MESACLIP Project

Project Overview:

Climate variations on seasonal-to-decadal (S2D) timescales can have enormous social, economic, and environmental impacts, making skillful predictions on these time scales an invaluable tool for policymakers and stakeholders. Such variations modulate the likelihood and intensity of extreme weather events including, tropical cyclones (TCs), heat waves, winter storms, atmospheric rivers (ARs), and floods, which have all been associated with (1) increases in human morbidity and mortality rates; (2) severe impacts on agriculture, energy use, and industrial activity; and (3) economic costs in the billions of dollars. Changes in prevailing climate patterns are also responsible for prolonged droughts, which can have profoundly negative effects on large segments of the world population. Enhancing our foreknowledge of climate variability on S2D time scales and understanding its influence on extreme weather events could help mitigate negative impacts on human and biological populations, making climate predictions an exceptionally important climate and social science frontier.

Over the past three years, our research team consisting of scientists at Texas A&M University (TAMU) and the U.S. National Science Foundation National Center for Atmospheric Research (NSF NCAR), through collaborations with our international partners, has made major breakthroughs in advancing high-resolution global climate modeling and prediction. Not only have we completed an unprecedented set of TC-permitting (0.25° atmosphere–land resolution) and ocean-mesoscale-eddy-resolving (0.1° ocean–sea-ice resolution) (hereafter simply referred to as high-resolution) historical and future climate simulations (Chang et al. 2020) but we also pioneered the first-ever ensemble of global high-resolution S2D climate prediction simulations. These trailblazing efforts have led to multiple thought-invoking and intriguing discoveries about the potentially important role of mesoscale atmosphere-ocean interactions in climate predictability and prediction at S2D timescales, which are now in need of more in-depth investigation and further scrutiny. Building on these initial efforts, the overall objective of the MESACLIP project is to advance our fundamental knowledge and understanding of the multi-scale dynamical processes underlying S2D predictability by 1) expanding the ensemble size of the existing high-resolution simulations to enable more robust and mechanistic insights into predictable dynamics from meso-to-basin scales, and 2) comparing the high-resolution prediction ensemble directly with the existing low-resolution (∼1° in all components) ensemble to quantify the benefits of increased model resolutions and how such benefits arise.

Model Version: The Community Earth System Model (CESM) code used to generate the high-resolution simulations is based on an earlier version of CESM1.3 described by Meehl et al. (2019) with many additional modifications and improvements, including the usage of the global eddy-resolving ocean model of Small et al. (2014). The most recent tag of the so-called cesm-ihesp-hires CESM branch is available here.

Resolutions:

• CESM-HR: Horizontal resolution of 0.25° (∼25 km) for the atmosphere and land models, and nominal 0.1° (∼10 km at the Equator down to ∼4 km at high latitudes) for the ocean and sea-ice models.
• CESM-LR: Horizontal resolution of ∼1° (∼100 km) in all components.

Years: 1920-2100

Experiments:

• A 3-member ensemble of Historical and Future Transient (HF-TNST) climate simulations is available to the community. It uses historical forcings from 1920 to 2005 and the representative concentration pathway 8.5 (RCP8.5) forcings from 2006 to 2100.
• This 3-member ensemble is being expanded to a 10-member set of HF-TNST simulations. The additional ensemble members will be made available to the community following the CESM Data Management & Distribution Plan. We anticipate that the full 10-member ensemble will be available by the end of 2024. Upon completion, the 10-member set will consist of over 1800 simulated model-years of CESM-HR integration.
• The CESM HRDP system is an ensemble forecast set using CESM-HR (Yeager et al. 2023). It is currently comprised of 10-member ensembles initialized on November 1st of even year between 1982 and 2022 and integrated for 62 months. We plan to augment HRDP to include every year initialization and add an additional May 1st initialization for each year. Upon completion, the HRDP ensemble set will account for over 2000 simulated model-years of CESM-HR integration.
• The CESM HighResMIP set contains data from the 1950-control simulation forced by perpetual 1950 Greenhouse Gas (GHG) emissions for 130 years and the accompanying transient climate simulations that follow the HighResMIP protocol forced by observed GHG emissions from 1950 to 2005 and then by projected GHG emissions from 2006 to 2050 based on RCP85. Both the high-resolution (HR) and low-resolution (LR) version of these datasets have been published on Earth Systems Grid Federation (ESGF) portal with the help of NSF NCAR's ESGF Data Node. Please use the following links for the 1950-control, the historical, and the RCP85 segments respectively.

Project leads: Ping Chang (TAMU) and Gokhan Danabasoglu (NSF NCAR)

Project co-leads: Dan Fu (TAMU) and Frederic Castruccio (NSF NCAR)

Project investigators: Steve Yeager (NSF NCAR), Xue Liu (TAMU), Nan Rosenbloom (NSF NCAR), Qiuying Zhang (TAMU), Gaopeng Xu (TAMU), Justin Small (NSF NCAR), Xiaoqi Wang (TAMU), Greta Olson (TAMU), and Teagan King (NSF NCAR).

