Large-scale Ocean Circulation Research Articles

Characterising global ocean mesoscale eddy by AVISO and Haiyang-2 altimeter

ABSTRACT This work compares the Haiyang-2 (HY-2) altimeter data with the well-recognized satellite oceanographic data (AVISO) product in the global ocean in their capability of detecting mesoscale eddy. A well-established method to detect mesoscale eddies from HY-2 and AVISO was applied to the sea level anomaly (SLA) data on a global scale in 2021−2022. It is found that the number of mesoscale eddies derived from the HY-2 dataset is three times more than that from the AVISO dataset and with larger eddy kinetic energy (EKE), shorter lifespan and smaller amplitude. Besides, the monthly-averaged number of generated and terminated mesoscale eddies is similar and the temporal variation of SLA exhibits strong lunar oscillation for both datasets. Most mesoscale eddies are generated in the mid-latitude oceans due to the Coriolis force and the strong El Niño. In the western boundary of the global ocean, equator, Antarctic Ocean and other areas with strong currents, the mesoscale eddies have stronger SLA amplitudes, EKEs and vorticity. Furthermore, EKE is low at the centre and high at the eddy meander. The spatial distribution characteristics of vorticity are the same as those of EKEs in the western boundary of oceans, but the vorticity value of HY-2 data near the equator is larger than that of AVISO data. However, considering the large detection error of eddy near the equator, no further exploration will be conducted in this paper. Furthermore, mesoscale eddies tend to move in the east–west direction due to Coriolis force and wind (Ekman transport) effects and large-scale ocean circulation or the pathway of drifters also have a certain impact. Overall, similar to AVISO data, the HY-2 data is also reliable for mesoscale identification in global oceans.

Paleoclimate data assimilation with CLIMBER-X: An ensemble Kalman filter for the last deglaciation.

Using the climate model CLIMBER-X, we present an efficient method for assimilating the temporal evolution of surface temperatures for the last deglaciation covering the period 22000 to 6500 years before the present. The data assimilation methodology combines the data and the underlying dynamical principles governing the climate system to provide a state estimate of the system, which is better than that which could be obtained using just the data or the model alone. In applying an ensemble Kalman filter approach, we make use of the advances in the parallel data assimilation framework (PDAF), which provides parallel data assimilation functionality with a relatively small increase in computation time. We find that the data assimilation solution depends strongly on the background evolution of the decaying ice sheets rather than the assimilated temperatures. Two different ice sheet reconstructions result in a different deglacial meltwater history, affecting the large-scale ocean circulation and, consequently, the surface temperature. We find that the influence of data assimilation is more pronounced on regional scales than on the global mean. In particular, data assimilation has a stronger effect during millennial warming and cooling phases, such as the Bølling-Allerød and Younger Dryas, especially at high latitudes with heterogeneous temperature patterns. Our approach is a step toward a comprehensive paleo-reanalysis on multi-millennial time scales, including incorporating available paleoclimate data and accounting for their uncertainties in representing regional climates.

Numerical simulation of immersion of a tunnel element - downscaling by CFD technology

During the immersion process of tunnel elements in the sea, the surrounding currents would inevitably be changed. A large scale ocean circulation model, which can simulate the sea currents, usually do not solve underwater structures. Thus, in this chapter, we use a downscaling Computational Fluid Dynamics model to simulate the flow characteristics around an immersed tunnel element for Shenzhong Link in China, under different velocity inlets and at different depths. Since E1 element is shielded from diversion dike and the flow velocity around is small, this paper focus on simulation of the flow field during the immersion process of E2 element after the completion of E1.

