2023
ANNUAL REPORTA T M O S P H E R I C

R A D I A T I O N

M E A S U R E M E N T

FROM THE
DIRECTOR
ARM Moves Forward on
Priorities With Facility’s
Mission in Mind
For more than 30 years, the Atmospheric
Radiation Measurement (ARM) user facility,
which is managed by the U.S. Department ofEnergy (DOE) Office of Science, has provided
freely available data and resources toscientists worldwide. Providing these services
effectively requires getting out in the fieldand engaging with the science community.
With COVID travel restrictions behind us, weare focused on connecting in person with
ARM users, establishing new partnerships,
and supporting fieldwork that might have
waited during the pandemic.
In this report, which focuses on activities infiscal year 2023 (FY2023), you will learn about
efforts across ARM to deliver meaningful data
to our users and to work with them to ensurethat we are meeting their needs.
In October 2022, we packed up an ARM
mobile observatory that had just completed
a yearlong deployment to study the effects ofatmospheric particles on storms around
Houston, Texas. It was a quick turnaround toprepare the observatory for a new field
campaign in La Jolla, California. This
campaign, called the Eastern Pacific Cloud
Aerosol Precipitation Experiment (EPCAPE), iscollecting a year’s worth of data on coastal
clouds until February 2024.

On the covers:
Front – From February 2023 to February 2024, the Ellen
Browning Scripps Memorial Pier in La Jolla, California,
is hosting ARM instruments for the Eastern Pacific Cloud
Aerosol Precipitation Experiment (EPCAPE).

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ARM ANNUAL REPORT | 2023

Inside – Snow builds up on and around the ARM
Mobile Facility operating as part of the Surface
Atmosphere Integrated Field Laboratory (SAIL)
campaign near Crested Butte, Colorado.

Meanwhile, scientists are digging into
the data from ARM’s Surface
Atmosphere Integrated Field
Laboratory (SAIL) campaign. SAIL
operations wrapped up in June 2023
after 21 months in Colorado’s East
River Watershed. ARM instruments
gathered data on atmosphericprocesses that influence mountainhydrology. Model development
efforts using observations from SAIL
and co-located campaigns are
already underway.
Tethered balloon system operations
continued at SAIL and the Southern
Great Plains (SGP) atmosphericobservatory in Oklahoma. The SGP
also hosted a series of three flight
missions for our ArcticShark
uncrewed aerial system. The last setof SGP flights featured the use of achase plane to track the ArcticSharkin the sky as it collected atmosphericmeasurements. Flying a chase plane
will allow us to expand ArcticShark
operations to other regions.
This report also includes updates on
our other two fixed-location
observatories: the North Slope of
Alaska, which has collected over 25
years of data; and the Eastern North
Atlantic, which celebrated its 10th
anniversary in the Azores in fall 2023.
While ARM staff were busy in thefield, we began to prepare for two
new mobile deployments
announced in FY2023. These
campaigns, which will both start incalendar year 2024, will study cloudand precipitation properties in
Tasmania and land-atmosphereinteractions around Baltimore,
Maryland. The Baltimore campaign
will support a DOE-funded laboratory
designed to study urban climatechange.
We are also gearing up to open our
newest atmospheric observatory, theBankhead National Forest (BNF) innorthern Alabama. This long-term
mobile observatory is expected tooperate for at least five years.
Scientists plan to use BNF data to
improve process understanding andmodel representations of aerosols,
clouds, and land-atmosphereinteractions.
Already, the BNF has helped us makenew connections with scientificcommunities within and outside DOE,
including underrepresented
institutions in science, technology,
engineering, and mathematics(STEM). We are excited about thepossibilities of these emerging
collaborations and what they could
do for BNF science.
Making up for lost in-person time
because of the pandemic, we held
two joint meetings in FY2023 with
scientists supported by DOE’s
Atmospheric System Research (ASR)
program. In this report, you will readabout some of the work presented atthese meetings.
We also took advantage of more
opportunities for science outreachthrough hybrid (in-person/virtual)
events. Staff traveled to conferences
and led short courses and workshops
to educate scientists on how to use
our data and capabilities. Several ofthese workshops included a focus onopen science and facilitating accessto ARM data.
ARM also continued to develop andupgrade science data products forvarious applications. Several data
products became available for SAIL
and ARM’s Houston-area campaign,
the TRacking Aerosol Convection
interactions ExpeRiment (TRACER).
Modeling products remained a focus
for ARM. While deep convection
data from ARM’s high-resolution
modeling activity moved to
production, ARM pushed ahead withplanning for future scenarios. One ofthose scenarios will focus on marine
clouds over the Eastern North
Atlantic observatory.

In FY2023, ARM made a great deal ofprogress on recommendations fromits 2020 Triennial Review and goals of
its Decadal Vision.
Throughout the year, ARM staff
engaged with earth system modelers
to learn how they are using ARM
data for model development andevaluation and to identify areas forpossible collaboration. Hopefullythese discussions go a long way
toward advancing ARM’s mission of
supplying data that will improve theunderstanding and modeling of
atmospheric processes.
Another key area of advancement
for ARM was delivering newcomputing resources to its users,
including the first phase of the ARM
Data Workbench, an interactive
environment that provides tools forworking with ARM data. With the firstphase of the workbench in place,scientists can use JupyterHub tocreate and reproduce complex
scientific workflows and share themwith others.
I hope you enjoy reading this reportand learning more about ARM’sactivities in FY2023.

JIM MATHERARM Director

TABLE OF CONTENTS

615FACILITY OVERVIEW

KEY ACCOMPLISHMENTS

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The World’s Premier GroundBased Observations Facility
to Advance AtmosphericResearch

Featured Field Campaigns

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ARM Observatories

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Cooperation andOversight Enable Success

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Collaborations

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Past Campaign Results

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Research Highlights

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ADVANCING CAPABILITIESFACILITY USAGE

33
Infrastructure Achievements

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New Data Products

41
Science OutreachOn December 4, 2022, in La Jolla, California, beachgoers takeadvantage of the weather and frolic in the Pacific Ocean while
ARM staff set up EPCAPE instruments on the Scripps Pier.

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FACILITY OVERVIEW
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ARM ANNUAL REPORT | 2023

The World’s Premier Ground-Based Observations Facility to Advance
Atmospheric ResearchThis report provides an overview of the Atmospheric Radiation Measurement (ARM) user facility and a sample ofachievements for fiscal year 2023 (FY2023).
ARM is a multi-laboratory, U.S. Department of Energy (DOE) Office of Science user facility and a key contributor tonational and international atmospheric and climate research efforts. ARM offers scientists cutting-edge, groundbased observatories, aerial observation capabilities, and high-performance computing. ARM’s capabilities haveenabled more than 30 years of continuous measurements of cloud and aerosol properties and their effects on
Earth’s energy balance.
Collected since 1992 in diverse climate regimes aroundthe world, ARM data are helping researchers answer
basic science questions about clouds, aerosols (small
particles in the air), cloud formation, and Earth’s energybalance.
ARM observations have yielded insights into a range ofscientific issues, including measuring absorption ofradiation (energy) from the sun by clouds, aerosols, andwater vapor; identifying factors that trigger cloudformation; and detailing the characteristics of aerosoland cloud properties, such as ice crystal sizes. ARM data
have led to greatly improved techniques for measuring
cloud properties from the ground.
In addition to advancing scientists’ understanding of how
the atmosphere works, ARM observations contribute toimproving the predictability of the earth system. ARM
observations are used to improve and evaluate therepresentations of clouds, aerosols, precipitation, andtheir interactions with Earth’s radiant energy in regionaland global-scale weather and earth system models.
Better models help our nation develop sustainable
solutions to energy and environmental challenges.

ARM was the first atmospheric research program to
deploy a comprehensive suite of ground-based,
cutting-edge instruments to continually measurecloud and aerosol properties and their effects on
Earth’s energy balance. This strategy revolutionizedscientists’ ability to collect long-term statistics ofdetailed cloud properties and now serves as a model
for similar programs around the world.

REFLECTEDRADIATION

INCOMING
SOLAR
RADIATION

Airborne
Instruments

OUTGOING
RADIATION
AEROSOL
INTERACTIONS

Surface
Instruments

Researchers use data collected from ARM ground-based andairborne instruments to study the natural phenomena that
occur in clouds and how those cloud conditions affectincoming and outgoing radiative energy.

Strong collaborations between nine DOE national laboratories enable ARM to successfully operate in remote locations
around the world. This unique partnership supports the DOE mission to provide for the energy security of the nation.
Without the support of the following laboratories, ARM would not be the state-of-the-art facility that it is today.

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A MEASUREMENT TREASURE TURNS 10
In fall 2023, ARM’s Eastern North Atlantic (ENA)
atmospheric observatory celebrated its 10-year anniversary ofoperations on Graciosa Island in the Azores.
Over the past decade, the ENA has collected the world’s
largest trove of continuous long-term atmospheric data in the
Earth’s marine midlatitudes.
Marine stratocumulus clouds are very sensitive to even small
atmospheric changes. In a climatically changing world,that adds urgency to improving models of the clouds that
predominate over oceans.
With the ENA in place, thanks to close collaboration with
the Regional Government of the Azores, the municipality ofGraciosa, and the University of the Azores/Fundação Gaspar
Frutuoso, “we can study (marine clouds) in great detail,” said
ARM user Mark Miller of Rutgers University. “In the last 10
years, I have learned more about stratocumulus in that regionand other regions than I had in all the 20 years before that.”

Researchers are also using ENA measurements to study
precipitation, turbulence, and aerosols. ENA instruments
have captured data on wildfire particles traveling from North
America over the Atlantic.
Machine learning and advanced computing capabilities areenabling different kinds of work with ENA data. Machinelearning helped scientists correct how global models represent
warm rain in marine cloud decks and detect small particles
that mark the early stages of drizzle’s life cycle. Meanwhile,
supercomputing allowed researchers to simulate how
clouds organize into heavily drizzling clusters called marine
boundary-layer convective complexes.
ARM’s publication database includes more than 130 papers
featuring ENA data, including 17 published in FY2023.

ARM’s Eastern North Atlantic atmospheric observatory has provided detailed information about marine clouds since beginning
operations in 2013.

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ARM Observatories
ARM operates three heavily instrumented fixedlocation atmospheric observatories, three mobile
facilities, and an aerial facility, and provides freely
available data for use by scientists around theworld. The sites of the fixed-location, long-term
observatories were chosen to represent a broad
range of atmospheric conditions and processes:
 Southern Great Plains (SGP) – Established in
1992, the first ARM observatory includes aheavily instrumented Central Facility near
Lamont, Oklahoma, and smaller satellite
facilities in Oklahoma and Kansas.
 North Slope of Alaska (NSA) – Since 1997, ARM
has operated a site at Utqiaġvik (formerly
Barrow) near the Arctic Ocean.
 Eastern North Atlantic (ENA) – In operation
since 2013, ARM’s youngest fixed observatory
is located on Graciosa Island in the Azores, anarea characterized by a wide variety of
meteorological conditions and cloud types,
including marine stratocumulus.

