Solar Variations Research Articles

Cyclic myocardial infarctions follow solar variations: A pilot study in Mediterranean populations

To map time-structures is a burgeoning scientific field enriching the (P4) medicine models. Relevant local evidence in Mediterranean populations is poorly investigated. Myocardial infarctions (MI) incidence and fatality rate is high, whilst its statistics fail to cover full etiology risk factors. This pilot study extents our previous work on stroke mortality variations [1] to MIs and aims to evaluate historical data of MI mortality events a. from Aghios Pavlos General Hospital in Thessaloniki (1955–1962) b. in Tel-Aviv (1972–1988) – periods free of confounding factors like life-style, pollution, stress. Sunspot numbers (Rz) were derived from the archives of measurements published by Solar Geographical Data. 930 Death events of myocardial infarctions from the archives of Aghios Pavlos General Hospital archives were collected and been evaluated by Δstatistics, while, 5667 publicly available MI deaths from Tel-Aviv hospitals were evaluated by correlation coefficient (r). MI variations and solar activity levels. Common cyclic variations of 2 and 4 years of sunspot numbers (as established marker of solar activity) and MI incidence was observed. The Correlation coefficient of Rz and monthly MI for Thessaloniki was r a = 0.402 P < 0.001, whilst for Tel-Aviv it was calculated as high as r b = 0.44 P < 0.001. Time structure patterns may provide novel insight in MI epidemic and, thus, contribute to future sophisticated public health planning and chronotherapy evaluations.

The Solar Radiation Climate of Greece

The solar radiation climate of Greece is investigated by using typical meteorological years (TMYs) at 43 locations in Greece based on a period of 10 years (2007–2016). These TMYs include hourly values of global, Hg, and diffuse, Hd, horizontal irradiances from which the direct, Hb, horizontal irradiance is estimated. Use of the diffuse fraction, kd, and the definition of the direct-beam fraction, kb, is made. Solar maps of annual mean Hg, Hd, kd, and kb are prepared over Greece under clear and all skies, which show interesting but explainable patterns. Additionally, the intra-annual and seasonal variabilities of these parameters are presented and regression equations are provided. It is found that Hb has a negative linear relationship with kd; the same applies to Hg with respect to kd or with respect to the latitude of the site. It is shown that kd (kb) can reflect the scattering (absorption) effects of the atmosphere on solar radiation, and, therefore, this parameter can be used as a scattering (absorption) index. An analysis shows that the influence of solar variability (sunspot cycle) on the Hg levels over Athens in the period 1953–2018 was less dominant than the anthropogenic (air-pollution) footprint that caused the global dimming effect.

A nonstationary and non‐Gaussian moving average model for solar irradiance

AbstractHistorically, power has flowed from large power plants to customers. Increasing penetration of distributed energy resources such as solar power from rooftop photovoltaic has made the distribution network a two‐way‐street with power being generated at the customer level. The incorporation of renewables introduces additional uncertainty and variability into the power grid. Distribution network operation studies are being adapted to include renewables; however, such studies require high quality solar irradiance data that adequately reflect realistic meteorological variability. Data from satellite‐based products are spatially complete, but temporally coarse, whereas solar irradiances exhibit high frequency variation at very fine timescales. We propose a new stochastic method for temporally downscaling global horizontal irradiance (GHI) to 1 min resolution, but we do not consider the spatial aspect due to limited availability of the in situ irradiance measurements. Solar irradiance's first and second‐order structures vary diurnally and seasonally, and our model adapts to such nonstationarity. Empirical irradiance data exhibits highly non‐Gaussian behavior; we develop a nonstationary and non‐Gaussian moving average model that is shown to capture realistic solar variability at multiple timescales. We also propose a new estimation scheme based on Cholesky factors of empirical autocovariance matrices, bypassing difficult and inaccessible likelihood‐based approaches. The model is demonstrated for a case study of three locations that are located in diverse climates through the United States. The model is compared against competitors from the literature and is shown to provide better uncertainty and variability quantification on testing data.

