Abstract
The Organization of Tropical East Pacific Convection (OTREC) field campaign, conducted August through October 2019, focuses on studying convection in the East Pacific and the Caribbean. An unprecedented number of dropsondes were deployed (648) during 22 missions to study the region of strong sea surface temperature (SST) gradients in the East Pacific region, the region just off the coast of Columbia, and in the uniform SST region in the southwest Caribbean. The dropsondes were assimilated in the European Center for Medium Range Weather Forecast model. This study quantifies departures, observed minus the model value of a variable, in dropsonde denial experiments, and studies time series of convective variables: saturation fraction which measures moisture, and instability index and deep convective inhibition which quantify atmospheric stability and boundary layer stability to convection, respectively. Departures are small whether dropsondes are assimilated or not, except in a special case of a precursor to tropical storm Ivo where wind departures are significantly larger when dropsondes are not assimilated. Departures are larger in cloudy regions compared to cloud free regions when comparing a vertically integrated departure with a cloudiness estimation. Above mentioned variables are all well represented by the model when com- pared to observations, with some systematic deviations in and above the boundary layer. Time series of these variables show artificial convective activity in the model, in the East Pacific region off the coast of Costa Rica, which we hypothesize occurs due to overestimation of moisture content in that region.
Highlights
The Organization of Tropical East Pacific Convection (OTREC) field campaign was performed from Aug 5 to Oct 3, 2019, in the regions of far East Pacific and the Caribbean
This paper evaluates the performance of the European Center for Medium-Range Weather Forecasts (ECMWF) model during the OTREC field campaign, held during Aug 5 to Oct 3, 2019, in the East Pacific and the Caribbean
Departures, defined as model values subtracted from observation values, are calculated at the moment of the drop to quantify the deviation of the model from observations for each dropsonde individually
Summary
The Organization of Tropical East Pacific Convection (OTREC) field campaign was performed from Aug 5 to Oct 3, 2019, in the regions of far East Pacific and the Caribbean. Raymond and Fuchs-Stone (2021), using OTREC data, identified three parameters important for convection in the region: saturation fraction, instability index, and deep convective inhibition (DCIN). The 3D-var analysis is calculated by a penalty function minimization Raymond and López Carrillo (2011); López Carrillo and Raymond (2011) which produces a gridded data set where the interpolated values in between dropsondes satisfy the mass continuity equation This 3D-var approach was used in many previous studies of convection Gjorgjievska and Raymond (2014); Fuchs-Stone et al (2020); Raymond and Fuchs-Stone (2021).
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