Preprints
https://doi.org/10.5194/gmd-2021-354
https://doi.org/10.5194/gmd-2021-354

Submitted as: development and technical paper 25 Oct 2021

Submitted as: development and technical paper | 25 Oct 2021

Review status: this preprint is currently under review for the journal GMD.

On the impact of dropsondes on the EC IFS model (Cy47r1) analysis of convection during OTREC

Stipo Sentić1, Peter Bechtold2, Željka Fuchs-Stone1,3, Mark Rodwell2, and David J. Raymond1,3 Stipo Sentić et al.
  • 1Climate and Water Consortium, New Mexico Tech, Socorro, NM, USA
  • 2European Center for Medium Range Weather Forecast, Reading, UK
  • 3Physics Department, New Mexico Tech, Socorro, NM, USA

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.

Stipo Sentić et al.

Status: open (until 20 Dec 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2021-354', Anonymous Referee #1, 22 Nov 2021 reply
  • RC2: 'Comment on gmd-2021-354', Anonymous Referee #2, 25 Nov 2021 reply
  • EC1: 'Comment on gmd-2021-354', Yuefei Zeng, 27 Nov 2021 reply

Stipo Sentić et al.

Stipo Sentić et al.

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Short summary
The OTREC field campaign focuses on studying convection in the east Pacific and the Caribbean. Observations obtained from dropsondes have been assimilated in the ECMWF model, and compared to a model run in which sondes have not been assimilated. The model performs well in both simulations, but assimilation of sondes helps to reduce the departure for pre-tropical storm conditions. Variables important for studying convection are also studied.