المؤلفون: Adhvaryu, Achyuta¹ (AUTHOR) aadhvaryu@ucsd.edu, Bharadwaj, Prashant¹ (AUTHOR), Fenske, James² (AUTHOR), Nyshadham, Anant³ (AUTHOR), Stanley, Richard⁴ (AUTHOR)

المصدر: Economic Journal. Apr2024, Vol. 134 Issue 659, p885-912. 28p.

مصطلحات موضوعية: *LOW-income countries, DUST, TRADE winds, CHILD mortality, INFANT mortality

مصطلحات جغرافية: WEST Africa

مستخلص: Using two decades of data from 12 low-income countries in West Africa, we show that dust carried by harmattan trade winds increases infant and child mortality. Health investments respond to dust exposure, consistent with compensating behaviours. Despite these efforts, surviving children still exhibit negative health impacts. Our data allow us to investigate differential impacts over time and across countries. We find declining impacts over time, suggesting adaptation. Using national-level measures of macroeconomic conditions and health resources, we find suggestive evidence that both economic development and public health improvements have contributed to this adaptation, with health improvements playing a larger role. [ABSTRACT FROM AUTHOR]

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المؤلفون: Chatterjee, Dwaipayan¹ (AUTHOR) dchatter@uni-koeln.de, Schnitt, Sabrina¹ (AUTHOR), Bigalke, Paula¹ (AUTHOR), Acquistapace, Claudia¹ (AUTHOR), Crewell, Susanne¹ (AUTHOR)

المصدر: Geophysical Research Letters. 6/28/2024, Vol. 51 Issue 12, p1-10. 10p.

مصطلحات موضوعية: *DEEP learning, *TRADE winds, *MACHINE learning, *GEOSTATIONARY satellites, *ATMOSPHERIC models, *SPATIAL arrangement

مصطلحات جغرافية: BARBADOS

مستخلص: At mesoscale, trade wind clouds organize with various spatial arrangements, shaping their effect on Earth's energy budget. Representing their fine‐scale dynamics even at 1 km scale climate simulations remains challenging. However, geostationary satellites (GS) offer high‐resolution cloud observation for gaining insights into trade wind cumuli from long‐term records. To capture the observed organizational variability, this work proposes an integrated framework using a continuous followed by discrete self‐supervised deep learning approach, which exploits cloud optical depth from GS measurements. We aim to simplify the entire mesoscale cloud spectrum by reducing the image complexity in the feature space and meaningfully partitioning it into seven classes whose connection to environmental conditions is illustrated with reanalysis data. Our framework facilitates comparing human‐labeled mesoscale classes with machine‐identified ones, addressing uncertainties in both methods. It advances previous methods by exploring transitions between regimes, a challenge for physical simulations, and illustrates a case study of sugar‐to‐flower transitions. Plain Language Summary: Clouds are a fundamental player affecting our planet's energy balance, making their accurate representation crucial in climate models. One open question is how they organize on a scale of a few 100 km (mesoscale) in the tropical northern Atlantic region east of Barbados. Satellite observations can help to categorize these clouds, but previous methods had limitations in capturing the full range of cloud arrangements and transitions between different cloud forms. We have introduced a novel approach that utilizes machine learning and geostationary satellite data to address this issue. Our machine learning model autonomously learns to recognize various cloud patterns and distributions. We conducted a comparative analysis between the categories generated by the machine and those identified by human experts to understand the strengths and weaknesses of both methods. Additionally, we explore a case study where clouds undergo a transformation, changing from a structure resembling sugar to one resembling flowers. This particular transformation was found difficult to capture with physical simulation before. The clear signatures of the transition identified by our machine learning approach can help to better understand cloud evolution, which is crucial for improving climate models and predicting how cloud behavior may change in a changing climate. Key Points: Mesoscale cloud organization can be taxonomized by a two‐step deep learning approach in the feature space continuumComparing seven machine‐identified classes with humans' four recognized categories underlines the significance of uncertainty estimatesNew diagnostic is provided to analyze the temporal transition between regimes, as illustrated for human‐labeled sugar‐to‐flower regimes [ABSTRACT FROM AUTHOR]

المؤلفون: Tian, Zijie¹ (AUTHOR), Ding, Ruiqiang² (AUTHOR) drq@bnu.edu.cn, Zhou, Xin¹ (AUTHOR)

المصدر: Climate Dynamics. May2024, Vol. 62 Issue 5, p3221-3230. 10p.

