contributor author | Song, Fengfei;Zhang, Guang J. | |
date accessioned | 2018-01-03T11:01:36Z | |
date available | 2018-01-03T11:01:36Z | |
date copyright | 8/1/2017 12:00:00 AM | |
date issued | 2017 | |
identifier other | jcli-d-17-0042.1.pdf | |
identifier uri | http://138.201.223.254:8080/yetl1/handle/yetl/4246212 | |
description abstract | AbstractUsing observations from the Green Ocean Amazon (GOAmazon) field campaign, this study aims to improve trigger functions of convection schemes. Results show that the CAPE generation rate (dCAPE)-type triggers are the first tier and that the Bechtold and heated condensation framework (HCF) triggers are a distant second tier. The composite analysis reveals that the undilute dCAPE trigger underpredicts convection when there is bottom-heavy upward motion but overpredicts convection with low-level downward and upper-level upward motions. The empirical orthogonal function (EOF) analysis on vertical velocity shows that EOF1 (62.65%) exhibits upward motion throughout the troposphere and that EOF2 (28.05%) has lower-level upward motion and upper-level downward motion. Both of them have close relationships with precipitation, indicating the role of vertical velocity in triggering convection. The skill sensitivity analysis shows that the inclusion of 700-hPa upward motion significantly enhances the undilute dCAPE trigger. For the dilute dCAPE trigger, entrainment rate and dCAPE threshold are optimized to improve it. Opposite to dCAPE-type triggers, the Bechtold trigger overemphasizes the low-level vertical velocity and underpredicts the mature and decaying phases of long-lasting convection events. The HCF trigger overemphasizes the near-surface moist static energy and overlooks the vertical velocity. The performance of dCAPE-type triggers on various convective systems over the Amazon region is examined. The eastward-propagating systems are best represented, with only a few underpredictions in their decaying stages. The weak locally occurring systems and marginal phases of westward-propagating systems are easy to underpredict. The revised dCAPE-type triggers perform better on different convection systems and the diurnal cycle of convection. | |
publisher | American Meteorological Society | |
title | Improving Trigger Functions for Convective Parameterization Schemes Using GOAmazon Observations | |
type | Journal Paper | |
journal volume | 30 | |
journal issue | 21 | |
journal title | Journal of Climate | |
identifier doi | 10.1175/JCLI-D-17-0042.1 | |
journal fristpage | 8711 | |
journal lastpage | 8726 | |
tree | Journal of Climate:;2017:;volume( 030 ):;issue: 021 | |
contenttype | Fulltext | |