April–September minimum temperature reconstruction based on Sabina tibetica ring-width chronology in the central eastern Tibetan Plateau, China

Minimum temperatures have remarkable impacts on tree growth at high-elevation sites on the Tibetan Plateau, but the shortage of long-term and high-resolution paleoclimate records inhibits understanding of recent minimum temperature anomalies. In this study, a warm season (April–September) reconstruction is presented for the past 467 years (1550–2016) based on Sabina tibetica ring-width chronology on the Lianbaoyeze Mountain of the central eastern Tibetan Plateau. Eight warm periods and eight cold periods were identified. Long-term minimum temperature variations revealed a high degree of coherence with nearby reconstructions. Spatial correlations between our reconstruction and global sea surface temperatures suggest that warm season minimum temperature anomalies in the central eastern Tibetan Plateau were strongly influenced by large-scale ocean atmospheric circulations, such as the El Niño-Southern Oscillation and the Atlantic Multidecadal Oscillation.

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Using an ensemble of atmosphere–ocean general circulation models (AOGCMs) in an idealized climate change experiment, this study evaluates the contribution of different ocean processes to Arctic Ocean warming. On the AOGCM-mean, the Arctic Ocean warming is greater than the global ocean warming, both in the volume-weighted mean, and at most depths within the upper 2000 m. However, the uncertainty of Arctic Ocean warming is much larger than the uncertainty of global ocean warming. The Arctic warming is greatest a few 100 m below the surface and is dominated by the import of extra heat, which is added to the ocean at lower latitudes and is conveyed to the Arctic mostly by the large-scale barotropic ocean circulation. The change in strength of this circulation in the North Atlantic is relatively small and not correlated with the Arctic Ocean warming. The Arctic Ocean warming is opposed and substantially mitigated by the weakening of the Atlantic meridional overturning circulation (AMOC), though the magnitude of this effect has a large model spread. By reducing the northward transport of heat, the AMOC weakening causes a redistribution of heat from high latitudes to low latitudes. Within the Arctic Ocean, the propagation of heat anomalies is influenced by broadening of cyclonic circulation in the east and weakening of anticyclonic circulation in the west. On the model-mean, the Arctic Ocean warming is most pronounced in the Eurasian Basin, with large spread across the AOGCMs, and accompanied by subsurface cooling by diapycnal mixing and heat redistribution by mesoscale eddies.

Should AMOC observations continue: how and why?

The Atlantic meridional overturning circulation (AMOC) is a large-scale circulation pattern responsible for northward heat transport in the Atlantic and is associated with climate variations on a wide range of time scales. Observing the time-varying AMOC has fundamentally changed our understanding of the large-scale ocean circulation and its interaction with the climate system, as well as identified shortcomings in numerical simulations. With a wide range of gains already achieved, some now ask whether AMOC observations should continue. A measured approach is required for a future observing system that addresses identified gaps in understanding, accounts for shortcomings in observing methods and maximizes the potential to guide improvements in ocean and climate models. Here, we outline a perspective on future AMOC observing and steps that the community should consider to move forward. This article is part of a discussion meeting issue 'Atlantic overturning: new observations and challenges'.

Drift bottle data hint at large-scale ocean circulation changes

Over the last two decades, in an effort to engage youth in polar science, the Students On Ice (SOI; https://studentsonice.com/) project has become a platform for youth to partake in scientific expeditions around the globe. Among the various activities offered, youth are able to join cruises in the North Atlantic or Arctic, and drop sealed glass bottles into the ocean. Of the thousands that have been deployed, 5% of bottles have been recovered and reported back to SOI with details on when and where they were found. Here, we compare the observational bottle data with virtual particle trajectories from a high resolution regional ocean model. Although modelling results indicate a higher likelihood of bottles reaching the shores of the western Atlantic, the majority of recovered bottles were found on the eastern side of the Atlantic. We attribute this disparity to differences in population density in Canada and Europe, biasing the recovery rates. Despite this bias, we find that changes in recovery locations over time are consistent with changes in the main ocean currents associated with the contraction and expansion of the North Atlantic Subpolar Gyre, as simulated in our ocean model. In 2007, a large number of bottles were found in Norway, coinciding with a contracted North Atlantic Subpolar Gyre during 2004-2008. While between 2012-2016, the majority of bottles were recovered on the British Isles, during a time of gyre expansion. These results underline the importance of large scale oceanic cycles for tracking marine debris and pollution, and show how even simple data collection methods, such as drift bottles, can provide clues to the changes in the large scale ocean circulation.