مصطلحات موضوعية: *OCEAN temperature, *TRADE winds, *TELECONNECTIONS (Climatology), *ATMOSPHERIC circulation, *OSCILLATIONS

مصطلحات جغرافية: EAST Asia

مستخلص: The North Pacific Oscillation (NPO) serves as a pivotal atmospheric circulation pattern within the North Pacific. It has a considerable influence on the climate of East Asia and North America in the North Pacific Basin, and can also affect the climate of more distant regions via the atmospheric teleconnections. Our study has revealed a significant eastward shift of the southern lobe of the NPO from 178°E to 155°W during the boreal winter (November–December–January–February–March, NDJFM) after 1993/1994 in observations. The eastward shift of the NPO after 1993/1994 leads to stronger subtropical northeasterly trade winds during the boreal winter over the eastern North Pacific. As the strongest climatic factor influencing the strength of the wind-evaporation-sea temperature (WES) feedback mechanism, the enhanced subtropical northeast trade winds after 1993/1994 stimulate a more efficient WES feedback mechanism over the eastern North Pacific. Furthermore, the intensification of the WES feedback mechanism after 1993/1994 subsequently enhances the influence of the NPO on the tropical Pacific sea surface temperature (SST). [ABSTRACT FROM AUTHOR]

المؤلفون: Graap, Skyler¹ (AUTHOR), Zarzycki, Colin M.¹ (AUTHOR) czarzycki@psu.edu

المصدر: Geoscientific Model Development. 2024, Vol. 17 Issue 4, p1627-1650. 24p.

مصطلحات موضوعية: *TRADE winds, *ATMOSPHERIC models, *ATMOSPHERIC boundary layer, *CLIMATE change models, *OCEAN-atmosphere interaction, *CUMULUS clouds

مستخلص: Improving the prediction of clouds in shallow-cumulus regimes via turbulence parameterization in the planetary boundary layer (PBL) will likely increase the global skill of global climate models (GCMs) because this cloud regime is common over tropical oceans where low-cloud fraction has a large impact on Earth's radiative budget. This study attempts to improve the prediction of PBL structure in tropical trade wind regimes in the Community Atmosphere Model (CAM) by updating its formulation of momentum flux in CLUBB (Cloud Layers Unified by Binormals), which currently does not by default allow for upgradient momentum fluxes. Hindcast CAM output from custom CLUBB configurations which permit countergradient momentum fluxes are compared to in situ observations from weather balloons collected during the ElUcidating the RolE of Cloud–Circulation Coupling in ClimAte and Atlantic Tradewind Ocean–Atmosphere Mesoscale Interaction Campaign (EUREC 4 A/ATOMIC) field campaign in the tropical Atlantic in early 2020. Comparing a version with CAM–CLUBB with a prognostic treatment of momentum fluxes results in vertical profiles that better match large-eddy simulation results. Countergradient fluxes are frequently simulated between 950 and 850 hPa over the EUREC 4 A/ATOMIC period in CAM–CLUBB. Further modification to the planetary boundary layer (PBL) parameterization by implementing a more generalized calculation of the turbulent length scale reduces model bias and root mean squared error (RMSE) relative to sounding data when coupled with the prognostic momentum configuration. Benefits are also seen in the diurnal cycle, although more systematic model errors persist. A cursory budget analysis suggests the buoyant production of momentum fluxes, both above and below the jet maximum, significantly contributes to the frequency and depth of countergradient vertical momentum fluxes in the study region. This paper provides evidence that higher-order turbulence parameterizations may offer pathways for improving the simulation of trade wind regimes in global models, particularly when evaluated in a process study framework. [ABSTRACT FROM AUTHOR]

المؤلفون: Pivotti, Valentina¹ (AUTHOR) valentina.pivotti@mau.se, Anderson, Bruce T.² (AUTHOR)

المصدر: Climate Dynamics. Feb2024, Vol. 62 Issue 2, p1487-1500. 14p.

