In a recent letter [K. Fraedrich and R. Blender, Phys. Rev. Lett. 90, 108501 (2003)], Fraedrich and Blender studied the scaling of atmosphere and ocean temperature. They analyzed the fluctuation functions F(s) ~ s^alpha of monthly temperature records (mostly from grid data) by using the detrended fluctuation analysis (DFA2) and claim that the scaling exponent alpha over the inner continents is equal to 0.5, being characteristic of uncorrelated random sequences. Here we show that this statement is (i) not supported by their own analysis and (ii) disagrees with the analysis of the daily observational data from which the grid monthly data have been derived. We conclude that also for the inner continents, the exponent is between 0.6 and 0.7, similar as for the coastline-stations.
Modeling globally averaged information on climate forcing from the land surface temperature data, the sea surface temperatures (SST) and the empirically determined relationship between the changes in SST and the turbulent diffusion of heat into the upper ocean demonstrates a consistent link. The modeling is accurate throughout the 20th century despite the different phases of the Interdecadal Pacific Oscillation (IPO) or the strong divergence between land and ocean surface warming. It only fails during the last 15 years when SST drops well below the trend. The finding reinforces the view that s…
The influence of atmospheric composition on the climates of present-day and early Earth has been studied extensively, but the role of ocean composition has received less attention. We use the ROCKE-3D ocean-atmosphere general circulation model to investigate the response of Earth's present-day and Archean climate system to low vs. high ocean salinity. We find that saltier oceans yield warmer climates in large part due to changes in ocean dynamics. Increasing ocean salinity from 20 g/kg to 50 g/kg results in a 71% reduction in sea ice cover in our present-day Earth scenario. This same salinity …
Atmosphere and ocean are coupled via air-sea interactions. The atmospheric conditions fuel the ocean circulation and its variability, but the extent to which ocean processes can affect the atmosphere at decadal time scales remains unclear. In particular, such low-frequency variability is difficult to extract from the short observational record, meaning that climate models are the primary tools deployed to resolve this question. Here, we assess how the ocean's intrinsic variability leads to patterns of upper-ocean heat content that vary at decadal time scales. These patterns have the potential …
We construct a network from climate records of atmospheric temperature at surface level, at different geographical sites in the globe, using reanalysis data from years 1948-2010. We find that the network correlates with the North Atlantic Oscillation (NAO), both locally in the north Atlantic, and through coupling to the southern Pacific Ocean. The existence of tele-connection links between those areas and their stability over time allows us to suggest a possible physical explanation for this phenomenon.
Understanding how climate change will affect oceanic fluid transport is crucial for environmental applications and human activities. However, a synoptic characterization of the influence of climate change on mesoscale stirring and transport in the surface ocean is missing. To bridge this gap, we exploit a high-resolution, fully-coupled climate model of the Mediterranean basin using a Network Theory approach. We project significant increases of horizontal stirring and kinetic energies in the next century, likely due to increments of available potential energy. The future evolution of basin-scal…
A set of idealized experiments are performed to analyze the competing effects of declining atmospheric CO2 concentrations, the opening of an ocean gateway, and varying orbital parameters. These forcing mechanisms, which influence the global mean climate state, may have played a role for triggering climate transitions of the past (for example during the Eocene-Oligocene climate transition and the build-up of the Antarctic Ice Sheet). Sensitivity simulations with a coupled atmosphere-ocean general circulation model are conducted to test these three forcings and their roles for the global climate…
In this report we set forth a simulation method for long-term simulations of NorESM, the Norwegian Earth System Model. In this the sediment is repeatedly decoupled and coupled to the ocean model (BLOM/iHAMOCC), a process called burst coupling. Through this, the ocean (seawater and sediment) is brought into an approximate steady state. We show that just the model has to run at least 50000 yr to get in an approximate steady state. With burst coupling this can be done in a computationally reasonable time (wall time in the order of one week). The method can be used to generate the sediment over hu…