Data acquisition: The datasets that have already been released to the public can be accessed on NSF NCAR Campaign Storage and/or the ESGF. We are actively seeking ways to make the data more broadly and easily accessible but the task is complicated by the large data volumes produced in these high resolution simulations. For now, data is being served upon request here.

Funding: The initial 3-member ensemble was completed through the International Laboratory for High Resolution Earth System Prediction (iHESP) project–a three-way collaboration between the Qingdao National Laboratory for Marine Science and Technology (QNLM), Texas A&M University (TAMU), and the U.S. National Science Foundation National Center for Atmospheric Research (NSF NCAR). The ensemble expansion from 3- to 10-member is supported by the National Science Foundation (NSF) Division of Atmospheric and Geospace Sciences (AGS) Climate & Large-Scale Dynamics program under Grant #2231237.

HPC resources: We acknowledge the Texas Advanced Computing Center (TACC ; http://www.tacc.utexas.edu) at The University of Texas at Austin (UT Austin) for providing HPC resources on Frontera. We also acknowledge high-performance computing support from Derecho: HPE Cray EX System (https://doi.org/10.5065/qx9a-pg09) provided by NSF NCAR's Computational and Information Systems Laboratory (CISL), sponsored by the National Science Foundation.

The CVDP package was used to create these diagnostics.

Products:

High-resolution CESM outputs relevant to extreme weather risk

Publications:

1. Ping Chang, Shaoqing Zhang, Gokhan Danabasoglu, Stephen G. Yeager, Haohuan Fu, Hong Wang, Frederic S. Castruccio, Yuhu Chen, James Edwards, Dan Fu, Yinglai Jia, Lucas C. Laurindo, Xue Liu, Nan Rosenbloom, R. Justin Small, Gaopeng Xu, Yunhui Zeng, Qiuying Zhang, Julio Bacmeister, David A. Bailey, Xiaohui Duan, Alice K. DuVivier, Dapeng Li, Yuxuan Li, Richard Neale, Achim Stössel, Li Wang, Yuan Zhuang, Allison Baker, Susan Bates, John Dennis, Xiliang Diao, Bolan Gan, Abishek Gopal, Dongning Jia, Zhao Jing, Xiaohui Ma, R. Saravanan, Warren G. Strand, Jian Tao, Haiyuan Yang, Xiaoqi Wang, Zhiqiang Wei, and Lixin Wu (2020). An unprecedented set of high-resolution earth system simulations for understanding multiscale interactions in climate variability and change. Journal of Advances in Modeling Earth Systems, 12, e2020MS002298. DOI: 10.1029/2020MS002298.
   Abstract
   We present an unprecedented set of high-resolution climate simulations, consisting of a 500-year pre-industrial control simulation and a 250-year historical and future climate simulation from 1850 to 2100. A high-resolution configuration of the Community Earth System Model version 1.3 (CESM1.3) is used for the simulations with a nominal horizontal resolution of 0.25° for the atmosphere and land models and 0.1° for the ocean and sea-ice models. At these resolutions, the model permits tropical cyclones and ocean mesoscale eddies, allowing interactions between these synoptic and mesoscale phenomena with large-scale circulations. An overview of the results from these simulations is provided with a focus on model drift, mean climate, internal modes of variability, representation of the historical and future climates, and extreme events. Comparisons are made to solutions from an identical set of simulations using the standard resolution (nominal 1°) CESM1.3 and to available observations for the historical period to address some key scientific questions concerning the impact and benefit of increasing model horizontal resolution in climate simulations. An emerging prominent feature of the high-resolution pre-industrial simulation is the intermittent occurrence of polynyas in the Weddell Sea and its interaction with an Interdecadal Pacific Oscillation. Overall, high-resolution simulations show significant improvements in representing global mean temperature changes, seasonal cycle of sea-surface temperature and mixed layer depth, extreme events and in relationships between extreme events and climate modes.
2. Ping Chang, Gaopeng Xu, Jaison Kurian, R. Justin Small, Gokhan Danabasoglu, Stephen Yeager, Frederic S. Castruccio, Qiuying Zhang, Nan Rosenbloom, and Piers Chapman (2023). Uncertain future of sustainable fisheries environment in eastern boundary upwelling zones under climate change. Communications Earth & Environment, 4, 19. DOI: 10.1038/s43247-023-00681-0.
   Abstract
   Upwelling along ocean eastern boundaries is expected to intensify due to coastal wind strengthening driven by increasing land-sea contrast according to the Bakun hypothesis. Here, the latest high-resolution climate simulations that exhibit drastic improvements of upwelling processes reveal far more complex future upwelling changes. The Southern Hemisphere upwelling systems show a future strengthening in coastal winds with a rapid coastal warming, whereas the Northern Hemisphere coastal winds show a decrease with a comparable warming trend. The Bakun mechanism cannot explain these changes. Heat budget analysis indicates that temperature change in the upwelling region is not simply controlled by vertical Ekman upwelling, but also influenced by horizontal heat advection driven by strong near-coast wind stress curl that is neglected in the Bakun hypothesis and poorly represented by the low-resolution models in the Coupled Model Intercomparison Project. The high-resolution climate simulations also reveal a strong spatial variation in future upwelling changes, which is missing in the low-resolution simulations.
3. Gerald A. Meehl, Dongxia Yang, Julie M. Arblaster, Susan C. Bates, Nan Rosenbloom, Richard Neale, Julio Bacmeister, Peter H. Lauritzen, Frank Bryan, Justin Small, John Truesdale, Cecile Hannay, Christine Shields, Warren G. Strand, John Dennis, and Gokhan Danabasoglu (2019). Effects of model resolution, physics, and coupling on Southern Hemisphere storm tracks in CESM1.3. Geophysical Research Letters, 46, 12408-12416. DOI: 10.1029/2019GL08405.
   Abstract
   Two high-resolution versions of a Coupled Earth System Model (CESM1.3: 0.25° atmosphere, 1° ocean; CESM1.1: .25° atmosphere, 0.1° ocean) are compared to the standard resolution CESM1.1 and CESM1.3 (1° atmosphere, 1° ocean). The CESM1.3 versions are documented, and the consequences of model resolution, air-sea coupling, and physics in the atmospheric models are studied with regard to storm tracks in the Southern Hemisphere as represented by 850-hPa eddy kinetic energy. Increasing the resolution from 1° to 0.25° in the atmosphere (same physics) coupled to the 1° ocean intensifies the strength of the storm tracks closer to observations. The 0.25° atmosphere with the older CESM1.1 physics coupled to the 0.1° ocean has fewer low clouds, warmer Southern Ocean sea surface temperatures, a weaker meridional temperature gradient, and a degraded storm track simulation compared to the 0.25° atmosphere with CESM1.3 physics coupled to the 1° ocean. Therefore, deficient physics in the atmospheric model can negate the gains attained by higher resolution in atmosphere and ocean.
4. R. Justin Small, Julio Bacmeister, David Bailey, Allison Baker, Stuart Bishop, Frank Bryan, Julie Caron, John Dennis, Peter Gent, Hsiao-ming Hsu, Markus Jochum, David Lawrence, Ernesto Muñoz, Pedro diNezio, Tim Scheitlin, Robert Tomas, Joseph Tribbia, Yu-heng Tseng,and Mariana Vertenstein (2014). A new synoptic scale resolving global climate simulation using the Community Earth System Model. Journal of Advances in Modeling Earth Systems, 6, 1065-1094, DOI: 10.1002/2014MS000363.
   Abstract
   High-resolution global climate modeling holds the promise of capturing planetary-scale climate modes and small-scale (regional and sometimes extreme) features simultaneously, including their mutual interaction. This paper discusses a new state-of-the-art high-resolution Community Earth System Model (CESM) simulation that was performed with these goals in mind. The atmospheric component was at 0.25° grid spacing, and ocean component at 0.1°. One hundred years "present-day" simulation were completed. Major results were that annual mean sea surface temperature (SST) in the equatorial Pacific and El-Niño Southern Oscillation variability were well simulated compared to standard resolution models. Tropical and southern Atlantic SST also had much reduced bias compared to previous versions of the model. In addition, the high resolution of the model enabled small-scale features of the climate system to be represented, such as air-sea interaction over ocean frontal zones, mesoscale systems generated by the Rockies, and Tropical Cyclones. Associated single component runs and standard resolution coupled runs are used to help attribute the strengths and weaknesses of the fully coupled run. The high-resolution run employed 23,404 cores, costing 250 thousand processor-hours per simulated year and made about two simulated years per day on the NCAR-Wyoming supercomputer "Yellowstone".
5. Stephen G. Yeager, Ping Chang, Gokhan Danabasoglu, Nan Rosenbloom, Qiuying Zhang, Frederic S. Castruccio, Abishek Gopal, M. Cameron Rencurrel, and Isla R. Simpson (2023). Reduced Southern Ocean warming enhances global skill and signal-to-noise in an eddy-resolving decadal prediction system. npj Climate and Atmospheric Science, 6, 107. DOI: 10.1038/s41612-023-00434-y. Abstract
   The impact of increased model horizontal resolution on climate prediction performance is examined by comparing results from low-resolution (LR) and high-resolution (HR) decadal prediction simulations conducted with the Community Earth System Model (CESM). There is general improvement in global skill and signal-to-noise characteristics, with particularly noteworthy improvements in the eastern tropical Pacific, when resolution is increased from order 1° in all components to order 0.1°/0.25° in the ocean/atmosphere. A key advance in the ocean eddy-resolving HR system is the reduction of unrealistic warming in the Southern Ocean (SO) which we hypothesize has global ramifications through its impacts on tropical Pacific multidecadal variability. The results suggest that accurate representation of SO processes is critical for improving decadal climate predictions globally and for addressing longstanding issues with coupled climate model simulations of recent Earth system change.

Figure: Sea surface temperature field from September 21, 2018, as represented in (top) CESM-HR and (bottom) CESM-LR simulations submitted to HighResMIP. Right panels show a blow-up of the Western North Atlantic region. The cold wake generated by a tropical cyclone is clearly visible east of the Bahamas in the HR panel (top right). Units are in degrees Celsus.