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C. Kummerow
,
J. Simpson
,
O. Thiele
,
W. Barnes
,
A. T. C. Chang
,
E. Stocker
,
R. F. Adler
,
A. Hou
,
R. Kakar
,
F. Wentz
,
P. Ashcroft
,
T. Kozu
,
Y. Hong
,
K. Okamoto
,
T. Iguchi
,
H. Kuroiwa
,
E. Im
,
Z. Haddad
,
G. Huffman
,
B. Ferrier
,
W. S. Olson
,
E. Zipser
,
E. A. Smith
,
T. T. Wilheit
,
G. North
,
T. Krishnamurti
, and
K. Nakamura

Abstract

The Tropical Rainfall Measuring Mission (TRMM) satellite was launched on 27 November 1997, and data from all the instruments first became available approximately 30 days after the launch. Since then, much progress has been made in the calibration of the sensors, the improvement of the rainfall algorithms, and applications of these results to areas such as data assimilation and model initialization. The TRMM Microwave Imager (TMI) calibration has been corrected and verified to account for a small source of radiation leaking into the TMI receiver. The precipitation radar calibration has been adjusted upward slightly (by 0.6 dBZ) to match better the ground reference targets; the visible and infrared sensor calibration remains largely unchanged. Two versions of the TRMM rainfall algorithms are discussed. The at-launch (version 4) algorithms showed differences of 40% when averaged over the global Tropics over 30-day periods. The improvements to the rainfall algorithms that were undertaken after launch are presented, and intercomparisons of these products (version 5) show agreement improving to 24% for global tropical monthly averages. The ground-based radar rainfall product generation is discussed. Quality-control issues have delayed the routine production of these products until the summer of 2000, but comparisons of TRMM products with early versions of the ground validation products as well as with rain gauge network data suggest that uncertainties among the TRMM algorithms are of approximately the same magnitude as differences between TRMM products and ground-based rainfall estimates. The TRMM field experiment program is discussed to describe active areas of measurements and plans to use these data for further algorithm improvements. In addition to the many papers in this special issue, results coming from the analysis of TRMM products to study the diurnal cycle, the climatological description of the vertical profile of precipitation, storm types, and the distribution of shallow convection, as well as advances in data assimilation of moisture and model forecast improvements using TRMM data, are discussed in a companion TRMM special issue in the Journal of Climate (1 December 2000, Vol. 13, No. 23).

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R. O. Knuteson
,
H. E. Revercomb
,
F. A. Best
,
N. C. Ciganovich
,
R. G. Dedecker
,
T. P. Dirkx
,
S. C. Ellington
,
W. F. Feltz
,
R. K. Garcia
,
H. B. Howell
,
W. L. Smith
,
J. F. Short
, and
D. C. Tobin

Abstract

A ground-based Fourier transform spectrometer has been developed to measure the atmospheric downwelling infrared radiance spectrum at the earth's surface with high absolute accuracy. The Atmospheric Emitted Radiance Interferometer (AERI) instrument was designed and fabricated by the University of Wisconsin Space Science and Engineering Center (UW-SSEC) for the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program. This paper emphasizes the key features of the UW-SSEC instrument design that contribute to meeting the AERI instrument requirements for the ARM Program. These features include a highly accurate radiometric calibration system, an instrument controller that provides continuous and autonomous operation, an extensive data acquisition system for monitoring calibration temperatures and instrument health, and a real-time data processing system. In particular, focus is placed on design issues crucial to meeting the ARM requirements for radiometric calibration, spectral calibration, noise performance, and operational reliability. The detailed performance characteristics of the AERI instruments built for the ARM Program are described in a companion paper.

Full access
R. O. Knuteson
,
H. E. Revercomb
,
F. A. Best
,
N. C. Ciganovich
,
R. G. Dedecker
,
T. P. Dirkx
,
S. C. Ellington
,
W. F. Feltz
,
R. K. Garcia
,
H. B. Howell
,
W. L. Smith
,
J. F. Short
, and
D. C. Tobin

Abstract

The Atmospheric Emitted Radiance Interferometer (AERI) instrument was developed for the Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program by the University of Wisconsin Space Science and Engineering Center (UW-SSEC). The infrared emission spectra measured by the instrument have the sensitivity and absolute accuracy needed for atmospheric remote sensing and climate studies. The instrument design is described in a companion paper. This paper describes in detail the measured performance characteristics of the AERI instruments built for the ARM Program. In particular, the AERI systems achieve an absolute radiometric calibration of better than 1% (3σ) of ambient radiance, with a reproducibility of better than 0.2%. The knowledge of the AERI spectral calibration is better than 1.5 ppm (1σ) in the wavenumber range 400– 3000 cm−1.