Each fixed or mobile observatory operates abroad suite of advanced measurement systems
to provide high-quality research data sets. The
current generation of instruments includes threedimensional cloud and precipitation radars,
advanced lidars that provide information such as
profiles of aerosol extinction and vertical air
motion, infrared interferometers that measureradiant energy from the atmosphere, in situ
aerosol observing systems, microwave
radiometers, and balloon-borne sounding
systems, among others.
Once collected, the data from all ARM
observatories are carefully reviewed for quality
and stored in the ARM Data Center for use by theatmospheric science community. As part of thiseffort, ARM personnel apply scientific methods
developed in the research community to create
enhanced value-added data products. All ARM
data products are made available at no cost forthe scientific community through the ARM Data
Center to aid in further research.

Measurements obtained at the fixed atmosphericobservatories are supplemented with dataobtained from intensive field campaigns
proposed by the scientific research community.
Campaigns may use an ARM Mobile Facility(AMF), a collection of advanced measurement
systems that can be deployed to locations
around the world for six months to two years, orcapabilities of the ARM Aerial Facility (AAF).

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This view overlooks the U.S. Forest Service’s Black Warrior Work Center in northwestern Alabama near the future home of ARM’s
Bankhead National Forest atmospheric observatory. The “Black Warrior” name is commonly seen in Alabama to recognize a
16th-century Native American chief.

NEW ALABAMA OBSERVATORY MOVES TOWARD OPERATIONS
ARM met a crucial February 2023 deadline to prepare land
for what will become the core of its Bankhead National
Forest (BNF) atmospheric observatory in northwestern
Alabama.
Most of the ARM Mobile Facility instruments will operate
in a 300-by-300-foot clearing immediately south of the U.S.
Forest Service’s Black Warrior Work Center (BWWC). The
Forest Service uses the BWWC for regular maintenanceactivities. ARM will have an office just north of the BWWC.
In addition, a 140-foot instrument tower will be located in
mixed pine-oak forest three-quarters of a mile west of the
BWWC. This area is representative of the larger Bankhead
and forests in the Southeastern United States.
ARM anticipates three installation phases for the expectedfive-year deployment.

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As ARM primed the BNF’s main site for construction,
staff at ARM’s Southern Great Plains observatory prepared
instruments and containers for the new deployment. It was
the first time ARM used its Oklahoma observatory to stage
and prepare a mobile facility.
Meanwhile, the BNF site science team, supported by ARM
and DOE’s Atmospheric System Research (ASR) program,
published its science plan for the new observatory. The
team aims to improve process understanding and model
representations of aerosols, clouds, and land-atmosphereinteractions, as well as coupled surface-atmosphere feedbacks
and aerosol-cloud interactions.
Like all ARM sites, the BNF will be open to scientists topropose guest instrument deployments and to use the data intheir own research projects and proposals. For example, ASR
has funded an initial set of science projects using BNF data.

Cooperation and OversightEnable Success
Nine DOE national laboratories and numerous
government agencies, universities, privatecompanies, and foreign organizations contributeto ARM. Each entity serves a vital role inmanaging and conducting the operation andadministration of the user facility. These entities
include: DOE’s Biological and Environmental Research
program in the Office of Science – Program
managers provide oversight andaccountability for ARM operations.
 Infrastructure Management Board (IMB)– DOE works with the IMB, whose members
represent all areas of the facility, tocoordinate and manage the scientific,
operational, data, financial, andadministrative functions of ARM.
 ARM Science Board – An independent review
body that reviews proposals for the ARM
Mobile Facility and ARM Aerial Facility toensure appropriate scientific use. The DOE
ARM program manager selects the board
members.
 Atmospheric System Research (ASR) – A
DOE-funded, observation-based atmosphericresearch program that represents the largest
group of ARM users. ASR is an importantsource of scientific guidance for establishing
ARM priorities.
 ARM User Executive Committee – An elected
constituent group that provides feedback on
the facility’s activities and serves as theofficial voice of the user community in its
interactions with ARM management.

ARM BROADENS OUTREACH TO
MODELING COMMUNITY
In response to recommendations from its 2020
Triennial Review, ARM is working to develop metrics
that better illustrate its impact on earth system model
improvements. Staff are also engaging with modelers
to learn how ARM data are being used for model
development and evaluation.
To help with its metrics, ARM reviewed the process for
tagging publications that are entered into its publications
database. Metadata tags now include different modeling
identifiers, such as earth system models, single-column
models, and cloud-resolving models. New publications
are assessed as they are entered online, and assessment ofhistorical publications is underway.
Meanwhile, ARM staff are dedicating additional effort
to modeling community outreach to identify areas inwhich ARM can further collaborate and expand its
resources for model development and evaluation. A
natural starting point for this effort is DOE’s highresolution Energy Exascale Earth System Model (E3SM)
project.
In April 2023, ARM Modeling Translator Shaocheng
Xie and ARM Associate Director for Research Jennifer
Comstock met with E3SM developers Peter Caldwell
and Peter Bogenschutz. The group identified several
cloud regimes and ARM field campaigns of interest as
important for evaluating the Simple Cloud-Resolving
E3SM Atmosphere Model (SCREAM) and its doubly
periodic configuration (DP-SCREAM).
ARM will keep working with the E3SM evaluation team
to identify specific ARM data sets and time periods ofinterest to focus future development efforts.
ARM also continues to engage with its constituent
groups, including the User Executive Committee, which
has a subgroup focused on enhancing communication
with the modeling community, including E3SM.

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ARM/ASR COMMUNITY COMES
TOGETHER FOR PAIR OF JOINTMEETINGSFY2023 saw not one but two annual meetings of the ARM/
Atmospheric System Research (ASR) community. ARM
users, ARM infrastructure staff, and ASR scientists gatheredin Rockville, Maryland, and online for hybrid joint meetings
in October 2022 and August 2023.
The Joint ARM User Facility/ASR Principal Investigators
Meeting is a venue to review progress and discuss scientificpriorities for ARM and ASR.
Participants expressed enthusiasm about meeting in person
after COVID restrictions prevented travel in 2020 and
2021. The 2022 meeting drew 431 attendees, while the 2023
edition had 421. At both meetings, most attended in person.
Both meetings began with plenary sessions, which included
programmatic updates, science talks, presentations on
diversity in the research community, and announcements of
new ARM deployments.

USER EXECUTIVE COMMITTEE BUILDSON PAST ACCOMPLISHMENTS
FY2023 brought a new election for ARM’s User Executive
Committee (UEC), a constituent group that represents
facility users in interactions with ARM management.
After a record 359 voters cast virtual ballots in the fall 2022
election, eight new members joined the UEC in January
2023. All are eligible to serve four-year terms.
Jennifer Delamere of the University of Alaska Fairbanks
succeeded Allison Aiken of Los Alamos National Laboratory
in New Mexico as the UEC chair. In 2021, the UEC
elected Delamere as vice-chair, meaning that she would
automatically ascend to chair once Aiken’s term ended.
Aiken, the fourth UEC chair overall and first woman tohold the position, was instrumental in setting up four UEC
subgroups to address important topics within the ARM
community:
 Enhancing Communication with the Satellite
Community

At the 2022 meeting, DOE ARM Program Manager Sally
McFarlane shared that ARM would conduct a 2024–2025
campaign in Tasmania to collect data on Southern Ocean
cloud and precipitation properties.

 Enhancing Communication with the Modeling/
DOE Energy Exascale Earth System Model (E3SM)
Community

During the 2023 meeting, McFarlane revealed that ARM
would go to Baltimore, Maryland, in late 2024 to supporta yearlong campaign aimed at understanding how different
surface-atmosphere interactions around a city influence its
climate.

 Undergraduate Engagement with a Focus on Diversity.

The meetings also featured a wide array of poster andbreakout sessions. Participants pored over ARM campaign
data and findings, planned for future deployments, anddiscussed community measurement needs.
New in 2023 was a three-part set of breakout sessions
focused on open science for ARM and ASR. The sessions
dovetailed with the federal government’s Year of OpenScience initiative.

 Measurement Uncertainty and Communicating
Calibrations
Comprising four to six members each, these subgroups
yielded an array of recommendations and accomplishments.
Highlights included fostering new interactions between thesatellite community and ARM as well as engaging a diversity,
equity, and inclusion speaker, Emily Fischer, for the 2022
Joint ARM User Facility/Atmospheric System Research(ASR) Principal Investigators Meeting.
Under Delamere’s leadership, the UEC has continued
with the subgroups established when Aiken was chair. The
group also hosted a diversity, equity, and inclusion speaker,
Solomon Bililign, during the 2023 ARM/ASR joint meeting.

A crowd gathers during a poster session at the 2023 Joint ARM User
Facility/ASR Principal Investigators Meeting in Rockville, Maryland.

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ARM ANNUAL REPORT | 2023

Collaborations
By its very nature, ARM is a collaborative entity. As anational scientific user facility, ARM was designed toprovide scientists with atmospheric observations
needed to conduct their research. While ARM works
closely with the Atmospheric System Research (ASR)
program to meet the objectives of DOE’s Earth andEnvironmental Systems Sciences Division, ARM also
supports research by scientists with diverse
programmatic and institutional affiliations around theUnited States—and the world.

In addition, ARM frequently leverages measurements
obtained by other organizations to provide a more
complete description of the environment around its
observatories and regularly coordinates with otheragencies on field campaigns. Though each agency
has its own goals and priorities, the coordination ofobservational activities produces morecomprehensive data and leads to broader science
outcomes. These collaborations are key to ARM’ssuccess.

SCIENCE WORKSHOP OUTLINES A TRACER FUTURE
In May 2023, a team of scientists met in Houston, Texas,
and online for a two-day science workshop focused on the
TRacking Aerosol Convection interactions ExpeRiment(TRACER).
The TRACER campaign was a multi-agency investigation ofstorm evolution near Houston from September 2021 throughOctober 2022.
While ARM provided the core instruments, 150 participantsfrom 45 institutions collected measurements during
TRACER. Researchers funded by DOE’s Atmospheric
System Research (ASR) program deployed their own
instruments for smaller related campaigns.
Other agency partners included NOAA, the National
Science Foundation, NASA, and the Texas Commission on
Environmental Quality.

An upcoming TRACER project will build upon previous
work comparing the representation of aerosol-convection
interactions in seven cloud-resolving models.
A recurrent theme was the combined power of satellite,
surface, and aircraft observations. TRACER has produced
the largest database so far on ground-based observations ofisolated convective cells.
The workshop also showcased the contributions of early
career scientists during TRACER, including data collection
and weather forecasting. Many of the scientists are now
working on data analysis and modeling efforts.
“The experience gained gives them the foundation tosomeday lead the next big field campaign,” said Jensen.

Texas Southern University was the host site of the science
workshop. TRACER Principal Investigator Michael Jensenof Brookhaven National Laboratory in New York convened
the workshop for scientists to share data, preliminary results,
collaborations, and future research plans.
One key early finding was a strong seasonal signal in theobserved aerosol concentrations. Summer air was cleaner
than in other seasons.

ARM operated the main TRACER site from October 2021
through September 2022 in La Porte, Texas.

