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Vol. 28 No. 3, August 20182018 GEWEX Extremes and Water
Science Conference on the Edge

Contents
Highlights from the 8th GEWEX Open Science
Conference

2

2018 Early Career Researcher Workshop at the
GEWEX Open Science Conference

3

Winners of the Early Career Researcher and Student
Presentation Competition
4
Announcements- Dawn Erlich: 24 Years with the International
GEWEX Project Office (IGPO)- Howard Wheater, Former SSG Vice-Chair,Wins Dooge Medal- New GEWEX SSG Co-Chair- H3S Plans for the 2018 Fall AGU Meeting

5
5
5
6

Process Evaluation Study on Warm Rain
(PROES-WR)

6

Meeting/Workshop Reports- Aerosol-Cloud-Precipitation Interactions: Analysis
of Satellite- and Ground-Based Data, and of
Cloud-Resolving Modeling, in the ACPC Initiative 8- Joint WCRP Grand Challenge on Weather andClimate Extremes/GEWEX GDAP Workshop on
Precipitation Extremes
11- Annual GLASS Science Panel Meeting
12
Nominations for 2018 Data and Modeling Prizes

16

GEWEX/WCRP Calendar

16

8th GEWEX Open Science Conferenceof conducting analyses was well represented in the session on“Global Energy and Water Cycles, Clouds, and Radiation.”

Highlights from the 8th GEWEXOpen Science Conference

Weather and climate extremes and the food-water-energy nexus,
the topics of the two WCRP Grand Challenges, were explored indetail in various sessions. Research on extremes in weather andclimate was a popular topic and its session was well attended.

Peter van Oevelen
Director, International GEWEX Project Office

GEWEX held its 8th Open Science Conference from 6-11
May 2018 in Canmore, Alberta, Canada, with over 380 in attendance. Scientists from 40 countries, a third of them female,
discussed and presented on issues ranging from mountain andhigh latitude hydrology to atmospheric and land modeling research and observations. The Conference covered both longstanding and emerging topics and featured the work of morethan 200 Early Career Researchers (ECRs). It left us very appreciative of the contributions from our community and theConference sponsors.
Themes of the Conference mirrored the diverse research of
the GEWEX community. The program reflected the science
represented by the four core Panels of GEWEX and the two
GEWEX-led World Climate Research Programme (WCRP)
Grand Challenges on “Weather and Climate Extremes” and“Water for the Food Baskets of the World.”
The Conference, organized into seven overarching themes and
26 individual sessions, was designed to cover as wide a gamutof topics on water and energy and climate and weather-related research as possible. This also allowed us to showcase thescience performed under the four GEWEX Panels as well as
the WCRP Grand Challenges. The GEWEX Global Atmospheric System Studies (GASS) Panel’s focus on atmosphericmodels was shown through contributions in sessions such
as “Energy and Water Budget Closure and Advances in Assessment Techniques.” The Global Land/Atmosphere System
Study (GLASS) Panel’s concentration on land surface model
development and evaluation was highlighted in sessions suchas “Satellite Observations for Climate Extremes, Water Cycle
Processes, and Land-Atmosphere Interactions.” The GEWEXHydroclimatology Panel (GHP)’s emphasis on regional hydroclimates was displayed particularly in the session on “Regional Hydroclimate Projects.” The GEWEX Data and Analysis (GDAP) Panel’s mission of guiding the production andevaluation of global data products as well as its newer direction
2

Given the Conference venue in the beautiful town of Canmore, located in the Canadian Rockies, mountainous regions
and their hydrology and climate were a focal point, boththroughout the Conference and in excursions led by John
Pomeroy and the excellent story teller and scientist Bob Sandford. High mountainous terrain, critical for regional watersupply and access, is still a frontier due to lack of research
infrastructure. Many unanswered questions on weather andclimate-related processes in these regions persist. During theConference, significant steps were made that may lead to a
new GEWEX Mountain Initiative to bring together the latest
scientific knowledge and models, such as convection-permitting models, and the relevant research communities.
The Early Career Researchers (ECRs) from the Young Earth
System Scientists (YESS) (http://www.yess-community.org/)
group and the Young Hydrologic Society (YHS) (https://younghs.com/) came together to hold the 2018 Joint YESS-YHS
ECR Workshop for a three day span before the Conference.
Participants discussed creating and disseminating regional information on different spatial and temporal scales, and you
can read more about the Workshop on the next page. A white
paper detailing outcomes and conclusions will be published in
the coming months. A good portion of students and ECRs attending the Conference also entered in the ECR and Student
Presentation Competition, and five outstanding researchers
came away with prizes, as described on page 4.
The Wednesday night banquet served as an opportunity towish our departing Scientific Steering Group Co-Chair, Sonia
Seneviratne, farewell and to thank her for her many contributions over the four years of her tenure. Her energy will bemissed. We would also like to thank the Conference sponsors(https://www.gewexevents.org/events/2018conference/sponsors/) formaking the event possible and funding the participation of early career researchers and scientists from developing countries.
Without their backing, we would not be able to put together
such a fantastic event. A great many thanks also to our host institution, the Global Institute for Water Security of the University of Saskatchewan, particularly to John Pomeroy and Chris
DeBeer for their fantastic input, support, and contributions.
A conference is only as good as it attendees and their contributions. We thank all who attended for sharing your enthusiasm,
your great research, and your willingness to openly discussand exchange ideas, which helped make the Conference sucha success. I also thank the staff of the International GEWEX
Project Office, Dawn, Shannon, and Fernande, for their tireless efforts before, during, and after the event. They were a
crucial part in making it work smoothly. Thank you!
August 2018

2018 Early Career Researcher Workshop
at the GEWEX Open Science Conference
Canmore, Alberta, Canada
3–5 May 2018
Marisol Osman1, Caroline Aubry-Wake2, Carla Gulizia1,
and Gaby Langendijk3
1

CIMA (CONICET/UBA), Universidad de Buenos Aires, Argentina; 2University of Saskatchewan, Canada; 3Climate Service Center Germany (GERICS)

On May 3-5, the Young Earth System Scientists (YESS)(http://www.yess-community.org/) and Young Hydrologic Society (YHS) (https://younghs.com/) held a Joint YESS-YHS
Early Career Researcher (ECR) Workshop prior to the 2018
GEWEX Open Science Conference (OSC). The 3-day workshop brought together 40 early careers researchers from 23 different countries for an in-depth interdisciplinary discussion on
generating regional information to improve our understanding of weather, water, and climate extreme events. The goal of
the workshop was to develop a shared ECR vision on challenges and ways forward to enhance the generation of usable

regional information for water, weather, and climate extremes,
and the utility of that information for users, decision makers,
and other stakeholders. During the three days, the discussions
centered on three topics: data sources (conventional and unconventional), scale-interactions, and user needs.
On the first day, after an introduction of the workshop dynamic, the agenda, and the participants, Peter van Oevelen, theDirector of International GEWEX Project Office, introduced
the role and mission of GEWEX in the international science
community. His talk outlined the function of the World Climate Research Programme (WRCP), World MeteorologicalOrganization (WMO), and GEWEX. After lunch, Prof. John
Pomeroy, Director of the Global Water Futures program, gave
a talk highlighting the importance of combining observations
and modeling to gain information on the processes at play inthe hydrological world. Drawing from multiple examples ofmountain and snow hydrology, Prof. Pomeroy explained how
intensive field observations can be used to develop models, toincrease our understanding of our study environment, and to
predict future changes. We then jumped in a yellow school
bus and headed into one of the highlights of the event: a trip
to the very frosty Fortress Snow and Climate Observatory.
Located in scenic Kananaskis Provincial Park 75 km from

Participants of the Joint YESS-YHS Early Career Researcher Workshop in Canmore, Alberta, Canada