Surface Heating Steers Planetary-Scale Ocean Circulation

Abstract Gyres are central features of large-scale ocean circulation and are involved in transporting tracers such as heat, nutrients, and carbon dioxide within and across ocean basins. Traditionally, the gyre circulation is thought to be driven by surface winds and quantified via Sverdrup balance, but it has been proposed that surface buoyancy fluxes may also contribute to gyre forcing. Through a series of eddy-permitting global ocean model simulations with perturbed surface forcing, the relative contribution of wind stress and surface heat flux forcing to the large-scale ocean circulation is investigated, focusing on the subtropical gyres. In addition to gyre strength being linearly proportional to wind stress, it is shown that the gyre circulation is strongly impacted by variations in the surface heat flux (specifically, its meridional gradient) through a rearrangement of the ocean’s buoyancy structure. On shorter time scales (∼10 years), the gyre circulation anomalies are proportional to the magnitude of the surface heat flux gradient perturbation, with up to ∼0.15 Sv (1 Sv ≡ 106 m3 s−1) anomaly induced per watt per square meter change in the surface heat flux. On time scales longer than a decade, the gyre response to surface buoyancy flux gradient perturbations becomes nonlinear as ocean circulation anomalies feed back onto the buoyancy structure induced by the surface buoyancy fluxes. These interactions complicate the development of a buoyancy-driven theory for the gyres to complement the Sverdrup relation. The flux-forced simulations underscore the importance of surface buoyancy forcing in steering the large-scale ocean circulation. Significance Statement Ocean gyres are large swirling circulation features that redistribute heat across ocean basins. It is commonly believed that surface winds are the sole driver of ocean gyres, but recent literature suggests that other mechanisms could also be influential. We perform a series of numerical simulations in which we artificially change either the winds or the heating at the ocean’s surface and investigate how each factor independently affects the ocean gyres. We find that gyres are steered by both winds and surface heating, and that the ocean circulation responds differently to heating on short and long time scales. In addition, the circulation depends on where the heating is applied at the ocean’s surface. Through these simulations, we argue that a complete theory about ocean gyres must consider heating at the ocean’s surface as a possible driver, in addition to the winds.

North Atlantic subpolar gyre provides downstream ocean predictability

Slowly varying large-scale ocean circulation can provide climate predictability on decadal time scales. It has been hypothesized that the North Atlantic subpolar gyre (SPG) exerts substantial influence on climate predictability. However, a clear identification of the downstream impact of SPG variations is still lacking. Using the MPI-ESM-LR1.2 decadal prediction system, we show that along the Atlantic water pathway, a dynamical link to the SPG causes salinity to be considerably better predicted than temperature. By modulating the slow northward ocean propagation, the subsurface memory of SPG variations enables salinity to be skillfully predicted up to 8 years ahead. In contrast, the SPG loses influence on temperature before Atlantic water penetrates into the Nordic Seas, and in turn, limits temperature to be predicted only 2 years ahead. This study identifies the key role of SPG signals in downstream prediction and highlights how SPG signals determine prediction time scales for different quantities, opening the door for investigating potentially associated predictions in the subarctic for the earth system, marine ecosystems in particular.

Hymenaea stignocarpa Mart. ex Hayne growth–climate relationships are regulated by soil water saturation in Cerrado-Pantanal ecotone