مصطلحات موضوعية: *TRADE winds, *SOUTHERN oscillation, *EFFECT of human beings on climate change, *MODES of variability (Climatology), *RADIATIVE forcing, EL Nino

مستخلص: The El Niño Southern Oscillation (ENSO), as one of the largest coupled climate modes, influences the livelihoods of millions of people and ecosystems survival. Thus, how ENSO is expected to behave under the influence of anthropogenic climate change is a substantial question to investigate. In this paper, we analyze future predictions of specific traits of ENSO, in combination with a subset of well-established precursors—the Trade Wind Charging and North Pacific Meridional Mode (TWC/NPMM). We study it across three sets of experiments from a protocol-driven ensemble from CMIP6—the High Resolution Model Intercomparison Project (HighResMIP). Namely, (1) experiments at constant 1950's radiative forcings, and (2) experiments of present (1950–2014) and (3) future (2015–2050) climate with prescribed increasing radiative forcings. We first investigate the current and predicted spatial characteristics of ENSO events, by calculating area, amplitude and longitude of the Center of Heat Index (CHI). We see that TWC/NPMM-charged events are consistently stronger, in both the presence and absence of external forcings; however, as anthropogenic forcings increase, the area of all ENSO events increases. Since the TWC/NPMM-ENSO relationship has been shown to affect the oscillatory behavior of ENSO, we analyze ENSO frequency by calculating CHI-analogous indicators on the Continuous Wavelet Transform (CWT) of its signal. With this new methodology, we show that across the ensemble, ENSO oscillates at different frequencies, and its oscillatory behavior shows different degrees of stochasticity, over time and across models. However, we see no consistent indication of future trends in the oscillatory behavior of ENSO and the TWC/NPMM-ENSO relationship. [ABSTRACT FROM AUTHOR]

المؤلفون: Vulawalu, Susana^1,2 (AUTHOR) s11133572@student.usp.ac.fj, Wirasatriya, Anindiya³ (AUTHOR) aninosi@yahoo.co.id

المصدر: AIP Conference Proceedings. 2023, Vol. 2877 Issue 1, p1-10. 10p.

مصطلحات موضوعية: *TRADE winds, *HEAT storage, *BIOLOGICAL productivity, *BLOCK trading

مصطلحات جغرافية: FIJI

مستخلص: The climatological mean and daily variation in sea surface temperature (SST) and sea surface winds (SSW) from 2018-2020 in Fiji waters were analyzed. This is the first of such studies investigating the island wake phenomenon in Fiji. The study was conducted on Vitilevu island, the main island of Fiji. This study aimed to investigate the occurrence of the island wake phenomenon on the western leeward side of Vitilevu island. The island wake may potentially occur due to the high topography on the eastern side with mountain peaks of about 1,300m in height blocking trade winds from inducing surface water mixing on the leeward side thus increasing heat storage and initiating the island wake phenomena. The island wake is investigated using GHRSST Lv. 4 daily data. We investigated 1,096 SST images, 217, 2020 and 241 cases of SST wake were found for 2018, 2019 and 2020 respectively. Wind was found to be the main factor inducing the occurrence of the SST wake, with the direction of the wake depending on the speed and direction of the wind. The occurrence of island wake was found to be dominant from November to April annually following the warm wet season in Fiji. The prevalence of the phenomenon on the leeward side of Vitilevu island may influence biological productivity in this area and requires further investigation. [ABSTRACT FROM AUTHOR]

المؤلفون: Dey, Dipanjan^1,2 (AUTHOR) dipanjanrocks01@gmail.com, Geen, Ruth^2,3 (AUTHOR), Lambert, F. Hugo² (AUTHOR), Agrawal, Shubhi^2,4 (AUTHOR), Vallis, Geoffrey² (AUTHOR), Marsh, Robert¹ (AUTHOR), Skliris, Nikolaos¹ (AUTHOR), Döös, Kristofer⁵ (AUTHOR)

المصدر: Quarterly Journal of the Royal Meteorological Society. Jan2024, Vol. 150 Issue 759, p763-775. 13p.