ARM ANNUAL REPORT | 2023

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ARM-EMSL USER FACILITY RESEARCH PARTNERSHIP GROWS STRONGER
ARM and the Environmental Molecular Sciences Laboratory(EMSL) continued to enable impactful science together in
FY2023.
The two DOE Office of Science user facilities co-hosted avirtual workshop to hear from DOE’s Atmospheric System
Research (ASR) and Environmental System Science (ESS)
program communities on how to improve understanding of
coupled land-atmosphere processes.
Then, for a third consecutive year, ARM and EMSL called
for joint research proposals through the Facilities Integrating
Collaborations for User Science (FICUS) program. FICUS
support enables researchers to capture aerosols during
ARM tethered balloon system (TBS) flights and analyze
the samples using advanced techniques at EMSL. FICUS
awardees can also analyze samples from past TBS missions orfrom missions already planned for a specific FY.

In FY2023, two EMSL-developed aerosol collectors operated
during TBS flights at ARM’s Southern Great Plainsatmospheric observatory. The collectors also flew during
the Surface Atmosphere Integrated Field Laboratory (SAIL)
campaign in Colorado.
Four new ARM/EMSL FICUS projects took place in
FY2023. Allison Aiken and Maria Zawadowicz eachexamined the vertical profiles of aerosols sampled during
SAIL. Meanwhile, Allen Goldstein researched aerosolcloud interactions and aerosol processes, and Allison Steiner
investigated vertical gradients of biological aerosols collectedduring the TRacking Aerosol Convection interactions
ExpeRiment (TRACER) in Texas.
Since the first ARM/EMSL call was announced in January
2021, eight projects have been selected for FICUS support.

Two new projects were chosen to start in FY2024. Rajan
Chakrabarty and Haofei Zhang will use ARM and EMSL
capabilities to study land-atmosphere processes and aerosolcloud interactions.

Researchers are using EMSL capabilities to study aerosol samples collected on tethered
balloon system flights in Guy, Texas, during ARM’s TRACER campaign.

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KEY ACCOMPLISHMENTS
ARM ANNUAL REPORT | 2023

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Featured Field Campaigns
In addition to providing continuous datacollections from fixed observatories
around the world, ARM sponsors field
campaigns for scientists to obtainspecific data sets or to test and validate
instruments. The following pages
highlight key campaigns in FY2023.

California Campaign Zeroes In on Coastal
Cloud Properties
Stratocumulus clouds cover about one-fifth of the
Earth’s surface, with most occurring over oceans,and create a net cooling effect globally. Suchclouds are a focus of ARM’s yearlong Eastern
Pacific Cloud Aerosol Precipitation Experiment(EPCAPE), which began in February 2023 in La
Jolla, California.
EPCAPE’s principal investigator is Lynn Russell from
Scripps Institution of Oceanography at the
University of California San Diego.
Coastal stratocumulus clouds around La Jolla are
influenced by a range of aerosols, including
particles coming down from ports in the Los
Angeles/Long Beach area.

As part of a project jointly funded by ASR and the
Office of Naval Research, scientists flew around the
EPCAPE study region on a Twin Otter research aircraft.
During the flights, researchers observed cloudformation, pollution dynamics, and environmental
interactions over land and water.
EPCAPE instruments also had a unique view of
Tropical Storm Hilary in August 2023. Hilary was thefirst tropical storm to hit Southern California since
1939.
Russell hopes EPCAPE will combine ARM’scomprehensive view of coastal stratocumulus clouds
with a precise chemical characterization of aerosoland cloud droplets affected by urban pollution.

EPCAPE researchers are studying how cloudlayers form and how related processes areaffected by human-made particles.
The campaign held intensive operational periodsin spring and summer 2023. The intensive periods
focused on observations of cloud chemistry andradiation, which could improve model simulationsof coastal clouds.
EPCAPE collaborations include projects
supported by DOE’s Atmospheric System
Research (ASR) program to collect airborne andsurface data on aerosols.

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ARM ANNUAL REPORT | 2023

EPCAPE Principal Investigator Lynn Russell speaks with ajournalist during a media day to help kick off the yearlong
campaign in La Jolla, California.

Mountain Hydrology Investigation in Colorado
Enters New Phase
Researchers are busy with next steps following theobservational phase of the Surface Atmosphere
Integrated Field Laboratory (SAIL) campaign.
ARM packed up SAIL instruments in June 2023 after
operating for 21 months near Crested Butte,Colorado. The instruments collected data on
atmospheric processes that influence the water cyclein the Upper Colorado River Basin. Scientists are now
focused on data analysis and modeling activities.
“SAIL created the foremost data set for mountainhydrology in North America―and perhaps beyond,”
said SAIL Principal Investigator Daniel Feldman of
Lawrence Berkeley National Laboratory in California.
The data and models from SAIL will help scientists
prepare for an uncertain future. Currently, two-thirdsof Earth’s freshwater originates in mountain ranges.
Warming mountains could mean less snowmelt,
shrinking water downstream.

SAIL so far has produced more than 100 data sets,
which are freely available from ARM. Representing “agiant set of puzzle pieces,” said Feldman, the data
sets “will advance predictive understanding of water
resources in the future.”
Modeling experts are already using the traditional
Weather Research and Forecasting model to place
SAIL data in context.
Feldman led a multi-institutional team in writing an
overview paper of SAIL. The Bulletin of the American
Meteorological Society (BAMS) published the paper
online in July 2023.
To help kick off new research collaborations, Feldman
co-organized a “science summit” for SAIL andco-located campaigns in November 2023. Scientists
are also planning to present SAIL findings at
upcoming scientific conferences. The work inprogress should produce “a burst of understanding,”
said Feldman.

Allison Aiken, a SAIL co-investigator, visits a set of instruments on Crested Butte Mountain.

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NEW STUDY TO EXPLORE
SOUTHERN OCEAN CLOUDS
AND PRECIPITATIONPLANNING BEGINS FOR URBAN
CAMPAIGN IN MID-ATLANTICUNITED STATESGlobal climate projections are sensitive to aerosolcloud-precipitation interactions in the atmosphere over
the Southern Ocean. Seasonal variations in Southern
Ocean aerosol properties are well documented, but toimprove the accuracy of climate models, scientists needmore information about the properties of low clouds andprecipitation in the region.

An upcoming ARM campaign, announced in August
2023, will study surface-atmosphere interactions around
Baltimore, Maryland, to see how they influence the city’s
climate.

ARM spent much of FY2023 preparing for a new
campaign that will fill in knowledge gaps about
the seasonal cycle of clouds and precipitation over
the Southern Ocean. The Cloud And Precipitation
Experiment at kennaook (CAPE-k) will take placefrom April 2024 to September 2025 in northwestern
Tasmania.
ARM’s CAPE-k instruments will operate at the
Kennaook/Cape Grim Baseline Air Pollution
Station. The Australian Bureau of Meteorology andCommonwealth Scientific and Industrial Research
Organisation jointly manage the station, which has
measured atmospheric composition since 1976.
Gerald “Jay” Mace of the University of Utah and Roger
Marchand of the University of Washington, principal
investigators for past ARM campaigns, will co-lead
CAPE-k.

The Kennaook/Cape Grim Baseline Air Pollution Station in
Tasmania will host ARM’s CAPE-k campaign.

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Ken Davis of Pennsylvania State University will leadthe yearlong Coast-Urban-Rural Atmospheric GradientExperiment (CoURAGE), which is expected to start inlate 2024.
DOE selected CoURAGE from a fall 2022 call seeking
proposals for ARM campaigns that would support the
DOE Biological and Environmental Research program’sinterest in urban climate systems.
CoURAGE data will complement measurements fromthe Baltimore Social-Environmental Collaborative(BSEC), one of four DOE Urban Integrated Field
Laboratories that will operate in U.S. cities to explore
urban climate change.
While BSEC collects long-term data on the urban
atmosphere and land-atmosphere interactions,
CoURAGE will provide additional coverage in theregion. ARM plans to set up a mobile observatory inBaltimore and two smaller sites outside the city.

Baltimore, Maryland, will be the focus of a new ARM urban
climate science campaign starting in 2024.

Past Campaign Results
Unique Antarctic Data Provide Snapshots of Changing Region
Researchers are watching ice in Antarctica with greatinterest—and concern. Between 1979 and 2017, thecontinent’s total ice loss reportedly grew sixfold. If theWest Antarctic Ice Sheet (WAIS) were to melt
completely, current projections indicate that the
global mean sea level would rise by 17 feet.
To gain a better understanding of how the region is
evolving, scientists need more observational data
than are usually possible to collect there. This is why
they are thankful to have 14 months of data from the2015–2017 ARM West Antarctic Radiation Experiment(AWARE).
Led by Dan Lubin from Scripps Institution of
Oceanography at the University of California San
Diego, AWARE was a joint campaign between DOE
and the U.S. Antarctic Program.
Lubin is quick to praise the work being done atinternational research stations in Antarctica. The
continent is more cold, arid, and windy thananywhere else on Earth, which can make it difficult tocollect atmospheric data. But if you were to sum up
the stations’ instruments, said Lubin, “All of themwould not equal one AWARE, (which) provided a
combination of instruments that was very unique.”
ARM deployed a mobile observatory at a coastal site
less than a mile from McMurdo Station. In addition, forabout six weeks, ARM operated a secondary site
about 1,000 miles to the northwest, at the WAIS Divide
Ice Camp. AWARE marked the first time since 1967
that significant atmospheric measurements weremade in West Antarctica.
As of late September 2023, AWARE data appeared in
43 journal articles. The newest study describedenergy-balance measurements from miniaturizedversions of AWARE instruments on Siple Dome, a
60-square-mile ice cap (Lubin et al. 2023). Other
recent AWARE studies have a similar theme: that a
new generation of simple, inexpensive, and robust

automated instruments can help overcome
Antarctica’s harsh environment.
Also notable: Two interconnecting studies
investigated blowing snow, which distributes aerosols
and affects ice-mass balance, thermodynamics, andatmospheric radiative properties (Loeb and Kennedy
2021, 2023). Another paper outlined the main
mechanisms of ice melt in West Antarctica, including
warm downslope winds that can raise ambient
temperatures in a matter of hours (Ghiz et al. 2021).
In the modeling arena, AWARE data informed aninvestigation of cold-cloud drizzle, which is more
persistent in antarctic environments than previously
thought (Silber et al. 2019).
AWARE data could soon pair with measurements fromother ARM campaigns, such as the 2023─2024
Eastern Pacific Cloud Aerosol Precipitation
Experiment (EPCAPE) in Southern California. Data
from EPCAPE and AWARE include measurements atcoastal sites affected by clouds. Lubin is a
co-investigator for EPCAPE.
In northwestern Tasmania, the 2024–2025 Cloud And
Precipitation Experiment at kennaook (CAPE-k) could
collect data that complement what AWARE gatheredon the opposite side of the Southern Ocean.

McMurdo Sound sea ice melts in West Antarctica, where
ARM instruments captured rare data during the 2015–2017
AWARE campaign.