August 20183

Canmore, the Fortress Snow and Climate Observatory is astate-of-the-art network of automated weather stations to investigate cold region mountain hydrology. Prof. Pomeroy addressed the challenges of establishing and maintaining an observation network, and the importance of such programs forhydrological and climate studies. This field visit was followedby an evening at the Canmore Brewing Company, where theworkshop participants socialized and enjoyed tasty beverages.
On the second day, Dr. Graeme Stephens, Co-Director of
National Aeronautics and Space Administration (NASA) Jet
Propulsion Lab (JPL), USA, gave an impulse talk on the challenges in the science of weather, water, and climate extremes.
After that, participants were split into two break-out groups,
each moderated by two ECRs, to discuss the workshop topics
of data sources and spatial scales for user needs. For the data
sources group, the goal was to explore the use of conventional
and unconventional data and new technologies to provide
better weather, water, and climate data services. The second
group’s objective was to investigate opportunities to provide
the required regional information at appropriate spatial scales
for varied user needs. Participants spent the day discussingthese issues in the context of water and weather extremes.
In these diverse groups, composed of ECRs from different
regions, with different expertise and at different stages in theircareer, the participants brought their own perspective to enrich the proceedings.
To finish the day, we split the attendees in small groups andwent for a walk outside to talk about the current state andchallenges of the ECR community. We discussed five topics: empowering early career scientists from underrepresented groups, increasing involvement in the global community, raising the scientific profile of the ECR communities,
engaging community members in the consolidation of the
networks, and developing interdisciplinarity. These conversations pointed out the dual purpose of networks such as YESS
and YHS: professional development, helping the transition
from student to professional researchers, and promotion of
ECRs on an international stage, pushing for a stronger voice
and presence of ECRs in the research community.
On the third day, the dialogue focused on the main outcomesof the working groups and the consolidation of an ECR perspective to be outlined in a white paper after the workshop.
We had a very inspiring and fruitful ECR workshop and arelooking forward to the write-up of our white paper, elaborating on an ECR perspective on regional information, to be published in an international scientific journal. Keep an eye out
towards the end of 2018 to hear the results of our discussions!
This workshop was jointly organized by YESS and YHS
in close consultation with the GEWEX OSC Organizing
Committee and was kindly supported by WMO, WCRP,
and GEWEX OSC sponsors. Travel support was provided
through direct sponsorship of WMO as well as through the
GEWEX OSC and its sponsors.
4

Winners of the Early Career Researcher
and Student Presentation Competition

Top photo, from left: GEWEX Scientific Steering Group Co-Chair Sonia Seneviratne, Andreas Prein, Emily Slinskey, Julián Giles, GEWEXScientific Steering Group Co-Chair Graeme Stephens, and Liyun Yang.

Early career researchers (ECRs) and students were invited tojoin a competition during the 8th GEWEX Open Science Conference, where volunteer judges evaluated talks and posters todetermine the top five presentations. Over 120 ECRs andstudents were assessed on the originality of their approach totheir research question; the analysis supporting their conclusions; their background knowledge; and the organization, clarity, and effectiveness of their submissions. Participants ranged
from students pursuing Master’s degrees and beyond to those
who received their terminal degree no more than five years ago.
Julián Giles of the Centro de Investigaciones del Mar y la Atmósfera, Mia Gross of the University of New South Wales,and Liyun Yang of Nanjing University were each awarded an
iPad. Andreas Prein of the National Center for AtmosphericResearch and Emily Slinskey of Portland State University won
a waiver granting them free registration to an American Meteorological Society (AMS) meeting of their choice, prizes generously donated by AMS. You can read more on the winners,
their presentations at the Conference, and their research interests at https://www.wcrp-climate.org/future-science-leadership/
spotlight-on-early-career-researchers.
The conference organizers would like to congratulate thewinners and thank the many volunteer judges for their time
and thoroughness. We would also like to extend gratitude to
Joshua Roundy, Mike Ek, and Catherine Michaut, who spearheaded the competition.
August 2018

Announcements
Dawn Erlich: 24 Years with theInternational GEWEX Project Office (IGPO)Paul Try
Former Director, International GEWEX Project Office

Congratulations to Dawn Erlich,
the bedrock of GEWEX, as she retires after 24 years with the IGPO.
It may be a cliché, but Dawn was the“glue” that held the IGPO together
and kept it on track through several
Directors and the usual funding
struggles. As GEWEX expanded
and added projects and committees(too many to count), changing its
name and logo, too, Dawn was there
steadying the progress. She managed the newsletter, planned
meetings and conferences of all sizes, traveled to events acrossthe globe, and found solutions for all of the glitches that occur
in a project of this size. At the hub of preparation for these
activities, Dawn is well known by many of the over 2,000 scientists participating in the project worldwide. As we Directors from the past and present come up with numerous wild
ideas for facilitating and encouraging the progress of GEWEX,
Dawn has been the one to provide more pragmatic solutions
to help the process.
We hope Dawn will remember her time at the IGPO as rewarding, given the great progress GEWEX has made over her
tenure. We also hope we can continue to count on Dawn forsome limited support in the future at the IGPO, as her past
support has been invaluable to all who have worked with her.

Howard Wheater, Former GEWEX SSG
Vice-Chair, Wins Dooge Medal
Professor Howard Wheater, who served as the GEWEX Scientific Steering Group (SSG)’s Vice-Chair from 2010 to 2014,
received the 2018 International Hydrology Prize Dooge Medal. The award recognizes those who make fundamental contributions to the science of hydrology. The Dooge Medal waspresented to Howard during a ceremony at the World Meteorological Organization in Geneva in early May 2018, “in recognition of his international leadership in hydrological researchof scientific excellence, coupled with its translation into policy
and practice and application worldwide.” Howard most recently served as the Canada Excellence Research Chair in Water
Security and Director of the Global Institute for Water Security at the University of Saskatchewan. His efforts have resulted
in science that benefits society, giving the field a better understanding of large scale hydrology and hydrological modeling.
August 2018

New GEWEX Scientific Steering Group(SSG) Co-Chair
We welcome Dr. Jan Polcher as GEWEX SSG Co-Chair, witha term beginning in June 2018. He joins Graeme Stephens tohead the SSG.
Dr. Polcher is Directeur de Recherche at the Centre National de la Recherche Scientifique (CNRS) andworks at the Laboratoire de Météorologie Dynamique (LMD), partof the Institut Pierre Simon Laplace(IPSL) in Paris. He studied oceanography and theoretical physics in the
1980’s in Kiel, Germany. He thenmoved to Paris to complete a Ph.D.
under the supervision of Katia Laval
at LMD in 1993. Since then, his main interest lies in climate
modeling of the water cycle, particularly land surface processes
and their interactions with the atmosphere. He is one of thefounding members of the Organizing Carbon and Hydrology
in Dynamic Ecosystems (ORCHIDEE) land-surface model at
IPSL and continues to participate in its development. Landsurface modeling was also the reason for his initial involvement
in GEWEX, where he led the creation of the Global Land/
Atmosphere System Study (GLASS) Panel panel in 1999.
In 2003, Dr. Polcher focused on regional climate problems
with the African Monsoon and Multidisciplinary Analyses(AMMA) project. He coordinated the project, which gathered 37 European and 22 African institutions around theobjective of enhancing our understanding of the West African Monsoon. AMMA also served to empower the African
research community to participate in research on climatechange. As chair of the GEWEX Hydroclimatology Panel(GHP), he continued to pursue that aim of enabling communities around the world to come together around regional
studies of the water cycle and its sensitivity to climate change
by encouraging new regional hydroclimate projects.
In the last few years, he has reunited his passion for modeling with his interest in regional water cycle issues by leading
the effort at IPSL to develop a regional climate model basedon the same components as those used for the global Earthsystem model. This effort is currently centered on the Mediterranean region and contributes to the Hydrological Cycle
in the Mediterranean Experiment (HyMeX) project. As thisregion’s water cycle is equally controlled by climate fluctuations and human water usage, Dr. Polcher is taking a keeninterest in including anthropogenic processes in land surface
models. This led him to accept the co-chair position for the
WCRP Grand Challenge on Water for the Food Baskets of
the World.
Throughout his career, Dr. Polcher has coordinated a numberof research projects funded by French and European agencies,
supervised or co-supervised 12 Ph.D. theses, and authored or
co-authored over 100 papers.
5Hydrology Section Student Subcommittee(H3S) Plans for the 2018 Fall AGU Meeting
Megan Brown
AGU H3S Chair