We use numerical climate simulations, paleoclimate data, and modern observations to study the effect of growing ice melt from Antarctica and Greenland. Meltwater tends to stabilize the ocean column, inducing amplifying feedbacks that increase subsurface ocean warming and ice shelf melting. Cold meltwater and induced dynamical effects cause ocean surface cooling in the Southern Ocean and North Atlantic, thus increasing Earth's energy imbalance and heat flux into most of the global ocean's surface. Southern Ocean surface cooling, while lower latitudes are warming, increases precipitation on the …
We present a set of idealised numerical experiments of a solstitial aquaplanet ocean and examine the thermodynamic and dynamic implications of surface gravity waves (SGWs) upon its mean state. The aquaplanet's oceanic circulation is dominated by an equatorial zonal jet and four Ekman driven meridional overturning circulation (MOC) cells aligned with the westerly atmospheric jet streams and easterly trade winds in both hemispheres. Including SGW parameterization (representing modulations of air-sea momentum fluxes, Langmuir circulation and Stokes-Coriolis force) increases mixed layer vertical m…
The Biogeochemical-Argo (BGC-Argo) program is building a network of globally distributed, sensor-equipped robotic profiling floats, improving our understanding of the climate system and how it is changing. These floats, however, are limited in the number of variables measured. In this study, we train neural networks to predict silicate and phosphate values in the Southern Ocean from temperature, pressure, salinity, oxygen, nitrate, and location and apply these models to earth system model (ESM) and BGC-Argo data to expand the utility of this ocean observation network. We trained our neural net…
The present study investigates how global thermodynamic properties of the climate system are affected by the changes in the intensity of the imposed oceanic heat transport in an atmospheric general circulation model in aqua-planet configuration. Increasing the poleward oceanic heat transport results in an overall increase in the surface temperature and a decrease in the equator-to-pole surface temperature difference as a result of the ice-albedo feedback. Following the classical ansatz by Stone, the atmospheric heat transport changes in such a way that the total poleward heat transport remains…
Improving observations of ocean heat content show that Earth is absorbing more energy from the sun than it is radiating to space as heat, even during the recent solar minimum. The inferred planetary energy imbalance, 0.59 \pm 0.15 W/m2 during the 6-year period 2005-2010, confirms the dominant role of the human-made greenhouse effect in driving global climate change. Observed surface temperature change and ocean heat gain together constrain the net climate forcing and ocean mixing rates. We conclude that most climate models mix heat too efficiently into the deep ocean and as a result underestim…
Hewlett Packard Enterprise（慧与公司）；National Center for Atmospheric Research（美国国家大气研究中心）；University of Victoria（维多利亚大学）
We demonstrate the first climate-scale, numerical ocean simulations improved through distributed, online inference of Deep Neural Networks (DNN) using SmartSim. SmartSim is a library dedicated to enabling online analysis and Machine Learning (ML) for traditional HPC simulations. In this paper, we detail the SmartSim architecture and provide benchmarks including online inference with a shared ML model on heterogeneous HPC systems. We demonstrate the capability of SmartSim by using it to run a 12-member ensemble of global-scale, high-resolution ocean simulations, each spanning 19 compute nodes, …
Various climate states at high obliquity are realized for a range of stellar irradiance using a dynamical atmosphere-ocean-sea ice climate model in an Aquaplanet configuration. Three stable climate states are obtained that differ in the extent of the sea ice cover. For low values of irradiance the model simulates a Cryoplanet that has a perennial global sea ice cover. By increasing stellar irradiance, transitions occur to an Uncapped Cryoplanet with a perennial equatorial sea ice belt, and eventually to an Aquaplanet with no ice. Using an emulator model we find that the Uncapped Cryoplanet is …
It is shown that, the wavelet regression detrended fluctuations of the monthly global temperature data (land and ocean combined) for the period 1880-2009yy, are completely dominated by one-third subharmonic resonance to annual forcing (both natural and anthropogenically induced). Role of the oceanic Rossby waves and the resonance contribution to the El Nino phenomenon have been discussed in detail.
