Surface diurnal cycle and boundary layer structure over Rondônia during the rainy season

Alan K. Betts, Jose Fuentes, Michael Garstang, John H. Ball

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

An integrated data set with simultaneous observations at the surface, from tethered balloons within the boundary layer and from rawinsonde ascents, was collected during the wet season experiment of the Large-Scale Biosphere-Atmosphere (LBA) Experiment in Amazonia during January and February of 1999 in support of the ground validation for the Tropical Rainfall Measuring Mission (TRMM). We analyze the surface diurnal cycles of temperature, humidity, lifting condensation level, equivalent potential temperature, andbx64the surface fluxes of sensible and latent heat, ground heat flux and net radiation, for easterly and westerly wind regimes in the lower troposphere. During the easterly wind regimes, the diurnal evolution of mixing ratio shows that the flux of water vapor through cloud base exceeds the large surface evaporation. There is a trend toward a wetter and cooler subcloud layer as the rainy season progresses. Daytime surface Bowen ratio for this pasture site is about 0.4, and falls slightly as the rainy season progresses: Typically in the afternoon, evaporatively driven dovvndrafts from convective rainbands transform the boundary layer. The fall of equivalent potential temperature in the boundary layer is similar for both regimes, but the boundary layer cooling by convective events during the westerly regimes is reduced, because the subcloud layer is shallower on average. Tethersonde ascents through the edges of gust fronts show that subcloud air is first cooled and moistened by rainfall evaporation before the arrival of downdraft air at the surface. These measurements provide a detailed observational basis for the validation and improvement of parameterizations for shallow and dee p convection in numerical forecast models.

Original languageEnglish (US)
JournalJournal of Geophysical Research Atmospheres
Volume107
Issue number20
DOIs
StatePublished - Jan 1 2002

Fingerprint

boundary layers
wet season
Boundary layers
boundary layer
cycles
ascent
potential temperature
westerly
tethered balloons
rawinsondes
evaporation
Rain
gusts
Evaporation
rainband
biosphere
Bowen ratio
gust
Fluxes
air

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

Cite this

@article{81f6ef4d802e472ba7ec4ba797748c5d,
title = "Surface diurnal cycle and boundary layer structure over Rond{\^o}nia during the rainy season",
abstract = "An integrated data set with simultaneous observations at the surface, from tethered balloons within the boundary layer and from rawinsonde ascents, was collected during the wet season experiment of the Large-Scale Biosphere-Atmosphere (LBA) Experiment in Amazonia during January and February of 1999 in support of the ground validation for the Tropical Rainfall Measuring Mission (TRMM). We analyze the surface diurnal cycles of temperature, humidity, lifting condensation level, equivalent potential temperature, andbx64the surface fluxes of sensible and latent heat, ground heat flux and net radiation, for easterly and westerly wind regimes in the lower troposphere. During the easterly wind regimes, the diurnal evolution of mixing ratio shows that the flux of water vapor through cloud base exceeds the large surface evaporation. There is a trend toward a wetter and cooler subcloud layer as the rainy season progresses. Daytime surface Bowen ratio for this pasture site is about 0.4, and falls slightly as the rainy season progresses: Typically in the afternoon, evaporatively driven dovvndrafts from convective rainbands transform the boundary layer. The fall of equivalent potential temperature in the boundary layer is similar for both regimes, but the boundary layer cooling by convective events during the westerly regimes is reduced, because the subcloud layer is shallower on average. Tethersonde ascents through the edges of gust fronts show that subcloud air is first cooled and moistened by rainfall evaporation before the arrival of downdraft air at the surface. These measurements provide a detailed observational basis for the validation and improvement of parameterizations for shallow and dee p convection in numerical forecast models.",
author = "Betts, {Alan K.} and Jose Fuentes and Michael Garstang and Ball, {John H.}",
year = "2002",
month = "1",
day = "1",
doi = "10.1029/2001JD000356",
language = "English (US)",
volume = "107",
journal = "Journal of Geophysical Research: Atmospheres",
issn = "2169-897X",
number = "20",

}

Surface diurnal cycle and boundary layer structure over Rondônia during the rainy season. / Betts, Alan K.; Fuentes, Jose; Garstang, Michael; Ball, John H.

