Understanding large-scale controls of nighttime elevated convections
over the Great Plains during PECAN field experiment
Abstract
Current General Circulation Models (GCMs) are struggling to capture the
observed diurnal cycle of precipitation. One major problem is that GCMs
usually have difficulties to simulate nocturnal deep convections.
Nocturnal deep convections are usually decoupled with the land surface
and are controlled by other factors aloft, which have not been fully
understood. The Plains Elevated Convection at Night (PECAN) is a
multi-institutional collaborated field experiment conducted at the
central Great Plains during summertime (1 June to 15 July) 2015 on the
purpose of improving the understanding and simulation of the processes
that initial and maintain deep convections at night. During the 45-day
PECAN period there are 31 intensive operational periods (IOP) of
nighttime deep convections, each last for one night. The unique part of
PECAN experiment is the use of 6 fixed and 4 mobile PECAN Integrated
Sounding Arrays (PISA) to take detailed measurements for each IOP. These
detailed measurements of thermodynamics, wind and water vapor profiles
in high temporal resolution (typically 90-min) allow the observation of
the evolution of boundary layer and propagating features. We will report
results from the analysis of these PISAs using a constrained variational
analysis method to understand the large-scale environment that control
the nighttime deep convections at the central Great Plains.