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References
Ghiz, M, R Scott, A Vogelmann, J Lenaerts, M Lazzara, and D
Lubin. 2021. “Energetics of surface melt in West Antarctica.” The
Cryosphere 15(7):3459-3494, https://doi.org/10.5194/tc-15-3459-2021.
Loeb, N, and A Kennedy. 2021. “Blowing Snow at McMurdo
Station, Antarctica during the AWARE Field Campaign: Surface
and Ceilometer Observations.” Journal of GeophysicalResearch: Atmospheres 126(7):e2020JD033935, https://doi.
org/10.1029/2020JD033935.

This AWARE site, which operated for about six weeks on theWest Antarctic Ice Sheet, gathered data early in Antarctica’s
summer of 2015–2016.

Loeb, N, and A Kennedy. 2023. “Blowing Snow at McMurdo
Station, Antarctica During the AWARE Field Campaign: MultiInstrument Observations of Blowing Snow.” Journal of GeophysicalResearch: Atmospheres 128(2):e2022JD037590, https://doi.
org/10.1029/2022JD037590.
Lubin, D, M Ghiz, S Castillo, R Scott, S LeBlanc, and I Silber. 2023.
“A Surface Radiation Balance Dataset from Siple Dome in West
Antarctica for Atmospheric and Climate Model Evaluation.”
Journal of Climate 36(19):6729-6748, https://doi.org/10.1175/
JCLI-D-22-0731.1.
Silber, I, A Fridlind, J Verlinde, A Ackerman, Y Chen, D Bromwich, S
Wang, M Cadeddu, and E Eloranta. 2019. “Persistent Supercooled
Drizzle at Temperatures below -25°C Observed at McMurdo Station,
Antarctica.” Journal of Geophysical Research: Atmospheres
124(20):10878-10895, https://doi.org/10.1029/2019JD030882.

A Decade Later, Amazon Campaign
Continues to Have Immense Impact
The Amazon rainforest is the closest modern
observations can get to capturing land as it was inpreindustrial times. The vast sea of trees has incrediblypristine areas found nowhere else in the world.
For researchers trying to study how human activities
have affected the atmosphere, the Amazon
represents a critical area where they can acquire
data on unpolluted air.

However, the Amazon is not fully isolated. The Green
Ocean Amazon (GoAmazon2014/15) field campaign,
led by Scot Martin of Harvard University, gathereddata in an area of the Amazon near the city of
Manaus for two years.
“The length of the GoAmazon campaign was criticalfor its impact,” said co-investigator Courtney
Schumacher of Texas A&M University. “Because thedata spans multiple years, we’ve been able to study
both seasonal and annual variability in atmosphericprocesses.”

ARM deployed this mobile observatory downwind of Manaus, Brazil, for the GoAmazon2014/15 campaign.

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Manaus produces a plume of pollution that acts as
the sole source of human-driven emissions for muchof the surrounding forest. The study location in
GoAmazon allowed the measurements to capture
both the undisturbed natural environment and theinfluence of a large urban center.
Through the data, researchers can explore
interactions between human-created aerosols andthe pristine forest background. Much of the datacollected from GoAmazon have provided insight into
how aerosols influence processes in the atmosphere.

GoAmazon’s impact continues to reverberate
throughout the scientific community, producing themost papers of any ARM campaign thus far. Since
2015, over 160 papers have been published using
campaign data. More than 20 of those papers were
published in 2023 alone. Some of this recently
published work uses the data to enhance modeling,either through high-level validation or by integrating
the data into simulations to understand the weather
and climate.

Scientists used GoAmazon data to show that urban
emissions greatly enhance natural aerosol processes,
leading to the formation of more secondary aerosols(Shrivastava et al. 2019). Another study identified how
the high concentrations of aerosol particles affectthe formation of storms and precipitation (Fan et al.
2018).
GoAmazon data also revealed that Amazonian forest
isoprene emissions could be as much as three times
higher than reported by satellite observations (Gu etal. 2017).
ARM, which deployed a mobile observatory and its
now-retired Gulfstream-159 (G-1) research aircraft, did
not accomplish GoAmazon alone. German scientists
added more aircraft resources, and Brazilian
researchers brought additional radar and aerosol
instrumentation as well as local knowledge (Martin etal. 2016).

Manaus is a city of about 2 million people in the central
Amazon. Pollution from Manaus travels into the surrounding
rainforest.

References
Fan, J, D Rosenfeld, Y Zhang, S Giangrande, Z Li, L Machado, S Martin, Y Yang, J Wang, P Artaxo, H Barbosa, R Braga, J Comstock, Z Feng, W Gao,
H Gomes, F Mei, C Pöhlker, M Pöhlker, U Pöschl, and R de Souza. 2018. “Substantial convection and precipitation enhancements by ultrafine
aerosol particles.” Science 359(6374):411-418, https://doi.org/10.1126/science.aan8461.
Gu, D, A Guenther, J Shilling, H Yu, M Huang, C Zhao, Q Yang, S Martin, P Artaxo, S Kim, R Seco, T Stavrakou, KM Longo, J Tóta, R de Souza, O
Vega, Y Liu, M Shrivastava, E Alves, F Santos, G Leng, and Z Hu. 2017. “Airborne observations reveal elevational gradient in tropical forest isopreneemissions.” Nature Communications 8:15541, https://doi.org/10.1038/ncomms15541.
Martin, ST, P Artaxo, L Machado, AO Manzi, RA Souza, C Schumacher, J Wang, T Biscaro, J Brito, A Calheiros, K Jardine, A Medeiros, B Portela,
SS de Sá, K Adachi, AC Aiken, R Albrecht, L Alexander, MO Andreae, HM Barbosa, P Buseck, D Chand, JM Comstock, DA Day, M Dubey, J Fan, J
Fast, G Fisch, E Fortner, S Giangrande, M Gilles, AH Goldstein, A Guenther, J Hubbe, M Jensen, JL Jimenez, FN 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, JE Shilling, MA Silva Dias,
JN Smith, JM Tomlinson, J Tóta, and M Wendisch. 2016. “The Green Ocean Amazon Experiment (GoAmazon2014/5) Observes Pollution Affecting
Gases, Aerosols, Clouds, and Rainfall over the Rain Forest.” Bulletin of the American Meteorological Society 98(5):981-997, https://doi.org/10.1175/
bams-d-15-00221.1.
Shrivastava, M, M Andreae, P Artaxo, H Barbosa, L Berg, J Brito, J Ching, R Easter, J Fan, J Fast, Z Feng, J Fuentes, M Glasius, A Goldstein, E Alves,
H Gomes, D Gu, A Guenther, S Jathar, S Kim, Y Liu, S Lou, S Martin, V McNeill, A Medeiros, S de Sá, J Shilling, S Springston, R Souza, J Thornton, G
Isaacman-VanWertz, L Yee, R Ynoue, R Zaveri, A Zelenyuk, and C Zhao. 2019. “Urban pollution greatly enhances formation of natural aerosols
over the Amazon rainforest.” Nature Communications 10:1046, https://doi.org/10.1038/s41467-019-08909-4.

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NORWEGIAN CAMPAIGN GRACES BAMS COVER
The May 2023 cover of the Bulletin of the American Meteorological Society(BAMS) featured an ARM mobile observatory operating in Nordmela,
Norway, during the Cold-Air Outbreaks in the Marine Boundary Layer
Experiment (COMBLE). David Oaks, COMBLE’s lead technician, took thephoto in May 2020.
The BAMS issue included key messages from a COMBLE overview paper
published online in May 2022.
Scientists are using data from the 2019–2020 campaign to evaluate andimprove the representation of mixed-phase clouds and boundary-layer
processes in numerical weather prediction models.
“COMBLE has stimulated further interest in the CAO (cold-air outbreak)cloud regime … a key component of the arctic amplification puzzle,” said
the campaign’s principal investigator, Bart Geerts of the University of
Wyoming.
Geerts added that several recent and upcoming international airborne field
campaigns in the far North Atlantic were “all inspired by COMBLE’s
pivotal measurements.”

The May 2023 BAMS print cover features a2020 photo of an ARM mobile observatory
in Nordmela, a fishing village on the
Norwegian island of Andøya, during theCOMBLE campaign.

Reference
Geerts, B, S Giangrande, G McFarquhar, L Xue, S Abel, J Comstock, S Crewell, P DeMott, K Ebell, P Field, T Hill, A Hunzinger, M Jensen, K
Johnson, T Juliano, P Kollias, B Kosovic, C Lackner, E Luke, C Lüpkes, A Matthews, R Neggers, M Ovchinnikov, H Powers, M Shupe, T Spengler, B
Swanson, M Tjernström, A Theisen, N Wales, Y Wang, M Wendisch, and P Wu. 2022. “The COMBLE campaign: a study of marine boundary-layer
clouds in Arctic cold-air outbreaks.” Bulletin of the American Meteorological Society 103(5):E1371-E1389, https://doi.org/10.1175/BAMS-D-21-0044.1.

ARCTIC CIRCLE PRIZE RECOGNIZESMASSIVE POLAR EXPEDITION
The Alfred Wegener Institute (AWI) and theMultidisciplinary Drifting Observatory for the Studyof Arctic Climate (MOSAiC) expedition won the 2022
Arctic Circle Prize for their extraordinary contributions
toward securing a sustainable and prosperous future in
the Arctic.

DOE and ARM were among the expedition’s earliest
supporters. ARM provided more than 50 atmosphericinstruments, which helped researchers identify and quantify
cloud, aerosol, weather, and other conditions during MOSAiC.
ARM is proud of its contribution to MOSAiC and its effort toexpand scientific understanding of the Arctic.

AWI Director Antje Boetius and expedition leader
Markus Rex accepted the prize during the October 2022
Arctic Circle Assembly in Reykjavik, Iceland.
MOSAiC is the largest-ever polar expedition. A German
research icebreaker embarked from Norway in September
2019. International teams of scientists, engineers, andtechnicians studied climate systems from the vessel as it
drifted, ice-locked, through the Arctic Ocean for a year.

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In December 2019, MOSAiC personnel set up a tower on ice
with the research icebreaker R/V Polarstern in the distance.

Research Highlights
Southern Ocean Data Useful in Tackling CloudModeling Issues
The Southern Ocean covers a vast region surrounding
Antarctica and is quite cloudy. The response of clouds
to a globally warming climate remains one of thelargest uncertainties in climate prediction. Becauseof the area’s relevance to climate change, it has
been the subject of significant modeling efforts.
Typically, climate models produce fewer clouds over
the Southern Ocean than reality. This has been
attributed to a bias in how they represent clouds,
such as simulating too many ice crystals in clouds andshorter cloud life cycles. A lack of low clouds means
too much solar radiation absorbed by the ocean anda warm bias at the surface. Identifying specific issues
in the model requires developing detailed
comparisons between observations and model
output.
Other than satellite data, few local measurements
exist. To help fill that need, ARM conducted the
Measurements of Aerosols, Radiation, and Clouds
over the Southern Ocean (MARCUS) field campaign
in 2017 and 2018.

This schematic shows the proposed mechanisms of enhanced
ice concentrations in the clouds observed over the Southern
Ocean during ARM’s MARCUS campaign. (a) Primary ice
production occurs near the cloud top, which seeds the lower
levels of the cloud, enhancing ice growth. (b) The process in (a)is modified by rime splintering, which leads to more but smaller
ice crystals. (Copyrighted image from the journal.)

