Vol. 24, No. 4 | Quarter 4 2019
GEWEX is a Core Project of the World Climate Research Programme on Global Energy and Water Exchanges

LS4P and TPEMIP:

Third Pole Land Surface and Subsurface Temperatures
May Have Substantial Remote Predictive Capability for
Subseasonal to Seasonal Precipitation

Inside This
EditionCommentary and NewsGEWEX to update its science
plan; a next-generation ISCCP
is in the works [2]
Bob Schiffer, pillar of the
GEWEX community, retires
this fall [3]Remembering Chuck Long [4]GeneralA new initiative studies landatmosphere interactions incold environments [4]Aerosol-cloud interactions playa progressively larger role inmodulating the occurrence andcharacteristics of heatwaves [6]Meeting Reports
The 8th G-VAP workshop concludes with new recommendations to produce global humidity profiles and troposphericwater vapor isotopologue data,
among other suggestions [10]Figure 1 (top). Figure 1. Comparison between observed anomalies and LS4P 20-Model Ensemble mean bias. 1(a) and 1(b) Observed May 2003 T-2m and June 2003 precipitation anomalies, respectively; 1(c) and 1(d) LASP model ensemble mean May 2003
T-2m bias and June 2003 precipitation bias when models have cold bias over the TP.
Every model has a large T-2m bias over the Tibetan Plateau area. For models with positive T-2m bias, the T-2m and precipitation biases are multiplied by -1 to be included in
the composite. Note: color scales are shown in Figure 2.
Figure 2(a) and 2(b) (bottom). Eight LS4P model ensemble mean for the May 2003
T-2m anomaly and June 2003 precipitation anomalies, respectively, after imposing an
LST/SUBT anomaly at the first model integration step.

The HyMeX Regional Hydroclimate Project is wrapping up
in 2020, but three ongoing field
campaigns may be a segue toa future project [12]The GLASS Panel reviews
current projects and discusses potential land-atmosphere
feedback observatories at its
annual meeting [15]Commentary:
Updates to the GEWEX Science Plan
Graeme Stephens
Co-Chair, GEWEX Scientific Steering GroupThe very first GEWEX newsletter released in spring 1991 provided contributions by both Dr. Moustafa Chahine, the Chairof the GEWEX Scientific Steering Group (SSG), and Professor
Pierre Morel, Director of WCRP. While Dr. Chahine outlined
the objectives of GEWEX that shaped the program for many
years to come, Professor Morel offered the insight that "A little
thought about the problem of climate and climatic variations
leads to an understanding that the main difficulty lies with getting the coupling right between the different components ofthe climate system, the global atmosphere, the world oceans,land and sea ice and the land surface hydrology including snow
and vegetation." Although both WCRP and GEWEX have
evolved from that time, many aspects of Morel's vision remaintrue today. As WCRP undergoes a reorganization and develops
its strategic plan for the coming years, its focus remains true toMorel's insight that the emphasis will be toward developing amore quantitative understanding of climate processes, which
are necessary for “getting the coupling right between the different components of the climate system.”
Water and its energy content are the main physical quantities that couple the different components of the climate system. GEWEX grew out of the realization springing from the
Global Atmosphere Research Programme (GARP) that there
was little understanding of the global energy and water budgets, and that this was not about to change with the major
programs of the time like the World Ocean Circulation Experiment (WOCE) and the Tropical Ocean and Global Atmosphere Project (TOGA). It also developed from the emergenceof global observations that served as a foundational elementof the program, such as the impending observations promised by the National Aeronautics and Space Administration(NASA)'s Earth Observing System (EOS) and satellite observations already being developed for the International Satellite
Cloud Climatology Project (ISCCP) and other efforts. Today,
GEWEX provides stewardship of major global climate data
sets that relate to understanding Earth's water and energy
budgets, and is influential in the development of the next generation of critical observations.
In late January 2020, the SSG will meet in Pasadena, California to complete the definition of GEWEX science plan. The
science plan is framed around three overarching objectives:
1. Prediction: the extent to which Earth's water cycle can bepredicted
2. Process: quantify the inter-relationships between the energy and water cycles
3. Anthropgenic Influences: measure the anthropogenic influences on Earth's water cycle
Key to progress are the initiatives being developed aroundboth modeling and observations. One of the new projects,
and one that may well be a flagship effort of WCRP, is thedevelopment of the next-generation version of the ISCCP, acoordinated effort across major operational satellite organizations to create global, high-resolution in space and time data
products (order 2km global, 10 minute) on clouds and related information that will have many applications. This isan ambitious plan and it has received great interest. The firstplanning meeting was held 28-30 October 2019 at the European Organisation for the Exploitation of Meteorological
Satellites (EUMETSAT) in Darmstadt, Germany. A strategicplan for the ISCCP-next generation is being drafted out ofthe deliberations of that meeting. A summary of that plan will
be provided in a forthcoming GEWEX newsletter. Initiatives
such as the new iteration of ISCCP will dovetail well with therefreshed objectives of the GEWEX science plan and provide afoundation for studying the prediction, processes and anthropogenic influences on the water cycle.

Table of Contents
Meeting and Workshop Reports

Commentary and News
Commentary: Updates to the GEWEX Science Plan

2

Retirement of Dr. Robert (Bob) A. Schiffer

3

In Memoriam: Chuck Long

4

GeneralLATICE—Land-Atmosphere Interactions in Cold
Environments
Understanding Aerosol-Cloud Interactions is Key for
Reliable Future Heatwave Projections

2

Remote Effects of Tibetan Plateau Spring Land Surface
Temperature on Global Summer Precipitation and its S2S
8Prediction: Second Workshop on LS4P and TPEMIPThe GEWEX Water Vapor Assessment (G-VAP):
Summary of the 8th Workshop

10

Report of the 12 HyMeX Workshop

12

GLASS Panel 2019 Annual Meeting

15

Alaska Soil Moisture and Wetland Mapping Validation
Workshop

18

GEWEX/WCRP Calendar

20

th

4
6

Quarter 4 2019

Retirement of Dr. Robert (Bob) A. SchifferPeter van Oevelen
Director, International GEWEX Project Office

On November 30, 2019, after 57 years of service at the National Aeronautics and Space Administration (NASA) [at the
Jet Propulsion Laboratory (JPL); NASA Headquarters; theGoddard Space Flight Center; University of Maryland, Baltimore County (UMBC); and the Universities Space Research
Association (USRA)], Bob Schiffer is retiring. Bob has been
one of the critical pillars of GEWEX since its inception, andhas been an excellent advisor, fabulous sound board and awonderful colleague to work with during my 15 years in the
GEWEX orbit. Bob’s professional experience, which is detailed
below, is characterized by great depth and breadth. He shouldbe very proud of all his accomplishments! I am grateful for all
the years I have had the pleasure of working with him, sitting
through many a meeting, putting out organizational fires, fixing programmatic issues and enjoying pleasant lunches andwonderful dinners. Bob, I thank you on behalf of the entire
GEWEX community, which is truly indebted to you. We wish
you much enjoyment during your retirement. I know I will
miss you, and I hope I can still call on you from time to time
for sage advice and to reminisce about the good old times!
Dr. Robert A. Schiffer served as Principal Scientist at USRA in
Columbia, MD. He retired from NASA in 2002 after 39 total
years of service, including 11 years as a research scientist andengineer at JPL and 28 years at NASA Headquarters in Washington, D.C., where he was Chief of the Atmospheric Sciences
Branch and then Deputy Director of the Research Division in
the Office of Earth Science. At JPL, he conducted research on
space and atmospheric environmental effects on launch vehicles and planetary spacecraft. At NASA Headquarters, Dr.
Schiffer was responsible for organizing and managing basic
and applied space technology research on global weather andclimate analysis and prediction, and served as lead program
scientist for a variety of space missions, including the Nimbus
and Earth Radiation Budget satellites. In 1981, he was detailed (part-time) to the World Meteorological Organization(WMO) Secretariat in Geneva, Switzerland, where he served
as Director of the Radiation Projects Office for the World Climate Research Programme (WCRP) for 15 years. His achievements there include key cornerstone efforts of future GEWEX
projects, such as the International Satellite Cloud Climatology
Project (ISCCP), the Surface Radiation Budget (SRB) project
and the GEWEX Radiative Flux Assessment. For more than 10
years, Dr. Schiffer chaired the U.S. Global Change Research
Program (USGCRP) Interagency Committee on Global Observations and Monitoring, and co-chaired the Interagency
Committee on the Global Water Cycle. He also acted as principal NASA liaison to the Board on Atmospheric Science andClimate (BASC) at the National Academy of Sciences, and to
the Director of the National Weather Service at the National
Oceanic and Atmospheric Administration (NOAA). In addition, he served as the Executive Director of the U.S. Secretariat for International Global Observing Systems Programs,
3

sponsored by the White House Office of Science and Technology Policy’s Committee on the Environment and Natural Resources (CENR), and co-chaired the U.S./U.S.S.R. BilateralWorking Group on Climate Research. During this period heworked as the Executive Secretary of the NASA Earth Scienceand Applications Advisory Committee. In 1999, he represented NASA at the United Nations Committee on the PeacefulUses of Outer Space (COPUOS) Scientific Forum on Climate
Variability and Global Change (UNISPACE Ill) in Vienna.
In 2000, he led a NASA delegation to Morocco to open discussions on potential cooperative projects with the Morocco
Remote Sensing Center in Rabat. After retiring from NASA,he served as Chief Scientist at the Goddard Earth Science andTechnology Center at UMBC, and as NASA principal investigator and Director of the International Project Office for
the WCRP Global Energy and Water Cycle Exchanges Project (GEWEX). Dr. Schiffer earned M.Sci. and Ph.D. degrees
in Atmospheric Physics from the University of California at
Los Angeles (UCLA), and B.Aero.E and M.Aero.E degrees(Aeronautical Engineering) from the Polytechnic Instituteof Brooklyn. His doctoral dissertation research at UCLA wason the “Depolarization of Multiply Scattered Atmospheric
Radiation due to Molecular Anisotropy”. He was licensed
as a Professional Engineer in New Jersey (Civil Engineering)and in California (Mechanical Engineering). For his service
to NASA, he was awarded the Distinguished Service Medal,
NASA’s highest award; two Medals for Outstanding Leadership, for his contributions to interagency and international climate research and global environmental observations; and two
TERRA awards for contributions to NASA’s Mission to Planet
Earth science program. He was elected a Fellow of the American Meteorological Society and continues to support NASAand the WCRP on global climate change scientific planningand space-based hydro-meteorological research. Overall, Dr.
Schiffer has led key components of NASA, interagency andinternational scientific research for over 57 years. His impressive career speaks to the caliber of his work, and the GEWEX
community is grateful for his contributions.

