Development of the New Zealand Earth System Model

Williams, Dean R; Morgenstern, J.; Varma, Vidya; Behrens,; Hayek,; Óliver,; Dean, Catherine M.; Mullan,

doi:10.2307/26779386

Cited by 24 publications

(22 citation statements)

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“…We use a global sea-ice coupled model to simulate the oceanic fields and investigate the links between oceanic heat content and MHWs in the Tasman Sea. The model output is based on a global forced ocean sea-ice configuration using NEMO (Madec, 2008) and CICE (Hunke and Lipscomb, 2010) as part of UKESM/NZESM (Williams et al, 2016). The global domain is defined by a coarse (nominal 1 • × 1 • at the equator) tripolar model grid known as eORCA1.…”

Section: Model Descriptionmentioning

confidence: 99%

Meridional Oceanic Heat Transport Influences Marine Heatwaves in the Tasman Sea on Interannual to Decadal Timescales

2019

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Marine heatwaves (MHWs) pose an increasing threat to the ocean's wellbeing as global warming progresses. Forecasting MHWs is challenging due to the various factors that affect their occurrence, including large variability in the atmospheric state. In this study we demonstrate a causal link between ocean heat content and the area and intensity of MHWs in the Tasman Sea on interannual to decadal time scales. Ocean heat content variations are more persistent than 'weather-related' atmospheric drivers (e.g., blocking high pressure systems) for MHWs and thus provide better predictive skill on timescales longer than weeks. Using data from a forced global ocean sea-ice model, we show that ocean heat content fluctuations in the Tasman Sea are predominantly controlled by oceanic meridional heat transport from the subtropics, which in turn is mainly characterized by the interplay of the East Australian Current and the Tasman Front. Variability in these currents is impacted by wind stress curl anomalies north of this region, following Sverdrup's and Godfrey's 'Island Rule' theories. Data from models and observations show that periods with positive upper (2000 m) ocean heat content anomalies or rapid increases in ocean heat content are characterized by more frequent, larger, longer and more intense MHWs on interannual to decadal timescales. Thus, the oceanic heat content in the Tasman Sea acts as a preconditioner and has a prolonged predictive skill compared to the atmospheric state (e.g., surface heat fluxes), making ocean heat content a useful indicator and measure of the likelihood of MHWs.

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Section: Model Descriptionmentioning

confidence: 99%

Meridional Oceanic Heat Transport Influences Marine Heatwaves in the Tasman Sea on Interannual to Decadal Timescales

2019

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“…HadGEM3-GC3.1 (Williams et al 2017;Kuhlbrodt et al 2018) is the coupled land-ocean-sea ice-atmosphere model that forms the physical core of the UK Earth System Model, and is the basis from which the New Zealand Earth System Model is being developed (Williams et al 2016). It uses GA7-GL7 for the atmosphere and land (Walters et al 2019), GO6 for the ocean (Storkey et al 2018), and GSI8.1 for the sea ice component (Ridley et al 2018).…”

Section: Model Descriptionmentioning

confidence: 99%

Interactions between Increasing CO2 and Antarctic Melt Rates

et al. 2020

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Meltwater from the Antarctic ice sheet is expected to increase the sea ice extent. However, such an expansion may be moderated by sea ice decline associated with global warming. Here we investigate the relative balance of these two processes through experiments using HadGEM3-GC3.1, and compare these to two standard idealised CMIP6 experiments. Our results show that the decline in sea ice projected under scenarios of increasing CO2 may be inhibited by simultaneously increasing melt fluxes. We find that Antarctic Bottom Water formation, projected to decline as CO2 increases, is likely to decline further with an increasing meltwater flux. In our simulations, the response of the westerly wind jet to increasing CO2 is enhanced when the meltwater flux increases, resulting in a stronger peak wind stress than is found when either CO2 or melt rates increase exclusively. We find that the sensitivity of the Antarctic Circumpolar Current to increasing melt fluxes in the Southern Ocean is countered by increasing CO2, removing or reducing a feedback mechanism that may otherwise allow more heat to be transported to the polar regions and drive increasing ice shelf melt rates. The insights presented here, and in the accompanying paper (which focuses on the effect of increasing melt fluxes under pre-industrial forcings) provide insights helpful to the interpretation of both future climate projections and sensitivity studies into the effect of increasing melt fluxes from the Antarctic ice sheet when different forcing scenarios are used.