Process Evaluation Study on
Warm Rain (PROES-WR)
Kentaroh Suzuki1, Hanii Takahashi2,3, and Graeme
Stephens3,4
University of Tokyo, Kashiwa, Japan; 2Joint Institute for Regional Earth System Science and Engineering, Universityof California, Los Angeles, California, USA; 3Jet Propulsion
Laboratory, California Institute of Technology, Pasadena,
California, USA; 4University of Reading, Reading, UK
1

The Hydrology Section Student Subcommittee (H3S) of theAmerican Geophysical Union (AGU) is hosting a few fun
activities this summer on our Twitter account, @AGU_H3S,
including “Haiku Your Research.” We invite you to write a
Haiku about your research and tweet it to our account. On
Thursday, September 27, 2018 at 2:00 PM Eastern Daylight
Time, we will hold a webinar in conjunction with the Consortium of Universities for the Advancement of Hydrologic
Science, Inc. (CUAHSI) (https://www.cuahsi.org/community/
news-events/cuahsi-news-events/) called “H3S, AGU, and You:
Navigating the 2018 AGU Fall Meeting as a student or early
career Hydrology Section member.” We invite everyone tojoin us and let us know what you’d like to see at the AGU Fall
Meetings and during the year. H3S is currently in the midstof planning numerous activities, both in terms of professional development and social networking, for students andearly career scientists at the AGU Fall Meeting from 10–14
December 2018 in Washington, D.C. Our events will takeadvantage of our Washington, D.C. location and the beginning of AGU’s Centennial.
Currently we are planning two workshops at the Meeting,one on the tools of the trade for research and another focusedon representative spatial scales for hydrologic modeling. In
addition, we will be hosting up to five Pop-Up Talk Sessions,back in their original format of short lightning talks; watch
for a call for abstracts in early fall! The topics of our Pop-Up
Talk Sessions include:• Building Communities Through Shared Experiences:
Social Dimensions in AGU• Frontiers in Hydrology: Paths Toward the Next Century in Water Research• Hydrology for Public Good: Best Practices and Lessons
Learned from Community Engagement• The Role of a Scientist in the 21st Century: Big Ideas
for the Next 100 Years and How to Get There• Bridging Science and Policy for Change: Best Practices
We are also proposing two Town Hall sessions on alternative careers to academia. We hope everyone will join us at
our Fall Meeting events. Keep an eye on our Twitter account,@AGU_H3S, for updates and news!

Follow @AGU_H3S on Twitter!
6

The GEWEX Process Evaluation Study (PROES) has beenlaunched as a community effort intended to integrate observation-based metrics for a better understanding of key physicalprocesses critical to climate and to improve their representations in numerical weather prediction and climate models(Stephens et al., 2015), thereby advancing the models at their“building-block” level. The PROES concept is developed differently from the vast array of activities now part of modelinter-comparison efforts, requiring a more direct engagementwith modeling groups and tailored diagnostics from them.
PROES activities seek to work directly with model development groups specifically on targeted processes, develop critical diagnostic tools to test them, and collaborate with thosegroups to address biases that are exposed by the study. Warmrain formation is one such process that governs how cloudwater suspended in the atmosphere is converted into precipitation. It thus largely controls cloudiness, a fundamental
cloud characteristic determining the radiative effect and significantly impacting our ability to simulate the climate (Golaz
et al., 2013). The warm rain process is also a pathway central
to aerosol impacts on clouds, or the aerosol indirect effect, amajor uncertainty in climate projection that is often “tuned”
to reproduce historical temperature evolution in climate models (e.g., Penner et al., 2010; Golaz et al., 2013). The latest
PROES will focus on the warm rain process, developing new
diagnostic methodologies and providing data to constrain representations of warm rain processes in models.
GEWEX-PROES Warm Rain (PROES-WR)
The warm rain process is typically represented in numericalmodels through parameterizations for two modes of the water
conversion process, i.e., auto-conversion and accretion, which
express the water conversion rate in a way that depends on
mixing ratios and number concentrations of cloud and rainwater. The functional form dictating this dependency, however, is subject to large uncertainty, which is also a major sourceof uncertainty in estimates of the aerosol indirect forcing.
There is a critical need for better constraints on the fundamental uncertainty in model cloud physics, which would leadto more reliable estimates of the aerosol indirect forcing andthus climate projection.
Recent measurement capabilities offered by space-borne active
and passive sensors within the A-Train satellite constellation
enable the simultaneous observation of clouds and precipitaAugust 2018

Figure 1. The probability density function (color shading in the unit of %/dBZ) of radar reflectivity (abscissa) normalized as a function of in-cloudoptical depth (ICOD) increasing downward (ordinate), which is further classified according to different ranges of cloud-top particle sizes (5-10μm
and 15-20μm) and separately shown over ocean and land. The statistics are compared between A-Train satellite observations, the Pacific Northwest
National Laboratory’s Multi-scale Modeling Framework (PNNL-MMF) model, the Hadley Centre Global Environment Model version 2 (HadGEM2),
and the Geophysical Fluid Dynamics Laboratory Coupled Model (GFDL-CM3) (adapted from Suzuki et al., 2015, and Takahashi et al., 2017).

tion, which provides unprecedented information about thecloud-to-precipitation water conversion process on the global
scale. Motivated by this recent progress in satellite observations, the GEWEX PROES Warm Rain (PROES-WR) initiative aims to develop new diagnostic methodologies thatspecifically probe the warm rain process parameterizations exploiting multi-sensor satellite observations, and then serve as
observation-based metrics to constrain model representationsof the process. The methodologies combine multiple satellite
observables of cloud and precipitation to construct particularstatistics that “fingerprint” the warm rain process.
PROES-WR Metrics
Fig. 1 shows an example of statistics depicting how vertical microphysical structure tends to transition from non-precipitating to precipitating types when vertical profiles of radar reflectivity (the primary observable from CloudSat) are represented
in the form of the probability density function normalized asa function of cloud optical depth, a major Moderate ResoluAugust 2018tion Imaging Spectroradiometer (MODIS) observable, andfurther classified according to cloud-top particle size, anotherkey MODIS observable (Suzuki et al., 2010). The figure also
highlights an important difference of the microphysical transition over land compared to over ocean, which can be traced
to different updraft velocities, implying a significant impact ofdynamics on microphysics (Takahashi et al., 2017). The corresponding statistics obtained from some of the global climate
models enabled by the Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulator Package (COSP)
satellite simulator (Bodas-Salcedo et al., 2011) are also shownin Fig. 1. The model-satellite comparisons in this form expose
the propensity of models for producing rain too efficiently,
even when the cloud-top particle size is small (Suzuki et al.,2015; Jing et al., 2017). The model biases thus identified can befurther traced back to uncertainty in formulations of cloud microphysical parameterizations (Suzuki et al., 2015), implyingthat the satellite-based statistics are able to serve as a reference
to constrain the model cloud physics. The statistics depicted in7

Fig. 1 are one of the primary metrics that will be developed in
PROES-WR to evaluate global models against satellite observations.
Scope of PROES-WR
The PROES-WR intends to extend this type of model diagnostics analysis to multiple global models, including state-of-theart climate models and next-generation global cloud-resolving
models, to expose their biases in representations of the warm rain
process and to help improve the models at the fundamental process level. Eight different modeling groups are engaged in this effort and some have already provided simulated observations thatare currently being analyzed. The “process-oriented” model constraint will also be contrasted against “top-down” requirements
on model performance, such as reproducing historical climate
warming, to explore how the process-level model constraint impacts the macroscopic aspect of global climate and how error
compensations inherent in climate models manifest themselves
when the particular “building block” of the model is constrained.
References
Bodas-Salcedo, A., et al., 2011. COSP: Satellite simulation
software for model assessment. Bull. Amer. Meteor. Soc., 92,1023-1043, doi:10.1175/2011BAMS2856.1.
Golaz, J.-C., L.W. Horowitz, and H. Levy, 2013. Cloud tuning
in a coupled climate model: Impact on 20th century warming.
Geophys. Res. Lett., 40, 2246-2251, doi:10.1002/grl.50232.
Jing, X., K. Suzuki, H. Guo, D. Goto, T. Ogura, T. Koshiro,
and J. Mulmenstadt, 2017. A multi-model study on warm
precipitation biases in global models compared to satellite
observations. J. Geophys. Res. Atmos., 122, 11806-11824,
doi:10.1002/2017JD027310.
Penner, J.E., M.J. Prather, I.S.A. Isaksen, J.S. Fuglestvedt, Z.
Klimont, and D.S. Stevenson, 2010. Short-lived uncertainty?
Nat. Geosci., 3, 587-588.
Stephens, G.L., C. Jakob, and G. Tselioudis, 2015. The
GEWEX Process Evaluation Study: GEWEX-PROES.
GEWEX News, 27, no. 4, 4-6.

