Nowcasting tracks of severe convective storms in West Africa from observations of land surface state
Nowcasting tracks of severe convective storms in West Africa from observations of land surface state
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从地表状态观测预报西非强对流风暴的轨迹
DOI：
10.1088/1748-9326/ac536d
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发表时间：
2022
影响因子：
6.7
通讯作者：
Taylor C
中科院分区：
文献类型：
--
作者：
Taylor C
在热带对流气候中，降雨的数值天气预报具有很高的不确定性，临近预报可提前数小时提供极端事件的必要警报。原则上，在土壤湿度控制地表通量的地区，对强对流风暴的短期预测可能受益于对缓慢演变的地表状态的了解。在这里，我们探讨了如何将近实时（NRT）卫星对地表和对流云的观测结合起来，以帮助在长达12小时的时间尺度上对萨赫勒地区的恶劣天气进行早期预警。使用地表温度（LST）作为土壤水分亏缺的代理，我们表征了NRT中地表能量平衡的状态。通过对云顶温度影像的空间滤波，确定了中尺度对流系统（mcs）中对流最活跃的部分。我们发现地表温度数据提供的预测能力在雨季早期达到最大，那时土壤更干燥，植被不太发达。预测强对流的陆地技术远远超出了下午，在更干旱的条件下，白天地表温度和MCS活动之间的强正相关一直持续到第二天早上。对于2021年9月的一次Forecasting Testbed事件，我们开发了一种简单的技术，将LST数据转换为NRT地图，仅基于陆地状态量化对流的可能性。我们使用这些地图结合对流特征来预报现有mcs的轨迹，并预测可能的新起始位置。据我们所知，这是第一次开发出主要基于陆地观测的临近预报工具。萨赫勒MCS对土壤湿度的强烈敏感性，加上MCS的寿命通常为6-18小时，为临近预报危险天气提供了机会，这远远超出了仅靠大气观测所能做到的，并且可以应用于半干旱热带的其他地方。
In tropical convective climates, where numerical weather prediction of rainfall has high uncertainty, nowcasting provides essential alerts of extreme events several hours ahead. In principle, short-term prediction of intense convective storms could benefit from knowledge of the slowly evolving land surface state in regions where soil moisture controls surface fluxes. Here we explore how near-real time (NRT) satellite observations of the land surface and convective clouds can be combined to aid early warning of severe weather in the Sahel on time scales of up to 12 h. Using land surface temperature (LST) as a proxy for soil moisture deficit, we characterise the state of the surface energy balance in NRT. We identify the most convectively active parts of mesoscale convective systems (MCSs) from spatial filtering of cloud-top temperature imagery. We find that predictive skill provided by LST data is maximised early in the rainy season, when soils are drier and vegetation less developed. Land-based skill in predicting intense convection extends well beyond the afternoon, with strong positive correlations between daytime LST and MCS activity persisting as far as the following morning in more arid conditions. For a Forecasting Testbed event during September 2021, we developed a simple technique to translate LST data into NRT maps quantifying the likelihood of convection based solely on land state. We used these maps in combination with convective features to nowcast the tracks of existing MCSs, and predict likely new initiation locations. This is the first time to our knowledge that nowcasting tools based principally on land observations have been developed. The strong sensitivity of Sahelian MCSs to soil moisture, in combination with MCS life times of typically 6–18 h, opens up the opportunity for nowcasting of hazardous weather well beyond what is possible from atmospheric observations alone, and could be applied elsewhere in the semi-arid tropics.
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影响因子：
5.2
作者：
B. Gallego-Elvira;C. Taylor;P. Harris;D. Ghent;K. Veal;S. Folwell
通讯作者：
B. Gallego-Elvira;C. Taylor;P. Harris;D. Ghent;K. Veal;S. Folwell
萨赫勒北部陆地表面和大气耦合天气波的简单模型
影响因子：
8.9
作者：
D. Parker
通讯作者：
D. Parker
使用气象卫星图像的地中海盆地中尺度对流系统自动临近预报系统。
影响因子：
2.7
作者：
S. Kolios;H. Feidas
通讯作者：
H. Feidas
将 CMIP 数据与区域对流允许模型和观测相结合，预测气候变化下的极端降雨
影响因子：
6.7
作者：
Klein C
通讯作者：
Klein C
影响因子：
56.9
作者：
Koster, RD;Dirmeyer, PA;Yamada, T
通讯作者：
Yamada, T