Peter and Bob at Bob's retirement lunch, hosted by USRA

Quarter 4 2019

In Memoriam: Chuck Long
The BSRN Community

LATICE—Land-Atmosphere Interactions
in Cold Environments
Lena M. Tallaksen, Frode Stordal, John Burkhart, Norbert Pirkt and Yeliz Yilmaz
Department of Geosciences, University of Oslo, Norway

The Baseline Surface Radiation Network (BSRN) and the greater radiation measurement community wish to express our collective grief in the wake of Chuck Long’s death on 21 November
2019. Chuck was a noted participant with BSRN and ultimately
succeeded Ellsworth Dutton as manager of the network in 2014,
maintaining that role until retirement in 2018. He was a cherished colleague, guide, mentor, and good friend to all. Some ofus have known Chuck since the nineties, during the early yearsof the BSRN; others met him later, but we were all immediately
taken with his innovative and practical approach to science, andespecially the kindness in his interactions with others.
Chuck was a hands-on scientist, always striving to improve radiation measurements by organizing and participating in many
field and laboratory experiments during his career. He had aknack for approaching problems from alternative directions,which resulted in insightful and pragmatic solutions that were
often revolutionary within the measurement community. It wasevident his solutions were based on a deep insight into radiative theory and backed by a substantial amount of research anddata management experience. Chuck was also an instrument
developer. Requiring an objective way to determine cloud fraction for his research but not finding a reasonably priced option
readily available, he set out to build his own solution. That
solution, the Total Sky Imager, is now a fully commercialized
instrument used by researchers around the world.
Always full of life, with a great sense of humor, and open to
discussing science with colleagues of any level, interacting with
Chuck was always a pleasure. It was a wise person who paid attention during those conversations as those who did undoubtedly benefited from his sage advice. He tirelessly encouraged
and supported younger colleagues, was a true mentor for
many BSRN participants, and a genuine pillar of BSRN andthe entire radiation measurement community.
Chuck left us an impressive and unique scientific and technical heritage, which we honor by striving to carry on ourcommon passion: increasing humanity’s knowledge of Earth’s
radiation balance. RIP, Chuck. We miss you.
Chuck’s Obituary: https://kochfuneralhome.com/tribute/details/2024/Charles-Long/obituary.html#tribute-start
4

The focus of LATICE, a strategic research initiative of the Faculty of Mathematics and Natural Sciences at the University ofOslo, is on cold-region land-surface exchange processes within
the Earth system for better prediction of future climate andland-surface states. LATICE is an interdisciplinary initiative toanalyze the role of atmospheric, biospheric, cryospheric and hydrospheric interactions in a changing climate. The goal of the
project is to improve the understanding of Earth processes andmodel representation of key features of northern environments,
including snow, permafrost, seasonal frost, wetlands and highlatitude vegetation that are not suitably represented in state-ofthe-art Earth system models. This will be achieved by linking
a wide range of observations and laboratory experiments formodel development (Figure 1). Observations comprise targetedfield studies, data from regular station networks and remotelysensed data with a focus on the interactions and feedbacks between the land and the atmosphere, including the boreal, alpine
and Arctic zones. This work will advance the land module in the
Norwegian Earth System Model (NorESM) Community Land
Model (currently CLM5.0, which has notable updates on soil,
plant hydrology, snow density, carbon and nitrogen cycling andcoupling; Lawrence et al., 2018), as well as assisting in evaluating the Functionally Assembled Terrestrial Ecosystem Simulated model (FATES; Fisher et al., 2018), a dynamic vegetation
module now under development.
A key achievement of the LATICE project has been the establishment of the Finse Eco-Hydrological Observatory (FinseEcHO) that integrates field and modeling efforts across observational systems. Finse-EcHO is a low-alpine site locatedin the central mountainous region of southern Norway at approximately 1200 m.a.s.l. (see Figure 1, lower panel). It is wellrecognized nationally as a key field site and is also becoming
so internationally. This is partly due to the unique locationof the LATICE Eddy-Covariance (EC) station (one of only
three EC stations in Norway). The infrastructure, combinedwith a wide range of distributed in situ observations of hydrometeorological variables, including snow cover and depth,
as well vegetation characteristics, make it a site of interest toa large community. Data are transmitted real time by a wireless sensor network to a database hosted at the University ofOslo. LATICE recently obtained funding for a climate container that will provide a unique facility to perform dedicatedsnow-vegetation-soil experiments and will supplement ongoing ecosystem experiments in a climate-controlled phytotron.
The LATICE project responds to the need for more researchon high-latitude vegetation, in particular in light of projected
strong Arctic and sub-Arctic warming and related biogeographical shifts. Vegetation interacts with climate through albedo,
roughness, evapotranspiration, carbon dioxide sequestration
Quarter 4 2019and by influencing snow accumulation and ablation. Overall, high-latitude vegetation lead to positive climate feedbacks
and is an important element in improving parameterization inland-surface models. This includes the lack of representativeplant function types typical for cold regions, such as lichen andmosses that cover large areas in the north. A preliminary comparison of snow depth with vegetation maps, created using the“Nature in Norway” system (https://www.nhm.uio.no/english/
research/projects/nin/), shows an immense potential for pioneering studies on interactions between climate and vegetation.
Recent work includes integration of fine-scale snow distribution
in a coupled land-surface model (Aas et al., 2017), improved
representation of snow in a distributed hydrological model(Matt et al., 2018), a high resolution climatology of rain-onsnow events for mainland Norway (Pall et al., 2019), improved
representation of snow and permafrost processes (Westermann
et al., 2016) and representation of thaw processes in ice-richpermafrost landscapes with laterally coupled tiles in a land-surface model (Aas et al., 2019). We are currently simulating andmeasuring the effect of snow patches on
the structure of the turbulent boundary
layer, which we hypothesize influencessnow melt significantly. Ecologists in LATICE have mapped the vegetation distribution based on drone aerial surveys
at two (1 x 1 km) sites at Finse; one at
the eddy covariance (EC)-flux tower andone at a dedicated snow monitoring site
for integrated research on atmosphere/
snow/vegetation processes. Furthermore, in collaboration with the University of Copenhagen, we are conducting
EC measurements of Biogenic Volatile
Organic Compounds emitted by thealpine vegetation at Finse. The LATICE
group also conducts EC measurements
at a permafrost peatland site (Martin etal., 2019) in northern Norway and leads
the eddy covariance flux monitoring ofa wetland restoration experiment by the
Norwegian Environment Agency.

The LATICE project is seeking to expand its international collaboration with CLM scientists at the U.S. National Center
for Atmospheric Research (NCAR) and the World Climate
Research Program (e.g., Earth System Model-Snow Model
Intercomparison Project; Krinner et al., 2018). A joint highlatitude model intercomparison project with the GEWEXGlobal Land/Atmosphere System Study (GLASS) Panel using
LATICE observations for model development and evaluation
studies is in the initial planning stages. For local and regional
scale studies, LATICE is interested in providing the GEWEXHydroclimatology Panel with their experiences related to water and energy exchanges For more information about LATICE, please visit http://www.mn.uio.no/latice.
References
Aas, K.S., K. Gisnås, S. Westermann and T.K. Berntsen, 2017. A Tiling Approach to Represent Subgrid Snow Variability in Coupled Land Surface–Atmosphere Models. J. Hydrometeor., 18, 49–63, DOI:10.1175/JHM-D-16-0026.1.
Aas K.S., L. Martin, J. Nitzbon, M. Langer,
J. Boike, H. Lee, T.K. Berntsen and S. Westermann, 2019. Thaw processes in ice-richpermafrost landscapes represented with laterally coupled tiles in a land surface model.
Cryosphere, 13, 591–609, DOI:10.5194/tc13-591-2019.
Fisher, R.A., C.D. Koven, W.R.L. Anderegg,
et al., 2018. Vegetation demographics inEarth System Models: A review of progress
and priorities. Global Change. Biol., 24, 35–
54, DOI:10.1111/gcb.13910.
Krinner, G., C. Derksen, R. Essery, et al.,2018. ESM-SnowMIP: assessing snow models
and quantifying snow-related climate feedbacks. Geosci. Model Dev., 11, 5027-5049,
DOI:10.5194/gmd-11-5027-2018.
Lawrence, D.M., R.A. Fisher, C.D. Koven,
K.W. Oleson, S.C. Swenson, G. Bonan etal., 2019. The Community Land Modelversion 5: Description of new features,
benchmarking, and impact of forcing uncertainty. J. Adv. Model Earth Sy., 11.
DOI:10.1029/2018MS001t583.

Ongoing studies are planned to evaluate
Martin, L.C.P., J. Nitzbon, K.S. Aas, B. Etand detect model deficiencies, find the Figure 1. The three pillars (laboratory experiments, land- zelmüller, H. Kristiansen and S. Westermann, 2019. Stability conditions of peatcause of model biases and improve mod- surface modeling and field observations) of LATICE.
plateaus and palsas in northern Norway. J.
el parameterization (see Figure 1). These
Geophys. Res.: Earth Surface, 124, 705– 719,
include:DOI:10.1029/2018JF004945.
• Representation of vegetation-cloud feedbacks (i.e., strong
Matt, F.N., and J.F. Burkhart, 2018. Assessing satellite‐derived radiative
bias in CMIP5 models in depicting correlations between
forcing from snow impurities through inverse hydrologic modeling. Geosatellite-based observations of cloud cover and Gross Priphys. Res. Lett., 45, 3531– 3541, DOI:10.1002/2018GL077133.
mary Productivity),
Pall, P., L.M. Tallaksen and F. Stordal, 2019. A Climatology of Rain-on• Biases in simulated vegetation distributions by the CLM4.5
Snow Events for Norway. J. Climate, 32, 6995–7016, DOI:10.1175/JCLIdynamic vegetation module for sites in Norway, andD-18-0529.1.
• The failure of CLM4.5 to reproduce seasonal snow coverWestermann, S., M. Lange, J. Boike, M. Heikenfeld, M. Peter, B. Etzelmülat high Arctic tundra sites (rather a continuous snow covler and G. Krinner, 2016. Simulating the thermal regime and thaw proer is simulated) leading to biased carbon and energy fluxes
cesses of ice-rich permafrost ground with the land-surface model CryoGridwith potentially large-scale implications.
3. Geosci. Model Dev., 9, 523-546, DOI:10.5194/gmd-9-523-2016.
5

Quarter 4 2019

Understanding Aerosol-Cloud
Interactions is Key for Reliable Future
Heatwave Projections
Alcide Zhao, Massimo A. Bollasina and David S. Stevenson
School of GeoSciences, University of Edinburgh, Edinburgh, UK