مصطلحات موضوعية: *TRADE winds, *WATER security, *RAINFALL, *MONSOONS, *SUMMER, *WATER use, *WESTERLIES

مصطلحات جغرافية: EAST Asia

مستخلص: The East Asian summer monsoon rainfall provides water security and socio‐economic benefit for over 20% of the global population. However, the sources of this rainfall and how it is carried to the East Asian landmass are still uncertain. To address this, atmospheric water sources and pathways associated with the East Asian summer rainfall are identified and quantified in this study using atmospheric water trajectories, calculated with a novel Lagrangian framework. Evaporated water from the East Asian landmass is found to be the major contributor to East Asian rainfall, amounting to local recycling. The results further indicated that the south Indian Ocean is a major non‐local source for rainfall over southern East Asia during June to August. The role of the south Indian Ocean as a source of atmospheric water is one of the major findings of the study and would help in better understanding and predicting the East Asian summer rainfall. Evaporated waters from the Pacific Ocean (particularly the far‐west Pacific Ocean) dominate the non‐local contribution to precipitation over northern East Asia during June to September and over southern East Asian rainfall during September. The spatial structure of the East Asian rainfall is reported to be determined by the atmospheric waters that are evaporated and transported from the non‐local sources. The role of the north Indian Ocean and the South Asian landmass as a source of water for East Asian precipitation is minimal and restricted to southern East Asia. The cross‐equatorial Somali jet and equatorial trade winds associated with the western North Pacific subtropical high are important pathways for East Asian precipitation sourced over the south Indian Ocean and the Pacific Ocean respectively. In contrast, minor roles are attributed to the Bay of Bengal as a source, and midlatitude westerlies as a transport pathway, for East Asian precipitation. [ABSTRACT FROM AUTHOR]

المؤلفون: Chen, Xuanyu^1,2 (AUTHOR) xuanyu.chen@colorado.edu, Dias, Juliana² (AUTHOR), Wolding, Brandon^1,2 (AUTHOR), Pincus, Robert³ (AUTHOR), DeMott, Charlotte⁴ (AUTHOR), Wick, Gary² (AUTHOR), Thompson, Elizabeth J.² (AUTHOR), Fairall, Chris W.² (AUTHOR)

المصدر: Journal of the Atmospheric Sciences. Dec2023, Vol. 80 Issue 12, p2969-2987. 19p.

مصطلحات موضوعية: *TRADE winds, *CLOUDINESS, *OCEAN-atmosphere interaction, *WIND speed, *HETEROGENEITY

مستخلص: The impact of weak submeso- to mesoscale SST anomalies on daily averaged trade cumulus cloudiness is investigated using satellite observations that have been validated against shipboard measurements from the Atlantic Tradewind Ocean–Atmosphere Mesoscale Interaction Campaign (ATOMIC). Daily spatial SST anomalies are identified from GOES–POES Blended SST analysis within a 10° × 10° region during January and February 2020. Daily averaged cloud fraction and 10-m neutral wind from satellite observations and reanalysis are composited over the identified SST features, using a common coordinate system based on the near-surface background wind directions. Composites of satellite cloud fraction show a statistically significant increase of cloudiness over the SST warm core with a reduction of cloudiness away from it. These responses are largely the same but with opposite signs over SST cold anomalies, suggesting that spatial heterogeneity in SST can locally imprint on daily cloud fraction. Composites of daily 10-m wind speed and wind convergence anomalies from both satellite and reanalysis show that surface wind speed is increased over SST warm anomalies, implying enhanced turbulence over warmer SSTs. Correspondingly, the surface convergence anomalies in these composites are located around the maximum downwind SST gradient, offset downwind from the cloudiness anomalies. These results indicate that the response of daily cloudiness to these SST anomalies is more likely generated by spatial variability of surface-driven turbulence and surface fluxes rather than that of surface or boundary layer convergence. [ABSTRACT FROM AUTHOR]

المؤلفون: Araujo, Rafael¹ js3317@columbia.edu, Assunção, Juliano², Hirota, Marina³, Scheinkman, José A.^4,5

المصدر: Proceedings of the National Academy of Sciences of the United States of America. 11/14/2023, Vol. 120 Issue 46, p1-8. 16p.