Meeting/Workshop Reports
Aerosol-Cloud-Precipitation Interactions:
Analysis of Satellite- and Ground-BasedData, and of Cloud-Resolving Modeling, in
the ACPC Initiative
Boulder, Colorado, USA
3–6 April 2018
Johannes Quaas1, Daniel Rosenfeld2, Meinrat Andreae3,
Graham Feingold4, Ann Fridlind5, Michael P. Jensen6,
Ralph Kahn7, Philip Stier8, Kentaroh Suzuki9, Sue vanden Heever10, Minghuai Wang11, Bethan White12, andRob Wood13
1
University of Leipzig, Germany; 2Hebrew University of Jerusalem, Israel; 3Max Planck Institute for Chemistry, Mainz,
Germany; 4NOAA, Boulder, USA; 5NASA Goddard Institutefor Space Studies, New York, USA; 6Brookhaven National
Laboratory, Upton, USA; 7NASA Goddard Space Flight Center, Greenbelt, USA; 8University of Oxford, UK; 9Universityof Tokyo, Japan; 10Colorado State University, Fort Collins,
USA; 11Nanjing University, China; 12Monash University, Melbourne, Australia; 13University of Washington, Seattle, USA

The goal of the Aerosols Clouds Precipitation and Climate(ACPC; www.acpcinitiative.org) initiative is to improve the understanding of the mechanisms by which aerosol perturbations
may modify clouds and precipitation, and to quantify the impact
these modifications may have on climate, particularly from theprocess to cloud field scale. The approach combines detailed observational studies with large eddy simulations and cloud-resolving and cloud-system-resolving models. Following the continued
progress of activities defined and discussed in a series of previous
meetings (e.g., Quaas et al., 2017), the ACPC group gathered at
the University of Colorado, Boulder, U.S., from 3–6 April 2018.

Suzuki, K., G. Stephens, A. Bodas-Salcedo, M. Wang, J.-C.
Golaz, T. Yokohata, and T. Koshiro, 2015. Evaluation of thewarm rain formation process in global models with satellite
observations. J. Atmos. Sci., 72, 3996-4014, doi:10.1175/JASD-14-0265.1.

At earlier meetings, the ACPC group defined two climaticallyimportant cloud regimes to study, deep convection and marine
boundary layer clouds, and formed specific sub-groups to define research objectives and roadmaps. The sub-groups at thismeeting reviewed topics ranging from pilot studies for tracking
convective cells and data analysis using an objective cell-tracking
algorithm for the deep convection regime to developing testable hypotheses for shallow clouds and conducting a joint investigation of warm rain processes from satellite data for cloudsystem resolving modeling. In both regimes, specific strategies
were chosen that aimed at detecting and attributing signaturesof aerosol effects on cloud and precipitation properties, using a
combination of modeling and analysis of observations.

Takahashi, H., K. Suzuki, and G. Stephens, 2017: Land-oceandifferences in the warm-rain formation process in satellite andground-based observations and model simulations. Q. J. Royal
Meteorol. Soc., 143, 1804-1815, doi:10.1002/qj.3042.

For the deep convective regime, the coastal region of Houston,
Texas, U.S. was selected to potentially distinguish between deep
convection influenced by aerosol emissions from the city and its
surrounding industry, and others, in the vicinity, that are not.

Suzuki, K., T.Y. Nakajima, and G.L. Stephens, 2010. Particle
growth and drop collection efficiency of warm clouds as inferred from joint CloudSat and MODIS observations. J. Atmos. Sci., 67, 3019-3032, doi:10.1175/2010JAS3463.1.

8

August 2018

Figure 1. A time series of the accumulated precipitation obtained from five of the different modeling frameworks being utilized to conduct
the “clean” (dashed lines) and “polluted” (solid lines) numerical experiments. The solid black line is the accumulated precipitation obtained
from the National Center for Environmental Prediction (NCEP)’s Stage IV quantitative precipitation estimate (QPE) multi-sensor product (figure produced by Max Heikenfeld and Peter Marinescu).
This coastal, urban area experiences convection throughout theyear with a significant peak in occurrence during the summertime months when onshore flow of moist air over the warm
land surface enhances convective initiation and propagation. In
terms of observations, a strong focus was put on the analysisof polarimetric radar data, with complementary observationsof aerosols, thermodynamics, and lightning. The methods already identified at the 2017 meeting have been refined in several ACPC pilot studies for application to tracking convective
cells using polarimetric radar observations and identifying how
processes (such as the microphysics in the updraft shafts) are
affected by various drivers. A chief conclusion of the tracking
pilot study is that operational weather radar observations canonly poorly resolve the rapid evolution of target convective cells,
strongly motivating efforts to deploy research-grade radars withadaptive scanning strategies. To optimize the strategy for an
observational identification of aerosol-convection interactions
from rapid-scanning instruments, radar forward simulations
from a regional model simulation (Tatarevic et al., 2018) werealso performed. The chief conclusions of the forward-simulation study are that radars should optimally be located less than
30 km away from the target for microphysical retrievals, andthat a network of three Doppler radars nearer than 10 km to thetarget would be optimal for vertical wind retrievals. Finally, four
years of operational weather data were analyzed using an objective cell-tracking algorithm. Results indicated the seasonality,
locations, frequency, and lifetime of typical isolated cells in the
Houston coastal region. On the basis of these and other results,
and on the basis of the ancillary observational information gathered by the ACPC group, a proposal was submitted to the U.S.
Department of Energy’s Atmospheric Radiation Measurement
Facility (DOE ARM) shortly after the Boulder workshop to
deploy instrumentation to observe the variability of convective
August 2018

cloud properties under varying aerosol conditions in the Houston area. The proposed campaign, which also benefits fromexisting operational meteorological, air quality, and lightning
networks, includes the yearlong deployment of a research-gradepolarimetric radar; detailed surface-based cloud, aerosol, andprecipitation measurements; and regular radiosonde profiling.
On the cloud system resolving modeling side of our twopronged model-observational approach, the investigation on
deep clouds has made substantial progress. A summer season
case study of isolated convective cells developing under onshore flow conditions in the Houston region was identified using a combination of ground-based weather radar and satellite
remote-sensing observations. An extensively tested case study
specification and experiment design were developed (van den
Heever et al., 2017). This included realistic bimodal aerosol
profiles representing clean versus polluted conditions in the
Houston area, derived from airborne in situ measurements obtained during NASA’s Deriving Information on Surface conditions from the Column and Vertically Resolved Observations
Relevant to Air Quality (DISCOVER-AQ) field campaign. Six
different modeling groups from Germany, England, Israel, andthe U.S. are contributing to the modeling study, thus highlighting the international collaborations facilitated by ACPC. Someemerging results about the aerosol-perturbation impact on theconvection were identified across models (e.g., shifts in precipitation intensity). However, substantial differences between themodels’ base state and response to aerosol perturbations remain,
as is evident from Figure 1 above. The chart demonstrates not
only variations in the magnitude of the precipitation responseto the aerosol perturbations, but also variations in the aerosolinduced trends. Once fully analyzed, the results of this investigation are to be published in the peer-reviewed literature.
9