The expected intensification of the dry season, and concentration of rainfall during the wet season, can disrupt tree growth and regional biodiversity in the Cerrado-Pantanal transition zone. Thus, this study aims to assess the climatic responses of Hymenaea stigonocarpa tree growth, a common tree species in this region. Incremental cores were collected at breast height (ca. 1.3 m) from 67 trees to construct a dendrochronological series to correlate annual growth with local meteorological variables and large-scale atmospheric circulation indices from the Pacific and Atlantic Oceans. Significant positive correlations were observed between tree growth and the Pacific Ocean indices. Maximum and average air temperatures of the previous dry season negatively influenced growth, while precipitation at the beginning of the growth season (November) positively influenced growth. Tree growth was not correlated with temperature or rainfall during the wet season. However, at the end of the wet season (February), tree growth was negatively correlated with air temperature and positively correlated with rainfall, but the relationship shifted in the next month (March) suggesting that soil water saturation reduced growth. Our results indicate that dendrochronological studies of H. stignocarpa are useful for assessing the environmental change on the Cerrado-Pantanal ecotone. Furthermore, variations in water availability and temperature associated with changes in large-scale oceanic circulation and local meteorological conditions will impact the growth dynamics of this important Cerrado tree species.

Observable Large-Scale Impacts of Tropical Cyclones on the Subtropical Gyre

Abstract The large-scale ocean circulation in an ocean basin was previously thought to be impacted cumulatively by all the overlying tropical cyclones (TCs). Based on idealized numerical experiments and altimetry observation, this study reveals that, unnecessarily by cumulative impacts, a single TC actually has the ability to plow the large-scale sea surface height (SSH) field due to the TC-induced geostrophic response. This ability is dictated by the along-track length scale of the geostrophic response, i.e., the total track length. Some of the observed along-track signals, including the SSH trough, jet, and SSH rise, can confirm the TC-induced large-scale impacts. Shortly after the TC passage, the observable large-scale signals are generally the SSH trough. However, the jet and the SSH rise easily emerge from the evolved SSH trough due to Rossby wave dispersion. By identifying and tracking the observable signals, this study demonstrates that the subtropical gyre primarily over 4°–20°N, 122°E–180° is plowed by nine typhoons (2015) into several large blocks of SSH troughs and SSH rises. These long-lived SSH troughs and SSH rises dominate the upper-layer circulation from April to December in 2015. If the large-scale signals cannot be observed, the estimated TC-induced mean SSH decreases suggest that the large-scale impacts may still exist but merely cannot be seen intuitively. This study provides compelling observational evidence for the TC-induced large-scale impacts, further highlighting that TCs may play a nonnegligible role in the upper-ocean dynamics in the subtropical gyre. Significance Statement This study aims to demonstrate the ability of a typhoon to affect the large-scale ocean dynamics. The ability manifests as some along-track signals in altimetry observations, including sea surface height trough, jet, and sea surface height rise, which can be frequently observed after some typhoons in 2015. The sea surface height field in the western North Pacific is continuously plowed by these typhoons into several large blocks of sea surface height troughs and rises. These long-lived sea surface height troughs and rises dominate the upper-layer circulation from April to December in 2015. This study indicates that typhoons play a vital role in the upper-ocean dynamics in the western North Pacific.

Paleobathymetric reconstructions of the SW Barents Seaway and their implications for Atlantic–Arctic ocean circulation

Unravelling past, large-scale ocean circulation patterns is crucial for deciphering the long-term global paleoclimate. Here we apply numerical modelling to reconstruct the detailed paleobathymetry-topography of the southwestern inlet of the Barents Seaway that presently connects the Atlantic and Arctic oceans. Subaerial topography was likely enough to block Atlantic Water from entering the Barents Seaway in the earliest Eocene (c. 55 Ma). The water may have entered in the middle Eocene (c. 47 Ma) as observed from major basin subsidence, but paleotopographic highs to the east may have hindered connections between the two oceans. From the Oligocene (c. 33 Ma) until the onset of the Quaternary (c. 2.7 Ma), basin shallowing and regional shelf uplift blocked Atlantic Water from entering the Barents Seaway. Our results imply that the Fram Strait remained the sole gateway for Atlantic Water into the Arctic Ocean since its opening in the Miocene until the Quaternary.

