Kruse, Irene L., Haerter, Jan O. ORCID: https://orcid.org/0000-0002-8617-3847 and Meyer, Bettina (2021) Cold pools over the Netherlands: A statistical study from tower and radar observations. Quarterly Journal of the Royal Meteorological Society . DOI https://doi.org/10.1002/qj.4223.

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Abstract

We provide a detailed analysis of convectively generated cold pools (CPs) overflat midlatitude land, combining ten-year high-frequency time series of mea-surements at several heights available from the 213-m tower observatory atCabauw, the Netherlands, with a collocated 2D radar rainfall dataset. This com-bination of data allows us to relate observations of the CP’s temporal and verticalstructure to the properties of each CP’s parent rain cell, which we identifyby rain-cell tracking. Using a new detection method, based on the anoma-lies of both the vertically averaged wind and the temperature, we monitor thearrival and passing of 189 CPs during ten summers (2010–2019). The time seriesshow a clear signature of vortex-like motion along the leading CP edge in thevertical and horizontal wind measurements. The arrival of CP gust fronts ischaracterized by a steep decrease in both temperature and moisture, with arecovery time of approximately two hours. We see no evidence of moisturerings on the gust front edge, and therefore no indications for thermodynamicconvective triggering. From the tower data, we obtain a median CP tempera-ture drop ofTdrop≈−2.9K and a height-averaged horizontal wind anomaly ofΔumax≈4.4m⋅s−1. Relating the individual CP’s horizontal wind anomalies andtemperature drops, we confirm the validity of the theoretical density currentrelationship,Δumax∝T1∕2drop. We further propose a simple statistical model torelate the CP strength defined byTdropto the environmental properties influenc-ing the CP: rain intensity and lower boundary-layer saturation. A multivariatelinear regression suggests a 1K colder CP for a 4mm⋅hr−1more intense raincell (instantaneous area-averaged rain intensity) or for a 2.5K larger pre-CPdew-point depression.

Document Type: Article
Programme Area: PA2
Research affiliation: Affiliations > Not ZMT
Integrated Modelling > Complexity and Climate
Refereed: Yes
Open Access Journal?: No
DOI etc.: https://doi.org/10.1002/qj.4223
ISSN: 0035-9009
Date Deposited: 12 Jan 2022 15:32
Last Modified: 05 Apr 2022 16:30
URI: http://cris.leibniz-zmt.de/id/eprint/4830

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