With regard to shallow clouds, the group decided to shift thegeographical region of interest from the Southeast Pacific to
the Southeast Atlantic Ocean. Recent field campaigns in thisarea (Zuidema et al., 2016), including Cloud-Aerosol-Radiation Interactions and Forcing (CLARIFY-2016), DOE ARM
Layered Atlantic Smoke Interactions with Clouds (LASIC),
and the NASA Observations of Clouds above Aerosols andtheir Interactions (ORACLES), provide new insights, andmotivate a number of modeling studies within as well as outside the ACPC group. On the basis of science performed byseveral teams participating in ACPC, a few testable hypotheses
have emerged. On the one hand, model research has shownthat the cloud adjustments to aerosol-radiation interactions(also called the semi-direct effect) may lead to a net increasein low-cloud liquid water path (a net negative effect on theradiation budget; Stjern et al., 2017). Due to strong solar absorption by biomass burning aerosol (BBA) in the Southeast
Atlantic region, a combination of modeling and observations
may allow researchers to investigate and test this hypothesis.
On the other hand, large eddy simulations suggest a strong
microphysical impact of free tropospheric BBA mixed into theboundary layer on cloud persistence and the life cycle of liquidwater path in the stratocumulus-to-cumulus transition over
the Southeast Atlantic (Yamaguchi et al., 2017; Zhou et al.,2018). These large eddy simulations disagree on the impact
of entraining BBA on the transition, but differences in themodel set-ups used may be important. The group now plans
to coordinate studies with ongoing work for the Southeast
Pacific, its former area of focus, to identify trajectories along
the cloud-system life cycle derived from regional models todrive reference large eddy simulations. In combination withthe field campaign measurements and satellite observations,the aim is to corroborate or falsify the described hypotheses.
Considerable insight into co-variation of aerosols, clouds, andprecipitation can be gleaned from satellite retrievals. With regards
to liquid-water clouds, the droplet number concentration, Nd, isa key parameter, central to the quantification of effects of aerosol
perturbations on cloud properties. However, the retrieval of Ndfrom satellite data is prone to uncertainties, and in this regard it
was a major achievement of the ACPC group to produce a comprehensive review that quantifies these uncertainties and proposes avenues towards better measurements (Grosvenor et al., 2018).
A new initiative in the shallow clouds group is the joint investigation of warm rain processes from satellite data. The idea
is to combine a suite of existing methodologies developed foranalyzing satellite data to probe the process and its susceptibility to aerosols in an attempt to integrate different approaches of process-oriented analysis. This includes the warm rainfrom radar reflectivity vs. cloud optical depth joint histogram(Suzuki et al., 2010), the probability-of-precipitation metric(Wang et al., 2012), and the warm rain occurrence fraction(Mülmenstädt et al., 2015).
A follow-up workshop is planned for 24–26 April 2019 atNanjing University in China. The ACPC group welcomes interested researchers to join the activities.
10

References
Grosvenor, D.P., et al., 2018. Remote sensing of cloud droplet
number concentration in warm clouds: A review of the current state of knowledge and perspectives. Rev. Geophys., 56,
doi:10.1029/2017RG000593.
Mülmenstädt, J., O. Sourdeval, J. Delanoë, and J. Quaas, 2015.
Frequency of occurrence of rain from liquid-, mixed- and icephase clouds derived from A-Train satellite retrievals. Geophys.
Res. Lett., 42, 6502-6509, doi:10.1002/2015GL064604.
Quaas, J., D. Rosenfeld, M. Andreae, G. Feingold, A. Fridlind,
R. Kahn, P. Stier, K. Suzuki, S. van den Heever, and R. Wood,2017. First Results from ACPC Case Studies on Aerosol Effects
on Shallow and Deep Clouds. GEWEX News, 27, no. 2, 7-8.
Stjern, C.W., B.H. Samset, G. Myhre, P.M. Forster, Ø. Hodnebrog, T. Andrews, O. Boucher, G. Faluvegi, T. Iversen, M.
Kasoar, V. Kharin, A. Kirkevåg, J.-F. Lamarque, D. Olivié,
T. Richardson, D. Shawki, D. Shindell, C.J. Smith, T. Takemura, and A. Voulgarakis, 2017. Rapid adjustments cause
weak surface temperature response to increased black carbon
concentrations. J. Geophys. Res. Atmos., 122, 11462–11481,
doi:10.1002/2017JD027326.
Suzuki, K., T.Y. Nakajima, and G.L. Stephens, 2010. Particle
growth and drop collection efficiency of warm clouds as inferred from joint CloudSat and MODIS observations. J. Atmos. Sci., 67, 3019–3032, doi:10.1175/2010JAS3463.1.
Tatarevic, A., P. Kollias, M. Oue, et al., 2018. User manual CR-SIM
software v3.1. 84 pp., available at https://www.bnl.gov/CMAS/cr-sim.php.
van den Heever, S., A.M. Fridlind, P.J. Marinescu, M. Heikenfeld, B. White, and P. Stier, 2017. Aerosol-Cloud-PrecipitationClimate (ACPC) Initiative: Deep Convective Cloud Group
Roadmap. 13 pp., available at http://acpcinitiative.org/Docs/
ACPC_DCC_Roadmap_171019.pdf.
Wang, M., S. Ghan, X. Liu, T.S. L’Ecuyer, K. Zhang, H. Morrison, M. Ovchinnikov, R. Easter, R. Marchand, D. Chand,
Y. Qian, and J.E. Penner, 2012. Constraining cloud lifetime
effects of aerosols using A-Train satellite observations. Geophys.
Res. Lett., 39, L15709, doi: 10.1029/2012GL052204.
Yamaguchi, T., G. Feingold, and J. Kazil, 2017. Stratocumulus to cumulus transition by drizzle. J. Adv. Model. Earth Syst.,
9(6), 2333-2349, doi:10.1002/2017MS001104.
Zhou, X., A.S. Ackerman, A.M. Fridlind, and P. Kollias, 2018.
Simulation of mesoscale cellular convection in marine stratocumulus. Part I: Drizzling conditions. J. Atmos. Sci., 75, 257274, doi:10.1175/JAS-D-17-0070.1.
Zuidema, P., J. Redemann, J. Haywood, R. Wood, S. Piketh,
M. Hipondoka, and P. Formenti, 2016. Smoke and Clouds
above the Southeast Atlantic: Upcoming Field Campaigns
Probe Absorbing Aerosol’s Impact on Climate. Bull. Amer. Meteorol. Soc., July 2016, 1131-1135.
August 2018

Joint WCRP Grand Challenge on Weather
and Climate Extremes/GEWEX GDAPWorkshop on Precipitation Extremes• Identify the form of a new International Precipitation
Working Group (IPWG)/GEWEX Precipitation assessment chapter on extreme precipitation, including theselection of chapter leads and other contributors

DWD, Offenbach, Germany
9–11 July 2018

• Finalize a best practice guidance document for the
WCRP Extremes GC on data use for assessing precipitation extremes, including the consideration of satellitebased measurements