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“…The UM is the atmospheric component, called Global Atmosphere (GA), of the HadGEM3-GC3.1 GCM and the UKESM1 earth system model (ESM). In this analysis we performed custom nudged runs of the UM (Telford et al, 2008) in the GA7.1 configuration with a 20 min time step and output temporal resolution on a New Zealand eScience Infrastructure (NeSI)-National Institute of Water & Atmospheric Research (NIWA) supercomputer (Williams et al, 2016). The model was nudged to the ERA-Interim (Dee et al, 2011) atmospheric fields of horizontal wind speed and potential temperature as well as the HadISST sea surface temperature (SST) and sea ice dataset (Rayner et al, 2003).…”

Section: Model and Gridmentioning

confidence: 99%

“…Ground-based remote sensing instruments include radars, lidars, ceilometers, radiometers and sky cameras. As pointed out by Williams and Bodas-Salcedo (2017), using a wide range of different observational datasets including satellite and ground-based observations for general circulation model (GCM) evaluation is important due to the limitations of each dataset.…”

Section: Introductionmentioning

confidence: 99%

Ground-based lidar processing and simulator framework for comparing models and observations (ALCF 1.0)

et al. 2021

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Abstract. Automatic lidars and ceilometers (ALCs) provide valuable information on cloud and aerosols but have not been systematically used in the evaluation of general circulation models (GCMs) and numerical weather prediction (NWP) models. Obstacles associated with the diversity of instruments, a lack of standardisation of data products and open processing tools mean that the value of large ALC networks worldwide is not being realised. We discuss a tool, called the Automatic Lidar and Ceilometer Framework (ALCF), that overcomes these problems and also includes a ground-based lidar simulator, which calculates the radiative transfer of laser radiation and allows one-to-one comparison with models. Our ground-based lidar simulator is based on the Cloud Feedback Model Intercomparison Project (CFMIP) Observation Simulator Package (COSP), which has been extensively used for spaceborne lidar intercomparisons. The ALCF implements all steps needed to transform and calibrate raw ALC data and create simulated attenuated volume backscattering coefficient profiles for one-to-one comparison and complete statistical analysis of clouds. The framework supports multiple common commercial ALCs (Vaisala CL31, CL51, Lufft CHM 15k and Droplet Measurement Technologies MiniMPL), reanalyses (JRA-55, ERA5 and MERRA-2) and models (the Unified Model and AMPS – the Antarctic Mesoscale Prediction System). To demonstrate its capabilities, we present case studies evaluating cloud in the supported reanalyses and models using CL31, CL51, CHM 15k and MiniMPL observations at three sites in New Zealand. We show that the reanalyses and models generally underestimate cloud fraction. If sufficiently high-temporal-resolution model output is available (better than 6-hourly), a direct comparison of individual clouds is also possible. We demonstrate that the ALCF can be used as a generic evaluation tool to examine cloud occurrence and cloud properties in reanalyses, NWP models, and GCMs, potentially utilising the large amounts of ALC data already available. This tool is likely to be particularly useful for the analysis and improvement of low-level cloud simulations which are not well monitored from space. This has previously been identified as a critical deficiency in contemporary models, limiting the accuracy of weather forecasts and future climate projections. While the current focus of the framework is on clouds, support for aerosol in the lidar simulator is planned in the future.

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Development of the New Zealand Earth System Model

Cited by 24 publications

References 0 publications

Meridional Oceanic Heat Transport Influences Marine Heatwaves in the Tasman Sea on Interannual to Decadal Timescales

Meridional Oceanic Heat Transport Influences Marine Heatwaves in the Tasman Sea on Interannual to Decadal Timescales

Interactions between Increasing CO2 and Antarctic Melt Rates

Ground-based lidar processing and simulator framework for comparing models and observations (ALCF 1.0)

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