A relay of anticyclonic eddies transferring North Pacific subtropical mode water into the South China Sea

North Pacific subtropical mode waters (STMWs), which are subducted with air-sea interaction signals and characterized by low potential vorticity (PV), play an important role in climate change issues. STMW (PV<2×10−10 m−1· s−1) can be advected westward by large-scale ocean circulation and mesoscale eddies. However, whether and how the STMW intrudes into the South China Sea (SCS) remains unclear. Low PV signals that originate from the STMW and intruding into the SCS are investigated by comparing observations and ocean general circulation models during 2003-2017. These signals mostly move across the Luzon Strait (LS) into the SCS during the 2008-2009 and 2014-2016 periods. The results of case studies selected from these two periods indicate that the low PV signals can move to the LS and are trapped by anticyclonic eddies (AEs). When the velocity vorticity is negative southwest of Taiwan Island, vertical stratification becomes weaker west of the coming AE (AE1), and low PV signals can consequently be transported along the STMW layer (25.0 σθ- 25.5 σθ isopycnal layer). Thus, an AE (AE2) forms east of AE1 and isolates the low PV signal from AE1, and then AE2 transports the low PV water southwestward in the SCS. In contrast, the low PV signal has difficulty migrating eastward when the velocity vorticity is positive west of AE1, as vertical stratification strengthens and then weakens that signal. The results suggest that only AEs can relay low PV signals from east of the LS and carry them over long distances in the SCS.

Ocean Mesoscale and Frontal-Scale Ocean–Atmosphere Interactions and Influence on Large-Scale Climate: A Review

Abstract Two decades of high-resolution satellite observations and climate modeling studies have indicated strong ocean–atmosphere coupled feedback mediated by ocean mesoscale processes, including semipermanent and meandrous SST fronts, mesoscale eddies, and filaments. The air–sea exchanges in latent heat, sensible heat, momentum, and carbon dioxide associated with this so-called mesoscale air–sea interaction are robust near the major western boundary currents, Southern Ocean fronts, and equatorial and coastal upwelling zones, but they are also ubiquitous over the global oceans wherever ocean mesoscale processes are active. Current theories, informed by rapidly advancing observational and modeling capabilities, have established the importance of mesoscale and frontal-scale air–sea interaction processes for understanding large-scale ocean circulation, biogeochemistry, and weather and climate variability. However, numerous challenges remain to accurately diagnose, observe, and simulate mesoscale air–sea interaction to quantify its impacts on large-scale processes. This article provides a comprehensive review of key aspects pertinent to mesoscale air–sea interaction, synthesizes current understanding with remaining gaps and uncertainties, and provides recommendations on theoretical, observational, and modeling strategies for future air–sea interaction research. Significance Statement Recent high-resolution satellite observations and climate models have shown a significant impact of coupled ocean–atmosphere interactions mediated by small-scale (mesoscale) ocean processes, including ocean eddies and fronts, on Earth’s climate. Ocean mesoscale-induced spatial temperature and current variability modulate the air–sea exchanges in heat, momentum, and mass (e.g., gases such as water vapor and carbon dioxide), altering coupled boundary layer processes. Studies suggest that skillful simulations and predictions of ocean circulation, biogeochemistry, and weather events and climate variability depend on accurate representation of the eddy-mediated air–sea interaction. However, numerous challenges remain in accurately diagnosing, observing, and simulating mesoscale air–sea interaction to quantify its large-scale impacts. This article synthesizes the latest understanding of mesoscale air–sea interaction, identifies remaining gaps and uncertainties, and provides recommendations on strategies for future ocean–weather–climate research.