Two May 2023 papers used MARCUS data to explore
shallow clouds over the region. The first paper
focused on analyzing observational data, while thesecond was modeling-based. Both paid special
attention to ice formation processes.
The scientists found that the shallow clouds observedby remote sensors aboard a supply vessel during
MARCUS contain substantial amounts of liquid. Theirstudy focused on shallow clouds in the cold sector of
weather systems over the Southern Ocean because
previous work showed that the model bias is largest
there. In the cold sector, the clouds are generally
above the freezing level and contain supercooled
liquid, but scientists also found that two-thirds of theclouds in the zero C to minus 5 C layer (32 F down to23 F) contain ice.
“The observed ice concentrations at relatively warm
temperatures are perplexing given the pristine natureof the Southern Ocean, which greatly limits theavailability of ice-nucleating particles,” said the
University of Oklahoma’s Zach Lebo, who
co-authored both papers. “Our model simulations
were unable to capture these observed occurrencesof ice. Through sensitivity analysis, we identified
potential mechanisms by which relatively high ice
concentrations could occur in such a pristine
environment.”

Shallow clouds over the Southern Ocean play an importantrole in reflecting sunlight and affecting the climate. Here, ARM
instruments operate aboard the Aurora Australis supply vessel
during MARCUS.

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Results from the modeling study showed that the standard simulation approach underestimates the amount of ice
and overestimates the amount of supercooled liquid in the clouds. The researchers found that ice production in themodel could be significantly improved by altering the representation and thresholds for several ice-related
processes.

References
Hu, Y, B Geerts, M Deng, C Grasmick, Y Wang, C Lackner, Y Hu, Z Lebo, and D Zhang. 2023. “Vertical structure and ice production processes ofshallow convective postfrontal clouds over the Southern Ocean in MARCUS. Part I: Observational study.” Journal of the Atmospheric Sciences80(5):1285-1306, https://doi.org/10.1175/JAS-D-21-0243.1.
Hu, Y, Z Lebo, B Geerts, Y Wang, and Y Hu. 2023. “Vertical structure and ice production processes of shallow convective postfrontal clouds
over the Southern Ocean in MARCUS. Part II: Modeling study.” Journal of the Atmospheric Sciences 80(5):1307-1327, https://doi.org/10.1175/
JAS-D-21-0272.1.

Scientists Identify Conditions That Promote Deep Cloud Growth
Puffy cumulus clouds require warm, humid, and unstable weather conditions to grow into thunderstorms. However,storms often do not form despite supposedly favorable conditions.

Composited radiosonde profiles of meteorological conditions from nearly 200 convective events show significantly moister near-cloud
conditions for storm events than days without storms. However, deep and shallow storms occur in very similar conditions. (Copyrighted
images from the journal.)

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Research published in May 2023 used data from
ARM’s 2018–2019 Cloud, Aerosol, and Complex Terrain
Interactions (CACTI) campaign to identify thedifferences in meteorological conditions and cloud
growth processes in events where storms did or did
not form. The data are from a region of Argentina
known for its intense and frequent thunderstorms.

The analysis showed correlations between these andother meteorological factors, and several physicalprocesses that affect the growth of clouds into
thunderstorms. While these connections have been
predicted by theory, this work represents the first timethat scientists validated the connections byobservational data collected from many events.

“The extensive data collected during the CACTI
campaign made this analysis possible,” said leadauthor James Marquis of Pacific Northwest National
Laboratory in Washington state. “Typically, the lack ofdata near growing clouds means these processes are
difficult to evaluate under real-world conditions. We
had enough measurements to compare deep storms,
shallow storms, and periods of time without storms
over numerous background meteorologicalconditions.”

This study also helps identify the important factorsthat lead to thunderstorm formation and need to be
represented in models. Understanding what
influences storm formation and growth is essential tocreating accurate weather and climate models.

The scientists found that relative humidity aloft isstrongly related to whether thunderstorms formed,
but it does not necessarily dictate the ultimate
intensity of storms. They also noted that the ability ofthe environment near the growing clouds to lift andmoisten air aloft and interactions between the windand local terrain play significant roles in thunderstorm
formation.

Reference
Marquis, J, Z Feng, A Varble, T Nelson, A Houston, J Peters, J
Mulholland, and J Hardin. 2023. “Near-cloud atmosphericingredients for deep convection initiation.” Monthly Weather
Review 151(5):1247-1267, https://doi.org/10.1175/MWR-D-22-0243.1.

Scientists studied convective clouds during ARM’s CACTI campaign in Argentina.

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Researchers Investigate Vertical Profile of New
Particle Formation
Particles in the atmosphere help form clouds andscatter light, with important effects on weather andclimate. While some of these particles enter theatmosphere fully developed, many form at different
points in the atmosphere. In a January 2023 paper, aresearch team explored how height may influence
the processes of new particle formation (NPF),
important for accurately modeling the atmosphere.
The scientists used measurements from the 2016
Holistic Interactions of Shallow Clouds, Aerosols, andLand-Ecosystems (HI-SCALE) campaign, whichcollected data around ARM’s Southern Great Plainsatmospheric observatory. They combined theobservations with modeling to better understand how
atmospheric gradients in temperature and gases
affect NPF.

Researchers looked at ground-based and aircraft
data from four NPF events and two time periods
without significant NPF. They compared those datawith a model of the chemistry and physics associatedwith atmospheric particles. The team found that themodel could generally reproduce the observations,with several simplifying assumptions in place.
The data showed that the temperature, gases, andamount of mixing in the air all affect NPF. New
particles form the fastest at the border of the lowest
and middle layers of the lower atmosphere. This is
likely due to the importance of temperature on NPF in
the model. Mixing the air has a significant effect on
NPF, as it affects the temperature and gas
composition of the different layers.
This work highlights particularly important processes
for NPF. This knowledge can help guide future model
development and observational data collection.

“The vertical profile of new particle formation is a key
knowledge gap in our understanding of aerosols andclimate,” said co-corresponding author Jeff Pierce ofColorado State University. “We’re grateful that the
HI-SCALE campaign provided the opportunity to help
constrain this profile.”

This schematic describes new particle formation, aerosol
growth, and particle and air transportation mechanisms
identified by modeling and analysis of data from ARM’s
HI-SCALE campaign. (Copyrighted image from the journal.)

A suite of measurements at ARM’s Southern Great Plainsatmospheric observatory allowed researchers to identify
factors that influence new particle formation.

Reference
O’Donnell, S, A Akherati, Y He, A Hodshire, J Shilling, C Kuang, J Fast, F Mei, S Schobesberger, J Thornton, J Smith, S Jathar, and J Pierce. 2023.
“Look Up: Probing the Vertical Profile of New Particle Formation and Growth in the Planetary Boundary Layer with Models and Observations.”
Journal of Geophysical Research: Atmospheres 128(3):e2022JD037525, https://doi.org/10.1029/2022JD037525.

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ARM Data Reveal Insights Into Life Cycle ofWildfire Particles
Wildfires are becoming increasingly frequent andmore intense worldwide. In addition to causing
massive damage, wildfires release large plumes full ofparticles, including ones containing black carbon.
Such particles strongly interact with sunlight, affecting
atmospheric dynamics and radiative transfer.
Researchers used measurements of particles frombiomass burning, including wildfire emissions,collected in the U.S. Pacific Northwest and South
Atlantic to better understand how black carboncontaining particles evolve during and after wildfire
events. The plumes ranged from 15 minutes to 10 days
old, allowing the scientists to create a more accurate
picture of how these particles evolve over time.
Analyzing ARM and NASA data, the team found threedifferent regimes in the life cycle of the black carboncontaining particles, beginning with the local orsource regime immediately following burning. There,
the particles’ properties are primarily controlled by
the active fire and local conditions, and they rapidly
attain a thick coating of mainly organic substances.

New research tracks how particles from wildfires changeover time.

After hours to days, the particles enter the regional
regime. At this point, competing chemical andphysical processes determine the particles’ growth.
After the regional regime, the particles move into theglobal regime. Here, the coating on the particles
gradually decreases because of chemical processingin the atmosphere.
Eventually, the particles leave the atmospherethrough rainfall or by falling out from gravity.
This research, published in October 2022, shows thecomplex behavior of black carbon-containing
particles produced by wildfires. Models havegenerally used data from the local regime torepresent the properties and behavior of theseparticles. However, the complexity identified in thiswork means that local data are not accurate forrepresenting particles farther from the fire, especiallyin how they form clouds and interact with sunlight. In
the future, models should incorporate additional
information about the life cycle of black carboncontaining particles to yield better climate
projections.

There are three primary regimes of wildfire particles. As theparticles age, the processes that control their properties
change, and the properties evolve. (Copyrighted image fromthe journal.)

Reference
Sedlacek, A, E Lewis, T Onasch, P Zuidema, J Redemann, D Jaffe, and L Kleinman. 2022. “Using the black carbon particle mixing state tocharacterize the lifecycle of biomass burning aerosols.” Environmental Science & Technology 56(20):14315-14325, https://doi.org/10.1021/acs.
est.2c03851.

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Study Characterizes Evolution of Boundary-Layer Energy and Moisture
Water and energy cycles are meaningfully affected by land-atmosphere interactions. For example, the amount ofmoisture in the soil or the type of plants can alter how much water enters the lower layer of the atmosphere.
Similarly, the mixing of air between the boundary layer and middle of the troposphere also affects the moisturelevel in the boundary layer.
To understand the complicated relationships and processes that occur, researchers can use mixing diagrams.
These represent changes in the moisture and energy of the lower boundary layer as well as different processes that
affect energy and moisture flows. These diagrams quickly illustrate the relative contributions from below, the side,
and above to the overall evolution of the boundary layer.
In a July 2023 paper, scientists described how
ground-based data from ARM’s Southern Great
Plains atmospheric observatory helped themcreate mixing diagrams of the local environment.
Humidity and temperature profiles derived froman infrared spectrometer at the site provided
crucial information that enabled the analysis.

This mixing diagram shows the evolution of the convective
boundary layer (black line), with the contributions from the surface(green), horizontal advection (blue), and entrainment from above(yellow). (Copyrighted image from the journal.)

Scientists used a network of infrared
spectrometers co-located with Doppler lidars,
which measure wind profiles, to determine thehorizontal transport of water vapor and energy.
Combining data from an infrared spectrometer inthe center of the domain with surface
measurements of water vapor and energy, theresearchers were able to create accurate mixing
diagrams.
The high resolution of the measurements allowed
the team to study how boundary-layer energy
and moisture evolve during daytime hours.

A new approach uses a network of ground-based instruments toquantify changes in heat and moisture in the atmosphere.

“This work provides a unique way to quantify themagnitude of entrainment of dry air from above
into the boundary layer,” said NOAA’s Dave
Turner, who led the project. “Entrainment isdifficult to measure, often probed with aircraft or
a combination of advanced lidar systems. While
ARM has advanced lidars, most other sites donot. This approach generates new opportunities
to study boundary-layer evolution at a wider
range of sites.”

