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Convective structure and its evolution in tropical cyclones as observed by passive microwave sensors in relation to intensity change

机译：通过被动微波传感器观察到的热带气旋中的对流结构及其在强度变化方面的演变

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摘要

The use of passive microwave sensors in analysis of tropical cyclones provide unique insight into the microphysical attributes and system structure opposed to other instruments that are only able to detect information about the cloud top. With the ability to infer information about key microphysical processes and structure at high resolution, these platforms provide a glimpse into tropical cyclone development and intensification over systems’ life cycles. In particular, passive microwave observations have the potential to depict crucial precursors of rapid intensification (RI; defined as a wind increase of 30 kt/24 hr).A dataset with a common resolution of 8 km across all channels is developed for the Special Sensor Microwave Imager (SSM/I) from 1987-2008 and Tropical Rainfall Measuring Mission Microwave Imager (TMI) for 1997-2008. Statistical metrics are calculated for each storm overpass using 85 GHz and 37 GHz polarization corrected temperatures as well as microwave rain rate estimates. These products are examined as a function of azimuth and annuli in true-north, storm-relative motion, and shear-relative coordinates and evaluated in terms of intensity (wind speed) and intensity change (wind speed change over time).To examine predictive potential of these sensors, the brightness temperature statistics are evaluated in terms of linear correlations between intensity and its change. Highest values occur on the order of 0.7, and are seen at radii of 110 km between median values for 85 GHz PCT and rain rates with observed intensity. An increase in skill is evident following the initial satellite overpass, suggesting a lag between latent heating at the time of overpass and the resultant intensification. Despite this, correlation is consistently less skillful for evaluations of intensity change with values at short time changes of around 0.3.The distribution of statistical values are also evaluated in the context of the dataset with median values at the 110 km distance showing the greatest distinction of 85 GHz PCTs and rain rates for storms at the onset of RI and those that are not, with less variation seen for percentiles > 90% that are indicative of isolated convective activity. With the differentiation in structure noted between RI and non-RI storms, composites are created for each of the brightness temperature products, with a distinct modest convective ring structure evident at the onset of RI that is not present in the non-RI class. Over time this convective ring shows a tendency to contract and intensify over the 24 hour period examined for RI, with the increased latent heating over a more focused area acting to increase the system intensity. Through these evaluations the continued importance spatial convective coverage and axisymmetricization is underscored in intensity and intensity change evaluation, with a lack of signal seen in more isolated convective predictors.
机译：与其他只能检测有关云顶信息的仪器相反，在分析热带气旋时使用无源微波传感器可提供对微观物理属性和系统结构的独特见解。这些平台具有高分辨率推断有关关键微物理过程和结构的信息的能力，可让您瞥见热带气旋的发展以及系统生命周期的加剧。特别是，被动微波观测有可能描绘出快速强化的关键前兆（RI;定义为风速增加30 kt / 24 hr）。为特殊传感器开发了一个所有通道的通用分辨率为8 km的数据集1987-2008年的微波成像仪（SSM / I）和1997-2008年的热带降雨测量任务微波成像仪（TMI）。使用85 GHz和37 GHz极化校正温度以及微波降雨率估算值，为每个风暴越过通道计算统计指标。检验这些乘积在真北，风暴相对运动和切变相对坐标中作为方位角和环空的函数，并根据强度（风速）和强度变化（风速随时间变化）进行评估。为了检查这些传感器的预测潜力，根据强度与其变化之间的线性相关性来评估亮度温度统计数据。最高值出现在0.7的数量级，并且在85 GHz PCT的中间值和具有观测强度的降雨率之间的110 km半径处可见。最初的卫星立交之后，技能的提高明显，这表明立交时的潜在加热与所产生的强化之间存在滞后。尽管如此，在强度变化的评估上，相关性始终不那么熟练，因为短时变化的值约为0.3。统计值的分布也将在数据集的背景下进行评估，其中110 km距离处的中值显示了最大的85 GHz PCTs和RI暴发与未暴发的暴雨的降雨率之间的最大差异，变化较小如果百分位数> 90％，则表明有单独的对流活动。由于在RI和非RI风暴之间存在结构差异，因此为每种亮度温度乘积创建了复合材料，并且在RI发作时明显出现了非RI类中不存在的明显的适度对流环结构。随着时间的流逝，对流环在RI检查的24小时内显示出收缩和强化的趋势，在更集中的区域上增加的潜热会增加系统强度。通过这些评估，强度和强度变化评估强调了空间对流覆盖和轴对称的持续重要性，而在更孤立的对流预报器中则看不到信号。

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    Harnos Daniel;

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  • 年度 2010
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  • 正文语种 {"code":"en","name":"English","id":9}
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