مصطلحات موضوعية: *TRADE winds, *RAIN forests, *DEFORESTATION, *INTERNATIONAL trade

مستخلص: The Amazon rainforests have been undergoing unprecedented levels of human-induced disturbances. In addition to local impacts, such changes are likely to cascade following the eastern-western atmospheric flow generated by trade winds. We propose a model of spatial and temporal interactions created by this flow to estimate the spread of effects from local disturbances to downwind locations along atmospheric trajectories. The spatial component captures cascading effects propagated by neighboring regions, while the temporal component captures the persistence of local disturbances. Importantly, all these network effects can be described by a single matrix, acting as a spatial multiplier that amplifies local forest disturbances. This matrix holds practical implications for policymakers as they can use it to easily map where the damage of an initial forest disturbance is amplified and propagated to. We identify regions that are likely to cause the largest impact throughout the basin and those that are the most vulnerable to shocks caused by remote deforestation. On average, the presence of cascading effects mediated by winds in the Amazon doubles the impact of an initial damage. However, there is heterogeneity in this impact. While damage in some regions does not propagate, in others, amplification can reach 250%. Since we only account for spillovers mediated by winds, our multiplier of 2 should be seen as a lower bound. [ABSTRACT FROM AUTHOR]

المؤلفون: Ferster, Brady S.^1,2 (AUTHOR) brady.ferster@locean.ipsl.fr, Fedorov, Alexey V.^2,3 (AUTHOR), Guilyardi, Eric^2,4 (AUTHOR), Mignot, Juliette² (AUTHOR)

المصدر: Geophysical Research Letters. 10/28/2023, Vol. 50 Issue 20, p1-11. 11p.

مصطلحات موضوعية: *TRADE winds, *OCEAN temperature, *SOUTHERN oscillation, *MERIDIONAL winds, *TROPICAL conditions, EL Nino

مستخلص: A notable shift in the El Niño‐Southern Oscillation (ENSO) has been observed in the early 21st century, characterized by an increased prevalence of Central Pacific (CP) events and strengthened Pacific trade winds. This shift may be attributed to the warming tropical Indian Ocean (TIO). To investigate this, we conduct perturbation experiments using the Insitut Pierre Simon Laplace climate model and nudge TIO surface temperatures to induce warming or cooling effects. Our findings reveal that TIO warming (or cooling) leads to amplified (weakened) mean trade winds and surface warming (cooling) in the Pacific region. Surprisingly, ENSO variability increases in both TIO cooling and warming scenarios. This result is linked to stronger positive feedbacks and a less stable Bjerknes index for either TIO forcing. Additionally, we find that TIO warming leads to more frequent CP events, meridional widening of wind anomalies, and broadening of the ENSO power spectrum toward lower frequencies. Plain Language Summary: The dominant mode of interannual climate variability, the El Niño‐Southern Oscillation (ENSO), has visibly changed in the past three decades, with maximum sea surface temperature (SST) anomalies during El Niño events occurring in the Central Pacific (CP) rather than in the Eastern Pacific and having weaker magnitudes. Recent studies suggest that the observed stronger Pacific trade winds could have contributed to this shift. One possible mechanism driving such changes is the enhanced warming trends in the tropical Indian Ocean (TIO) relative to the rest of the tropics. Here, we conduct sensitivity experiments to investigate the effect of TIO SST on the Pacific. Our experiments with a climate model indicate that the Pacific trade winds change proportionally to the imposed forcing, with stronger trades corresponding to a warmer TIO. We find that ENSO variability increases strongly in the TIO cooling experiments, driven by weaker trade winds associated with TIO cooling. In the TIO warming experiments we find a shift toward CP‐like events; however, we also observe a modest ENSO strengthening, which can be attributed to stronger positive feedbacks resulting from the remotely induced warming of the Pacific. Key Points: Initial response to Indian Ocean warming (cooling) produces La Niña‐like (El Niño‐line) conditions in the tropical PacificEquilibrium response to Indian Ocean warming (cooling) shows stronger (weaker) Pacific trade winds but warmer (colder) ocean temperaturesBoth warming and cooling of the Indian Ocean result in a stronger El Niño‐Southern Oscillation due to greater positive feedbacks in the Bjerknes stability index [ABSTRACT FROM AUTHOR]