Reference
Wakefield, R, D Turner, T Rosenberger, T Heus, T Wagner, J Santanello, and J Basara. 2023. “A methodology for estimating the energy andmoisture budget of the convective boundary layer using continuous ground-based infrared spectrometer observations.” Journal of Applied
Meteorology and Climatology 62(7):901-914, https://doi.org/10.1175/JAMC-D-22-0163.1.

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Sea Salt Produced by Blowing Snow
Contributes to Arctic Warming
The Arctic is warming four times faster than the global
average. Researchers have shown that aerosols play
an important role in the Arctic’s dramatic climatechange. Arctic aerosol studies have found significant
amounts of sea salt particles during the spring andwinter, but their production mechanisms and impacts
on the Arctic’s climate have remained unclear.
In a September 2023 paper, scientists used ARM datafrom the 2019–2020 Multidisciplinary Drifting
Observatory for the Study of Arctic Climate (MOSAiC)
expedition to identify the sources and climate effectsof the sea salt aerosols. Comprehensive MOSAiC
measurements of aerosols, blowing snow, clouds, andmeteorological variables allowed the researchers tomake comparisons across seasons.
“Our study reveals that local blowing snow, which
produces fine sea salt particles, contributes a
substantial fraction to the total aerosol population in
the central Arctic,” said corresponding author Jian
Wang of Washington University in St. Louis.

Blowing snow produces a significant amount of sea salt
aerosols. Scientists found that these particles are contributing
to warming in the central Arctic. (Copyrighted image from thejournal.)From November to April, there is blowing snow over
20% of the time in the central Arctic. This blowing
snow produces a substantial amount of sea salt
aerosols. These aerosols represent approximately 30%
of all particles observed during the MOSAiC
expedition in months with high blowing snow.
The significant amount of sea salt aerosols
dramatically increases the number of particles that
can act as formation sites for cloud droplets over theArctic. Having more of these particles present affects
the properties of clouds, leading them to trap andemit more infrared radiation and warm the surface.
Identifying the source of the sea salt aerosols is
important for accurately modeling the Arctic’s
climate. The scientists used a representation of
blowing snow producing aerosols in a model andfound that it more accurately reproduced the
MOSAiC data. They could then estimate surface
warming due to the sea salt particles generated byblowing snow.

Light beams from the icebreaker R/V Polarstern, illuminating
blowing snow during the MOSAiC expedition.

Reference
Gong, X, J Zhang, B Croft, X Yang, M Frey, N Bergner, R Chang, J Creamean, C Kuang, R Martin, A Ranjithkumar, A Sedlacek, J Uin, S Willmes,
M Zawadowicz, J Pierce, M Shupe, J Schmale, and J Wang. 2023. “Arctic warming by abundant fine sea salt aerosols from blowing snow.”
Nature Geoscience 16(9):768-774, https://doi.org/10.1038/s41561-023-01254-8.

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A New Picture Develops of Shallow Cloud
Formation
Complicated interactions between the land andatmosphere help shape both weather and climate.
Aspects of the land surface, such as moisture content
and temperature, can affect how energy moves
through the atmosphere.

The results of this work provide an important
perspective on how shallow clouds form. It helps
create a deeper understanding of how soil moistureand the land surface affect cloud formation. Thisknowledge could lead to improvements in predicting
where clouds form and where rain will fall.

Researchers conducted simulations using data from
ARM’s 2016 Holistic Interactions of Shallow Clouds,
Aerosols, and Land-Ecosystems (HI-SCALE) field
campaign in Oklahoma to explore how the land
surface affects cloud formation. They combined
detailed atmospheric simulations with an interactive
land model. By removing background wind, they
could isolate the specific role of land surface
variations on atmospheric energy movement. Theirfindings appeared in a February 2023 paper.
“Our work allowed us to deeply study the intricate
interplay between the land surface, boundary layer,
and clouds,” said lead author Jingyi Chen of PacificNorthwest National Laboratory in Washington state.
“We discovered that variations in the land surface,such as moisture content and temperature, exert a
profound influence on how energy circulates within
the atmosphere.”

Mixing of moist and dry air over heterogeneous land
surfaces contributes to the formation of shallow clouds.
(Copyrighted image from the journal.)

Scientists specifically focused on areas with the samepotential temperature. Their work shows that shallow
clouds form over areas with high amounts of water
vapor, reflected in high energy values. They also
found that soil moisture plays a significant role in the
movement of energy.
Having a larger difference in moisture from one area
to another creates bigger moisture gradients. Thesebigger gradients are associated with stronger air
mixing and greater energy movement.
Soil moisture and atmospheric energy affect where clouds
form across the Southern Great Plains.

Reference
Chen, J, S Hagos, H Xiao, J Fast, and Z Feng. 2023. “Multiscale Analysis of Surface Heterogeneity–Induced Convection on Isentropic
Coordinates.” Journal of the Atmospheric Sciences 80(4):983-1001, https://doi.org/10.1175/JAS-D-21-0198.1.

30

ARM ANNUAL REPORT | 2023

EDGE COMPUTING OFFERS EXCITING POTENTIAL FOR ARM DATA PROCESSING
Understanding and characterizing cloud behavior requires wind and precipitation data. Doppler lidars at ARM’s Southern
Great Plains atmospheric observatory provide these measurements, but transmission and management of such large data can bechallenging.
In response, researchers developed a machine learning method to identify cloudy periods, when the data are most useful. The
scientists trained the algorithm on hand-labeled lidar images, with typical signal-to-noise ratios, to classify clear and cloudy periods
with about 96% accuracy.
Their approach, detailed in a September 2023 paper, retains only the data fromcloudy periods by classifying the data in near-real time using an edge computing
platform in the field. This is intended to streamline the transfer of full Doppler
spectra and their associated data from the instrument to the ARM Data Center.
Researchers will be able to use the spectra to develop a more detailed
understanding of turbulence, wind, and precipitation near the Earth’s surface.
ReferenceJackson, R, B Raut, D Dematties, S Collis, N Ferrier, P Beckman, R Sankaran, Y
Kim, S Park, S Shahkarami, and R Newsom. 2023. “ARMing the Edge: Designingedge computing-capable machine learning algorithms to target ARM Doppler lidar
processing.” Artificial Intelligence for the Earth Systems 2(4):220062, https://doi.
org/10.1175/AIES-D-22-0062.1.

These processing steps convert lidar
spectra into analyzable data for themachine learning algorithm.
(Copyrighted image from the journal.)

FUNDAMENTALS OF ICE NUCLEATION
Atmospheric ice nucleation plays a central role in precipitation,affects cloud properties, and influences the climate. Ice nucleates
through different pathways, across varying temperatures andhumidity and other conditions. These aspects make ice formation
challenging to accurately model in large-scale climate simulations.
In a March 2023 paper, a pair of scientists explored the current
scientific understanding of ice nucleation. They focused on thetheoretical understanding of how the process occurs, an essential
connector between laboratory-based experiments, large-scalemodels, and data from ARM and other entities.
Research over the past two decades shows that a measurable
quantity directly related to ambient humidity, known as particle
water activity, serves as a predictor for ice nucleation. For several
ice nucleation pathways, theoretical underpinnings connecting
water activity to freezing temperature and specific particle
composition already exist. Use of particle water activity in models
will help improve representation of ice nucleation, leading to morereliable predictions of cloud properties and future climate.

At the coldest temperatures, ice nucleates from aqueous
solution (I) or water (II) droplets. Ice deposits from thesupersaturated vapor phase onto an ice-nucleating
particle (III). An ice-nucleating particle immersed insupercooled water (IV) or aqueous solution (V) can
initiate freezing. (Copyrighted image from the journal.)

Reference
Knopf, D, and P Alpert. 2023. “Atmospheric ice nucleation.” Nature Reviews Physics 5:203-217, https://doi.org/10.1038/s42254-023-00570-7.

ARM ANNUAL REPORT | 2023

31

ADVANCING CAPABILITIES32

ARM ANNUAL REPORT | 2023

Infrastructure Achievements
Maintaining multiple instrumented observatories around the world is no easy feat. ARM uses ateam of science, engineering, and technical personnel to ensure effective operations, keep up
with technology developments, deliver high-quality data, and provide scientific outreach to a
global audience.
Data Flow Again From Alaska After Undersea
Cable Cut

ARM Adds JupyterHub Access to Further
Enable Open Science

ARM found an alternate solution to restore datatransmission from its North Slope of Alaska (NSA)
atmospheric observatory to the ARM Data Center
after a severed undersea fiber optic cable disrupted
telecommunications service in the region.

One of the newest additions to ARM’s available
computing resources is JupyterHub, a popular tool for
supporting scientific analysis through notebookbased computational environments.

The North Slope Borough issued an emergency
declaration related to the internet and phone
outages, which began in June 2023. The NSA had
enough onsite storage to hold more than 30 days of
incoming data, but connectivity to the observatory
was minimal, which increased the difficulty inmonitoring and troubleshooting instruments.
ARM and many other customers in the region ended
up turning to Starlink satellite internet, which ARM’stethered balloon system team uses in the field. The
Starlink systems took a few weeks to be shipped andinstalled, but the NSA continued to collect data
during that time and did not lose any data.
Eventually, it took 14 weeks to fix the cable about 34
miles north of Oliktok Point. The cause of the cable
cut was ice scouring, which is when ice drifts into
shallower waters and drags along the seafloor.

In JupyterHub, people can build and executeinteractive Jupyter Notebooks. Much like physicalnotebooks one might use in a classroom, Jupyter
Notebooks contain text notes and equations, as well
as a software environment, which allows users to run
code next to their notes. This enables users to
document their work and reproduce the code theyused to obtain their scientific results.
Users can work with ARM data in individual or sharedworkspaces managed by ARM system administrators.
JupyterHub does not require setup or installation, and
it is accessible from ARM’s Data Discovery home
page.
Different service levels are available to ARM users
depending on their computing and access needs.
JupyterHub functions as part of the ARM Data
Workbench, a new ecosystem for interacting with
ARM data. Currently in development, the workbench
will offer a free suite of tools forusers to select, access,visualize, and analyze data.
In April 2023, ARM hosted awebinar to educate scientists
on how to use JupyterHub on
the ARM Data Workbench.

A Starlink system is shown at ARM’s North Slope of Alaska
atmospheric observatory.

ARM ANNUAL REPORT | 2023

33

ARM Marks New Set of Engineering andDevelopment Achievements
ARM prioritizes its engineering and development
activities each fiscal year to meet user needs andachieve mission-critical facility goals.
In FY2023, priorities included preparation for the
Bankhead National Forest atmospheric observatory
in Alabama. A major accomplishment was thedesign, procurement, and development of instrument
systems for the observatory’s 140-foot walk-up tower.
Systems will be deployed in FY2024.
Other ARM instrument development activities
revolved around expanding aerosol instrumentation
at the North Slope of Alaska observatory andupgrading existing instrumentation, such as Ka-Band
ARM Zenith Radars.

ARM’s ArcticShark uncrewed aerial system flies above a cropduster in northern Oklahoma in June 2023.