Diagnosing Scale-Dependent Energy Cycles in a High-Resolution Isopycnal Ocean Model

Abstract Energy exchanges between large-scale ocean currents and mesoscale eddies play an important role in setting the large-scale ocean circulation but are not fully captured in models. To better understand and quantify the ocean energy cycle, we apply along-isopycnal spatial filtering to output from an isopycnal 1/32° primitive equation model with idealized Atlantic and Southern Ocean geometry and topography. We diagnose the energy cycle in two frameworks: 1) a non-thickness-weighted framework, resulting in a Lorenz-like energy cycle, and 2) a thickness-weighted framework, resulting in the Bleck energy cycle. This paper shows that framework 2 is more useful for studying energy pathways when an isopycnal average is used. Next, we investigate the Bleck cycle as a function of filter scale. Baroclinic conversion generates mesoscale eddy kinetic energy over a wide range of scales and peaks near the deformation scale at high latitudes but below the deformation scale at low latitudes. Away from topography, an inverse cascade transfers kinetic energy from the mesoscales to larger scales. The upscale energy transfer peaks near the energy-containing scale at high latitudes but below the deformation scale at low latitudes. Regions downstream of topography are characterized by a downscale kinetic energy transfer, in which mesoscale eddies are generated through barotropic instability. The scale- and flow-dependent energy pathways diagnosed in this paper provide a basis for evaluating and developing scale- and flow-aware mesoscale eddy parameterizations. Significance Statement Blowing winds provide a major energy source for the large-scale ocean circulation. A substantial fraction of this energy is converted to smaller-scale eddies, which swirl through the ocean as sea cyclones. Ocean turbulence causes these eddies to transfer part of their energy back to the large-scale ocean currents. This ocean energy cycle is not fully simulated in numerical models, but it plays an important role in transporting heat, carbon, and nutrients throughout the world’s oceans. The purpose of this study is to quantify the ocean energy cycle by using fine-scale idealized numerical simulations of the Atlantic and Southern Oceans. Our results provide a basis for how to include unrepresented energy exchanges in coarse global climate models.

A century-long eddy-resolving simulation of global oceanic large- and mesoscale state

Investigating oceanic variations at multiple spatial and temporal scales is vital for an in-depth understanding of the ocean response to global climate change. However, the available observational datasets contain uncertainties and deficiencies that leave them insufficient for investigating global ocean variability with long temporal scales and/or meso spatial scales. Here, we present a daily and century-long (1901–2010) global oceanic simulation dataset with high resolution (1/10° horizontal resolution and 55 vertical layers) forced by 6-hour atmospheric data from ERA-20C. Preliminary evaluations demonstrate that this simulation can realistically reproduce the large-scale global ocean circulation and capture the essential features of global surface mesoscale eddies. This long-running high-resolution simulation dataset provides temporally highly resolved oceanic and flux variables. Together with its good performance in simulating the global oceanic state, this eddy-resolving simulation has the potential to help toward a better understanding of ocean variability at multiple spatial and temporal scales.

Numerical Study of Effects of Winds and Tides on Monthly-Mean Circulation and Hydrography over the Southwestern Scotian Shelf

A nested-grid modelling system is used to quantify effects of winds and tides on the three-dimensional (3D) circulation and hydrography over the southwestern Scotian Shelf (swScS) and surrounding areas in 2018. The performance of the nested-grid modelling system is assessed by comparing model results with observations and reanalysis data. Analysis of model results demonstrates that both winds and tides enhance the vertical mixing and modify the 3D circulation over the swScS. In winter (summer), the wind-induced vertical mixing warms (significantly cools) the sea surface temperature (SST) over the Scotian Shelf (ScS). In addition to intense vertical mixing associated with winter convection, the wind-induced mixing raises the sea surface salinity (SSS) by entraining the relatively salty sub-surface waters with the surface waters. The effect of wind-induced vertical mixing is evident in the upper water columns of ~40 m (~15 m) in February (August) 2018 over the swScS, reflecting the typically stronger wind forcing in winter than in summer. The wind forcing also enhances the seaward spreading of river runoff. Strong tidal mixing and advection also play an important role in affecting the hydrography and density-driven currents over the Bay of Fundy (BoF), Georges Bank (GeB), and swScS. In summer, tides significantly reduce the SST, increase the SSS, and affect large density-driven currents over the BoF, GeB, and swScS. Winds and tides also modify the large-scale ocean circulation, eddies, meanders, and frontal structures in the deep waters off the swScS through the modulation of baroclinic hydrodynamics.