SOLAR PHYSICS AND THE CLIMATE PROBLEM

When I delivered a paper on solar activity at the first SPD meeting, none of us thought it had anything to do with Earth's climate. Scientists of earlier generations had published correlations between solar variations and one or another terrestrial phenomenon, but by 1970 modern statistical analysis had driven out everyone but cranks. However, in 1976 Jack Eddy boldly nailed down the existence of a long period of low solar activity coinciding with the 'Little Ice Age' familiar to climate historians. Meanwhile solar activity was increasing to historic highs—and so was global temperature. Most experts thought the global warming was caused by emissions of greenhouse gases, but corporations that profited from emissions and others who despised government regulation exploited the hypothetical solar-climate connection to deny that we faced dangerous climate change. Debate exploded, invoking complex mechanisms whereby solar activity might affect Earth's atmosphere. These arguments collapsed when solar activity dropped yet global temperature climbed ever faster. Nevertheless, the zombie belief that global warming is a harmless 'natural cycle' persists, helping to impede urgent policy changes.

Reconstructing solar irradiance from historical Ca II K observations

Context.Knowledge of solar irradiance variability is critical to Earth’s climate models and understanding the solar influence on Earth’s climate. Direct solar irradiance measurements have only been available since 1978. Reconstructions of past variability typically rely on sunspot data. However, sunspot records provide only indirect information on the facular and network regions, which are decisive contributors to irradiance variability on timescales of the solar cycle and longer.Aims.Our ultimate goal is to reconstruct past solar irradiance variations using historical full-disc Ca IIK observations to describe the facular contribution independently of sunspot observations. Here, we develop the method and test it extensively by using modern CCD-based (charge-coupled device) Ca IIK observations. We also carry out initial tests on two photographic archives.Methods.We employ carefully reduced and calibrated Ca IIK images from 13 datasets, including some of the most prominent series, such as those from the Meudon, Mt Wilson, and Rome observatories. We convert them to unsigned magnetic field maps and then use them as input to the adapted Spectral and Total Irradiance Reconstruction (SATIRE) model to reconstruct total solar irradiance (TSI) variations over the period 1978–2019, for which direct irradiance measurements are available.Results.The reconstructed irradiance from the analysed Ca IIK archives agrees well with direct irradiance measurements and existing reconstructions. The model also returns good results on data taken with different bandpasses and images with low spatial resolution. Historical Ca IIK archives suffer from numerous inconsistencies, but we show that these archives can still be used to reconstruct TSI with reasonable accuracy provided the observations are accurately processed and the effects of changes in instrumentation and instrumental parameters are identified and accounted for. The reconstructions are relatively insensitive to the TSI reference record used to fix the single free parameter of the model. Furthermore, even employment of a series, itself reconstructed from Ca IIK data, as a reference for further reconstructions returns nearly equally accurate results. This will enable the Ca IIK archives without an overlap with direct irradiance measurements to be used to reconstruct past irradiance.Conclusions.By using the unsigned magnetic maps of the Sun reconstructed from modern high-quality Ca IIK observations as input into the SATIRE model, we can reconstruct solar irradiance variations nearly as accurately as from directly recorded magnetograms. Historical Ca IIK observations can also be used for past irradiance reconstructions but need additional care, for example identifying and accounting for discontinuities and changes in the quality of the data with time.

Modeling Inner Proton Belt Variability at Energies 1 to 10 MeV Using BAS‐PRO

AbstractGeomagnetically trapped protons forming Earth's proton radiation belt pose a hazard to orbiting spacecraft. In particular, solar cell degradation is caused by non‐ionising collisions with protons at energies of several megaelectron volts (MeV), which can shorten mission lifespan. Dynamic enhancements in trapped proton flux following solar energetic particle events have been observed to last several months, and there is a strong need for physics‐based modeling to predict the impact on spacecraft. However, modeling proton belt variability at this energy is challenging because radial diffusion coefficients are not well constrained. We address this by using the British Antarctic Survey proton belt model BAS‐PRO to perform 3D simulations of the proton belt in the region 1.15 ≤ L ≤ 2 from 2014 to 2018. The model is driven by measurements from the Radiation Belt Storm Probes Ion Composition Experiment and Magnetic Electron Ion Spectrometer instruments carried by the Van Allen Probe satellites. To investigate sensitivity, simulations are repeated for three different sets of proton radial diffusion coefficients DLL taken from previous literature. Comparing the time evolution of each result, we find that solar cycle variability can drive up to a ∼75% increase in 7.5 MeV flux at L = 1.3 over four years due to the increased importance of collisional loss at low energies. We also show how the anisotropy of proton pitch angle distributions varies with L and energy, depending on DLL. However we find that phase space density can vary by three orders of magnitude at L = 1.4 and μ = 20 MeV/G due to uncertainty in DLL, highlighting the need to better constrain proton DLL at low energy.