The past few years have witnessed numerous heatwaves aroundthe world that have been reported as “record-breaking,” “abnormal,” “rare” and “catastrophic” by the media. These extreme
events have resulted in catastrophic damage to both humansociety and ecosystems. As the climate warms, it is projected tointensify the frequency and duration of severe heatwaves. Although large gaps still exist in our understanding of the underpinning mechanisms, many studies have identified anthropogenic impacts on heatwave changes (Perkins, 2015). While theincrease in well-mixed greenhouse gases (GHG) from humanactivities is one of the major drivers of heatwaves, the important role of anthropogenic aerosols has also been documented
at both global and regional scales.
Aerosols can influence climate by absorbing and scattering shortwave radiation (aerosol-radiation interactions) and by modifying cloud microphysics and precipitation processes (aerosolcloud interactions). Yet, aerosol forcing remains the dominant
uncertainty in current estimates of radiative forcing of climate
since the industrial period. Quantifying the influence of anthropogenic aerosols on climate is particularly challenging due
to compounding uncertainties associated with the large spatial
and temporal variability of aerosols, their short lifetimes, theirdiverse physical and chemical properties and complex interactions that take place with radiation and microphysical processes(Fan et al., 2016). Worldwide anthropogenic aerosol emissions
are projected to decline in the coming decades through measures aimed at improving air quality, thus unmasking a considerable fraction of the GHG-induced warming and substantiallymodulating the projected near-future climate response. In lightof their important role, it is crucial to quantify the potential
impact of aerosol declines on changes in future heatwaves.
Our work (Zhao et al. 2019) made use of the fully-coupled
Community Earth System Model (CESM1) large ensemble
simulations (Kay et al., 2015) to investigate future changes inheatwaves under the Representative Concentration Pathway
8.5 scenario (RCP8.5). The impact of aerosol reductions wascalculated as the difference between experiments forced by the
RCP8.5 forcings and a paired set of simulations where aerosol
emissions were fixed at 2005 levels.
Future GHG increases will result in heatwaves that are, when
globally averaged over land, significantly more intense (2.4K), longer (17 days), and more frequent (12 more per year),compared to present-day by 2081–2100. These changes will
be further aggravated by aerosol reductions. Namely, an additional increase of 0.6 K (25%), 7 days (41%) and 2 per year
(12%) in intensity, duration and frequency, respectively, on top
6of the GHG-related changes. Changes in heatwave magnitude(an integration of intensity and duration) are driven mainly bymean climate warming and show only a small contribution fromchanges in future climate variability (internal processes that cause
fluctuations around the average without causing the long-term
average itself to change). Following the RCP8.5 scenario, wefind that on global average, present-day (1986–2005) heatwave
magnitude records will be exceeded in about 65% of the years
in the second half of the twenty-first century (i.e., 2051–2100).
The earliest emergence of record-breaking heatwave events will
occur in the tropics as their small temperature variability makes
present-day records much easier to be disrupted with a relatively
small amount of warming. Record-breaking heatwaves, especially those in the tropics and the Southern Hemisphere, stem
primarily from GHG increases. However, a prominent aerosol
signal is recognizable in the Northern Hemisphere, in particularover Europe, China and eastern USA.
Future GHG increases and aerosol reductions both result inclimate warming and increases in heatwave metrics. However, when normalized by the amount of global mean warming, aerosol reductions, compared to GHG increases, leadto much stronger responses in heatwave magnitudes (Figure1a). By 2081–2100, while aerosol-driven changes in monthly
mean surface air temperature tend to stabilize, heatwave duration continues to rise concurrently with changes in daily maximum temperature (Figure 1b), leading heatwave magnitude toincrease exponentially with warming. Changes in cloud liquidwater path (Figure 1c) and in top-of-the-atmosphere clear-sky
shortwave radiation (Figure 1d) reflect the predominant role ofaerosol-cloud interactions in increasing daily maximum temperature and, thereby, heatwave duration/magnitude. Morespecifically, the response of cloud droplet size and cloud albedo
to a given change in aerosol loading is exponentially larger incleaner air, resulting in coherent variations in daytime surface
shortwave radiation and atmospheric stability. Therefore, witha decrease in aerosols, daytime temperatures progressively increase and become more variable, while nighttime temperatures
are less influenced by aerosol-cloud interactions. Consequently,
unlike mean temperature and daily minimum temperature, thedaily maximum temperature continues to increase. Such different changes in daily minimum, mean and maximum temperatures may indicate the fact that aerosols have strong impacts on
the temperature diurnal cycle. This will be investigated in our
future works.
We note that the various RCP scenarios have similar aerosol
but different GHG emission pathways. In particular, the lower
GHG increases in other RCP scenarios compared to RCP8.5
may induce smaller changes in heatwave metrics. However, inother RCP scenarios, compared to GHGs, aerosols are likely toplay a more important role in future heatwave projections. In
addition, policy measures to control climate change, as well as
air pollution, could follow many possible future aerosol emission
pathways. For example, the responses of heatwaves may differ
under other future scenarios such as the shared socio-economic
pathways in which the spatial patterns of emission reductions
differ compared to the RCP scenarios (Gidden et al., 2018).
Quarter 4 2019

Figure 1. Scatterplots of changes (ensemble mean of annual mean) in landarea-weighted mean
heatwave magnitude(K*days)againstglobal land meansurface temperaturechange. Also shown
are changes in the annual mean of globalarea-weighted mean(b) monthly maximum
temperature (TX, K),(c) cloud liquid water path (g m-2) and(d) total net clear-sky
shortwave radiation
at top-of-the-atmosphere (W m-2), allplotted against landarea-weighted meansurface temperaturechange (K). All scatterplots are plotted
separately for theperiod
2006–2080(filled small dots) and
2081–2100(largecircles). The color
conventions are: redfor RCP8.5 (GHGs+ aerosols), blue for
RCP8.5_FixA (GHGsonly) and magenta foraerosols, isolated by
the difference RCP8.5- RCP8.5_FixA.

The results described here suggest a critical and progressively
larger role of aerosol-cloud interactions in modulating the occurrence and characteristics of future heatwaves worldwide, withconsequent crucial implications for human health, societies, infrastructures and ecosystems. In light of the models’ large discrepancies in representing the poorly-constrained aerosol-cloudinteraction related processes (Fan et al., 2016), these findings
further emphasize the compelling need to address this potentially large source of uncertainty in future climate projections.
Even further, the non-linear response of the magnitude of thetemperature response to changes in aerosol loading and the buffering of the aerosol indirect effects may translate into even larger
uncertainties in aerosol-mediated responses in future climate.
In short, given the detrimental impacts of changes in future
heatwaves, and to more effectively manage climate risks, wecall the attention of the community to prioritize efforts towards reducing uncertainties in aerosol-cloud-radiation interactions. These will help achieve more reliable projectionsof future climate extremes, as well as effective strategies forclimate risk management.
7

References
Fan, J., Y. Wang, D. Rosenfeld and X. Liu, 2016. Review of aerosol-cloudinteractions: Mechanisms, significance, and challenges. J. Atmos. Sci., 73,
4221-4252.
Gidden, M., K. Riahi, S. Smith, S. Fujimori, G. Luderer, E. Kriegler,
D.P. van Vuuren, M. van den Berg, L. Feng and D. Klein, 2018. Global
emissions pathways under different socioeconomic scenarios for use in
CMIP6: a dataset of harmonized emissions trajectories through the endof the century. Geosci. Model Dev., 1-42.
Kay, J., C. Deser, A. Phillips, A. Mai, C. Hannay, G. Strand, J. Arblaster,S. Bates, G. Danabasoglu and J. Edwards, 2015. The Community Earth
System Model (CESM) large ensemble project: A community resource
for studying climate change in the presence of internal climate variability. Bull. Amer. Meteorol. Soc., 96, 1333-1349.
Perkins, S.E. 2015. A review on the scientific understanding of heatwaves—their measurement, driving mechanisms, and changes at the
global scale. J. Atmos. Res., 164, 242-267.
Zhao, A., M. Bollasina and D. Stevenson, 2019. Strong influence of aerosol reductions on future heatwaves. Geophys. Res. Lett., 46, 4913-4923.

Quarter 4 2019

Meeting/Workshop Reports
Remote Effects of Tibetan Plateau Spring
Land Surface Temperature on Global Summer Precipitation and its S2S Prediction:
Second Workshop on LS4P and TPEMIP
Nanjing, China
7–9 July, 2019
Yongkang Xue1, William K.-M. Lau2, Tandong Yao3 andAaron Boone4
1
University of California, Los Angeles (UCLA), USA;
2
University of Maryland, College Park, USA; 3Institute ofTibetan Plateau Research, Chinese Academy of Sciences,
China; 4Centre National de Recherches Météorologiques/
CNRS, Météo-France, France

After the first workshop on the “Impact of initialized land
temperature and snowpack on sub-seasonal to seasonal prediction” (LS4P) and “Third Pole Experiment Multi-Model
Intercomparison” (TPEMIP) during the 2018 American
Geophysical Union (AGU) Fall Meeting in Washington,
D.C., USA (Xue et al., 2019), more observational and modeling studies have supported the concept that the high elevation land surface temperature/subsurface temperature(LST/SUBT) in the Third Pole region (TP) has a substantial
remote predictive capability for precipitation at subseasonal
to seasonal scales (S2S). Following recommendations fromthe first LS4P Workshop in Washington, D.C., the second
workshop on LS4P and TPEMIP was held at Nanjing University in China from 7–9 July 2019. Its aim was to engage
the broader international scientific community in order toreview the progress and issues in using Earth system models(ESMs) and regional climate models (RCMs) to a) identify therole of TP LST/SUBT on S2S prediction, b) initiate researchon the effect of light absorbing aerosols (LAA) in the snowon the LST anomaly in the TP and on S2S prediction and c)
promote and pursue RCM intercomparison TP studies.
Attended by 47 participants from different institutions aroundthe world, the workshop was very productive with five sessions
and many inspiring presentations. GEWEX, the Third Pole
Experiment (TPE) program, UCLA and Nanjing University
sponsored the event. The workshop information and relevantmaterials can be found on the LS4P project website (http://ls4p.geog.ucla.edu). Dr. Tandong Yao, Co-Chair of the TPE
program, presented the TPE scientific and societal foci andinterdisciplinary research activities in the TP. Dr. Peter Van
Oevelen of the International GEWEX Project Office reported on GEWEX’s current and planned high mountain activities. Various measurements from TPE and the Third Tibetan
Plateau Atmospheric Scientific Experiment (TIPEX-III), as
8well as satellite remote sensing of components of the water
cycle, cryosphere, vegetation, radiation, land surface properties, aerosols and planetary boundary layer in the TP, were
presented during the workshop. Dr. Xin Li of the Instituteof Tibetan Plateau Research, China, provided an overview of
the Big Data Center for the TP, which not only provides various data sets for TP research, but will also host the databasethat will store the LS4P model products. Dr. Chunxiang Shi
of the Chinese National Meteorological Information Center
discussed efforts to produce the most up-to-date TP 2-meter
temperature data set spanning the past 30+ years with halfdegree resolution and adequate topographic information.
This data set will be used by the LS4P for model evaluationand experimental design.
After the first workshop, the LS4P teams succeeded in accomplishing major tasks assigned during the first phase of activity, and the preliminary analyses were reported. Twenty LS4P
ESM groups submitted Task 1 results, which aim to show the
relationship between the ESM-produced May 2003 T-2m
temperature bias in the TP and the June 2003 precipitation
bias. May 2003 was a very cold month in the TP. Figures 1aand 1b (see cover for all figures) show the observed cold T-2m
anomaly in the TP in May 2003 and the observed global June
2003 precipitation anomaly patterns, respectively. Every ESM
has a large T-2m bias in the TP. Eleven (nine) LS4P models
have positive (negative) May 2003 T-2m biases, respectively.
For models with positive May T-2m bias, their temperatureand precipitation biases are multiplied by -1 to be includedin the ensemble mean composite, which is compared with theobserved anomalies. Figures 1c and 1d show the simulationbiases from the 20-ESM ensemble means for the May 2003
T-2m and June 2003 precipitation, respectively. Both Figure
1a and Figure 1c show that with a cold May TP, the IranianPlateau to the west of the TP was also cold, and the Eurasiancontinent shows planetary wave-like warm-cold-warm patterns. The observed 2003 June precipitation anomaly andJune precipitation simulation bias as shown in Figures 1b and1d, respectively, have a remarkable similarity, with the global
spatial correlation coefficient being 0.57. In particular, theprecipitation bias patterns in the U.S. and southern Canada,
northern South America, West Africa, Western and Eastern
Europe and the Eurasian Russia continent, South Asia, Indonesia and Australia are generally consistent. East Asia, which
was our original focus area (Xue et al., 2018), only constitutes
a small portion of all these similar patterns. The agreement
between model results and observations from diverse independent sources greatly stimulates our scientific curiosity toextend our assessment of the TP LST/SUBT effect expanding
from our original focus on East Asia to the entire globe.
Since every ESM has large positive/negative bias in the TP
May T-2m simulation, in order to generate the observed May
2003 T-2m cold anomaly in the TP, each modeling group participating in LS4P Task 3 imposed a LST/SUBT anomaly in
the TP at the initial time step aiming to reproduce the observed May 2003 cold anomaly. Due to current models’ inability to preserve the surface temperature anomaly, the ESMs still
Quarter 4 2019