Lisa Alexander1, Rémy Roca2, Sonia Seneviratne3,
Andreas Becker4, Ali Behrangi5, Steefan Contractor1,
Felix Dietzsch4, Markus Donat1, Robert Dunn6, Hayley
Fowler7, Chris Funk8, Adrien Guérou9, Rainer Hollmann4, Pierre Kirstetter10, Katharina Lengfeld4, Maarit
Lockhoff4, Hirohiko Masunanga11, Heewon Moon3,
Caroline Muller9, Marc Schroeder4, Udo Schneider4,
Yukari Takayabu12, V. Venugopal13, Martin Werscheck4
University of New South Wales, Sydney, Australia;
Laboratoire d’Etudes en Geophysique et Oceanographie
Spatiales, Toulouse, France; 3ETH Zürich, Zürich, Switzerland; 4Deutscher Wetterdienst, Offenbach, Germany;
5
University of Arizona, Tucson, USA; 6Met Office, Exeter,UK; 7Newcastle University, Newcastle upon Tyne, UK; 8US
Geological Survey/University of California Santa Barbara,
Santa Barbara, USA; 9Centre National de la Recherche
Scientifique, Toulouse, France; 10University of Oklahoma
Advanced Radar Research Center/NOAA National Severe
Storms Laboratory, Norman, USA; 11Nagoya University,
Nagoya, Japan; 12University of Tokyo, Tokyo, Japan; 13Indian Institute of Science, Bangalore, India
1
2

The WCRP Grand Challenge (GC) on Weather and Climate Extremes and the GEWEX Data and Analysis Panel(GDAP) held a joint workshop on “Precipitation Extremes”
at Deutscher Wetterdienst (DWD) in Offenbach, Germany
from 9-11 July 2018. The workshop objectives were to:• Integrate the efforts of the remote sensing community
in the literature on precipitation extremes that will beassessed for the Intergovernmental Panel on Climate
Change (IPCC) Sixth Assessment Report (AR6)The workshop had 23 invited participants, bringing together
experts from the communities addressing climate-scale perspectives in extreme precipitation observations to identify gaps
and agree on common goals for future work.
As part of the groundwork for the meeting, the organizers prepared a range of satellite-based, ground-based, and reanalysis
datasets in the same format and on the same grid so that these
could be compared and assessed at the workshop. Preliminary
investigations performed by participants during the event werepromising, highlighting both discrepancies and convergences
between datasets.
In order to meet the workshop objectives, participants prepared an outline for a journal special issue on the topic of precipitation extremes and remote sensing datasets. The purposeof this special issue is to address the three main workshop objectives and inform the broader research community of these
efforts. Lead authors for publications of the special issue wereagreed upon and submission of the articles is planned for December 2018. We expect as an outcome that satellite-based
products may be more extensively used in the climate extremes
community, and in addition, the remote sensing community
may identify avenues for future product development
dedicated to extremes research. A community-based
guidance document will also
be developed on the use andreliability of datasets for assessing precipitation extremes
targeted primarily at aiding
global climate model evaluation.
The group endorsed the outcomes of the workshop as
contributing to key goals of
WCRP GC on Extremes,
GDAP, and the joint effort
on precipitation by GDAP
and IPWG.

Participants of the Precipitation Extremes Workshop

August 201811

Annual GLASS Science Panel Meeting
Canmore, Alberta, Canada
3–4 May 2018
Michael Ek1, Gab Abramowitz2, and the GEWEX GLASS
Panel3
1
The National Center for Atmospheric Research, Boulder,
USA; 2Climate Change Research Centre, University of New
South Wales, Sydney, Australia; 3For more information on
the GLASS Panel members, visit https://www.gewex.org/
panels/global-landatmosphere-system-study-panel/glasspanel/

The Global Land/Atmosphere System Study (GLASS) Science Panel Meeting was held prior to the 8th GEWEX OpenScience Conference at the Coast Canmore Hotel and Conference Centre in Canmore, Alberta, Canada from 3–4 May
2018, with 21 panel members and guests attending (six remotely). As in previous meetings, community activities under the three GLASS Panel elements were reviewed: (1) landmodel benchmarking to improve understanding and representation of land surface processes, (2) land-atmosphere interaction and feedbacks, and (3) the role of land surface inpredictability, as well as associated GEWEX projects and related crosscut activities.
LoCo 						The Local Land-Atmosphere Coupling (LoCo) project andworking group (WG) updates were presented by Joe Santanello. LoCo science, modeling, and observational advances
made over the last year include publishing a Bulletin of theAmerican Meteorological Society overview article in June 2018,
convening Land-Atmosphere (L-A) sessions at the American
Geophysical Union and American Meteorological Society
meetings, producing numerous WG publications across anarray of L-A focal areas, launching field campaigns focusedon L-A interactions (Land-Atmosphere Feedback Experiment,
LAFE; August 2017) and irrigation (Great Plains Irrigation
Experiment, GRAINEX; summer 2018), pushing to improveplanetary boundary layer (PBL) observations in the 2017 National Research Council (NRC) Decadal Survey, and providing input to the U.S. Climate Modeling Summit on advancing L-A coupling metrics in global climate models (GCMs).
Much progress has been made over the last decade on developing and applying a range of integrated metrics across scales(Fig. 1 on the next page), and producing public resources suchas the LoCo Metrics “Cheat Sheets” (http://cola.gmu.edu/dirmeyer/Coupling_metrics.html) and Coupling Metrics Toolkit(CoMeT; http://www.coupling-metrics.com). As the broader
atmospheric and hydrological/land surface communities continue to learn the importance of integrated, quantitative diagnostics in model development, LoCo will continue to growand play a pivotal role in delivering metrics and approaches toimproving L-A understanding and prediction.
12

PLUMBER, PALS, and Land Data Assimilation		Martyn Clark led a discussion on the next phase of the landmodel benchmarking experiment called Protocol for the Analysis of Land Surface models (PALS) Land Surface Model Benchmarking Evaluation Project-2 (PLUMBER2), which will havea greater process-oriented focus. The goal is to ask all participants to run their models for a larger number of sites and toprovide much more comprehensive model output, such as allstates, fluxes, and parameter values. More model output will allow us to reconstruct model parameterizations (e.g., by plotting
fluxes against states) and hence figure out why different models
behave differently. More sites will enable us to examine the data
in different ways, and understand model behavior under different environmental conditions. This experiment will greatly
improve our insight into land model weaknesses. As part of
PLUMBER2, a land data assimilation (DA) component will be
introduced where model-run variants employing assimilation of
remote sensing data will be encouraged and later used to assessthe utility of remote sensing data towards model benchmarking.
The PALS web application used for the original PLUMBER experiment is transitioning to a new, more flexible workflow andarchitecture at https://modelevaluation.org (“PALS2”). Creating
new and more varied analyses, PALS2 will support public community participation in the analysis of the new process-oriented
PLUMBER2 experiment. It also allows use of observational
datasets for analyses that are not downloadable by users, potentially removing a barrier to better integration of the land-surface
modeling and data collection communities.
GSWP3 and LS3MIP					Hyungjun Kim gave an update on the status of the Global
Soil Wetness Project Phase 3 (GSWP3) and the Land Surface, Soil-moisture, and Snow Model Intercomparison Project(LS3MIP). The GSWP3 forcing dataset has been updated in
response to community feedback, and the official version has
been tested carefully and packaged for release. LS3MIP had akick-off meeting in September 2017 with participants from15 institutions where nine modeling groups reconfirmed theircontributions. A wiki has been set up to share feedback andup-to-date information (https://wiki.c2sm.ethz.ch/LS3MIP).
Also, Hyungjun is acting as a liaison between the GLASS and
Coupled Model Intercomparison Project (CMIP) communities to expand Climate and Forecast (CF) metadata conventions to cover variables newly requested by LS3MIP. Sometechnical features to be incorporated in CMIP6, including
data requests, are still being adjusted.
ILAMB and LUMIP					David Lawrence discussed the International Land Model
Benchmarking version 2 (ILAMBv2) package that is currently being utilized by several modeling centers. The ILAMB
metrics protocol is documented in Collier et al., 2018. New
datasets continue to be added, including some for GEWEXrelated quantities including snow depth, permafrost extent,
and evaporative fraction. A diurnal cycle metrics package isunder development. Focus over the next year will be to implement more process-oriented metrics including metrics on
August 2018

snow thermal insulation, snow-albedo feedbacks, soil carbon
turnover times, and potentially dry-down responses. ILAMB
continues to prepare for CMIP6 results and will be applied to
the LS3MIP land-history simulations. Dave also provided updates on the Land Use Model Intercomparison Project (LUMIP) and the Land-Use Harmonization version 2 (LUH2)
dataset. This recently-released dataset describes land use andland management for the years 850 to 2100. LUMIP is mainly on hold at this stage until model simulations start to become available in 2018 and 2019. A “LandMIPs in CMIP6”
workshop is planned for October 2018 in Toulouse, France.
Groups have begun to register their interest in analyses of the
LUMIP simulations at the LUMIP webpage (https://cmip.ucar.
edu/lumip).

of common interest shared between GLASS and its sister panel. Two continuing GASS projects of particular interest are (1)the Clouds Above the United States and Errors at the Surface(CAUSES) project, which is concerned with identifying the
deficiencies in models that lead to a prevalent warm bias in thecentral U.S. in summer and has led to four papers this year,
e.g., Morcrette et al., 2018; and (2) the GEWEX Atmospheric
Boundary Layer Study phase 4 (GABLS4), which is concernedwith the simulation of the diurnal cycle in summer on the
Antarctic Plateau and the role of the stable boundary layer.
Potential projects of particular interest to GLASS concern themodeling of fog, the representation of momentum drag, andthe influence of the initial state of the land surface and thesnow pack on seasonal forecasts.