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W. L. Smith
,
H. E. Rvercomb
,
H. B. Howell
,
H. M. Woolf
,
R. O. Knuteson
,
R G. Decker
,
M. J. Lynch
,
E. R. Westwater
,
R. G. Strauch
,
K. P. Moran
,
B. Stankov
,
M. J. Falls
,
J. Jordan
,
M. Jacobsen
,
W. F. Dabberdt
,
R. McBeth
,
G. Albright
,
C. Paneitz
,
G. Wright
,
P. T. May
, and
M. T. Decker

During the week 29 October–4 November 1988, a Ground-based Atmospheric Profiling Experiment (GAPEX) was conducted at Denver Stapleton International Airport. The objective of GAPEX was to acquire and analyze atomspheric-temperature and moisture-profile data from state-of-the-art remote sensors. The sensors included a six-spectral-channel, passive Microwave Profiler (MWP), a passive, infrared High-Resolution Interferometer Sounder (HIS) that provides more than 1500 spectral channels, and an active Radio Acoustic Sounding System (RASS). A Cross-Chain Loran Atmospheric Sounding System (CLASS) was used to provide research-quality in situ thermodynamic observations to verify the accuracy and resolution characteristics of each of the three remote sensors. The first results of the project are presented here to inform the meteorological community of the progress achieved during the GAPEX field phase. These results also serve to demonstrate the excellent prospects for an accurate, continuous thermodynamic profiling system to complement NOAA's forthcoming operational wind profiler.

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Kevin J. Noone
,
Elisabeth Öström
,
Ronald J. Ferek
,
Tim Garrett
,
Peter V. Hobbs
,
Doug W. Johnson
,
Jonathan P. Taylor
,
Lynn M. Russell
,
Richard C. Flagan
,
John H. Seinfeld
,
Colin D. O’Dowd
,
Michael H. Smith
,
Philip A. Durkee
,
Kurt Nielsen
,
James G. Hudson
,
Robert A. Pockalny
,
Lieve De Bock
,
René E. Van Grieken
,
Richard F. Gasparovic
, and
Ian Brooks

Abstract

The effects of anthropogenic particulate emissions from ships on the radiative, microphysical, and chemical properties of moderately polluted marine stratiform clouds are examined. A case study of two ships in the same air mass is presented where one of the vessels caused a discernible ship track while the other did not. In situ measurements of cloud droplet size distributions, liquid water content, and cloud radiative properties, as well as aerosol size distributions (outside cloud, interstitial, and cloud droplet residual particles) and aerosol chemistry, are presented. These are related to measurements of cloud radiative properties. The differences between the aerosol in the two ship plumes are discussed;these indicate that combustion-derived particles in the size range of about 0.03–0.3-μm radius were those that caused the microphysical changes in the clouds that were responsible for the ship track.

The authors examine the processes behind ship track formation in a moderately polluted marine boundary layer as an example of the effects that anthropogenic particulate pollution can have in the albedo of marine stratiform clouds.

Full access
Kevin J. Noone
,
Doug W. Johnson
,
Jonathan P. Taylor
,
Ronald J. Ferek
,
Tim Garrett
,
Peter V. Hobbs
,
Philip A. Durkee
,
Kurt Nielsen
,
Elisabeth Öström
,
Colin O’Dowd
,
Michael H. Smith
,
Lynn M. Russell
,
Richard C. Flagan
,
John H. Seinfeld
,
Lieve De Bock
,
René E. Van Grieken
,
James G. Hudson
,
Ian Brooks
,
Richard F. Gasparovic
, and
Robert A. Pockalny

Abstract

A case study of the effects of ship emissions on the microphysical, radiative, and chemical properties of polluted marine boundary layer clouds is presented. Two ship tracks are discussed in detail. In situ measurements of cloud drop size distributions, liquid water content, and cloud radiative properties, as well as aerosol size distributions (outside-cloud, interstitial, and cloud droplet residual particles) and aerosol chemistry, are presented. These are related to remotely sensed measurements of cloud radiative properties.

The authors examine the processes behind ship track formation in a polluted marine boundary layer as an example of the effects of anthropogenic particulate pollution on the albedo of marine stratiform clouds.