Daily Variations of Plasma Density in the Solar Streamer Belt

Abstract Improved space weather diagnostics depend critically on improving our understanding of the evolution of the slow solar wind in the streamer belts near the Sun. Recent innovations in tomography techniques are opening a new window on this complex environment. In this work, a new time-dependent technique is applied to COR2A/Solar Terrestrial Relations Observatory observations from a period near solar minimum (2018 November 11) for heliocentric distances of 4–8 R ⊙. For the first time, we find density variations of large amplitude throughout the quiescent streamer belt, ranging between 50% and 150% of the mean density, on timescales of tens of hours to days. Good agreement is found with Parker Solar Probe measurements at perihelion; thus, the variations revealed by tomography must form a major component of the slow solar wind variability, distinct from coronal mass ejections or smaller transients. A comparison of time series at different heights reveals a consistent time lag, so that changes at 4 R ⊙ occur later at increasing height, corresponding to an outward propagation speed of around 100 km s−1. This speed may correspond to either the plasma sound speed or the bulk outflow speed depending on an important question: are the density variations caused by the spatial movement of a narrow streamer belt (moving magnetic field, constant plasma density), or changes in plasma density within a nonmoving streamer belt (rigid magnetic field, variable density), or a combination of both?

Last millennium climate changes over the Antarctic Peninsula and southern Patagonia in CESM-LME simulations: Differences between Medieval Climate Anomaly and present-day temperatures

This paper describes differences between Medieval Climate Anomaly (MCA) and present-day temperatures in the area composed of the Antarctic Peninsula, southern Patagonia, and the surrounding southern oceans. The investigation is conducted with the simulation results from the Community Earth System Model Last Millennium Ensemble (CESM-LME) considering the impact of each natural (volcanic activity and solar variability) and anthropogenic (greenhouse gas, ozone-aerosols and land use/land cover) individual forcing relative to the full forced simulations. Model results show generalized warming during the MCA in the study area. However, the simulated MCA temperatures are significantly colder than present-day mean values due to the influence of increased atmospheric greenhouse gas concentrations since the beginning of the modern Industrial Era in the ∼1850s. In fact, model runs in which only natural forcings were applied show that, in the absence of greenhouse gas forcing, present-day temperatures in the Antarctic Peninsula and southern Patagonia would be lower than or similar to those during the MCA. The study demonstrates the value of paleoclimate proxy–model comparisons but also highlights the limitations of current available proxy information to perform that integration in the study area.

Centennial to millennial variability of greenhouse climate across the mid-Cenomanian event

Abstract Centennial- to millennial-scale climate variations are often attributed to solar forcing or internal climate system variability, but recognition of such variations in the deep-time paleoclimate record is extremely rare. We present an exceptionally well-preserved, millimeter-scale laminated marlstone from a succession of precession-driven limestone-marlstone couplets deposited in the Western Interior Seaway (North America) immediately preceding and during the Cretaceous mid-Cenomanian event (ca. 96.5 Ma). Sedimentological, geochemical, and micropaleontological data indicate that individual pairs of light-dark laminae record alternations in the extent of water-column mixing and oxygenation. Principal component analysis of X-ray fluorescence element counts and a grayscale scan of a continuous thin section through the marlstone reveal variations with 80–100 yr, 200–230 yr, 350–500 yr, ∼1650 yr, and 4843 yr periodicities. A substantial fraction of the data indicates an anoxic bottom water variation with a pronounced 10,784 yr cycle. The centennial to millennial variations are reminiscent of those found in Holocene total solar irradiance variability, and the 10,784 yr anoxia cycle may be a manifestation of semi-precession-influenced Tethyan oxygen minimum zone waters entering the seaway.

Low-dimensional scenario generation method of solar and wind availability for representative days in energy modeling

We present a scenario generation method for representative days of wind and solar power availability for use in energy-system models. The method uses principal component analysis (PCA) such that the correlations between solar and wind can be captured. PCA is applied to daily time series of hourly profiles of regional solar and wind power availability to yield low-dimensional scenarios, which can be used in regional energy system or energy market models that represent the year with a limited set of representative days. Subsequently, the scenarios generated with PCA are used as building blocks for daily multi-regional scenarios under different assumption on dependence, which can include extreme joint events. As an application, the impact of variability of intermittent renewables with a – numerically tractable – low number of scenarios is applied in an electricity market model, where the increase in resulting price variation caused by solar and wind variability is investigated. Strengths and limits of the approach are also shown in terms of dimensional extensions and by comparison with hierarchical clustering. – The documented software code of the statistical analysis is freely available.