Joint Projects and Crosscut Activities

GHP							Craig Ferguson, GLASS liaison to the GEWEX Hydroclimatology Panel (GHP), reported on current GHP activities andplans. Notably, there are three tentative Regional Hydroclimate Projects (RHPs), the Hydroclimate Research Program

GASS							John Edwards, GLASS liaison to the GEWEX Global Atmosphere Systems Studies (GASS) Panel, considered several areas

Figure 1. LoCo metrics across temporal scales (x-axis), relationship to the LoCo process-chain connecting soil moisture to precipitation along they-axis, and statistical vs. process-based nature of each (elliptical outlines). Green background shading indicates land surface related states andfluxes, while blue indicates PBL and atmospheric variables.

August 201813

core members of the LIAISE science team are seeking funds tocomplete the campaign. It is anticipated that this project willlead to several GLASS-GASS-GHP community experiments.
Pere Quintana Seguí, liaison to the GLASS Panel from the
GHP RHP Hydrological cycle in the Mediterranean Experiment (HyMeX), reported that the HyMeX Drought and Water Resources Science Team (HyMeX DWR) is working on anenhancement to the studies of drought at the Mediterranean
scale, gathering data that covers the entire region in order tobetter understand drought and drought-related mechanisms inthis area. HyMeX DWR is investing in land-surface modelingand remote sensing to improve knowledge of the continental
water cycle, including the impacts of irrigation. The LIAISE
field campaign, which was discussed at the HyMeX workshop
in May, will study land-surface processes in semi-arid areas
and the impact of irrigation on both the atmospheric boundary layer and hydrology.
Participants at the GLASS Meetingfor the Andes (ANDEX), the Land-surface Interactions with
the Atmosphere over the Iberian Semi-arid Environment (LIAISE) project (discussed below), and a potential U.S. RHP,
all responsive to the World Climate Research Programme’s
GEWEX-led Grand Challenge on Water for the Food Basketsof the World. The fully-active HyMeX and initiating PannEX
RHPs also have research thrusts in isolating the role of land
and water management on local climate predictability. The
proposed GHP crosscut on Water Management in Models
would serve to support and coordinate modeling aspects ofthis work. GLASS is particularly well-positioned to contributeto the development, implementation, and evaluation of water management representation in land models following the
PALS/PLUMBER benchmarking framework.
Aaron Boone gave an update on the potential GHP RHP
called LIAISE, noting that one of the biggest challenges facing environmental science is understanding future changes inthe terrestrial water cycle and the subsequent impact on water
resources. In particular, climate projections predict that theMediterranean region will be a so-called climate change “hotspot” during the twenty-first century. The LIAISE projectseeks to address the challenges posed by modeling semi-arid
regions with a field campaign in 2020 that will bring together ground-based and airborne measurements with modelingstudies to lead to an improved understanding of processes
such as soil moisture, evapotranspiration, and precipitation
through atmospheric coupling and the subsequent feedbacks
to the Mediterranean atmospheric boundary layer and basinhydrology, including aspects like streamflow and instances ofhuman influence such as irrigation and water extraction methods. In 2018, a workshop was held in January at the University of Barcelona with members of the Spanish research community, and the status of the project was presented during the
HyMeX Workshop (May 2018, Lecce, Italy). Currently, the14

SoilWat					Anne Verhoef gave a summary of the GEWEX Soil and Water Initiative (SoilWat) Pedotransfer Functions (PTF) activity,
which relates to testing and improving soil hydraulic and thermal properties in land-surface models (LSMs). Activities so far
involve testing the effect of (1) different PTFs and hydraulicmodels (Mualem-van Genuchten vs. Brooks-Corey) on water flow simulation and (2) different hydraulic functions and
PTFs and thermal functions (and related thermal PTFs) on
the energy and water balance, the soil (surface) temperature,and soil moisture content. Model runs were conducted with
Hydrus-1D for 14 years (2001-2014) with half-hourly datafrom Avignon, France for a bare soil profile, with various landmodel thermal equations implemented in Hydrus-1D for thisexercise. Thermal conductivity was also compared with measured values. Large differences were found between the various
LSMs, both for the hydraulic and thermal functions and forthe fluxes, but less so for the state variables (for the thermalruns). These results will be described in a journal publication.
The community plans further activities, including the creationof a global map of thermal parameters. Matthias Cuntz reported on another SoilWat activity, the Soil Parameter Model
Intercomparison Project (SP-MIP), which is assessing the influence of soil parameters on the variability of LSMs, where
SP-MIP follows LS3MIP conventions as closely as possible.
Currently, eight modeling groups have committed, half ofwhich have already started or even finished the experiments,
while the other half are scheduled to complete their runs thissummer.
Urban Effects in Land Models				Mathew Lipson presented an overview on including urban
effects in land models, i.e., the Project for Intercomparisonof Land Surface Parameterization Schemes (PILPS)-Urban,
the first (offline) urban land model intercomparison project(Best and Grimmond, 2015). The urban representations providing most benefit were an appropriate urban bulk albedo,
radiation reflections within street canyons, separate roof andstreet canyons, and urban vegetation. However, simpler urban
August 2018

models performed similarly well for the scales of weather andclimate models, so new and more complex processes should
not be included unless it can be demonstrated that they provide additional benefits. The Single-column Urban Boundary
Layer Inter-comparison Model Experiment (SUBLIME) was
also reviewed, where urban land model runs with and withoutboundary layer interactions were made over central London
for two days; submissions are complete and the first results
will be presented at the International Association for Urban
Climate (ICUC) conference in August 2018. Also discussed
was a suggestion to run PLUMBER-style experiments formany urban flux sites that differ in their urban characteristics,
with a potential to use the new PALS2 framework. Future fociinclude urban boundary layer theory, observations and modeling, and human behavioral drivers and impacts (e.g., Barlow
et al., 2017).
S2S							Paul Dirmeyer updated the Panel on Subseasonal to Seasonal(S2S) efforts relevant to GLASS. The International S2S Prediction Project (https:www.s2sprediction.net) is coming to theend of its original 5-year mandate for global operational centers to produce S2S hindcast and forecast data sets. A proposal
for a second 5-year phase, which would have a much stronger
emphasis on the role of land surface in S2S prediction, wassubmitted to WMO in February 2018. Three core questions
relevant to GLASS research are proposed: What is the impactof the observing system on land initialization and S2S forecasts? How well are the coupled land-atmosphere processes
represented in S2S models? How might anomalies in land surface states contribute to extremes? In the U.S., the National
Oceanic and Atmospheric Administration (NOAA)’s S2S Task
Force, comprised of investigators funded by the NOAA Climate Project Office, includes two projects with direct GLASS
relevance, one led by Trent Ford (Southern Illinois University)and the other by Zhichang Guo (George Mason University).
A sister NOAA-supported effort called SubX is similar to the
S2S Prediction Project except that it includes research/climate
models, enforces greater consistency among models to promote multi-model ensemble studies, and is somewhat betterat saving output variables relevant to land-atmosphere interactions. Lastly, the annual U.S. Climate Modeling Summit
featured a workshop on land-atmosphere interactions, which
was an opportunity to educate U.S. agency leadership at thesix U.S. climate modeling centers and their funding agencies about the scientifically-established impact of land surface
feedbacks on climate. The U.S. modeling community is now
more aware and highly interested in GLASS-led activities
and scientific progress, and is exhibiting some momentum toencourage enhanced efforts toward L-A-related model assessment and development.
Other							Paul Dirmeyer and Mike Ek attended the World Climate
Research Programme (WCRP) Monsoon Panel side meeting
during the May 2018 GEWEX Open Science Conference,
where understanding and modeling land-hydrology processes
are key in representing monsoon circulations. Eleanor Blyth
August 2018

