EPIC ITCZ Summary

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EPIC - ITCZ Summary
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EPIC Scientific Objective (ITCZ)

• To observe and understand the ocean-atmosphere
  processes responsible for the structure and
  evolution of the large-scale atmospheric heating
  gradients in the equatorial and northeastern
  Pacific portions of the cold-tongue/ITCZ complex,
  including

(a) Mechanisms governing temperature and salinity
field evolution in the oceanic cold tongue and in
the region of strong meridional gradient in sea
surface temperature from the oceanic cold tongue
through the ITCZ (air-sea interaction). (b)
Atmospheric planetary boundary layer structure
and evolution from the equator through the ITCZ,
primarily in the southerly monsoonal regime (c)
The processes determining the existence,
character and strength of deep convection in the
northeast Pacific ITCZ.
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• Objective (a) air-sea interaction

• instrument/acoustic raingauge (Nystuen and Ma )
• synoptic waves (Serra)
• MJO (Maloney and Esbensen Bielli et al.)
• shallow circulation and entrainment (Zhang et
  al.)
• zonal wind (Raymond)

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• Objective (b) Boundary layer

• momentum budget (Zhang et al.)
• zonal winds/MJO (Raymond)
• model - observation comparison (Zeng et al.)

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• Objective (c) deep convection

• radar/satellite/region intercomparisons (Cefilli
  et al. Nesbitt et al. Pereira et al.)
• zonal winds (Raymond)
• ABL entropy (Carrillo and Raymond)
• waves (Kiladis and Straub Cifelli et al.
  Serra Raymond Maloney and Esbensen Bielli et
  al.)
• orographic effects (Xie et al.)
• vertical structure (Zuidema)
• instrument/lidar (Baumgardner et al.)

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Synthesis of EPIC ITCZ Research

• Deep convection in the ITCZ is affected by
  atmospheric wave activities (easterly, Kelvin,
  MJO)
• Do these waves simply redistribute deep
  convective precipitation in space and time or
  modulate the total amount of precipitation in the
  mean?

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Synthesis of EPIC ITCZ Research

• (2) ITCZ convection is susceptible to ABL
  entropy, surface fluxes, northerly and southerly
  inflow/convergence,

What is the importance of aerosol, mid and
upper level humidity, and large-scale subsidence?
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Synthesis of EPIC ITCZ Research

• (3) There are significant differences among deep
  convective systems in the regions of EPIC, TEPPS,
  and LBA

How different are deep convective systems in
the eastern Pacific from those in the western
Pacific (TOGA COARE), North American monsoon
(NAME), Atlantic ITCZ and Africa (AMMA/AMI)?
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Synthesis of EPIC ITCZ Research

• (4) The vertical structure of convection in the
  ITCZ is of multi-mode

Is the bimodal distribution in ITCZ convection
caused by convective-scale or large-scale
dynamics? How is the bimodal distribution in
ITCZ convection related to the bimodal
distribution in the large-scale meridional
overturning circulation?
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Synthesis of EPIC ITCZ Research

• (5) The vertical-meridional circulation in the
  eastern Pacific is featured of a deep and a
  shallow cell.

What are the dynamics and climate significance
of the shallow meridional circulation?
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Synthesis of EPIC ITCZ Research

• (6) Air-sea interaction may take place in and
  near the ITCZ through modulations of surface
  winds by wave activities, zonal wind, and
  boundary-layer entrainment

Are perturbations in SST important to the wave
activities in the ITCZ? Can the relative
importance of absolute SST in the ITCZ vs. SST
gradient to ITCZ convection be quantified?
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Synthesis of EPIC ITCZ Research

• (7) Model deficiencies in the EPIC region
  include underestimate of the ABL height,
  misrepresentation of the orography,

Can models reproduce the multi-mode vertical
structure of ITCZ convection, the shallow
meridional circulation, the ABL structure, the
regional dependence of convection/precipitation,
and the effects of waves on ITCZ convection?
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Synthesis of EPIC ITCZ Research

• (8) EPIC atmospheric observation sources include
  ship (radars, soundings, .), aircraft (radar,
  lidar, dropsondes, ..), moorings, satellite, etc.

need integrating approaches to combine these
observations need integrating approaches to
combine atmospheric and oceanic observations
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Whats New?
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Structures of cloud and precipitation in the ITCZ

• Convective Variability Across the East Pacific
  A comparison of Precipitation Structure in the
  TEPPS and EPIC Domains - Robert Cifelli, Steve
  Nesbitt, and Steven A. Rutledge
• EPIC and Other Recent Field Campaign Radar Data
  Collected in the Context of the TRMM PR
  Climatology - Stephen W. Nesbitt, Robert Cifelli,
  and Steven A. Rutledge
• Convective Characteristics over the East Pacific
  and Southwest Amazon Regions A Radar Perspective
  - Luis Gustavo Paiva Pereira and Steven A.
  Rutledge
• On the Vertical Structure of the Upper Tropical
  Troposphere observed during EPIC by Cloud Radar
  and Soundings - P. Zuidema

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Convection - Circulation Interaction I
Boundary-Layer Dynamics

• Role of PBL-Top Zonal Winds in East Pacific ITCZ
  Dynamics - David J. Raymond
• Role of the ITCZ in Air-Sea Interaction - Chidong
  Zhang, Michael McGauley, and Nick Bond
• Spatial Variability of Entropy in the Boundary
  Layer - C. Lopez Carrillo and Dave J. Raymond
• Marine Atmospheric Boundary Layer Height over the
  Eastern Pacific Data Analysis and Model
  Evaluation - Xubin Zeng, M.A. Brunke, M. Zhou, C.
  Fairall, N.A. Bond, D.H. Lenschow

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Convection - Circulation Interaction II Wave
Dynamics

• Atmospheric Kelvin waves and Convective
  Variability over the EPIC Study Region - George
  N. Kiladis
• Synoptic Disturbances in the East Pacific ITCZ
  and Their Effects on the Boundary Layer and
  Upper-Ocean Mixed Layer - Yolande L. Serra
• The Amplification of East Pacific Intraseasonal
  Oscillation Convection and Wind Anomalies during
  June-November - Eric D. Maloney, Steven K.
  Esbensen
• Maximum Covariance Analysis of the Summertime MJO
  in the Eastern Pacific - Soline Bielli, Dennis L.
  Hartmann, David J. Lorenz

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Instrumentation

• EPIC 2001 Lidar "Calibrations" with In Situ
  Measurements - D. Baumgardner, G.B. Raga and J.C.
  Jimenez
• Acoustic Rain Gauge Measurements in the Eastern
  Tropical Pacific Ocean - Jeffrey A Nystuen and
  Barry Ma

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Large-Scale Circulation

• Predicting The Onset Of The North American
  Monsoon And Progress Toward A Mechanistic
  Understanding - David L. Mitchell, Beth Hall,
  Miguel F. Lavíin, Dorothea Ivanova 1and Kelly
  Redmond
• Satellite observations and numerical simulation
  of eastern Pacific climate - Shang-Ping Xie,
  Haiming Xu, Yuqing Wang, and Justin Small