Weide Luiz, Eduardo and Fiedler, Stephanie (2023) Can convective cold pools lead to the development of low-level jets?. Geophysical Research Letters, 50 (11). Art.Nr. e2023GL103252. DOI 10.1029/2023GL103252.

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Abstract

We present the first observational evidence for convectively generated cold pools (CP) as driving mechanism for low-level jets (LLJ). Our findings are based on a unique campaign data set that allowed us to perform a systematic assessment of the process. During the three-month campaign in Germany, 6.8% of all identified LLJ profiles were connected to a CP (CPLLJ). Most measured CPLLJs appeared with the CP front and lasted for up to two hours. Moreover, we have observed a CP favoring the formation of a several-hours long LLJ. In that case, a strong LLJ and cooling of the atmosphere between the surface and at least 400 m a.g.l. were seen when the density current reached the measurement site. The development led to the formation of a near-surface temperature inversion during daytime as a prerequisite for the LLJ, not unlike the mechanism of nocturnal LLJs.

Key Points:

- Observed low-level jets connected to convective cold pools were about 7% of all jet profiles during summer campaign in Germany
- Convective cold pools favored reduced frictional coupling of the wind field as a prerequisite for generating low-level jets during daytime
- Low-level jets connected to convective cold pools were on average weaker but gustier than nocturnal jets

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