Modulation of centennial-scale hydroclimate variations in the middle Yangtze River Valley by the East Asian-Pacific pattern and ENSO over the past two millennia

Meteorological observations reveal an inverse relationship of summer monsoon rainfall between the tropical western North Pacific (WNP) and middle Yangtze River Valley (mid-YRV) on interannual and intraseasonal timescales. This seesaw-like pattern, named the East Asian-Pacific (EAP) pattern, is one of the major teleconnections that affect summer precipitation in the mid-YRV. However, due to the scarcity of long and continuous instrumental data, the behavior and mechanism of the EAP pattern on a long timescale are poorly understood. Here, we present a composite high-resolution summer monsoon rainfall record from 230 BC to 1810 AD, based on 1221 δ18O measurements and 22 230Th dates from two stalagmites (EB1 and EB5) in Shenqi Cave over the mid-YRV. Our new record shows that monsoon rainfall in the mid-YRV varies at a dominant periodicity of ∼100 years, probably linked to solar activity and ENSO variability. The multi-centennial fluctuations in the EB record, broadly consistent with the North Hemisphere temperature reconstruction, display strong similarities to two stalagmite δ18O records from nearby Heshang and Luoshui caves. To represent the integrated hydroclimate variations over the mid-YRV, we extracted the first principal component (PC1) of these three cave δ18O records by using the principal component analysis. We reveal a striking inverse relationship of wet/dry conditions between the mid-YRV and tropical WNP, suggesting that changes in the EAP pattern have an important impact on centennial-scale monsoon precipitation changes. Furthermore, we compile monsoon rainfall records from the mid-YRV and WNP to reconstruct a new EAP index. This EAP index exhibits a strong correlation with the ENSO proxy, confirming that the ENSO variability may play a key role in modulating the monsoon rainfall in the mid-YRV through the EAP teleconnection.

Equinoctial Asymmetry in Solar Quiet Fields along the 120° E Meridian Chain

Equinoctial asymmetry of the range of the solar quiet day variation (Sq) of the horizontal geomagnetic field (H) has been found in some low latitude geomagnetic observatories. This study conducted an investigation of its latitude distribution and the relationship with the solar cycle by using the H field measurements from six observatories along the 120° E meridian chain in the years 1957–2013. Results illustrate a significant equinoctial asymmetry of the SqH range at all observatories. Three main features were identified. First, the signature of the equinoctial asymmetry of the SqH range is opposite for observatories located at the northern and southern sides of the Northern Hemisphere Sq current focus. It shows larger values around spring than autumn equinox at southern observatories, and the converse is seen at northern observatories. Second, the asymmetry increases with the distance from the Sq current focus, suggesting the stronger sensitivity of the distant observatories than observatories around the focus. The result of linear fitting presents a positive dependence of the asymmetry coefficient on geographic latitude, with a reversal of the asymmetry occurring at 28.1° N near the focus of the average Sq current. Third, there is no obvious dependence of the equinoctial asymmetry of the SqH range on solar activity, suggesting a possible cause from some regional factors related to the ionospheric dynamo process.

Similar patterns of tropical precipitation and circulation changes under solar and greenhouse gas forcing

Theory and model evidence indicate a higher global hydrological sensitivity for the same amount of surface warming to solar as to greenhouse gas (GHG) forcing, but regional patterns are highly uncertain due to their dependence on circulation and dynamics. We analyse a multi-model ensemble of idealized experiments and a set of simulations of the last millennium and we demonstrate similar global signatures and patterns of forced response in the tropical Pacific, of higher sensitivity for the solar forcing. In the idealized simulations, both solar and GHG forcing warm the equatorial Pacific, enhance precipitation in the central Pacific, and weaken and shift the Walker circulation eastward. Centennial variations in the solar forcing over the last millennium cause similar patterns of enhanced equatorial precipitation and slowdown of the Walker circulation in response to periods with stronger solar forcing. Similar forced patterns albeit of considerably weaker magnitude are identified for variations in GHG concentrations over the 20th century, with the lower sensitivity explained by fast atmospheric adjustments. These findings differ from previous studies that have typically suggested divergent responses in tropical precipitation and circulation between the solar and GHG forcings. We conclude that tropical Walker circulation and precipitation might be more susceptible to solar variability rather than GHG variations during the last-millennium, assuming comparable global mean surface temperature changes.