We build a conceptual coupled model of the climate and tidal evolution of the Earth-Moon system to find the influence of the former on the latter. An energy balance model is applied to calculate steady-state temperature field from the mean annual insolation as a function of varying astronomical parameters. A harmonic oscillator model is applied to integrate the lunar orbit and Earth's rotation with the tidal torque dependent on the dominant natural frequency of ocean. An ocean geometry acts as a bridge between temperature and oceanic frequency. On assumptions of a fixed hemispherical continent…
Atmospheric transient eddies and low-frequency flow contribution to the ocean surface wave climate in the North Atlantic during boreal winter is investigated (1980 - 2016). We conduct a set of numerical simulations with a state-of-the-art spectral wave model Wavewatch III forced by decomposed wind fields derived from the ERA-Interim reanalysis (0.7° horizontal resolution). Synoptic-scale processes (2-10 day bandpassed winds) are found to have the largest impact on the formation of wind waves in the western mid-latitude North Atlantic along the North American and western Greenland coasts. The e…
Sensitivity of the ECMWF seasonal forecast model to CO2 and anthropogenic aerosol forcings: Experimental design and impact on climate trends
ECMWF（欧洲中期天气预报中心）；Department of Meteorology and Geophysics, University of Vienna（维也纳大学气象与地球物理系）；NCAS, University of Oxford, Atmospheric, Oceanic and Planetary Physics（牛津大学大气、海洋和行星物理国家环境科学研究中心）
We propose a method to reconstruct and analyze a complex network from data generated by a spatio-temporal dynamical system, relying on the nonlinear mutual information of time series analysis and betweenness centrality of complex network theory. We show, that this approach reveals a rich internal structure in complex climate networks constructed from reanalysis and model surface air temperature data. Our novel method uncovers peculiar wave-like structures of high energy flow, that we relate to global surface ocean currents. This points to a major role of the oceanic surface circulation in coup…
Drought poses a significant threat to the delicate economies in subsaharan Africa. This study investigates the influence of large scale ocean oscillation on drought in West Africa. Standardized Precipitation Index for the region was computed using monthly precipitation data from the Climate Research Unit during the period 1961 -1990. The impact of three ocean oscillation indices - Southern Ocean Index (SOI), Pacific Decadal Oscillation (PDO) and North Atlantic Oscillation (NAO) on drought over West Africa was investigated using linear correlation, co-integration test, mutual information and no…
Over recent decades, the Arctic Ocean has experienced dramatic changes due to climate change. Retreating sea ice has opened up large areas of ocean, resulting in an enhanced wave climate. Taking into account the intense seasonality and the rapid changes to the Arctic climate, a non-stationary approach is applied to time-varying statistical properties to investigate historical trends of extreme values. The analysis is based on a 28-year wave hindcast (from 1991 to 2018) carried out with the WAVEWATCH III wave model forced by ERA5 wind speed. The results show notable seasonal differences and rob…
Data-driven Global Ocean Modeling for Seasonal to Decadal Prediction
School of Computer Science, Fudan University（复旦大学计算机科学学院）；Shanghai Artificial Intelligence Laboratory（上海人工智能实验室）；Potsdam Institute for Climate Impact Research（波茨坦气候影响研究所）；Japan Agency for Marine-Earth Science and Technology（日本海洋研究开发机构）；Institut de Recherche pour le Développement (IRD)（法国发展研究院）；French National Research Institute for Sustained Development (IRD)（法国可持续发展研究院）；Cooperative Institute for Research in Environmental Sciences（合作环境科学研究所）；NOAA Physical Sciences Laboratory（美国国家海洋和大气管理局物理科学实验室）；Nanjing University of Information Science and Technology（南京信息工程大学）；Technical University of Munich（慕尼黑工业大学）；University of Colorado Boulder（科罗拉多大学博尔德分校）
The Atlantic Meridional Overturning Circulation (MOC) is a crucial part of the climate system because of its associated northward heat transport. The present-day MOC is sensitive to freshwater anomalies and may collapse to a state with a strongly reduced northward heat transport. A future collapse of the Atlantic MOC has been identified as one of the most dangerous tipping points in the climate system. It is therefore crucial to develop early warning indicators for such a potential collapse based on relatively short time series. So far, attempts to use indicators based on critical slowdown hav…