Full access
G. de Boer
,
C. Diehl
,
J. Jacob
,
A. Houston
,
S. W. Smith
,
P. Chilson
,
D. G. Schmale III
,
J. Intrieri
,
J. Pinto
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J. Elston
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D. Brus
,
O. Kemppinen
,
A. Clark
,
D. Lawrence
,
S. C. C. Bailey
,
M.P. Sama
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A. Frazier
,
C. Crick
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V. Natalie
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E. Pillar-Little
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P. Klein
,
S. Waugh
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J. K. Lundquist
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L. Barbieri
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S. T. Kral
,
A. A. Jensen
,
C. Dixon
,
S. Borenstein
,
D. Hesselius
,
K. Human
,
P. Hall
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B. Argrow
,
T. Thornberry
,
R. Wright
, and
J. T. Kelly
Full access
D. R. Feldman
,
A. C. Aiken
,
W. R. Boos
,
R. W. H. Carroll
,
V. Chandrasekar
,
S. Collis
,
J. M. Creamean
,
G. de Boer
,
J. Deems
,
P. J. DeMott
,
J. Fan
,
A. N. Flores
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D. Gochis
,
M. Grover
,
T. C. J. Hill
,
A. Hodshire
,
E. Hulm
,
C. C. Hume
,
R. Jackson
,
F. Junyent
,
A. Kennedy
,
M. Kumjian
,
E. J. T. Levin
,
J. D. Lundquist
,
J. O’Brien
,
M. S. Raleigh
,
J. Reithel
,
A. Rhoades
,
K. Rittger
,
W. Rudisill
,
Z. Sherman
,
E. Siirila-Woodburn
,
S. M. Skiles
,
J. N. Smith
,
R. C. Sullivan
,
A. Theisen
,
M. Tuftedal
,
A. C. Varble
,
A. Wiedlea
,
S. Wielandt
,
K. Williams
, and
Z. Xu

Abstract

The science of mountainous hydrology spans the atmosphere through the bedrock and inherently crosses physical and disciplinary boundaries: land–atmosphere interactions in complex terrain enhance clouds and precipitation, while watersheds retain and release water over a large range of spatial and temporal scales. Limited observations in complex terrain challenge efforts to improve predictive models of the hydrology in the face of rapid changes. The Upper Colorado River exemplifies these challenges, especially with ongoing mismatches between precipitation, snowpack, and discharge. Consequently, the U.S. Department of Energy’s (DOE) Atmospheric Radiation Measurement (ARM) user facility has deployed an observatory to the East River Watershed near Crested Butte, Colorado, between September 2021 and June 2023 to measure the main atmospheric drivers of water resources, including precipitation, clouds, winds, aerosols, radiation, temperature, and humidity. This effort, called the Surface Atmosphere Integrated Field Laboratory (SAIL), is also working in tandem with DOE-sponsored surface and subsurface hydrologists and other federal, state, and local partners. SAIL data can be benchmarks for model development by producing a wide range of observational information on precipitation and its associated processes, including those processes that impact snowpack sublimation and redistribution, aerosol direct radiative effects in the atmosphere and in the snowpack, aerosol impacts on clouds and precipitation, and processes controlling surface fluxes of energy and mass. Preliminary data from SAIL’s first year showcase the rich information content in SAIL’s many datastreams and support testing hypotheses that will ultimately improve scientific understanding and predictability of Upper Colorado River hydrology in 2023 and beyond.

Open access
S. T. Martin
,
P. Artaxo
,
L. Machado
,
A. O. Manzi
,
R. A. F. Souza
,
C. Schumacher
,
J. Wang
,
T. Biscaro
,
J. Brito
,
A. Calheiros
,
K. Jardine
,
A. Medeiros
,
B. Portela
,
S. S. de Sá
,
K. Adachi
,
A. C. Aiken
,
R. Albrecht
,
L. Alexander
,
M. O. Andreae
,
H. M. J. Barbosa
,
P. Buseck
,
D. Chand
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J. M. Comstock
,
D. A. Day
,
M. Dubey
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J. Fan
,
J. Fast
,
G. Fisch
,
E. Fortner
,
S. Giangrande
,
M. Gilles
,
A. H. Goldstein
,
A. Guenther
,
J. Hubbe
,
M. Jensen
,
J. L. Jimenez
,
F. N. Keutsch
,
S. Kim
,
C. Kuang
,
A. Laskin
,
K. McKinney
,
F. Mei
,
M. Miller
,
R. Nascimento
,
T. Pauliquevis
,
M. Pekour
,
J. Peres
,
T. Petäjä
,
C. Pöhlker
,
U. Pöschl
,
L. Rizzo
,
B. Schmid
,
J. E. Shilling
,
M. A. Silva Dias
,
J. N. Smith
,
J. M. Tomlinson
,
J. Tóta
, and
M. Wendisch

