Makshtas
大气边界层 (ABL) 结构的测量在俄罗斯“巴拉诺瓦角冰基”天文台（北纬 79.280°，东经 101.620°）使用 SODAR（声音探测和测距）进行了三年（2017 年 10 月至 2020 年 8 月）。这些测量是德俄联合项目范围内 YOPP（极地预测年）项目“高北极边界层测量”(CATS_BL) 的一部分。除了 SODAR 得出的风速和风向垂直剖面之外，天文台还提供了一套补充测量数据。 ABL测量用于验证2017-2020年分辨率为5公里的区域气候模型COSMO-CLM（CCLM）。 CCLM 在测量期间以预测模式嵌套在 ERA5 数据中运行。 SODAR 测量主要限于风速 <12 m/s，因为信号经常因风速较大而丢失。 SODAR 数据显示最低 100 m 的风场和一些低空急流 (LLJ) 存在地形通道效应。 CCLM 与天文台近地表数据的验证表明风的一致性良好，2 m 温度存在负偏差。与 SODAR 数据的比较显示，100 m 以下的风速存在约 1 m/s 的正偏差，在更高级别时，风速增加到 1.5 m/s。与 SODAR 数据相反，CCLM 数据显示，与肖卡尔斯基海峡地形通道相关的低空急流频繁出现。尽管 SODAR 风廓线的范围有限且存在很大差距，但它们代表了用于模型验证的宝贵数据集。然而，只有利用模型数据才能获得 ABL 结构和窜流事件气候学的全貌。气候评估表明，巴拉诺瓦角的风场不仅受到南风穿过肖卡尔斯基海峡条件下的直接地形传导的影响，而且还受到山隙西风传导的影响。在 37% 的剖面中检测到低空急流，大多数低空急流与窜流有关，特别是喷射速度≥15 m/s 的低空急流（占所有低空急流的 29%）。模拟10 m风场分析表明，99%风速达到18 m/s，在肖卡尔斯基海峡出口处清晰地呈现出通道风偶极子结构。窜流事件的气候学表明，这种偶极子结构是由两个出口处频繁发生窜流造成的。每年约62天在肖卡尔斯基海峡两个出口都会发生持续至少12小时的窜气事件。
Measurements of the atmospheric boundary layer (ABL) structure were performed for three years (October 2017–August 2020) at the Russian observatory “Ice Base Cape Baranova” (79.280° N, 101.620° E) using SODAR (Sound Detection And Ranging). These measurements were part of the YOPP (Year of Polar Prediction) project “Boundary layer measurements in the high Arctic” (CATS_BL) within the scope of a joint German–Russian project. In addition to SODAR-derived vertical profiles of wind speed and direction, a suite of complementary measurements at the observatory was available. ABL measurements were used for verification of the regional climate model COSMO-CLM (CCLM) with a 5 km resolution for 2017–2020. The CCLM was run with nesting in ERA5 data in a forecast mode for the measurement period. SODAR measurements were mostly limited to wind speeds <12 m/s since the signal was often lost for higher winds. The SODAR data showed a topographical channeling effect for the wind field in the lowest 100 m and some low-level jets (LLJs). The verification of the CCLM with near-surface data of the observatory showed good agreement for the wind and a negative bias for the 2 m temperature. The comparison with SODAR data showed a positive bias for the wind speed of about 1 m/s below 100 m, which increased to 1.5 m/s for higher levels. In contrast to the SODAR data, the CCLM data showed the frequent presence of LLJs associated with the topographic channeling in Shokalsky Strait. Although SODAR wind profiles are limited in range and have a lot of gaps, they represent a valuable data set for model verification. However, a full picture of the ABL structure and the climatology of channeling events could be obtained only with the model data. The climatological evaluation showed that the wind field at Cape Baranova was not only influenced by direct topographic channeling under conditions of southerly winds through the Shokalsky Strait but also by channeling through a mountain gap for westerly winds. LLJs were detected in 37% of all profiles and most LLJs were associated with channeling, particularly LLJs with a jet speed ≥15 m/s (which were 29% of all LLJs). The analysis of the simulated 10 m wind field showed that the 99%-tile of the wind speed reached 18 m/s and clearly showed a dipole structure of channeled wind at both exits of Shokalsky Strait. The climatology of channeling events showed that this dipole structure was caused by the frequent occurrence of channeling at both exits. Channeling events lasting at least 12 h occurred on about 62 days per year at both exits of Shokalsky Strait.