talked about synergies between GEWEX and the Integrated
Land Ecosystem-Atmosphere Processes Study (iLEAPS) and“Future Earth”, including possible collaborations. In particular, PLUMBER2 should include carbon fluxes in addition toenergy and water, with a joint workshop on land surface modeling to be held in Oxford in 2020 focusing on the impact ofcarbon dioxide on water use efficiency. Mike Ek briefed thePanel on liaison activities with the WMO Working Group on
Numerical Experimentation (WGNE) and the WCRP Modelling Advisory Council (WMAC). WGNE is interested in
improving global weather and climate models and WMAC
coordinates high-level aspects of modeling across WCRP.
GLASS presence in these groups focuses on improving landmodeling and land-atmosphere interaction, particularly landdata assimilation in the case of WGNE. Kun Yang noted thehigh spatial heterogeneity of land properties and the associated uncertainties in specifying parameters used in land model
parameterizations. To address this challenge, he suggested that
it is perhaps time to promote methods for deriving land parameters and calibrating land surface models through satellite
remote sensing and data assimilation (e.g., Yang et al., 2016;
Pinington et al., 2018). This and other related activities should
be explored further as possible areas to increase collaboration
with the GEWEX Data and Analysis Panel (GDAP).
References
Barlow, J., et al., 2017. Developing a research strategy to better understand, observe, and simulate urban atmospheric processes at kilometer to sub-kilometer scales. Bull. Am. Meteorol.
Soc., doi.org/10.1175/BAMS-D-17-0106.1.
Best, M.J., and C.S.B. Grimmond, 2015. Key Conclusions of
the First International Urban Land Surface Model Comparison Project. Bull. Am. Meteorol. Soc., doi.org/10.1175/BAMSD-14-00122.1.
Collier, N., F.M. Hoffman, D.M. Lawrence, G. Keppel-Aleks,
C.D. Koven, W.J. Riley, M. Mu, and J.T. Randerson, 2018.
The International Land 1 Model Benchmarking (ILAMB)
System: Design, Theory, and Implementation. Submitted to
J. Adv. Model. Earth Sy.
Morcrette, C.J., and co-authors, 2018. Introduction to
CAUSES: Description of weather and climate models andtheir near‐surface temperature errors in 5-day hindcasts
near the southern Great Plains. J. Geophys. Res.-Atmos., doi.
org/10.1002/2017JD027199.
Pinnington, E., T. Quaife, and E. Black, 2018. Impact of remotely-sensed soil moisture and precipitation on soil moistureprediction in a data assimilation system with the JULES land
surface model. Hydrol. Earth Syst. Sc., 22, 2575-2588.
Yang, K., et al., 2016. Land surface model calibration throughmicrowave data assimilation for improving soil moisture simulations. J. Hydrology, 533, 266-276.
15

Nominations Open for 2018 Data andModeling Prizes
The World Climate Research Programme (WCRP), together
with the World Weather Research Programme (WWRP) and
the Global Climate Observing System (GCOS), is awarding
two prizes for notable achievements in model and data development. The “WCRP/WWRP International Prize for Model
Development” has been awarded since 2014 for outstanding
contributions to model development by WCRP and WWRP. In
2016, the “WCRP/GCOS International Data Prize” was established by WCRP and GCOS to reward climate or Earth systemdata that has had a tangible impact on the community.
The WCRP/WWRP International Prize for Model Development will be awarded to an early- to mid-career researcher
for an outstanding contribution to model development for the
Earth System, its components, and their coupling. Candidates
should be within the first ten years of their career as measured
by receipt of a Ph.D. or highest qualification; made a significant
contribution to the development of a model with a demonstrable
impact on the model results; and engaged with the wider community through achievements such as publications, editorships,
organizing/convening activities, operational implementation,or strong engagement in national and international modelingprograms.
The WCRP/GCOS International Data Prize is awarded annually to an early- to mid-career researcher for his or her outstanding contribution to the Earth system science community. The
Prize may honor achievements in data product generation,
data management, data preservation, data monitoring, andother data relevant activities. In particularly successful cases,
the establishment of standards or infrastructure for global
data repositories may be considered for eligibility. Candidates
should be within the first ten years of their career as measured
by receipt of a Ph.D. or highest qualification; made a significant contribution to the provision of climate or Earth systemdata, preferably with a visible impact on and by studies basedon said data; and have visible achievements within the wider
community as demonstrated through publications, editorships,
organizing or convening activities, and/or strong engagement
in community efforts for data provision, standardization, andutilization.
Together, these two prizes for notable achievements in modeland data development aim to recognize and foster research
activities in their respective fields, as well as stress their mutual interdependence.
Nominations are now open for 2018, and the deadline is 1
October 2018. For details, see each respective announcement page:• WCRP/WWRP International Prize for Model Development 2018: https://www.wcrp-climate.org/wmac-activities/ipmd-2018• WCRP/GCOS International Data Prize 2018: https://www.wcrp-climate.org/wdac-activities/idp-2018

16

GEWEX/WCRP Calendar
For the complete Calendar, see http://www.gewex.org/events/
27–31 August 2018—NASA JPL Center for Climate Sciences Summer School 2018— Pasadena, California, USA
3–7 September 2018—EMS Annual Meeting: European Conference for Applied Meteorology and Climatology 2018—Budapest,
Hungary
4–6 September 2018—2nd GEWEX Convection-Permitting Climate
Modeling Workshop—Boulder, Colorado, USA
4 September 2018—4th PannEx Workshop: The ELTE Meeting—
Budapest, Hungary
10–19 September 2018—Potsdam Summer School 2018: The Skinof the Earth - The Earth Surface System—Potsdam, Germany
17–19 September 2018—International Conferences on Subseasonal to Decadal Prediction—Boulder, Colorado, USA
24–26 September 2018—8th Third Pole Environment (TPE) Workshop—Gothenburg, Sweden
1–5 October 2018—SPARC General Assembly—Kyoto, Japan
16–18 October 2018—IV International Conference on El Niño
Southern Oscillation: ENSO in a Warmer Climate—Guayaquil, Ecuador
22–26 October 2018—2018 ANDEX/GHP/INARCH Meetings—
Santiago and Portillo, Chile
22–23 October 2018—GEWEX UTCC PROES Workshop—Paris,
France13–16 November 2018—2018 WCRP Workshop: The Earth’s Energy Imbalance and Its Implications (EEI)—Toulouse, France
26–29 November 2018—2018 GEWEX Data and Analysis Panel(GDAP) Meeting—Lisboa, Portugal
10–14 December 2018—2018 AGU Fall Meeting—Washington,
D.C., USA
6–10 January 2019—99th Annual AMS Meeting—Phoenix, Arizona,USA
25 February – 1 March, 2019—GEWEX SSG-31—Geneva, Switzerland

GEWEX NEWS
Published by the International GEWEX Project OfficePeter J. van Oevelen, Director
Shannon F. Macken, Editor
International GEWEX Project Officec/o USRA
425 3rd Street SW, Suite 605
Washington, DC 20024 USA
Tel: 1-202-527-1827
E-mail: gewex@gewex.org
Website: http://www.gewex.org

August 2018