Meanwhile, ARM completed site data system network
infrastructure upgrades for the Southern Great Plains(SGP) observatory and second ARM Mobile Facility.
In March, June, and August 2023, the ARM Aerial
Facility conducted a successful series of flights over
the SGP with the ArcticShark uncrewed aerial system.
Atmospheric data collected during the flights areavailable for use. At the end of September, ARM
opened a proposal call for FY2024 ArcticShark flights
in the SGP region.
In the science products area, ARM continued to focus
on developing user-requested value-added products(VAPs) for boundary-layer, aerosol, and precipitation
processes, and model evaluation.
Developers also used a new workflow for
reprocessing VAPs. The main goal is to ensure that
VAPs are reprocessed when input data change. The
workflow streamlines the process, enabling fasterdata delivery to users.
To further support users, ARM’s data services teamreleased the first phase of the ARM Data Workbench,
an ecosystem for working with ARM data. The teamalso updated ARM’s Online Metadata Editor tool,
which scientists can use to submit guest instrument
data from ARM field campaigns and principal
investigator products.

NEW FRONTIERS AHEAD FOR ARM’S HIGH-RESOLUTION MODELING ACTIVITY
The Large-Eddy Simulation (LES) ARM Symbiotic Simulation and Observation(LASSO) activity provides high-resolution model simulations vetted by ARM
observations. In FY2023, LASSO’s development team moved forward with plans to
expand the activity to new sites and atmospheric phenomena.
LASSO’s initial scenario targeted shallow clouds at ARM’s Southern Great Plainsatmospheric observatory. For its second scenario, the LASSO team focused on
deep convection observed during a 2018–2019 ARM field campaign in Argentina.
Production data from this scenario became available in the summer of 2023.
In July, the LASSO team hosted a workshop for scientists to provide feedback on thedevelopment of a marine cloud scenario at ARM’s Eastern North Atlantic observatory.
The team later announced it would hold a Future of LASSO Workshop in November.
To build the workshop agenda, the team asked researchers to submit white papers on
how LASSO might further evolve for greatest scientific impact.

34

ARM ANNUAL REPORT | 2023

The LASSO activity produced new model
simulations based on deep convection
observed during an ARM field campaign
in Argentina.

New Data Products
ARM Provides More Products for Aerosol
Community
For scientists studying the intricacies of tiny
atmospheric particles, ARM expanded its collectionof aerosol value-added products (VAPs) in FY2023.
Production data for nine ARM sites became available
from a VAP that calculates hygroscopic—moistureabsorbing—properties of aerosols from cloud
condensation nuclei (CCN) measurements andaerosol size distributions from the scanning mobility
particle sizer (SMPS).
A new VAP calculates hygroscopic properties ofaerosols using CCN and size distribution
measurements from the ultra-high-sensitivity aerosol
spectrometer (UHSAS). This VAP will provide data forsites without an SMPS.

Both VAPs derive the hygroscopicity parameterkappa, which quantifies a particle’s capacity toactivate into a cloud droplet. Scientists can use thesekappa products to evaluate aerosol properties
simulated in global earth system models.
ARM now provides a set of products that merge
aerosol size distribution measurements from several
sources. Individual instruments measure different size
ranges of aerosols, so the merged products create
consistent size distributions across wider size ranges.
The original VAP merges measurements from the
SMPS and aerodynamic particle sizer (APS). A new
VAP merges SMPS- and UHSAS-measured size
distributions. Another new VAP improves the quality ofthe merged SMPS/APS data through machinelearning.
The merged products can help scientists calculate
aerosol scattering and mass loading, estimate theimpact of aerosol on clouds, and verify aerosolrelated quantities in models.
ARM also developed a VAP
that corrects time-of-flightaerosol chemical speciation
monitor data for compositiondependent collection
efficiency, or the non-unity
detection of particle mass by
the instrument. This VAP brings
the instrument data into better
agreement with co-locatedaerosol measurements.

This sample plot from ARM’s TRACER campaign near Houston, Texas, shows a selection ofaerosol mass concentrations from the time-of-flight aerosol chemical speciation monitor
corrected for composition-dependent collection efficiency.

ARM ANNUAL REPORT | 2023

35

ARM Delivers Modeling Products for Stormy Campaign in Argentina
In FY2023, ARM released new modeling products for the 2018–2019 Cloud, Aerosol, and Complex Terrain
Interactions (CACTI) field campaign, which captured unique views of convective clouds in central Argentina.
The Large-Eddy Simulation (LES) ARM Symbiotic Simulation and Observation (LASSO) activity generated highresolution simulations of deep convection observed during CACTI. Scientists can use the production version of the
LASSO-CACTI data set to learn more about convective processes and potentially improve their representation inclimate models.
ARM also produced two versions of continuous large-scale forcing data for CACTI. Both versions are based on
atmospheric reanalysis data and constrained by observed surface precipitation and satellite-derived top-ofatmosphere radiative fluxes. Scientists can use these data to drive single-column models, cloud-resolving models,and LES models for different cloud and convective systems.
One version was originally designed fora cylindrical atmospheric column. It
uses an algorithm that assumes theanalysis domain has a flat surface, withthe surface pressure equal to thepressure at the center of the domain.
The other version uses a new algorithm
designed to better treat the varying
slope of the terrain in the analysis sothat the effect of the surface terrain on
the derived large-scale forcing fields
can be captured and represented.

The map shows the analysis domain (enclosed by the red circle) for the CACTI
large-scale forcing data. The first ARM Mobile Facility (AMF1) at Córdoba,
Argentina, is located near the southwestern corner of the domain.

36

ARM ANNUAL REPORT | 2023

Gridded Data Products Give Scientists a Unique Look at Clouds
ARM offers several gridded
value-added products (VAPs)
that deliver a
multidimensional view ofclouds.
In FY2023, two gridded
VAPs—Surface Cloud Grid
(SFCCLDGRID) and Clouds
Optically Gridded by Stereo(COGS)—transitioned from
evaluation to production.
SFCCLDGRID compiles
spatially distributed
measurements of cloud andradiation properties over
ARM’s Southern Great Plains(SGP) atmosphericobservatory. These values
enable more accuratecomparisons of model/
satellite grid boxes andground-based SGP
observations, as well as an
estimate of the regionalvariability of cloud andradiation properties.
COGS provides a fourdimensional (4D) map of
The figure illustrates SFCCLDGRID cloud fraction on the morning of April 1, 2017, when thecloudiness generated bySouthern Great Plains (SGP) atmospheric observatory experienced partly cloudy
stitching together
conditions with clear skies to the east and overcast conditions to the west and north. The
reconstructed cloud points
yellow ball represents the sun in the sky, the SGP Central Facility is noted in red, and other
SGP facilities are noted in green.
from a ring of stereo cameras
at the SGP. The VAP also
includes a verticallyprojected cloud fraction and cloud base height estimate. Scientists can use COGS data to study the life cycles
and macrophysical attributes of shallow cumulus clouds.
Meanwhile, the Scanning ARM Cloud Radar Grid (SACRGRID) family of VAPs provides radar moments andquantities on a Cartesian grid. For a past campaign in Norway, ARM produced two new SACRGRID releases forevaluation. These releases use calibrated data from two different types of scans as input.
SACRGRID products make it easier to use scanning ARM cloud radar observations from the entire campaign.

ARM ANNUAL REPORT | 2023

37

New Workflow Eases Challenges of Interacting
With Radar Data
During the 2021–2023 Surface Atmosphere Integrated
Field Laboratory (SAIL) campaign near Crested Butte,Colorado, ARM supported the deployment of an
X-band scanning precipitation radar from Colorado
State University. Mountains often blocked the radar
beam, which could present challenges for data users.
To help overcome these challenges, ARM processed
the radar data using a new workflow called Surface
Quantitative Precipitation Estimation (SQUIRE). The
SQUIRE workflow projects the data from native
antenna coordinates to Cartesian coordinates (e.g.,x, y or latitude, longitude). It also extracts the lowest
gate, or 3-dimensional (3D) grid point, available foreach grid cell in the domain. This provides data fields
on a grid that modelers or other scientists can add totheir analysis, including surface estimates of liquid
precipitation.

For input, SQUIRE uses data from the Corrected
Moments in Antenna Coordinates (CMAC) valueadded product. CMAC corrects raw scanning radar
data for atmospheric phenomena and instrument
characteristics, and it also retrieves precipitation
quantities from the radar measurements.
CMAC precipitation estimates are derived from anensemble of existing radar reflectivity and snowfall
rate relationships. Within SQUIRE, the estimates are
mapped to a Cartesian grid. To address terrain
complexity, reflectivity and snowfall rates areprojected from the lowest valid elevation to thesurface.

This map of the gridded estimated snowfall rate from Colorado State University’s X-band radar on
March 14, 2022, highlights the East River Watershed and ARM Mobile Facility (AMF) site in Gothic,
Colorado, northwest of the radar on Crested Butte Mountain.

38

ARM ANNUAL REPORT | 2023

Diverse Group of Data Products Generated From
Texas Campaign
In FY2023, ARM prioritized the delivery of data products
from the TRacking Aerosol Convection interactions
ExpeRiment (TRACER). Scientists are using data from the2021–2022 campaign to study the effects of aerosols on
thunderstorms around Houston, Texas.
TRACER data became available from existing ARM
value-added products (VAPs) for assessing surface
radiation measurements, calculating radiative fluxes,
retrieving variables from microwave radiometermeasurements, determining cloud microphysicalproperties, and generating cloud masks from lidar data.

ARM released merged aerosol size
distribution data from TRACER instruments,
in addition to ice-nucleating particle
concentrations based on filter samples.
For the evaluation of global climate
models, ARM produced best-estimate
atmospheric, cloud, and radiation
quantities from TRACER. Also, scientists
can use large-scale forcing data from thecampaign to drive models of different
cloud and convective systems.
Meanwhile, ARM included TRACER in theinitial releases of three new VAPs. One of
the VAPs calculates radiosonde
parameters within convective cloudenvironments. Another combines datafrom the tethered balloon system andground-based ceilometer to allow for
examination of cloud-base andboundary-layer heights. ARM also
released a VAP that corrects time-of-flightaerosol chemical speciation monitor data
for non-unity detection of particle massby the instrument.
A principal investigator product includes
data on more than 1,000 convective cells
tracked under a framework that helped
capture fast-evolving radar parameters
associated with dynamical andmicrophysical cloud processes. ARM
funded the development of the celltracking software used for TRACER.

This skew-T plot shows the pressure and temperature recorded by aradiosonde launched June 1, 2022, at the ARM Mobile Facility site in La
Porte, Texas, during the TRACER campaign. Red, blue, and green dots
indicate different radiosonde parameters.

ARM ANNUAL REPORT | 2023

39

COASTAL CAMPAIGN GETS FIRSTHANDLOOK AT HISTORIC TROPICAL STORMA DECADE OF THE PYTHON ARM
RADAR TOOLKITIn August 2023, ARM instruments recorded an unexpected
event during the Eastern Pacific Cloud Aerosol Precipitation
Experiment (EPCAPE) in La Jolla, California.

In 2012, DOE scientists developed an open-source package
to interact with ARM radar data. Since becoming publicly
available a decade ago, the Python ARM Radar Toolkit(Py-ART) has built up a worldwide community of thousandsof users working with radar data from ARM and otherorganizations.

