Summertime low-level jet characteristics measured by sodars over rural and urban areas

This work is devoted to the study of nocturnal low-level jet streams (LLJ) at altitudes up to 400 m agl, with the help of Doppler sodars. The objective was twofold: firstly, to study the origin and behavior of LLJ in a mid-latitude region, and secondly, to compare the LLJ characteristics over urban and rural areas. To this end, simultaneous measurements of wind velocity profiles over the center of Moscow city and over a nearby countryside were carried out. The sodar data on wind speed and direction collected continuously during 27 days in July 2005 were analyzed together with in situ data from a meteorological mast. A good correlation between the height of the LLJ core and the inversion height was found. Empirical distributions of the maximum speed of the jet streams, the height of the jet core, and the wind turning across the stream were obtained. The relationships between the LLJs characteristics and some surface layer parameters were found. Over the urban area the jet streams appeared less frequently and at heigher altitudes than over the countryside

Estimating tropical cyclone surface winds: Current status, emerging technologies, historical evolution, and a look to the future

This article provides a review of tropical cyclone (TC) surface wind estimation from an operational forecasting perspective. First, we provide a summary of operational forecast center practices and historical databases. Next, we discuss current and emerging objective estimates of TC surface winds, including algorithms, archive datasets, and individual algorithm strengths and weaknesses as applied to operational TC surface wind forecast parameters. Our review leads to recommendations about required surface coverage – an area covering at least 1100 km from center of TC at a 2-km resolution in the inner-core, and at a frequency of at least once every six hours. This is enough coverage to support a complete analysis of the TC surface wind field from center to the extent of the 34-kt (17 m s-1) winds at 6-h intervals. We also suggest future designs of TC surface wind capabilities include funding to ensure near real-time data delivery to operators so that operational evaluation and use are feasible within proposed budgets. Finally, we suggest that users of archived operational wind radii datasets contact operational organizations to ensure these datasets are appropriate for their needs as the datasets vary in quality through time and space, even from a single organization