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Invited Science Talks - Plenary, Wednesday June 8th, 2016, 10 am to 2 pm
Evaluating monsoon circulations in ACME v1 ne30 experiments, Bryce Harrop, Phil Rasch, Po-Lun Ma
The monsoon circulations are the dominant mode of seasonal variability in the tropics. Marked by its strong annual cycle in precipitation, the global monsoon system brings water to approximately half of the world’s population. Despite the importance of the monsoon in the current climate, several shortcomings still exist in our understanding as well as our ability to accurately model monsoon behavior. As part of the development of the Accelerated Climate Modeling for Energy model version 1 (ACME v1), it is important to evaluate the model’s ability to represent the monsoon (both globally and regionally). To evaluate the monsoon circulation within ACME v1, we compare with an older version of the model (ACME v0), another commonly used climate model (the Community Atmosphere Model), and a number of observational datasets. Several important metrics have been identified from the literature as important markers of the monsoon circulation and these are used to quantify the evaluation of the monsoon. Globally, the monsoon simulated by ACME v1 compares well with observations, but regional biases remain.
Initial Results from Fully Coupled High-Resolution ACME V0.1, Julie McClean, David C. Bader, Mark Taylor, Mathew Maltrud, Milena Veneziani, Qi Tang, Jack Ritchie, Marcia Branstetter, Kate Evans, Salil Mahajan
The explicit simulation of oceanic and atmospheric mesoscale phenomena with spatial scales of 10s and 100s of kilometers, respectively, are expected to enhance the prediction capability of fully coupled climate models by reproducing mesoscale air-sea interactions, eddy-mean flow interactions, and realistic mesoscale ocean mixing processes. Towards this goal, a 100-year 1850 pre-industrial control (PICNTRL) simulation and an ensemble of idealized transient simulations approximating 1970-2010 climate change, were carried out using fully coupled high-resolution ACME V0.1. This model has enhanced horizontal resolution in each of its components relative to standard coupled climate model resolution, and consists of the 1/4° Community Atmosphere Model 5 - Spectral Element (CAM5-SE) /Community Land Model 5 (CLM5), and 1/10° Parallel Ocean Program 2 (POP2)/CICE4 (sea ice model). The atmospheric model parameters used in the PICNTRL control were adjusted (“tuned”) in fully coupled mode to produce an acceptably small top of the atmosphere (TOA) radiation imbalance.
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Initial Results from Fully Coupled High-Resolution ACME V0.1, Julie McClean, David C. Bader, Mark Taylor, Mathew Maltrud, Milena Veneziani, Qi Tang, Jack Ritchie, Marcia Branstetter, Kate Evans, Salil Mahajan
The explicit simulation of oceanic and atmospheric mesoscale phenomena with spatial scales of 10s and 100s of kilometers, respectively, are expected to enhance the prediction capability of fully coupled climate models by reproducing mesoscale air-sea interactions, eddy-mean flow interactions, and realistic mesoscale ocean mixing processes. Towards this goal, a 100-year 1850 pre-industrial control (PICNTRL) simulation and an ensemble of idealized transient simulations approximating 1970-2010 climate change, were carried out using fully coupled high-resolution ACME V0.1. This model has enhanced horizontal resolution in each of its components relative to standard coupled climate model resolution, and consists of the 1/4° Community Atmosphere Model 5 - Spectral Element (CAM5-SE) /Community Land Model 5 (CLM5), and 1/10° Parallel Ocean Program 2 (POP2)/CICE4 (sea ice model). The atmospheric model parameters used in the PICNTRL control were adjusted (“tuned”) in fully coupled mode to produce an acceptably small top of the atmosphere (TOA) radiation imbalance.
The transient ensemble members were initialized from an atmospheric reanalysis-forced 0.1° POP2/CICE4 simulation configured in the same framework as the fully coupled model. This initialization approach has been used in decadal predictability studies, hence we adopted it here as our prediction time scales are multi-decadal rather than centennial. Initial conditions were selected to represent a spread in climate mode variability from the late 1960s to the late 1970s. The transients were run for 1970-2015. The transient ensemble member TOA imbalances reduced to roughly the observed present-day value during the last decade of the simulations. The simulated climate system was then assessed in terms of drift and bias, especially focusing on comparisons of present-day observations and the transient ensemble. Particularly, we examined sea surface temperature biases, the meridional ocean heat transport and overturning circulation, sea ice thickness and concentration biases, and the veracity of the simulated climate mode variability.
Ocean Cavities Below Ice Shelves, Mark Petersen, Xylar Asay-Davis, Douglas Jacobsen, Jeremy Fyke, Matthew Hoffman, Adrian Turner, Jon Wolfe, Stephen Price
Sub-ice shelf ocean cavities are a significant new capability in ACME. Ice shelf-ocean interactions are important to the global climate system. Warmer ocean currents may speed up ice shelf melting and retreat. At the same time, changing land ice fluxes could affect ocean temperature, salinity, and currents below ice shelves, altering Southern Ocean water mass formation.
The Ronne-Filchner and Ross ice shelves sit on top of areas of ocean, each at least the size of California. Despite this, ice shelf cavities have not been included in any fully-coupled global climate model to date because of the numerical modeling challenges and lack of observational data for validation.
This talk will summarize the ACME effort to add static ice shelf cavities, the technical challenges, and early results. The work is the result of tight collaboration between staff with expertise in ocean, land ice, and sea ice modeling, software engineering, and coupling.
Evaluating monsoon circulations in ACME v1 ne30 experiments, Bryce Harrop, Phil Rasch, Po-Lun Ma
The monsoon circulations are the dominant mode of seasonal variability in the tropics. Marked by its strong annual cycle in precipitation, the global monsoon system brings water to approximately half of the world’s population. Despite the importance of the monsoon in the current climate, several shortcomings still exist in our understanding as well as our ability to accurately model monsoon behavior. As part of the development of the Accelerated Climate Modeling for Energy model version 1 (ACME v1), it is important to evaluate the model’s ability to represent the monsoon (both globally and regionally). To evaluate the monsoon circulation within ACME v1, we compare with an older version of the model (ACME v0), another commonly used climate model (the Community Atmosphere Model), and a number of observational datasets. Several important metrics have been identified from the literature as important markers of the monsoon circulation and these are used to quantify the evaluation of the monsoon. Globally, the monsoon simulated by ACME v1 compares well with observations, but regional biases remain.
Huge divergence in land-atmosphere carbon exchange resulting from ambiguous numerical coupling between carbon and nitrogen dynamics, Jinyun Tang, Bill Riley
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