Participants of the Second LS4P atnd TPEMIP Workshop

have difficulty fully reproducing the observed May 2003 T-2m
anomaly. Nevertheless, 10 model groups have submitted theirpreliminary results for Task 3, which reproduced the observed
May 2003 TP T-2m anomaly to various degree of realism.
These modeling groups and ESMs include the Bureau of Meteorology Australian Community Climate and Earth-System
Simulator version S2 (BOM-ACCESS-S2), the European
Centre for Medium-Range Weather Forecasting Integrated
Forecasting System (ECMWF-IFS), the Institute of Atmospheric Physics/Chinese Academy of Sciences (IAP/CAS),
the Climate Forecast System of the Indian Institute of Tropical Management (CFS_IITM), the Japan Meteorological
Agency (JMA)/Meteorological Research Institute (MRI), theKorea Institute of Atmospheric Prediction Systems (KIAPS)/
Korea Meteorological Administration (KMA), the State Key
Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics (LASG)/CAS in
China, Météo-France and the Centre National de Recherches Météorologiques-Climate Model 6 (CNRM-CM6),
the Lawrence Livermore National Laboratory(LLNL)/U.S.
Department of Energy (DOE) Energy Exascale Earth System Model (E3SMv1), and the University of California, Los
Angeles (UCLA)-Climate Forecast System (CFS)/Simplified
Simple Biosphere (SSiB) model in the U.S. Figure 2a showsthat after imposing the LST/SUBT anomaly at the first integration time, the model ensemble mean produces a clear
but weaker May 2003 T-2m anomaly in the TP. Please notethat the results in Figures 2a and 2b correspond to thosereported at the workshop, which were based on results froman 8-model mean. The simulated ensemble mean of the June
2003 precipitation anomaly is shown in Figure 2b. By comparing Figures 1b and 2b, the potential hot spots of Tibetan
Plateau effects are identified. The areas having the most possible effects from the TP LST/SUBT are: the eastern part ofChina, South Asia, the continental U.S. and southern Canada, northern South America, West Africa, Western and Eastern Europe and the Eurasian Russian continent, Indonesia
and Australia. In Figure 2b, the signals are weaker over some9

areas than what is shown in Figure 1b, which seems to beconsistent with the weaker May T-2m anomaly in the ensemble mean (Figure 2a). We started the LS4P initiative for East
Asia. Within the past year, we have found that it turns out tobe a global issue. Since the Task 3 test is still ongoing and themodel-produced LST anomaly is still weaker than observed,
more tests with improved modeling are required to further
confirm TP LST/SUBT effects. However, from the preliminary results from Task 1 and Task 3, as well as from Task 2
and other data analyses based on observations (not shown),
for the first time it has been suggested that the spring LST/
SUBT in the TP may have a global impact on summer precipitation and its S2S prediction. All these findings provide
assurance that our approach is in the right direction.
In addition to the LST/SUBT, another factor under investigation in LS4P is the LAA in the snow, which affects thesnow melt and spring LST/SUBT in the TP and the monsoon in South and East Asia. A review of measurements andmodeling of light-absorbing particles in snow/ice over the
TP and their climatic and hydrological impact was reported
by Dr. Yun Qian of the Pacific Northwest National Laboratory. Dr. Shichang Kang of the State Key Laboratory of
Cryospheric Science at the Chinese Academy of Sciences discussed the sources and temporal and spatial characteristics
of some aerosols in the TP. Dr. William Lau of the University of Maryland and Dr. Xiaohong Liu of the Universityof Wyoming presented the impact of LAA in terms of the
impact of snow effects on the monsoon and possible underlying mechanisms.
In addition to the ESM, the RCM is also an important
tool in identifying the LST/SUBT effect (Xue et al., 2018).
While RCMs have exhibited skillful downscaling ability in
S2S regional prediction in different regions of the world, Dr.
Guiling Wang of the University of Connecticut showed thatmodeling of S2S TP weather/climate and associated prediction of rainfall in downwind regions remain scientifically
Quarter 4 2019

challenging. Drs. Deliang Chen of the University of Gothenburg, Shiori Sugumoto of the Japan Agency of MarineEarth Science, and Tomonori Sato of Hokkaido University
all demonstrated the urgent need to conduct high-resolution
RCM downscaling in TP research. Dr. Kun Yang of Tsinghua University has demonstrated that some features, suchas complex terrain effects and west-east precipitation oscillation in lake areas caused by lake-air interaction in the TP,
can only be produced by fine-resolution RCMs. However, healso pointed out that using high-resolution models requires
high computational cost and sometimes is associated withless numerical stability. In addition to RCM downscaling,some promising results from preliminary testing using the
RCM with a larger domain to test LST/SUBT effect in the
TP were also reported.
In the breakout discussion session, the ESM, RCM and LAA
groups discussed issues and future plans for the next stageof research. For the ESM group, modeling groups will workon the improvement of the LST memory simulation to produce a more stable T-2m anomaly close to the observed one.
This problem may be rooted in the deficiency in producing
proper soil memory and land/atmosphere interaction. To improve the simulation, some technical suggestions were distributed to the ESM group members. Meanwhile, a test of
the sea surface temperature effect will be conducted as Task
4 for comparison with the LST/SUBT effect. For the LAA
group, the objectives are better understanding of the relationship among LAA deposition, snowmelt/albedo reduction,
TP land-atmosphere coupling and Asian summer Monsoon
rainfall variability and predictability. The focus will be on therelationship between snow darkening effect and LST/SUBT
anomalies, surface energy and water balance (including runoff) and S2S prediction. The LAA experiments will be coordinated with the main LS4P experiments. The RCM group
discussed issues in RCM intercomparison and the experiment
to test the LST/SUBT remote effect. The RCM domain size
and resolution were reviewed, and the RCM model output
list is available on the LS4P website. LS4P will complete thefirst three tasks around the end of 2019. There are two LS4P
sessions at the 2019 AGU Fall Meeting along with a miniworkshop in order to discuss the LS4P main results, a special
issue in Climate Dynamics, and a possible LS4P article in ahigh impact journal.
References
Xue, Y., I. Diallo, W. Li, J.D. Neelin, P.C. Chu, R. Vasic, W. Guo, Q. Li,
D.A. Robinson, Y. Zhu, C. Fu and C.M. Oaida, 2018. Spring land surface and subsurface temperature anomalies and subsequent downstream latespring-summer droughts/floods in North America and East Asia. J. Geophys.
Res. Atmos., 123, 5001-5019. https://doi.org/10.1029/2017JD028246.
Xue, Y., A. Boone and T. Yao, 2019. Remote effects of high elevation
land surface temperature on S2S precipitation prediction—International
Workshop of First Phase of GEWEX/GASS LS4P Initiative and TPEMIP.
GEWEX News, Vol. 29, No. 1, 14-16. International GEWEX Project Office, Washington, D.C, USA.

10

The GEWEX Water Vapor Assessment(G-VAP): Summary of the 8th Workshop
Madrid, Spain
13–14 June 2019
Marc Schröder1, Hélène Brogniez2, Shu-peng Ho3 andParticipants of the 8th G-VAP Workshop
1
DWD, Offenbach, Germany; 2Laboratoire Atmosphères,Milieux, Observations Spatiales/Paris-Saclay University,
Paris, France; 3NOAA, College Park, MD, USA

The major purpose of G-VAP is to quantify the state-of-theart in water vapor products being constructed for climate applications, and by this, support the selection process of suitable water vapor products by the GEWEX Data and Analysis
Panel (GDAP) for its production of globally-consistent waterand energy cycle products. Workshops are carried out on anannual basis to discuss recent findings, to further refine theplan and to implement new activities as well as to draft andconsolidate the assessment reports. The 8th G-VAP workshop
was hosted by the Agencia Estatal de Meteorologia (AEMET)
in Madrid, Spain, and took place on 13 and 14 June 2019.
Approximately 20 participants from research institutes [Consiglio Nazionale delle Ricerche (CNR), Laboratoire de Météorologie Dynamique-Institut Pierre Simon Laplace (LMDIPSL), Karlsruhe Institute of Technology (KIT), Max Planck
Institute for Chemistry (MPI-C)], universities (Free U. Berlin,
U. of Bremen, U. of Cologne, Colorado State U., U. of Leicester, U. of Miami, U. of Michigan, U. of Paris-Saclay, Vanderbilt U.), from weather services [AEMET, the Danish Meteorological Institute (DMI), Deutscher Wetterdienst (DWD), theNational Oceanic and Atmospheric Administration (NOAA)]
as well as from space agencies [the European Space Agency(ESA), the European Organization for the Exploitation of
Meteorological Satellites (EUMETSAT)] attended the workshop. A group photo of workshop participants is shown infigure 1. The presentations of the 8th G-VAP workshop are
available at www.gewex-vap.org. The main objectives of the 8thworkshop were to present updates on water vapor data records
and associated retrievals; to present and discuss results fromthe analysis and the characterization of water vapor products;
to discuss the next steps of G-VAP, including potential new
activities; to initiate a special issue in a peer-reviewed journal;
and to discuss time line changes and the G-VAP data archive.
The workshop started with a welcome address by AEMET andintroductory presentations on G-VAP and on the objectivesof the meeting. After an overview talk on water vapor in the
climate system, the first block of presentations focused on userneeds and applications, i.e., from GEWEX and the climate
modeling community. Participants discussed gathering feedback from climate modeling groups, including the Climate
Modeling User Group of the ESA Climate Change Initiative(CCI) program, on how to intercompare data records in orderto provide useful information to them.
A series of presentations provided updates on retrievals, data
records and related validation results. Also, uncertainty estiQuarter 4 2019mates were evaluated and through this, the consistency amongobserving systems was analyzed as well. Among other items,
the need for synchronized satellite/Global Climate Observing
System (GCOS) Reference Upper-Air Network (GRUAN)
observations was mentioned and the value of a multi-hyperspectral profile product was discussed and emphasized. The
general consensus was that model dependency of retrieval
schemes should be minimized, if not completely avoided, because forecasters typically want to compare a model-free observation with their own model. Then, G-VAP activities were
presented with a focus on process studies, introduced by apresentation on the GEWEX Upper Tropospheric Clouds andConvection Process Evaluation Study (UTCC PROES).

peer-reviewed publications on the analysis of atmospheric water vapor in Copernicus journals, e.g., Atmospheric Chemistry and Physics, Atmospheric Measurement Techniques, Earth
System Science Data and Geoscientific Model Development.