Future changes in the location of the intertropical convergence zone (ITCZ) due to climate change are of high interest since they could substantially alter precipitation patterns in the tropics and subtropics. Although models predict a future narrowing of the ITCZ during the 21st century in response to climate warming, uncertainties remain large regarding its future position, with most past work focusing on the zonal-mean ITCZ shifts. Here we use projections from 27 state-of-the-art climate models (CMIP6) to investigate future changes in ITCZ location as a function of longitude and season, in …
Freshwater forcing from a retreating Antarctic Ice Sheet could have a wide range of impacts on future global climate. Here, we report on multi-century (present-2250) climate simulations performed using a fully coupled numerical model integrated under future greenhouse gas emissions scenarios IPCC RCP4.5 and 8.5, with meltwater discharge provided by a dynamic-thermodynamic ice sheet model. Accounting for Antarctica's meltwater contribution raises sub-surface ocean temperatures by 1 C at the ice margin, beyond rates currently projected. In contrast, 2-10 C cooler surface air and ocean temperatur…
In recent years extensive studies on the Earth's climate system have been carried out by means of advanced complex network statistics. The great majority of these studies, however, have been focusing on investigating correlation structures within single climatic fields directly on or parallel to the Earth's surface. Here, we develop a novel approach of node weighted coupled network measures to study correlations between ocean and atmosphere in the Northern Hemisphere extratropics and construct 18 coupled climate networks, each consisting of two subnetworks. In all cases, one subnetwork represe…
Climate change in California may require construction of a barrier separating the Pacific Ocean from San Francisco Bay and the Sacramento River-San Joaquin River Delta simply because Southern California is remarkably dependent on freshwater exported from the Delta. We offer a new kind of salt barrier, a macroproject built of impermeable textile materials stretched across the Golden Gate beneath the famous bridge. We anticipate it might eventually substitute for a recently proposed San Francisco In-Stream Tidal Power Plant harnessing a 1.7 m tide at the Bay entrance if future climate conditions…
Data-driven global ocean model resolving ocean-atmosphere coupling dynamics
Center for Climate and Carbon Cycle Research, Korea Institute of Science and Technology, Seoul, Republic of Korea（韩国科学技术院气候与碳循环研究中心，首尔，大韩民国）；Department of Environment and Energy, Jeonbuk National University, Jeonju, Republic of Korea（全南国立大学环境与能源系，全州，大韩民国）；School of Earth and Environmental Sciences, Seoul National University, Seoul, Republic of Korea（首尔国立大学地球与环境科学学院，首尔，大韩民国）；Department of Environmental Management, Seoul National University, Seoul, Republic of Korea（首尔国立大学环境管理系，首尔，大韩民国）
A global hybrid coupled model is developed, with the aim of studying the effects of ocean-atmosphere feedbacks on the stability of the Atlantic meridional overturning circulation. The model includes a global ocean general circulation model and a statistical atmosphere model. The statistical atmosphere model is based on linear regressions of data from a fully coupled climate model on sea surface temperature both locally and hemispherically averaged, being the footprint of Atlantic meridional overturning variability. It provides dynamic boundary conditions to the ocean model for heat, freshwater…
The carbon pump of the world's ocean plays a vital role in the biosphere and climate of the earth, urging improved understanding of the functions and influences of the ocean for climate change analyses. State-of-the-art techniques are required to develop models that can capture the complexity of ocean currents and temperature flows. This work explores the benefits of using physics-informed neural networks (PINNs) for solving partial differential equations related to ocean modeling; such as the Burgers, wave, and advection-diffusion equations. We explore the trade-offs of using data vs. physica…
This is simply a long list of papers that I have found useful. They are generally related to aspects of the search for evidence that the Sun influences the climate somehow. There are papers on Data, on Methods and papers that just discuss the problems. So far the list is not structured, but it is planned that later versions will have lists that are sorted into general subject classes.