Abstract

The Observations and Modeling of the Green Ocean Amazon 2014–2015 (GoAmazon2014/5) experiment took place around the urban region of Manaus in central Amazonia across 2 years. The urban pollution plume was used to study the susceptibility of gases, aerosols, clouds, and rainfall to human activities in a tropical environment. Many aspects of air quality, weather, terrestrial ecosystems, and climate work differently in the tropics than in the more thoroughly studied temperate regions of Earth. GoAmazon2014/5, a cooperative project of Brazil, Germany, and the United States, employed an unparalleled suite of measurements at nine ground sites and on board two aircraft to investigate the flow of background air into Manaus, the emissions into the air over the city, and the advection of the pollution downwind of the city. Herein, to visualize this train of processes and its effects, observations aboard a low-flying aircraft are presented. Comparative measurements within and adjacent to the plume followed the emissions of biogenic volatile organic carbon compounds (BVOCs) from the tropical forest, their transformations by the atmospheric oxidant cycle, alterations of this cycle by the influence of the pollutants, transformations of the chemical products into aerosol particles, the relationship of these particles to cloud condensation nuclei (CCN) activity, and the differences in cloud properties and rainfall for background compared to polluted conditions. The observations of the GoAmazon2014/5 experiment illustrate how the hydrologic cycle, radiation balance, and carbon recycling may be affected by present-day as well as future economic development and pollution over the Amazonian tropical forest.

Full access
I. A. Renfrew
,
R. S. Pickart
,
K. Våge
,
G. W. K. Moore
,
T. J. Bracegirdle
,
A. D. Elvidge
,
E. Jeansson
,
T. Lachlan-Cope
,
L. T. McRaven
,
L. Papritz
,
J. Reuder
,
H. Sodemann
,
A. Terpstra
,
S. Waterman
,
H. Valdimarsson
,
A. Weiss
,
M. Almansi
,
F. Bahr
,
A. Brakstad
,
C. Barrell
,
J. K. Brooke
,
B. J. Brooks
,
I. M. Brooks
,
M. E. Brooks
,
E. M. Bruvik
,
C. Duscha
,
I. Fer
,
H. M. Golid
,
M. Hallerstig
,
I. Hessevik
,
J. Huang
,
L. Houghton
,
S. Jónsson
,
M. Jonassen
,
K. Jackson
,
K. Kvalsund
,
E. W. Kolstad
,
K. Konstali
,
J. Kristiansen
,
R. Ladkin
,
P. Lin
,
A. Macrander
,
A. Mitchell
,
H. Olafsson
,
A. Pacini
,
C. Payne
,
B. Palmason
,
M. D. Pérez-Hernández
,
A. K. Peterson
,
G. N. Petersen
,
M. N. Pisareva
,
J. O. Pope
,
A. Seidl
,
S. Semper
,
D. Sergeev
,
S. Skjelsvik
,
H. Søiland
,
D. Smith
,
M. A. Spall
,
T. Spengler
,
A. Touzeau
,
G. Tupper
,
Y. Weng
,
K. D. Williams
,
X. Yang
, and
S. Zhou

Abstract

The Iceland Greenland Seas Project (IGP) is a coordinated atmosphere–ocean research program investigating climate processes in the source region of the densest waters of the Atlantic meridional overturning circulation. During February and March 2018, a field campaign was executed over the Iceland and southern Greenland Seas that utilized a range of observing platforms to investigate critical processes in the region, including a research vessel, a research aircraft, moorings, sea gliders, floats, and a meteorological buoy. A remarkable feature of the field campaign was the highly coordinated deployment of the observing platforms, whereby the research vessel and aircraft tracks were planned in concert to allow simultaneous sampling of the atmosphere, the ocean, and their interactions. This joint planning was supported by tailor-made convection-permitting weather forecasts and novel diagnostics from an ensemble prediction system. The scientific aims of the IGP are to characterize the atmospheric forcing and the ocean response of coupled processes; in particular, cold-air outbreaks in the vicinity of the marginal ice zone and their triggering of oceanic heat loss, and the role of freshwater in the generation of dense water masses. The campaign observed the life cycle of a long-lasting cold-air outbreak over the Iceland Sea and the development of a cold-air outbreak over the Greenland Sea. Repeated profiling revealed the immediate impact on the ocean, while a comprehensive hydrographic survey provided a rare picture of these subpolar seas in winter. A joint atmosphere–ocean approach is also being used in the analysis phase, with coupled observational analysis and coordinated numerical modeling activities underway.

Open access