On the assessment of the moisture transport by the Great Plains low-level jet
FECHA:
2019-02-18
IDENTIFICADOR UNIVERSAL: http://hdl.handle.net/11093/4059
VERSIÓN EDITADA: https://esd.copernicus.org/articles/10/107/2019/
TIPO DE DOCUMENTO: article
RESUMEN
Low-level jets (LLJs) can be defined as wind corridors of anomalously high
wind speed values located within the first kilometre of the troposphere.
These structures are one of the major meteorological systems in the
meridional transport of moisture on a global scale. In this work, we focus on
the southerly Great Plains low-level jet, which plays an important role in
the moisture transport balance over the central United States. The Gulf of
Mexico is the main moisture source for the Great Plains low-level jet
(GPLLJ), which has been identified as a key factor for rainfall modulation
over the eastern and central US. The relationship between moisture transport from the Gulf of Mexico to the
Great Plains and precipitation has been well documented in previous studies.
Nevertheless, a large uncertainty still remains in the quantification of the
moisture amount actually carried by the GPLLJ. The main goal of this work is
to address this question. For this purpose, a relatively new tool, the
regional atmospheric Weather Research and Forecasting Model with 3-D water
vapour tracers (WRF-WVT; Insua-Costa and Miguez-Macho, 2018) is used together
with the Lagrangian model FLEXPART to estimate the load of precipitable water
advected within the GPLLJ. Both models were fed with data from ERA Interim. From a climatology of jet intensity
over a 37-year period, which follows a Gaussian distribution, we select five
cases for study, representing the mean and 1 and 2 standard deviations above
and below it. Results show that the jet is responsible for roughly
70 %–80 % of the moisture transport occurring in the southern Great
Plains when a jet event occurs. Furthermore, moisture transport by the GPLLJ
extends to the north-east US, accounting for 50 % of the total in areas
near the Great Lakes. Vertical distributions show the maximum of moisture
advected by the GPLLJ at surface levels and maximum values of moisture flux
about 500 m above, in coincidence with the wind speed profile.