In addition to proposals outlined in the WCRP report on
G-VAP (Schröder et al., 2017), new recommendations weremade at the close of the workshop. The analysis of the global
water and energy budgets requires, among other things, global
humidity profiles at high temporal resolution as consistent input to the various variables of the closures studies. Thus, it isnecessary to assess options to merge or combine the various observing systems to provide such data. Deliberations following
a presentation on water vapor isotopologues concluded withthe call for the sustained provision of tropospheric water vapor
One study observed a dry bias during the day between theisotopologue data. After presentations on uncertainty analysis
Infrared Atmospheric Sounding Instrument (IASI) and GRUwere given, participants noted that the need to provide uncerAN, while comparisons between Global Positioning System
tainty estimates and their
Radio Occultation (GPSevaluation requires subRO) and GRUAN exhibit
stantial resources. This isa wet bias during night.
not sufficiently covered by
It was agreed that the Gcurrent funding schemes,
VAP team working on theeven though substantialconsistency activity will
progress was made in varifurther analyze this conous projects. Thus, activitrast. Other uncertainty
ties around uncertainty
sources, i.e., not related toestimation and evaluation
GRUAN approaches, may
require increased fundexplain these differences,ing budgets. Related toe.g., potential issues in thethe quality analysis, conwater vapor continuum
cerns about the potential
absorption. It was theimpact of 5G telecomconsensus that uncertainmunication links on mity analysis is of relevancecrowave observations wereto G-VAP (reconfirming
raised and discussed. It isan existing G-VAP recomimportant to ensure thatmendation) and results
developments around 5Gfrom related analyses will
telecommunication links
be summarized in the
do not impact microwave
next WCRP report. Also,th
Figure 1. Group photo of participants of the 8 G-VAP workshop
the analysis of free tropoobservations around 23
spheric humidity (FTH) variability in subsiding regions urGHz via radio-frequency interference.
gently requires the temporal extension of the existing FTH
The next workshop will take place at DMI, Copenhagen,data record (current temporal coverage until 2009). The last
Denmark tentatively in October 2020.
scientific talk introduced the ESA Water_Vapour_cci projectand its various links to G-VAP. These links include an analysis
References:of the clear-sky bias in response to a G-VAP recommendation.
Finally, the time line, the update of the G-VAP archive andthe initiation of a special issue were discussed. The submission of the next WCRP report will be postponed to fall 2021.
The assessment plan v2, available at http://gewex-vap.org/?page_
id=19, will need to be updated accordingly. Also, new versions and data records will comprise the G-VAP data archive
version 2. The archive will be an update of the G-VAP dataarchive version 1 (Schröder et al., 2018). However, the common period will be changed to the temporal coverages of eachindividual data record. The archive will be closed in Quarter 1of 2021. Lastly, participants decided to initiate a collection of
11

Schröder, M., M. Lockhoff, L. Shi, T. August, R. Bennartz, E. Borbas, H.
Brogniez, X. Calbet, S. Crewell, S. Eikenberg, F. Fell, J. Forsythe, A. Gambacorta, K. Graw, S.-P. Ho, H. Höschen, J. Kinzel, E. R. Kursinski, A. Reale,
J. Roman, N. Scott, S. Steinke, B. Sun, T. Trent, A. Walther, U. Willen,
Q. Yang, 2017. GEWEX water vapor assessment (G-VAP). WCRP Report
16/2017, World Climate Research Programme, Geneva, Switzerland, 216 pp.
Schröder, M., M. Lockhoff, F. Fell, J. Forsythe, T. Trent, R. Bennartz, E.
Borbas, M.G. Bosilovich, E. Castelli, H. Hersbach, M. Kachi, S. Kobayashi,
E.R. Kursinski, D. Loyola, C. Mears, R. Preusker, W.B. Rossow, S. andSaha, 2018. The GEWEX Water Vapor Assessment archive of water vapour
products from satellite observations and reanalyses. Earth Syst. Sci. Data, 10,1093-1117, https://doi.org/10.5194/essd-10-1093-2018.

Quarter 4 2019

Report of the 12th HyMeX Workshop
Split, Croatia
20–23 May 2019
Philippe Drobinski1, Véronique Ducrocq2, Clea Denamiel3, Kristian Horvath4, Branka Ivancan-Picek4,
Hrvoje Mihanovic 3 and Ivica Vilibic3
1
IPSL/LMD, France; 2CNRM, France; 3Institute of Oceanography and Fisheries, Croatia; 4Croatian Meteorological andHydrological Service, Croatia
Introduction

The 2019 HYdrological cycle in the Mediterranean EXperiment (HyMeX) Workshop was the twelfth in a series of annual workshops, held this year in Split, Croatia, between 20
and 23 May. The general objectives of the HyMeX workshops
are to present and discuss recent scientific progress in the understanding of the Mediterranean water cycle, from multiscale
and multidisciplinary approaches, and to foster further collaborations within the HyMeX community. The HyMeX andMediterranean water cycle science topics encompass heavy
precipitation, flash floods and social vulnerability, integrated
prediction of heavy precipitation and impacts, Mediterranean
cyclones, ocean circulation and processes, drought and water resources, the water cycle and renewable energy. The 12th
HyMeX Workshop consisted of plenary and parallel sessions,both oral and poster, as well as meetings on future work within HyMeX and beyond. Sessions and meetings were dedicatedto recent and future field campaigns: Exploiting new Atmospheric Electricity Data for Research and the Environment(EXAEDRE), Pelagic Ecosystem Response to dense water formation in the Levant Experiment (PERLE) and Land surface
Interactions with the Atmosphere over the Iberian Semi-arid
Environment (LIAISE). Over 100 scientists from more than
10 countries participated in the event (Fig. 1).

Figure 1. Participants of the 12th HyMeX workshop in Split, 20-23 May
2019. Source: P. Drobinski.

12

Continuum Scale and Integrated Analysis

About 60 talks and 35 posters presented scientific resultson the main HyMeX topics in plenary and parallel sessions.
The sessions included heavy precipitation, ocean circulation
processes, cyclones and strong winds, flash floods and vulnerability, flash-flood prediction, the water budget, drought
and water resources and integrated prediction. Seven parallelworking sessions for each HyMeX science team enabled transdisciplinary discussion and promoted exchange on current
and future field campaigns.
This year, the regional climate modeling community attended
a number of Mediterranean Coordinated Regional Downscaling Experiment (Med-CORDEX) workshops, as the second
modeling exercise is underway. This group was therefore underrepresented with respect to previous years.
The workshop program, presentations and more information
about HyMex are available at: http://www.hymex.org.
Ongoing and Future Field Campaigns

Three current or planned campaigns were designed within
the framework of HyMeX to complement finished field experiments from the Enhanced Observation Period (Braud etal., 2014) and Special Observation Periods (SOP1, Ducrocq
et al., 2014; Ferretti et al., 2014 and SOP2, Estournel et al.,2016) (see Drobinski et al., 2014 for a full overview). The new
field experiments are (Fig. 2):•

EXAEDRE, which took place between September andOctober 2018 and centered on atmospheric electricity,
completing the activities of SOP1 (Defer et al., 2015)•

PERLE, an oceanic experiment that was initiated in October 2018 with the PERLE-1 cruise and continued in
March 2019 with the PERLE-2 cruise, complementing

Figure 2. Location of the three recent and future field campaigns
planned within the HyMeX framework.

Quarter 4 2019

the activities of SOP2 (Estournel et al., 2016) but in theLevantine region in the Eastern Mediterranean•

LIAISE, which will be conducted between April 2020 andMarch 2021 with a focus on land surface interactions overthe Iberian semi-arid environment

instrumental studies are ongoing at lightning flash, electricalcell, storm and regional scales based on the EXAEDRE special, enhanced and long observation period (SOP, EOP, LOP)
data sets. EXAEDRE is promoted on Youtube at https://youtu.
be/eYT2VsBOwRo.

The PERLE action, shared between the HyMeX and Marine Ecosystem Response in the Mediterranean Experiment
The EXAEDRE campaign objectives are to: (1) provide in situ
(MerMeX) programs, aims at describing the formation andmeasurements to characterize the electrical and microphysispreading of Levantine Intermediate Water and determining
cal cloud properties for a better understanding and modelits role in the distribution of nutrients and in the structuration
ing of microphysical, dynamical and electrical processes inof the planktonic ecosystems in the eastern Mediterranean. It
thunderstorms; and (2) validate new airborne and groundis a complement to the SOP2 experiments conducted in thebased instrument concepts developed within EXAEDRE.
northwestern Mediterranean in winter 2013 with similar obThe campaign took place between 13 September and 8 Ocjectives. The first two
tober 2018 with a pricruises started in Ocmary regional target:
tober 2018 and March
Corsica (<150 km).
2019 with profiling
About 26 flight hours
floats deployed during
were completed, with
the PERLE-1 cruise
weather forecast guidin October 2018 andance provided by themoorings
deployed
students and teachers
during the PERLE-1of the Météo-France(October 2018) andMeteorology School.
PERLE-2
cruisesOn the ground, a su(March 2019). Glider
per site was set up at
sampling started in
San Guiliano. Figure
October 2018 and will
3 shows an example
be repeated until Juneof a cross-section of2020. Figure 4 shows
Radar Aéroporté etone cross-section of
Sol de Télédétection
the temperature, salindes propriétés nuAity and oxygen meageuses (RASTA) cloud
surements
collected
radar measurements
by a glider between 10(wind velocity, reflecDecember 2018 andtivity, etc.) on board
14 February 2019.
the French Falcon
20 during a thunderFinally, the LIAISE
storm of the Intensive
field campaign willObservation
Periodexplore the surface/#7. The airborne meaatmosphere interacsurements were madeFigure3.
Cross-section
of
RASTA
cloud
radar
measurements
onboardtheFrenchFalcontions over the Iberian
in the vicinity of thePeninsula. Specifically,ground-based site, and 20 during the IOP 7 (courtesy of E. Defer).
its goal is to achieve better understanding of the dry down
included Doppler cloud radar measurements, in situ measureof soils after the winter rainfall has ended, as this is a critiments, electric field mills, 3D-wind retrieval from the Doppler
cal season for the Mediterranean climate. Funding is currently
radar (3 antennas looking up and 3 antennas looking down)being secured (e.g., the recent support of the French Nationaland microphysical properties (ice water content, etc.).
Research Agency, ANR), so the campaign schedule stands. It
will be held in 2020 and will end in the summer, following theIn brief, the field campaign was very successful. Different
vegetation phenological cycle (Boone et al., 2019).
young, mature and old electrical cloud systems were documented. Most airborne data have been quality controlled and
HyMeX Activities in 2020are ready for scientific investigation. The data set is available
in the HyMeX database. In the case with most electrical activHyMeX was designed as a 10-year program starting in 2010ity (IOP2), an electric field up to 50 kV/m was measured inand ending in 2020, and wrap-up activities are planned for its
cloud regions with graupels measured at flight level (8-10 km)
final year. A joint special issue is being organized, and as deand with a large variety of lightning flashes at different alticided during the workshop, each science team will contributetude ranges. Observational- and modeling-based scientific andone or two scientific review papers in addition to the overview
13

