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Raul E. Lopez
,
David O. Blanchard
,
Ronald L. Holle
,
Jack L. Thomas
,
David Atlas
, and
Daniel Rosenfeld

Abstract

This work extends the Area Time Integral (ATI) method of Doneaud et al., developed for the lifetime rainfall from an individual storm, and the instantaneous areawide rainfall method of Atlas et al., to the measurement of the cumulative areawide rainfall for periods up to 12 h. The database is the radar and rainfall network data for the three summers of the Florida Area Cumulus Experiment (FACE) II. For 12-h accumulations, V, over the area of 3.6 × 104 km2, we find correlations of 0.92 between radar deduced rainfall and ATI where the latter is computed at intervals from 5 min up to 1 h. The slope of the regression line V/(ATI) is 3.4 mm h−1. Using a gage network with density of 1/11 km2 over an area 1.5 × 104 km2 the correlation coefficient drops to 0.84, still sufficiently high to confirm the validity of the ATI approach. Also, with the gages the V/(ATI) slope decreases to 2.6 mm h−1. The decrease in the correlation is due largely to anomalous propagation which falsely increases storm areas, and partly to the poorer sampling by the gages. The decrease in the rain volume from radar to gage-determined values is probably due to: 1) underestimation of the rain cores by the spaced gages; 2) the use of the wide beam WSR-57 and low threshold for echo area measurements, which detects weak anvil and other precipitation debris to increase the effective echo area without a proportional increase in surface rainfall; and 3) an inappropriate ZR relation. A comparison of the V/(ATI) ratios using either radar or gage rainfall to the value expected theoretically on the basis of the probability distribution of rain rate at Miami shows that one should expect about twice the volume per unit echo area as those observed. This too is believed to be due to the wide beam and the low threshold which tends to enlarge the echo areas excessively. Improved correlations and better agreement with theory are expected at higher radar/rain rate thresholds and with narrower beams.

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EXECUTIVE COMMITTEE
,
D. Atlas
,
C. L. Hosler Jr.
,
D. S. Johnson
,
W. H. Best Jr.
,
P. M. Austin
,
E. S. Epstein
,
K. C. Spengler
, and
D. F. Landrigan
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EXECUTIVE COMMITTEE
,
C. L. Hosler
,
W. A. Baum
,
D. Atlas
,
P. M. Austin
,
E. S. Epstein
,
R. L. Leep Jr.
,
K. C. Spengler
, and
D. F. Landrigan
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L. L. Pan
,
E. L. Atlas
,
R. J. Salawitch
,
S. B. Honomichl
,
J. F. Bresch
,
W. J. Randel
,
E. C. Apel
,
R. S. Hornbrook
,
A. J. Weinheimer
,
D. C. Anderson
,
S. J. Andrews
,
S. Baidar
,
S. P. Beaton
,
T. L. Campos
,
L. J. Carpenter
,
D. Chen
,
B. Dix
,
V. Donets
,
S. R. Hall
,
T. F. Hanisco
,
C. R. Homeyer
,
L. G. Huey
,
J. B. Jensen
,
L. Kaser
,
D. E. Kinnison
,
T. K. Koenig
,
J.-F. Lamarque
,
C. Liu
,
J. Luo
,
Z. J. Luo
,
D. D. Montzka
,
J. M. Nicely
,
R. B. Pierce
,
D. D. Riemer
,
T. Robinson
,
P. Romashkin
,
A. Saiz-Lopez
,
S. Schauffler
,
O. Shieh
,
M. H. Stell
,
K. Ullmann
,
G. Vaughan
,
R. Volkamer
, and
G. Wolfe

Abstract

The Convective Transport of Active Species in the Tropics (CONTRAST) experiment was conducted from Guam (13.5°N, 144.8°E) during January–February 2014. Using the NSF/NCAR Gulfstream V research aircraft, the experiment investigated the photochemical environment over the tropical western Pacific (TWP) warm pool, a region of massive deep convection and the major pathway for air to enter the stratosphere during Northern Hemisphere (NH) winter. The new observations provide a wealth of information for quantifying the influence of convection on the vertical distributions of active species. The airborne in situ measurements up to 15-km altitude fill a significant gap by characterizing the abundance and altitude variation of a wide suite of trace gases. These measurements, together with observations of dynamical and microphysical parameters, provide significant new data for constraining and evaluating global chemistry–climate models. Measurements include precursor and product gas species of reactive halogen compounds that impact ozone in the upper troposphere/lower stratosphere. High-accuracy, in situ measurements of ozone obtained during CONTRAST quantify ozone concentration profiles in the upper troposphere, where previous observations from balloonborne ozonesondes were often near or below the limit of detection. CONTRAST was one of the three coordinated experiments to observe the TWP during January–February 2014. Together, CONTRAST, Airborne Tropical Tropopause Experiment (ATTREX), and Coordinated Airborne Studies in the Tropics (CAST), using complementary capabilities of the three aircraft platforms as well as ground-based instrumentation, provide a comprehensive quantification of the regional distribution and vertical structure of natural and pollutant trace gases in the TWP during NH winter, from the oceanic boundary to the lower stratosphere.

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Eric J. Jensen
,
Leonhard Pfister
,
David E. Jordan
,
Thaopaul V. Bui
,
Rei Ueyama
,
Hanwant B. Singh
,
Troy D. Thornberry
,
Andrew W. Rollins
,
Ru-Shan Gao
,
David W. Fahey
,
Karen H. Rosenlof
,
James W. Elkins
,
Glenn S. Diskin
,
Joshua P. DiGangi
,
R. Paul Lawson
,
Sarah Woods
,
Elliot L. Atlas
,
Maria A. Navarro Rodriguez
,
Steven C. Wofsy
,
Jasna Pittman
,
Charles G. Bardeen
,
Owen B. Toon
,
Bruce C. Kindel
,
Paul A. Newman
,
Matthew J. McGill
,
Dennis L. Hlavka
,
Leslie R. Lait
,
Mark R. Schoeberl
,
John W. Bergman
,
Henry B. Selkirk
,
M. Joan Alexander
,
Ji-Eun Kim
,
Boon H. Lim
,
Jochen Stutz
, and
Klaus Pfeilsticker

Abstract

The February–March 2014 deployment of the National Aeronautics and Space Administration (NASA) Airborne Tropical Tropopause Experiment (ATTREX) provided unique in situ measurements in the western Pacific tropical tropopause layer (TTL). Six flights were conducted from Guam with the long-range, high-altitude, unmanned Global Hawk aircraft. The ATTREX Global Hawk payload provided measurements of water vapor, meteorological conditions, cloud properties, tracer and chemical radical concentrations, and radiative fluxes. The campaign was partially coincident with the Convective Transport of Active Species in the Tropics (CONTRAST) and the Coordinated Airborne Studies in the Tropics (CAST) airborne campaigns based in Guam using lower-altitude aircraft (see companion articles in this issue). The ATTREX dataset is being used for investigations of TTL cloud, transport, dynamical, and chemical processes, as well as for evaluation and improvement of global-model representations of TTL processes. The ATTREX data are publicly available online (at https://espoarchive.nasa.gov/).

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