Hurricane Hilary moved up Mexico’s west coast before
becoming the first tropical storm to hit Southern California
in 84 years, generating extensive rainfall and strong winds.
Most of the ARM instruments at EPCAPE (excluding
the scanning radars, which were shut down because of thehigh wind predictions) acquired data as the cyclone moved
through the region.
Rain totals at EPCAPE surpassed 3 inches in about 18 hours.
Data from the Ka-Band ARM Zenith Radar indicated amelting layer above which snow particles were generated. The
particles then precipitated to the surface as relatively fastfalling rain.
Meanwhile, ARM’s Doppler lidar captured persistent highwinds (exceeding about 45 mph) and wind veering features.
EPCAPE data from Tropical Storm Hilary are freely
available in the ARM Data Center.

Py-ART is a Python library organized by modules oriented todifferent functions: storage, formatting, display, correction,
gridding and mapping data, and calculation of geophysicalvariables such as rainfall rate.
A main use of Py-ART is extracting information needed to
improve weather and climate models, but radars can observe
more than clouds and precipitation. In a growing universe of
applications, Py-ART users have mapped mayfly populations,surveyed waterfowl in flight, visualized the life cycles ofstorm clouds generated by massive wildfires, and identified
likely meteorite fall zones.
Anyone can use Py-ART, and many users give back bycontributing new code.

This Py-ART image from ARM’s TRACER campaign near Houston,
Texas, showcases vertical cross-sections through deep
convective cells.
This figure from the EPCAPE campaign shows lowertroposphere 3D wind profiles retrieved by the Doppler lidar
during Tropical Storm Hilary on August 20, 2023.

40

ARM ANNUAL REPORT | 2023

Science Outreach
ARM Activities Support Federal Year of OpenScience Initiative
In January 2023, the White House Office of Scienceand Technology Policy launched the Year of OpenScience to advance national open science policies
across the federal government.
Since 1992, ARM has made its data freely available toscientists worldwide, but open-source capabilities are
opening up new ways to work with the data.
ARM staff and users have developed open-source
tools that make it easier to visualize and analyze ARM
data and are teaching others how to use them.
Before the 2023 American Meteorological Society(AMS) Annual Meeting in Denver, Colorado, ARM
organized a short course on open science andworking with data from the Surface Atmosphere
Integrated Field Laboratory (SAIL) campaign. This
daylong short course was the result of a collaboration
between ARM field campaign scientists, datatranslators, and developers. The course drew 20
attendees, including professors, research scientists,and graduate students.

The short course was also a concrete example ofactivities that ARM is supporting to advance its
Decadal Vision by enabling open-source software
practices to support code sharing across the ARM
community.
Following science-focused discussion on SAIL,
attendees received tutorials on ARM data, ARM’sopen-source software tools, the GitHub softwaredevelopment platform, and different computing
resources available from ARM.
Open science was also a key focus of the August2023 Joint ARM User Facility/Atmospheric System
Research (ASR) Principal Investigators Meeting in
Rockville, Maryland. The meeting included a threepart set of breakout sessions focused on open
science for ARM and ASR.
The sessions included an introduction to open
science in ARM, toolkit tutorials, and solicited talks.
A few weeks later, the 40th AMS Conference on
Radar Meteorology in Minneapolis, Minnesota,
featured an open radar short course organized by
ARM staff. More than 40 attendees explored using
open-source toolkits to work with weather radar data,primarily C- and S-band data near the new ARM
observatory in Alabama’s Bankhead National Forest.

AMS open radar short course students and instructors pause for a photo.

ARM ANNUAL REPORT | 2023

41

Back In Person, ARM Makes Splash at Major
Scientific Conferences

Houston, Texas, to help scientists understand how
aerosols might affect thunderstorms.

After COVID altered meeting plans the previous two
years, FY2023 brought a welcome return to in-person
scientific conferences for many members of the ARM
community.

Researchers also mined data from ARM’s Surface
Atmosphere Integrated Field Laboratory (SAIL)
campaign near Crested Butte, Colorado. SAIL, which
ended in June 2023, collected data about physicalprocesses and interactions that affect mountainhydrology.

ARM users and staff flocked to the December 2022
American Geophysical Union (AGU) Fall Meeting in
Chicago, Illinois. Right after the new year came the2023 American Meteorological Society (AMS) Annual
Meeting in Denver, Colorado.

An AMS short course showed attendees how to use
ARM-supported open-source tools to work with SAIL
data.

An ARM exhibit drew close to 300 visitors at AGU andmore than 500 at AMS.
With eyes on ARM’s future, ARM Director Jim Mather
led an AGU town hall on new capabilities andestablishing development priorities within the user
facility.
Demonstrating the scientific impact of ARM data, theARM community reported 168 presentations at AGU
and 74 at AMS.
Despite ending two months before AGU, the TRacking
Aerosol Convection interactions ExpeRiment(TRACER) had plenty of early results to report. The
yearlong ARM campaign gathered data near

SHARING ARM’S UNCREWED AERIALSYSTEM WITH THE NEXT GENERATION
While in Oklahoma for a June 2023 deployment of ARM’sArcticShark uncrewed aerial system (UAS), ARM Aerial
Facility (AAF) staff introduced the UAS technology toan aspiring group of young aviators from the Northern
Oklahoma Flight Academy.
Ranging from sixth graders to high school seniors, thestudents toured the UAS Mobile Operations Center, groundcontrol station, hangar, and maintenance areas. They
learned about the AAF mission and how ARM uses different
instruments to collect aerial data.

42

ARM ANNUAL REPORT | 2023

ARM welcomes visitors to its exhibit during the 2022 AGU Fall
Meeting in Chicago, Illinois.

“It was gratifying to see the next generation stepping up withso much interest in climate science and aviation,” said AAF
Manager Beat Schmid. “I mean, holy cow! These kids are
the smartest of the smartest, and they asked great questions.
It was an honor to share what we do and hopefully make an
impact on their future.”

ARM Aerial Facility
Manager Beat
Schmid describes
ArcticShark
components to agroup of young
aviators from theNorthern
Oklahoma Flight
Academy.

FACILITY USAGE
ARM ANNUAL REPORT | 2023

43

1,15734

COUNTRIES/TERRITORIES

Users bycountry/
territory

44

ARM ANNUAL REPORT | 2023

United States 842
China 88
Germany 46
United Kingdom 24
Brazil 22
Canada 20
France 12
Sweden 11
Netherlands 10
Puerto Rico 10
India 9Japan 9Switzerland 8
Italy 7
South Korea 6
Australia 5
Finland 4
Argentina 3
Spain 3
Norway 2
Pakistan 2
Taiwan 2
Armenia 1
Austria 1

French Polynesia 1
Greece 1
Indonesia 1
Ireland 1
Israel 1
Kenya 1New Zealand 1
Poland 1
Portugal 1
Russia 1

USER STATISTICS
Universities (U.S.)

524

Foreign Entities

315

DOE Labs

194

Other U.S. Gov.

77

Industry

47

45%
27%
17%
7%
4%

PUBLICATIONS USING ARM* 1,455 TOTAL
1,202

190

58

3

2

Abstracts andPresentations

Journal
ArticlesTechnical
Reports

Book
Chapters

Conference
Papers*Publication statistics were collected as of December 2023. Journal article numbers will continue to increase over time.

FACILITY USAGE

7,000+

Publicly Available
Datastreams

460+

Instruments Collect
Atmospheric Data

Data
800

Remote221

Onsite
136

69%

19%

12%

4,500 +

Journal Articles
Since 1990

ARM ANNUAL REPORT | 2023

45

FIELD CAMPAIGNSAMF 35OFFSITE 7

SGP 20

ENA 3

9%

77

26%

NSA 12TOTAL
45%

WEBSITE VISITORS
7,548

7,429
5,532

5,451

16%

6,866

4%

6,941
6,022

5,491

6,691

6,178

5,859
4,881

2,684

2,341

2,086

2,398

2,814

2,972

2,703

2,716

2,404

2,251

2,746

2,836

OCT

NOV

DEC

JAN

FEB

MAR

APR

MAY

JUN

JUL

AUG

SEP

Website Visitors Total

More than 9 Visits

DATA PRODUCTS

3

7

8

3

Released to
Production

Released to
Evaluation

Approved forDevelopment

Existing VAPs
Updated• COGS• MERGEDSMPSAPS• SONDEPARAM• CCNUHSASKAPPA• DLMCPROF-WIND• MERGEDSMPSAPSML• MERGEDSMPSUHSAS• MPLCAL• SQUIRE• XPRECIPCMAC• AAFMERGED• AMERIFLUX• CLOUDRADARCOR• CSAPR2-CMAC• LIDARAEROMASK• Mixed Phase• PPHIYD• RWPPRECIPCOR• AREALAVEALB• AOD-MFRSR• MFRSRCLDOD1MIN

To learn more about the value-added data products, visit www.arm.gov/capabilities/science-data-products/vaps.

46

ARM ANNUAL REPORT | 2023

Image Credits:
Thank you to the many people over the years who provided images in the ARM annual report. Here are theimage contributors from FY2023 and the pages on which their images appear:
Karen Steinbock.................................................................................................................................................... freelance (Front cover)
Travis Guy....................................................................................................................................... Hamelmann Communications (2, 15)Andrea Starr...........................................................................................................................Pacific Northwest National Laboratory (3)John Bilberry..................................................................................................................................... Los Alamos National Laboratory (4)Nathan Bilow.......................................................................................................................................................................freelance (6, 17)
Shawn Serbin........................................formerly Brookhaven National Laboratory; now NASA Goddard Space Flight Center (10)
Guy Tubbs................................................................................................................................................................................freelance (13)Brent Peterson...................................................................................................................................... Sandia National Laboratories (14)Gary Geernaert............................................................................................................................................................................... DOE (16)Australian Bureau of Meteorology......................................................................................................................................................... (18)
*Larry Syverson.......................................................................................................................................................................freelance (18)David Oaks.........................................................................................................................................Hamelmann Communications (22)*Esther Horvath.............................................................................................................................................Alfred Wegener Institute (22)
Jason Tomlinson............................................................................................................Pacific Northwest National Laboratory (25, 26)
Matthew Shupe..................................................................................................................................University of Colorado Boulder (29)
Tim McLain............................................................................................................................Pacific Northwest National Laboratory (32)Fred Helsel............................................................................................................................................Sandia National Laboratories (33)
Jonathan Stratman.............................................................................................................Pacific Northwest National Laboratory (34)
Vagner Castro......................................................................................................................Pacific Northwest National Laboratory (34)
Max Grover...........................................................................................................................................Argonne National Laboratory (41)Pete Carroll...........................................................................................................................Pacific Northwest National Laboratory (42)
Ben Bishop............................................................................................................................................Sandia National Laboratories (43)
Tercio Silva...............................................................................................................................................Fundação Gaspar Frutuoso (47)*Syverson: “Baltimore Skyline” is licensed under CC BY-SA 2.0. *Horvath: Photo is licensed under CC BY 4.0.

On Graciosa Island in the Azores, ARM’s decade-old Eastern North Atlantic atmospheric observatory, seen
here in September 2023, collects continuous cloud, precipitation, and aerosol data.

ARM ANNUAL REPORT | 2023

47

www.arm.gov

DOE/SC-ARM-23-047