Quarter 4 2019

the HyMeX International Scientific Steering Committee. The
The 2020 HyMeX
group gathers experts ofworkshop will containvarious disciplines andplenaries, a limited
is composed of Aaron
number of parallel andBoone, Eric Defer,poster sessions and sesEmmanouil Flaounas,
sions with a specificSamiro Khodayar, Cinscope, including: 10dy Lebeaupin Brossier,year achievements with
Olivier Payrastre, Pere
final syntheses and reQuintana-Segui, Hélène
view, transfer to sociRoux, Alexandre Stegner
ety, and beyond 2020.
and Yves Tramblay. OthThe workshop scientific
er volunteers are welcommittee, composedcome to join the board.
of Science Team LeadIts tasks will be to set up
ers, will be set up by
a process to engage with
October 2019. This
other communities orcommittee will also be
program steering groups,
responsible for the reprovide a synthesis of
Figure 4. Cross-section of glider measurements of temperature, salinity and oxyviews that will be prethe tangible (database,gen measured during the 2018-2019 survey between 10 December 2018 and 14
sented at the workshop.
website, mailing lists)
February 2019 (PERLE-1 cruise) (courtesy of P. Testor).
and intangible assets of
HyMeX Beyond 2020
HyMeX, define new andupdated objectives to be possibly compiled in a new whitebook
The duration of HyMeX is 10 years, with the program set toand to define a platform to meet and present the new scope andconclude in 2020. Some activities will end next year while othconfiguration options at the 2020 HyMeX workshop.
ers will continue. A transition is planned to bridge the current
version of HyMeX to a program that will extend beyond 2020.
The HyMeX database is being transferred under the umbrellaof the French Data and Services Cluster for the Atmosphere
Some projects with campaigns and their exploitation phase, as(AERIS), a new service building a general portal for geophysiwell as existing collaborations within Science Teams, will concal data. The HyMeX data policy will first be extended andtinue past 2020. The community has also expressed its interest
then a review of the data sets will be carried out to check thein regular workshops as meeting points.
provider, access level and terms, preparing for an evolution of
the data policy and access granted on a data set basis.
The form of the representation of HyMeX within the World
Weather Research Programme (WWRP), the World Climate
References
Research Programme (WCRP) and GEWEX has yet to be disBoone, A., et al., 2019. Land Surface Interactions with the Atmosphere over thecussed. The current iteration of HyMeX will end as a GEWEX
Iberian Semi-Arid Environment (LIAISE). GEWEX Newsletter, 29(1), 8-10.
Regional Hydroclimate Project (RHP), without excluding the
Braud, I., et al., 2014. Multi-scale hydrometeorological observation and modpossibility that the governance of the future program will proelling for flash-flood understanding. Hydrol. Earth Syst. Sci., 18, 3733-3761.
pose a new RHP. Discussions with the WCRP Joint ScienDefer, E., et al., 2015. An overview of the lightning and atmospheric electific Committee (JSC) should be organized, with GEWEX as
tricity observations collected in Southern France during the HYdrologicalan intermediary, as the JSC has launched four core programs
cycle in Mediterranean EXperiment (HyMeX), Special Observation Period
where regional activities are key. As other Mediterranean pro1. Atmos. Meas. Tech., 8, 649-669.
grams will soon or have already ended [e.g., the Mediterranean
Drobinski, P., et al., 2014. HyMeX, a 10-year multidisciplinary program on
Experiment (MEDEX), Mediterranean Climate and Ocean–the Mediterranean water cycle. Bull. Amer. Meteorol. Soc., 95, 1063-1082.
Variability, Predictability, and Change (Med-CLIVAR), MedDucrocq, V., et al., 2014. HyMeX-SOP1, the field campaign dedicated to
CORDEX, Impact of Climate Change (IMPACTCC), Mediheavy precipitation and flash-flooding in northwestern Mediterranean. Bull.
terranean Experts on Climate and environmental Change
Amer. Meteorol. Soc., 95, 1083-1100.
(MEDECC), Mediterranean Science Commission (CIESM),
Estournel, C., et al., 2016. HyMeX-SOP2, the field campaign dedicated toetc.], discussions should be organized to envisage, if relevant,dense water formation in the northwestern Mediterranean. Oceanography,
a more integrated or at least coordinated effort in the region.
paper on HyMeX’s
greatest achievements.

A new preliminary coordinating board was put in place at the12th HyMeX Workshop, which will coexist during the 2019–2020 transition period with the exiting coordinating board,
14

29,196-206.

Ferretti, R., et al., 2014. Overview of the first HyMeX Special Observation
Period over Italy: observations and model results. Hydrol. Earth Syst. Sci.,
18, 1953-1977.

Quarter 4 2019

GLASS Panel 2019 Annual Meeting
Boulder, CO, USA
6–8 August 2019
Kirsten Findell1 and Mike Ek2, GLASS Co-Chairs
1Geophysical Fluid Dynamics Laboratory, Princeton, NJ,
USA; 2The National Center for Atmospheric Research,
Boulder, CO, USA

The 2019 Global Land/Atmosphere System Study (GLASS)
Panel Meeting was held over three days in early August at the
National Center for Atmospheric Research (NCAR)’s Foothills Lab in Boulder, Colorado. About twenty-five people participated in the event. A recurring theme was the need for
coordinated observations to improve understanding of theland-atmosphere system in different climatic regimes andconfront and improve Earth system models. The meeting covered a range of topics including project updates, explorationof mutual interests between GLASS and other GEWEX Panels, and presentations from new GLASS members. We heard
about numerous observationally-driven initiatives, including
the Land-Atmosphere Feedback Experiment (LAFE) field
campaign at the Southern Great Plains site in Oklahoma andKansas, and the associated Land-Atmosphere Feedback Observatory (LAFO) at Hohenheim University; the upcoming
Land surface Interactions with the Atmosphere over the Iberian Semi-arid Environment (LIAISE) experiment in Spain;
and the Bedrock to Boundary Layer meeting as a National
Oceanic and Atmospheric Administration (NOAA)-centeredinitiative to address these issues. The Local Land-Atmosphere
Coupling (LoCo) project update included mention of a handful of other important field campaigns and/or new monitoring
stations [the Great Plains Irrigation Experiment (GRAINEX),
Nebraska, USA; the Ruisdael Observatory, The Netherlands;
the Finse Eco-Hydrological Laboratory, Norway]. On the final day, we discussed a proposal presented by Volker Wulfmeyer for GLASS Land-Atmosphere Feedback Observatories(GLAFOs), building on the success of LAFE and LAFO. Allof these field efforts stem from the recognition that the evolution of clouds and precipitation is dependent on the evolutionof the boundary layer (BL), which has long been difficult toadequately observe and monitor. Recent advances in instrumentation are now making better BL observations a reality.
The GLAFO vision includes defining a standard set of measurement devices that would allow for full and continuous
characterization of the boundary layer, surface layer, soil profile and vegetation, and installing these suites of devices at various sites in different climatic regimes. We intend to followup with this meeting discussion by first determining where
existing field sites can be augmented to include the full suiteof GLAFO instruments, and then by writing a paper outlining the justification and benefits of a consistent and compatible measurement platform at different field locations. We are
hopeful that international and national funding agencies willhear this unified voice from the land-atmosphere scientificcommunity as an opportunity to advance land-atmosphereinteraction science rapidly.
15

In addition to these themes, we heard research presentations fromtwo new Panel members, Nate Chaney and Samiro Khodayar
Pardo. We also heard brief reports on various GLASS-relevant
activities including efforts at National Aeronautics and Space
Administration (NASA)-Goddard to model irrigation (Patricia
Lawston), single-column modeling work at NCAR (Grant Firl),
precipitation downscaling efforts at the University of Kansas(Joshua Roundy), research from the Geophysical Fluid Dynamics Laboratory (GFDL) on the changing continental hydrologic
cycle (Kirsten Findell), efforts at NCAR related to the North
American Coordinated Regional Climate Downscaling Experiment (CORDEX) project (Rachel McCrary) and research onwater security projections from NCAR (Flavio Lehner).
The GLASS Panel meeting was an excellent forum for sharing
advances in observing and modeling the land and land-atmosphere system. We look forward to building on the progressand momentum of the meeting in the months ahead.
LoCo Project

The LoCo project and working group update was presented by
Joseph Santanello. LoCo consists of 18 international scientists
across academia and government, with a LoCo review article
recently published in the Bulletin of the American Meteorological Society (Santanello et al., 2018) summarizing the last decade of research. LoCo has identified three near-term objectives that it has made significant progress on: 1) promoting
the importance and development of improved observations of
the land-atmosphere (L-A) system, namely planetary boundary layer (PBL) profiles, as well as improved utilization of soil
moisture and surface flux measurements in models; 2) pursuing adoption of LoCo metrics by operational numerical weather prediction (NWP) and climate centers; and 3) expanding
the scope and reach of LoCo in terms of processes and scale
beyond that of warm season thermodynamics and beyond thatof 1-D column assumptions. Progress on those goals is evident
in the recent NASA Decadal Survey prioritization of PBL measurements and spaceborne mission concepts, and in the new
NOAA/U.S. Department of Energy (DOE) Climate Process
Team (including six GLASS panel members) tackling the difficult issue of communicating subgrid-scale heterogeneity between the land and the atmosphere. Numerous proposals arebeing submitted to other funding agencies to address remaining goals and continue this momentum of LoCo outreach tothe scientific, modeling and observational communities.
SoilWatAnne Verhoef reported on the GEWEX Soil and Water (SoilWat) Initiative GLASS working group, which has as its main
objective to improve the representation of water-related soil
and subsurface processes in land models (LMs) and climate
models, and to identify the most pressing challenges and topics related to this effort. This activity has already produced
review papers on pedotransfer functions (PTFs) and on infiltration, as well as related datasets (Van Looy et al., 2017;
Vereecken et al., 2019). During the meeting, Anne gave an
overview of a selected number of SoilWat activities relating to
Quarter 4 2019

the assessment and improvement of PTFs used in land models, and the incorporation and assessment of the effects of soil
structure on land surface fluxes on the plot and global scale.
LUMIP and ILAMBDavid Lawrence presented updates for both the Land Use
Model Intercomparison Project (LUMIP) and the International LAnd Model Benchmarking Project (ILAMB). LUMIP
simulations are ongoing at the modeling centers, and datais starting to appear at the Coupled Model Intercomparison
Project Phase 6 (CMIP6) data distribution site. Analysis plans
are in place, and these efforts were discussed at a workshop
in September 2019 at the Aspen Global Change Institute. A
paper documenting the ILAMB package has been published(Collier et al., 2018). ILAMB is being used by several modeling centers and model intercomparison projects. Analysis of
CMIP6 (versus CMIP5) models using ILAMB is underway.
The Panel discussed the possibility of providing input
to the Climate Data Guide(https://climatedataguide.ucar.
edu/) on datasets of high relevance to the GLASS community. The Climate Data Guide
is a data portal that combines
data discovery, metadata, figures and world-class expertiseon the strengths, limitations
and applications of climate
data. The Panel agreed thatproviding data pages for
key GLASS-related datasets
would be valuable, though alead to push this idea throughhas not yet been identified.

