Earth System Modeling & Prediction Processes & Observations

Transcription

1 Earth System Modeling & Prediction Processes & Observations The ESMP/P&O programmes in the Deep South National Science Challenge Olaf Morgenstern 1 & Adrian McDonald 2 1 NIWA, Wellington 2 U. Canterbury, Christchurch

2 Mission Statement of the Deep South National Science Challenge: The mission of the Deep South (Te Kōmata o Te Tonga) National Science Challenge is to enable New Zealanders to adapt, manage risk, and thrive in a changing climate. This will be underpinned by improved knowledge and observations of climate processes in the Southern Ocean and Antarctica and will include development of a world-class Earth System Model to predict Aotearoa/New Zealand's climate.

3 Structure of the Deep South NSC Programmes under the Deep South National Science Challenge: Processes and Observations Earth System Modelling and Prediction Impacts and Implications Vision Mātauranga Engagement

4 What is an Earth System Model? A climate model represents the physics of the climate system. An earth system model additionally represents simplified chemistry and biology. ESMs are state-of-the-art in climate modelling.

5 New Zealand develops own ESM? Developing an ESM from scratch requires 100s of developers and 1000s of person-years. This is too big a project for the NZ community. Hence we require an established overseas partner. We now join forces with the UK Met Office and their partners. The model development will feed into the development of the UK Earth System Model. (poster by Jonny Williams et al.)

6 What science do we work on? The 5 th Assessment Report of IPCC (2013) identified several shortcomings in the simulation of Antarctic and Southern-Ocean climate that will strongly influence climate projections over New Zealand. High-quality observational datasets are required for model validation and the development of new understanding (finding missing physics) to improve model projections. IPCC AR5 also identified decadal prediction as a new application for climate models. Attribution and projection of extreme events

7 Improving the NZESM: Ocean 2-3 km km ~80 km Resolution matters!

8 Improving the NZESM: Ocean Long-term average sea-surface temperature bias in 22 CMIP5 models. (from Wang et al., NCC, 2014) Present-generation models often have warm Southern-Ocean biases possibly linked to clouds.

9 Improving NZESM: Sea ice 5 th Assessment Report of IPCC states: It is very likely that the annual mean Antarctic sea ice extent increased at a rate in the range of 1.2 to 1.8% per decade between 1979 and 2012 Most models simulate a small downward trend in Antarctic sea ice extent Sea Ice Extent (miilion km 2 ) As well as getting the sign of the trend wrong, CMIP5 models also generally get the extent and seasonality of sea ice wrong. Taken from Turner et al. (2013). Month

10 Improving NZESM: Sea ice Amongst other efforts, the sea ice project has focussed on the sensitivity of sea ice to variations in ice shelf meltwater flux. The Figure to the right shows that different resolution models also have an impact on sea ice extent. To further validate potential sea ice improvement, measurements of sea ice thickness using the EMBird in Antarctica have also been made.

11 Improving NZESM: Cloud Problem 5 th Assessment Report of IPCC states: the response of low clouds to a warming are responsible for most of the spread in modelbased estimates of equilibrium climate sensitivity Several studies have highlighted the potential importance and poor simulation of subpolar clouds in the Arctic and Southern Oceans. Solution The C&A project focusses on using observations to identify and improve NZESM simulations. This includes the use of satellite observations and detailed measurements of low-level cloud and aerosols in the Southern Ocean. Error in cloud radiative forcing in NZESM.

12 Using the NZESM: Decadal prediction (from IPCC AR5) Decadal prediction sits between numerical weather prediction / seasonal prediction and climate projection. New topic identified in IPCC 5 th Assessment Report. Southern Hemisphere decadal prediction has received much less attention than the North.

13 Extreme events High-impact extreme events are projected to become more frequent under climate change. Often small-scale in nature. Difficult to model in an ESM. (10000s of realizations produced on home computers) Edgecumbe flood (April 2017) Come to the mini-symposia on Wednesday: Approaches to attributing observed events to climate change: How do we predict extremes? Frequency of specific circulation patterns over New Zealand, red dots identify anomalous conditions during the 2013 North Island Drought. Taken from Harrington et al. (2016).

14 Evaluating the NZESM Validation of a climate model requires highquality observational data sets (e.g. aerosols, clouds and ozone). Satellite-derived total column ozone snapshot from the Assessment and Validation project below. Seasonal climatology of cloud fraction and cloud phase over the Ross Sea derived from CALIPSO satellite observations above. Taken from Jolly et al. (2017)

15 Integrated effort CORE Projects Contestable projects 4-D Drones: W. Rack Single-column model: J. Conway Sulphur cycle: L. Revell Stratospheric Chemistry: O. Morgenstern Satellite Simulators: A. McDonald Sea-ice Modelling: I. Smith Southern-Ocean Radiocarbon: J. Turnbull Ross-Sea outflow: M. Bowen ESMP/P&O core projects address key issues in climate research. Contestable projects in ESMP/P&O space support core projects and look to the future.

16 International Connections Deep South ESMP and P&O science is well connected internationally. Capability project: leverages off the partnership between NIWA and the Met Office. Sea ice project: contributed personnel and instruments to the National Science Foundation (PIPERS (Polynyas, Ice Production and seasonal Evolution in the Ross Sea) voyage. Assessment and Validation project: works closely with the ACRE (Atmospheric Circulation Reconstructions over the Earth) international programme and the Bureau of Meteorology (Australia). Clouds & Aerosols project: connected to SOCRATES (Southern Ocean Clouds, Radiation, Aerosol Transport Experimental Study - joint USA/Australian programme) and ACRE (Antarctic Cloud and Radiation Experiment - Australian programme) international programmes, and the modelling effort is working closely with the Met Office (UK). Ocean project: works closely with scientists at CSIRO (Australia). Come to the NZESM symposium, Tuesday 2 pm

17 ESMP/P&O Results are starting to flow.