In: Journal of Geophysical Research Atmospheres, Vol. 107, No. 20, 01.01.2002.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Surface diurnal cycle and boundary layer structure over Rondônia during the rainy season

AU - Betts, Alan K.

AU - Fuentes, Jose

AU - Garstang, Michael

AU - Ball, John H.

PY - 2002/1/1

Y1 - 2002/1/1

N2 - An integrated data set with simultaneous observations at the surface, from tethered balloons within the boundary layer and from rawinsonde ascents, was collected during the wet season experiment of the Large-Scale Biosphere-Atmosphere (LBA) Experiment in Amazonia during January and February of 1999 in support of the ground validation for the Tropical Rainfall Measuring Mission (TRMM). We analyze the surface diurnal cycles of temperature, humidity, lifting condensation level, equivalent potential temperature, andbx64the surface fluxes of sensible and latent heat, ground heat flux and net radiation, for easterly and westerly wind regimes in the lower troposphere. During the easterly wind regimes, the diurnal evolution of mixing ratio shows that the flux of water vapor through cloud base exceeds the large surface evaporation. There is a trend toward a wetter and cooler subcloud layer as the rainy season progresses. Daytime surface Bowen ratio for this pasture site is about 0.4, and falls slightly as the rainy season progresses: Typically in the afternoon, evaporatively driven dovvndrafts from convective rainbands transform the boundary layer. The fall of equivalent potential temperature in the boundary layer is similar for both regimes, but the boundary layer cooling by convective events during the westerly regimes is reduced, because the subcloud layer is shallower on average. Tethersonde ascents through the edges of gust fronts show that subcloud air is first cooled and moistened by rainfall evaporation before the arrival of downdraft air at the surface. These measurements provide a detailed observational basis for the validation and improvement of parameterizations for shallow and dee p convection in numerical forecast models.

AB - An integrated data set with simultaneous observations at the surface, from tethered balloons within the boundary layer and from rawinsonde ascents, was collected during the wet season experiment of the Large-Scale Biosphere-Atmosphere (LBA) Experiment in Amazonia during January and February of 1999 in support of the ground validation for the Tropical Rainfall Measuring Mission (TRMM). We analyze the surface diurnal cycles of temperature, humidity, lifting condensation level, equivalent potential temperature, andbx64the surface fluxes of sensible and latent heat, ground heat flux and net radiation, for easterly and westerly wind regimes in the lower troposphere. During the easterly wind regimes, the diurnal evolution of mixing ratio shows that the flux of water vapor through cloud base exceeds the large surface evaporation. There is a trend toward a wetter and cooler subcloud layer as the rainy season progresses. Daytime surface Bowen ratio for this pasture site is about 0.4, and falls slightly as the rainy season progresses: Typically in the afternoon, evaporatively driven dovvndrafts from convective rainbands transform the boundary layer. The fall of equivalent potential temperature in the boundary layer is similar for both regimes, but the boundary layer cooling by convective events during the westerly regimes is reduced, because the subcloud layer is shallower on average. Tethersonde ascents through the edges of gust fronts show that subcloud air is first cooled and moistened by rainfall evaporation before the arrival of downdraft air at the surface. These measurements provide a detailed observational basis for the validation and improvement of parameterizations for shallow and dee p convection in numerical forecast models.

UR - http://www.scopus.com/inward/record.url?scp=33646524936&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=33646524936&partnerID=8YFLogxK

U2 - 10.1029/2001JD000356

DO - 10.1029/2001JD000356

M3 - Article

AN - SCOPUS:33646524936

VL - 107

JO - Journal of Geophysical Research: Atmospheres

JF - Journal of Geophysical Research: Atmospheres

SN - 2169-897X

IS - 20

ER -