more informative than simply quantifying model-observational discrepancy for different products using traditional metrics.
Finally, progress with PLUMBER2 was discussed. Sample
Network Common Data Form (NetCDF) driving data has
been distributed to participants, and the facility to assess model output formats on PALS is ready. Some of the tower dataprocessing issues were outlined, noting that this had slowed
progress somewhat. It is anticipated that all data for the experiment should be released within a month or two, with a
total of 200-300 sites anticipated in the final product. Initial
analyses were outlined to include an improved empirical model hierarchy (following Haughton et al, 2018), quantile-based(rather than rank-based) metric averaging and a Budyko-styleanalysis following recent work by Martyn Clark.
Discussion around the synthetic experiment part of PLUMBER2 suggested that the nature of the synthetic forcing datasets
still required some iteration
with the GLASS community, but there was agreementthat this would likely be avaluable addition. Details of
relatively flexible data assimilation-based submissions to
PLUMBER2 (using whichever sources participants chose)were presented with slides
provided by Sujay Kumar.
GSWP3 and LS3MIP

Hyungjun
Kimsharedprogress on the Global Soil
Wetness Project Phase 3(GSWP3) and on the Land
Surface, Snow and Soil MoisGroup photo of participants of the annual 2019 GLASS Workshop
ture Model Intercomparison
Project(LS3MIP).
GSWP3’sgoal
is to produce a century-long
PLUMBER2 and Modelevaluation.org
comprehensive set of quantities for hydro-energy-eco systems
Gab Abramowitz presented progress on the Protocol for thein order to investigate the long-term changes of energy-waterAnalysis of Land Surface models (PALS, now at modelevalucarbon cycle components and their interactions. Hyungjun
ation.org) and the PALS Land Surface Model Benchmarking
showed the progress to-date by comparing preliminary output
Evaluation Project Phase 2 (PLUMBER2) land model interfrom three participating models of snow cover, evapotranscomparison experiment. Gab showed an example of PALS
piration (ET), runoff and terrestrial water storage anomalies
aiding development of the Community Atmosphere–Biowith observational equivalents. Additional pilot studies tackle
sphere Land Exchange (CABLE) land model through benchquestions of long-term variability and trends of runoff at globmarking multiple model configurations, following the originalal and continental scales. The LS3MIP experiment is designed
PLUMBER framework. The full functionality of the ILAMB
to provide a comprehensive assessment of land surface, snow
suite is also available through PALS as one of the analysis enand soil moisture-climate feedbacks and to diagnose systemgines. PALS is hosting PLUMBER2 and Urban-PLUMBER.
atic biases in the land modules of current Earth system models
using constrained land-module-only experiments. These exA proposed global-scale land surface budget-based experiment
periments are being conducted as part of the CMIP6 initiawas also shown, using the Derived Optimal Linear Combinative; significant progress is expected in the coming months astion Evapotranspiration (DOLCE) and Conserving Land-AtCMIP6 deadlines approach.
mosphere Synthesis Suite (CLASS) products (Hobeichi et al,
2018, 2019), focusing observationally constrained uncertainty
Crosscuts and Projects with Other GEWEX Panels
estimates for surface energy and water budget terms. It was arCraig Ferguson provided an overview of the current portfogued that understanding the circumstances in which land models were outside observational uncertainty ranges was likely
lio of the GEWEX Hydroclimatology Panel (GHP) Regional
16

Quarter 4 2019

Hydroclimate Projects (RHPs), crosscuts, and data centers.
Of direct relevance to GLASS’s current activities are the HYdrological cycle in the Mediterranean Experiment (HyMeX)
RHP’s 2020 field campaign, Land surface Interactions with
the Atmosphere over the Iberian Semi-arid Environment (LIAISE), and the crosscutting initiatives related to evapotranspiration and water management in models. Martin Best provided a presentation about many of the details of the LIAISE
experiment. Large-scale irrigation, vegetation heat and water
stress response and the land-atmospheric processes that determine land anomaly impacts on regional climate variability at
the heart of these GHP activities are also central to multiple
GLASS projects [e.g., phase 2 of the Diurnal Land/Atmosphere Coupling Experiment (DICE-2), LoCo, PLUMBER2].
GLASS was well represented at the evapotranspiration crosscut workshop in October 2019. Over the coming months,
GLASS will work together with GHP and the GEWEX Data
and Analysis Panel (GDAP) to define and team-build for thewater management crosscut.
John Edwards shared information on some of the Global Atmospheric System Studies (GASS) Panel efforts that are relevant to the GLASS community. Papers on the large-eddy andsingle column model intercomparisons in the fourth phase of
the GEWEX Atmospheric Boundary Layer Study (GABLS4)
are in an advanced stage of drafting and submission is expected in the near future. Following the Pan-GASS workshop in
Melbourne last year, a number of new projects on drag, fog
modeling and convective processes have been launched. The
analysis of results from some of these is beginning.
Paul Dirmeyer provided an update on the beginnings of thesecond phase of the International Subseasonal to Seasonal(S2S) Prediction effort. The parallel Subseasonal Experiment(SubX) project, centered on North American models, is undergoing review to determine whether and how it will continue. There are currently several other multi-model projects
with bearing on the role of various aspects of the land surface
on S2S timescales: the “Changing Arctic Cryosphere: Snow
and Sea-Ice Impact on Prediction and Climate over Europe
and Asia” (SNOWGLACE, on snow initial states), the Global
Land-Atmosphere Coupling Experiment–Earth System Model (GLACE-ESM, on vegetation states), the Impact of Initialized Land Temperature and Snowpack on Sub-seasonal to
Seasonal Prediction project (LS4P, on initial soil temperaturein elevated terrain) and the Land Feedback Model Intercomparison Project with a pseudo-observed boundary condition(LFMIP-Pobs, including all land states, especially soil moisture). All of these efforts produce large global sets of model
forecast output on daily or finer time scales that can be mined
to examine the impact of the land on subseasonal predictions
in a range of frameworks from operational forecasting to predictability in a changing climate. A summer school at NCARon the S2S topic will occur in July 2020, providing an opportunity to expose and educate 80-100 students and young
scientists on the role of the land in subseasonal prediction.
Eleanor Blyth presented an overview of the Integrated Land
17

Ecosystem Atmosphere Processes Study (iLEAPS) program.
The five core themes in their science strategy are the urban environment, managed land, forests, arctic and mountain regions,and arid and semi-arid regions. In each of these themes, iLEAPS
coordinates science that relates to the ecosystem-atmosphereinteractions of water, carbon and other biogeochemicals. Twomeetings of interest include the joint iLEAPS-GEWEX workshop for land model developers in September 2020 in Oxford,
UK, and the 6th Open Science conference in collaboration with
OzFlux in February 2021 in Auckland, New Zealand.
The Land Atmosphere Feedback Experiment (LAFE)

Volker Wulfmeyer gave an overview of the Land Atmosphere
Feedback Experiment (LAFE) from the Southern Great Plainsin 2017 (www.arm.gov/research/campaigns/sgp2017lafe). This
experiment included simultaneous measurements of sensible
and latent heat flux profiles and the comparison of varianceprofiles with similarity relationships, where surface layer observations strongly question the applicability of Monin-Obukhov
similarity theory. The use of a bulk Richardson number relationship showed much better agreement with observations.
Also, the current state of turbulence-permitting modeling andthe use of these simulations and the LAFE observations forcomparisons with turbulence parameterizations was outlined.
The new operational Atmospheric Raman Temperature and
Humidity Sounder (ARTHUS), which typically has resolutions of 10 s and 100 m during daytime and nighttime in thelower troposphere, will contribute significantly to process understanding, parameterization development and data assimilation efforts if operated 24/7 at various sites such as the new
Land Atmosphere Feedback Observatory (LAFO, https://lafo.
uni-hohenheim.de/en).
Volker also presented the new integrated Land System Modeldeveloped within the German Research Foundation Collaborative Research Unit 1695 at the University of Hohenheim(https://klimawandel.uni-hohenheim.de). This model system iscapable of simulating crop growth and yield, as well as the
feedback to farming activities and management by couplingwith a multi-agent system. He showed that the implementation of crop growth had a significant positive impact on thesimulation of surface temperatures and two-legged feedback
metrics between soil moisture, latent heat flux, and convective
available potential energy. The CORDEX Flagship Pilot Study(FPS) Land Use and Climate Across Scales (LUCAS) was alsopresented (www.hzg.de/ms/cordex_fps_lucas). Land use modifications from the current land use to forest or grassland has
significant influence on L-A coupling strengths, particularly
over south central and eastern Europe.
Presentations from New GLASS Panel Members

Samiro Khodayar Pardo is a senior scientist at the Mediterranean Center of Environmental Studies (CEAM) in Valencia, Spain, and leader of the junior research group “Extreme
Weather in a Changing Climate” at the Institute of Meteorology and Climate research, Karlsruhe Institute of Technology(KIT, Germany). Her scientific work focuses on the improved
Quarter 4 2019

understanding and modeling of extreme weather and climate
phenomena, with particular interest on the role of land-atmosphere interactions. For these investigations, she applies
process-based evaluations across space/time scales using thesynergy of state-of-the-art observations and high-resolution
modeling. She is also an International Scientific Steering
Committee member for the HyMeX program, where she coordinates the scientific team on heavy precipitation.
Nate Chaney is an Assistant Professor at Duke University inNorth Carolina, USA. Nate spoke about the availability ofpetabytes of data from satellite remote sensing providing uswith a unique opportunity to make large improvements in the
representation of land surface heterogeneity in Earth systemmodels. The synthesis of these data through clustering at the
sub-grid level enables an effective and efficient use of thesedata for their representation within large-scale models. Theseadvances in the representation of sub-grid heterogeneity canthen be used to understand how a more robust representationof sub-grid land surface heterogeneity impacts the coupledland and atmosphere. Building on this work, a recently assembled climate process team (led by Nate) will explore how
the coupling of the land and atmosphere at sub-grid scales
influences the macroscale response of the coupled land-atmosphere. This project, dubbed the Coupling of Land and Atmospheric Subgrid Parameterizations (CLASP), will provide amore formal coupling between sub-grid parameterizations ofheterogeneity between the land and atmosphere in a suite of
U.S. climate models.
References
Collier, N., et al., 2018. The International Land Model Benchmarking (ILAMB) System: Design, Theory, and Implementation. J. Adv. Model Earth
Sy., https://doi.org/10.1029/2018MS001354.
Haughton, N., et al, 2018. The Plumbing of Land Surface Models: Is Poor
Performance a Result of Methodology or Data Quality? J. Hydrometeorol.,17(6), DOI: 10.1175/JHM-D-15-0171.1.
Hobeichi, S., G. Abramowitz, J. Evans and A. Ukkola, 2018. Derived Optimal Linear Combination Evapotranspiration (DOLCE): a global gridded
synthesis ET estimate. Hydrol. Earth Syst. Sci., 22(2), 1317–1336, 2018,https://doi.org/10.5194/hess-22-1317-2018.
Hobeichi, S., G. Abramowitz, J. Evans and H.E. Beck, 2019. Linear Optimal Runoff Aggregate (LORA): a global gridded synthesis runoff product.
Hydrol. Earth Syst. Sci., 23(2), 851–870, https://doi.org/10.5194/hess-23851-2019.
Santanello, J.A., Jr. et al, 2018. Land–Atmosphere Interactions: The
LoCo Perspective. Bull. Amer. Meteor. Soc., https://doi.org/10.1175/BAMSD-17-0001.1.
Van Looy, K., et al., 2017. Pedotransfer Functions in Earth System Science: Challenges and Perspectives. Rev. Geophys., https://doi.
org/10.1002/2017RG000581.
Vereecken et al., 2019 Vereecken, H., et al, 2019. Infiltration from the Pedon to Global Grid Scales: An Overview and Outlook for Land Surface
Modeling. Vadose Zone J., doi:10.2136/vzj2018.10.0191.