Effects of Northern Hemisphere Annular Mode on terrestrial near-surface wind speed over eastern China from 1979 to 2017

Large-scale ocean‒atmosphere circulations (LOACs) have a pronounced effect on the near-surface wind speed (NSWS). In this study, we discussed the contributions of zonal and meridional flows to NSWS changes and identify the possible association between the Northern Hemisphere Annular Mode (NAM) and the NSWS changes over eastern China from 1979 to 2017. Results show that the reduction in NSWS over eastern China was mainly dominated by the weakening of the zonal wind component. NAM has a considerable effect on the NSWS over eastern China. When the NAM exhibits positive phases, the zonal-mean westerly weakens at low-to-mid-latitudes (10°–40°N). Meanwhile, descending flows prevail near 40°N, and ascending flows persist near 65°N in the troposphere. In the lower troposphere, there are northerly anomalies at low-to-mid-latitudes and southerly anomalies at mid-to-high latitudes (40°–70°N). The anomalous meridional flows transport heat from low to high latitudes and weaken the north‒south air temperature gradient. The decreased air temperature gradient over East Asia reduces the pressure gradient near the surface, decreasing NSWS in eastern China. NAM variations could dominate (32.0 ± 15.8)% of the changes in the annual mean NSWS. Nevertheless, the contribution of NAM to the interannual changes of the zonal component in NSWS could reach (45.0 ± 12.9)%.

Icebergs Melting

Iceberg calving accounts for half of the mass discharge from the Greenland and Antarctic ice sheets, which has increased dramatically over the last two decades. Through their displacement and progressive melt, icebergs can impact both the regional and large-scale ocean circulation and marine ecosystems by affecting their stratification and nutrient and carbon cycling. Freshwater input due to iceberg melt has the potential to impact regional sea ice distribution and the global overturning circulation. Notwithstanding their importance, our understanding of where and how icebergs melt is limited and their representation in ocean and climate models is oversimplistic, in part because they are informed by only a handful of observations. As a result, model-based predictions of iceberg melt rates, of the fate of the meltwater, and of its impact on the ocean are highly uncertain. New observational, modeling, and experimental studies are needed to improve our understanding of iceberg melting and hence, the forecasting power of climate models.

Analysis and Prediction of Wind Speed Effects in East Asia and the Western Pacific Based on Multi-Source Data

With the increasing problem of global warming caused by the massive use of fossil fuels, biomass energy as a renewable energy source has attracted widespread attention throughout the globe. In this paper, we analyzed the spatial and temporal variation in wind energy in the East Asia and Western Pacific areas using IGRA site data, ERA5, and NCEP/NCAR reanalysis data from 2000 to 2021, and multi-variate empirical orthogonal function (MV-EOF) decomposition with the Pettitt mutation test, and the seasonal autoregression integrated moving average (SARIMA) model was used to predict the trend of wind speed. The spatial and temporal variations in wind energy in East Asia and Western Pacific areas were analyzed, and it was found that the richer wind-energy resources were mainly concentrated in the “Three Norths” (North China, Northwest China, and Northeast China) and Mongolia, followed by the Western Pacific areas. In addition, the T’ai-hang Mountains and the Qinghai-Tibet Plateau in China block the wind resources in the eastern and southern regions of East Asia, resulting in a shortage of wind resources in this region. In addition, the summer wind speed is significantly lower than in the other three seasons. The first-mode contributions of the MV-EOF wind field and geopotential heights, respectively, are 29.47% and 37.75%. The results show that: (1) There are significant seasonal differences in wind-energy resources in the study area, with the lowest wind speed in summer and the highest wind speed in winter. (2) The wind energy in the study area has significant regional characteristics. For example, China’s Qinghai-Tibet Plateau, Inner Mongolia, Xinjiang region, and Mongolia are rich in wind-energy resources. (3) Wind-energy resources in the study area have gradually increased since 2010, mainly due to changes in large-scale oceanic and atmospheric circulation patterns caused by global warming.