18

Alaska Soil Moisture andWetland Mapping Validation Workshop
Fairbanks, AK, USA
9–13 September 2019
Bergit Uhran1, John Qu2, Zhiliang Zhu1 and Hélène Genet3
U.S. Geological Survey, Reston, VA; 2George Mason University, Fairfax, VA; 3Institute of Arctic Biology, University of
Alaska Fairbanks, Fairbanks, AK
1

The Alaska Soil Moisture and Wetland Mapping and Validation Workshop was hosted at the University of Alaska Fairbanks(UAF) from 9–13 September 2019. The workshop was organized by UAF, the U.S. Geological Survey (USGS) and George
Mason University, and was sponsored by the World Meteorological Organization. One objective of this workshop was toimprove soil moisture and wetland mapping over high latitudes
to support a better understanding of the Soil-Ecosystem-Carbon-Climate (SECC) nexus, or the feedbacks between soils
and ecosystem carbon cycling and the climate. The workshop
included two days of presentations with discussions and threedays of visits to long-term study sites in and around Fairbanks.
The presentations and discussions focused on (1) assessing thecurrent understanding and state-of-the-art techniques for detection of soil moisture and wetlands in high latitude ecosystems, and (b) identifying current and future research directions
and data gaps. Field site visits included the Alaska Peatland
Experiment (APEX) fen and bog ecosystems, the U.S. Army
Corp of Engineers Cold Regions Research and Engineering
Laboratory (CRREL) Permafrost Tunnel and the upland boreal ecosystems at Nome Creek. In collaboration with the National Aeronautics and Space Administration (NASA)’s Arctic
Boreal Vulnerability Experiment (ABoVE), a small crew of participants also collected in situ soil moisture data synchronizedwith the airborne imagery acquisition campaign conducted by
NASA’s L -band fully polarimetric Uninhabited Aerial Vehicle
Synthetic Aperture Radar (UAVSAR) instrument. These in situ
observations will contribute to the calibration and validation
effort of soil moisture remote sensing products in the region.
High latitude areas, defined as above 60°N latitude, are warming faster than other regions. Permafrost landscapes contain
38% of the world’s surface waters, but the characterization of
surface water dynamics across northern high latitudes remains
highly uncertain, as does the influence of permafrost on hydrology, leading to major challenges in mapping and characterizing
soil moisture and wetlands in the region. Permafrost is actively
thawing in high latitudes in response to climate warming, affecting soil moisture and saturation. Changes in soil moistureaffect carbon sequestration potential by impacting water availability for plant growth, and by influencing soil decomposition
rates and the relative contribution of aerobic and anaerobic
processes driving soil carbon emissions (in the form of carbon dioxide and methane). Soil moisture also affects the risksof wildfires that are common in this region and that alter thelandscape in many ways, producing massive carbon emissions
to the atmosphere, altering permafrost and vegetation compoQuarter 4 2019

sition and reducing soil carbon storage. Wetlands are hotspotsof methane production and have the potential to significantly
affect radiative forcing at the regional level. In ice-rich permafrost regions, permafrost degradation can result in groundsubsidence and the formation of new wetlands or lakes (i.e.,thermokarsts) with drastically different carbon dynamics thanpermafrost plateau ecosystems. While thermokarsts can resultin a local increase in water accumulation and soil moisture, thedeepening of the permafrost table and the reshaping of the local
hydrological network may result in drying soils in upland anddraining areas. Permafrost thaw may also result in lake drainage and loss of lakes to dry meadows. Therefore, the dynamics
of soil moisture and wetland distribution and their importancefor regional carbon dynamics, water resources, wildlife habitat,
infrastructure development and landscape accessibility remaina critical science priority for the high latitude regions. The support and maintenance of a long-term and dense network offield observation sites is critical for a better characterization of
the spatio-temporal patternsof soil moisture and permafrost dynamics in high latitude regions.

tude wetland ecology, such as the NASA ABoVE program, theNext Generation Ecosystem Experiments Arctic Project thataims to better understand the terrestrial carbon system and the
USGS permafrost and hydrology research in the region.

Remote sensing methods used to develop soil moisture and wetland map products include NASA’s Soil Moisture Active Passive (SMAP) and Landsat 8 satellites, and the European Space
Agency (ESA)’s Soil Moisture and Ocean Salinity (SMOS),
Sentinel 1 and Sentinel 2 satellites. Optical, microwave, radar and Synthetic Aperture Radar (SAR) are used to help
characterize wetland mapping and detect land cover change,vegetation productivity and fine-scale terrain in Alaska. These
products are also being used to understand the effects of snow
cover on soil moisture, water table depth and fire in high latitude ecosystems. Remote sensing data can cover a broader area
than in situ measurements, but it has its own restrictions suchas limited temporal resolution, difficulty penetrating clouds,
inability to access deep soils and difficulties in detecting land
cover, snow, ice, water andother attributes, including
rapid changes from disturbances such as wildfires orthermokarsts. Furthermore,
Under a projected 2°C
because of the high spatial
warming scenario by thevariability of ecological proend of the century, ecosyscesses in these landscapes,
tem models predict a loss of
efficient calibration and
33–55% of the permafrost
validation of spatial prodextent in Alaska by 2100,
ucts from remote sensing
and an associated increase
data rely on a high density
in the release of greenhouseof ground-truth in situ data.
gasses. These estimates only
Empirical modeling that
account for the effect ofincorporates machine learnpermafrost thaw on the ining, algorithms and intercrease in soil carbon stocks
mediate-scale measurements
such as remote sensing via
Workshop attendees outside an APEX bog site
available for decomposition.
aircraft can help bridge the
The impact of soil moisture
gap between in situ and remote sensing information, allow for
modified by permafrost thaw on soil greenhouse gas release
more automatic mapping from optical and radar remote senshas yet to be determined. Additionally, the direction and maging or be used for calibration and validation of large-scale renitude of the changes in lateral transport of carbon associatedmote sensing data. Furthermore, large international databases,
with permafrost thaw are still unknown.
such as the International Soil Moisture Network, centralize insitu observations, and their development and maintenance are
Wetlands in Alaska are widely used by local native and nonof critical importance to improve the calibration and validanative communities and the recreation and tourism industries.
tion of spatial products.
Arctic wetlands are also threatened by oil and gas extraction,mining and climate change. Predicting the consequences from
In situ monitoring of high latitude soil moisture and wetlands
these forces allows more intelligent management and accuincludes gravimetric analysis, vegetation descriptions, electrirate, up-to-date geospatial wetland information is key to thiscal resistivity tomography (ERT), nuclear magnetic resonanceprocess. This information may also be essential for infrastruc(NMR), time-domain electromagnetics (TDEM), gas collecture planning and maintenance. Many of the wetland wildlife
tion and passive seismology. NMR can determine soil pore
habitats in Alaska are located in managed public lands. Data
size, moisture content and soil texture up to 100m below
on wetland distribution and dynamics can inform land manground, and ERT can be used along 50-500m transects atagement decisions in this critical environment, including decidepths to 20m. Ambient seismology can be used to take consions to help species adapt to environmental change. Surface
tinuous measurements over tens to hundreds of square metersand subsurface processes in high latitude ecosystems have been
at depths to 20m and can complement other methods of data
identified as research priorities by the U.S. Global Change Recollection. In situ measurements can capture fine scale spatiosearch Program in the Fourth National Climate Assessment
temporal variations and document processes that remote sensand the Second State of the Carbon Cycle Report. Large naing acquisition cannot. However, in situ measurements varytional research programs are supporting advances in high lati19

Quarter 4 2019

GEWEX/WCRP Calendar

For the complete Calendar, see http://www.gewex.org/events/
12–16 January 2020—100th American Meteorological Society
Meeting—Boston, Massachusetts, USA
22–24 January 2020—2020 GDAP Meeting—Tucson, Arizona,USA
27–31 January 2020—32nd Session of the GEWEX Scientific
Steering Group (SSG)—Pasadena, California, USA
27–31 January 2020—2020 Sun-Climate Symposium: What is
the Quiet Sun and What are the Subsequent Climate Implications?—Tucson, Arizona, USA

Attendees walk outside a National Ecological Observatory Network(NEON) data collection station near Denali National Park, AK.

highly over small spatial scales, can be costly and time consuming and may be difficult to collect due to limited access.
Process-based biosphere models are an effective tool in integrating remotely-sensed map products and in situ measurements in high latitude regions. They constitute an important
forecasting tool to help improve our understanding of the fateof high latitude ecosystems under a changing climate. Improved
accuracy and spatio-temporal resolution for remote sensing
products and extensive in situ observations are critical to inform
biosphere models and improve their capacity to represent theprocess interactions at play in high latitude ecosystems. Biosphere models help quantify how environmental shifts resulting from historical and projected changes in climate and disturbance regimes may impact the regional carbon balance andits feedback to climate as well as the capacity of high latitude
ecosystems to provide other ecosystem services critical for local
and global populations. With the significant improvement of remote-sensing products, it is critical that biosphere models add tothe traditional use of in situ observations for model parameterization and validation, developing data assimilation techniquesthat allow a dynamic, real-time integration of remote-sensing
data. This integration will improve the capacity of process-basedmodels to represent the spatial variability of environmental variables needed to better understand and predict changes to highlatitude wetlands and understand their global significance. Thereis a strong need for increased spatial resolution, particularly forsmall wetlands, increased frequency of data collection and moreground measurements to calibrate and validate remote sensing.
Bringing together scientists who approach and use wetlandand soil moisture mapping in different ways helps build anunderstanding of the state of the science and our future needs.
Different methods of study complement one another to enhance our overall understanding of these important systems.
Future workshops may be planned to expand on soil moisturemapping outside the boundaries of Alaska and reach out tothe international high latitude community.
20

3–14 February 2020—2020 Australian Climate and Water Summer Institute—Canberra, Australia
3–4 February 2020—Discussion Meeting on Intensification of
Short-Duration Rainfall Extremes and Implications for Flash
Flood Risks—London, UK
10–12 March 2020—Nansen Tutu Centre 10th Anniversary Symposium—Cape Town, South Africa
31 March–1 April 2020—5th Annual Workshop of the International
Network for Alpine Research Catchment Hydrology (INARCH)—
Zaragoza and Benasque, Spain
31 March–2 April 2020—Workshop on Societally-Relevant MultiYear Climate Predictions—Boulder, Colorado, USA
1–3 April 2020—Challenges in Meteorology 7: Meteorology Supporting Public Authorities—Zagreb, Croatia
3–8 May 2020—European Geosciences Union (EGU) General
Assembly 2020—Vienna, Austria

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

Quarter 4 2019