Continuous Solar Observations from the Ground—Assessing Duty Cycle from GONG Observations

Continuous observations play an important role in the studies of solar variability. While such observations can be achieved from space with an almost 100% duty cycle, it is difficult to accomplish a very high duty cycle from the ground. In this context, we assess the duty cycle that has been achieved from the ground by analyzing the observations of a six station network of identical instruments, the Global Oscillation Network Group (GONG). We provide a detailed analysis of the duty cycle using GONG observations spanning over 18 yr. We also discuss the duty cycle of individual sites and point out various factors that may impact individual site or network duty cycles. The mean duty cycle of the network is 93%, however it reduces by about 5% after all images pass through the stringent quality-control checks. The standard deviations in monthly and yearly duty cycle values are found to be 1.9% and 2.2%, respectively. These results provide a baseline that can be used in the planning of future ground-based networks.

The linkage between renewable energy potential and sustainable development: Understanding solar energy variability and photovoltaic power potential in Tibet, China

The accurate pattern of systematic assessment of regional-level solar energy resource potential including seasonal variability and annual trends is essential during renewable solar energy project development. Understanding the linkage between solar energy potential and photovoltaic (PV) development is of particular interest to developers and financers. However, a dearth of long-term, high-resolution solar radiation data makes these patterns and linkages challenging, and thus techniques to improve these characterizations are of great value. To improve knowledge of the renewable energy potential and sustainable development, we assessed high-resolution global surface solar radiation (SSR) dataset derived from remote sensing, and explicitly linked spatio-temporal pattern of solar energy potential across different timescales and PV development in Tibet using geographical statistics methods. With the framework, we provided an intuitive SSR mapping and more than 330 kWh/m2 of PV power potential was predicted in most areas of Tibet. We found spatio-temporal heterogeneity of solar energy seasonal variability: The SSR variation is less than 26% in most areas of Tibet in spring and summer, greater than 30% for autumn and winter; while the middle reaches of Yarlung Zangbo River remains at a low level. We also found PV power was not affected by SSR annual trends in most areas of Tibet during 2000–2016, ranging from −2 to 2 kWh/m2 per year. Additionally, we identified the mismatch between solar energy potential and PV development, characterized by a low average PV installed capacity with affluent solar energy potential, unstable power generation and a high light abandonment rate for PV. The main challenges facing long-term strategic development plans for solar PV was also assessed. Framework and findings herein provide a helpful guide to those responsible for making better decisions in some of the key stages of solar energy development at local and regional scale.

Discontinuity in the production rate due to the solar resource intermittency

The economic risk of solar plant projects due to the inter-annual solar resource variability is usually quantified by the exceedance probabilities. The estimation of these probabilities depends on the datasets used for the study; actually, the uncertainty associated to these datasets affects the viability study of the project. Due to this dependence, in this work two different types of datasets are used in the estimation of the exceedance probabilities and their uncertainties: synthetic datasets and satellite-derived datasets.Besides, the intra-annual variability of the irradiation variations (intermittency) can affect the production rate of the solar plant. Thus, the knowledge of this variability allows us to foresee the discontinuities in the production rate of the solar plants and to plan the needs for high or low storage capacity according to different temporal periods. In order to quantify the effect of the intra-annual variability in the viability study, a Viability Index based on Discontinuity in the production rate, VID, is proposed, which estimates viability from the exceedance probabilities of the variations. The inclusion of this analysis can provide us with important information about the viability assessment of the projects.

Solar Irradiance Prediction with Machine Learning Algorithms: A Brazilian Case Study on Photovoltaic Electricity Generation

Forecasting photovoltaic electricity generation is one of the key components to reducing the impacts of solar power natural variability, nurturing the penetration of renewable energy sources. Machine learning is a well-known method that relies on the principle that systems can learn from previously measured data, detecting patterns which are then used to predict future values of a target variable. These algorithms have been used successfully to predict incident solar irradiation, but the results depend on the specificities of the studied location due to the natural variability of the meteorological parameters. This paper presents an extensive comparison of the three ML algorithms most used worldwide for forecasting solar radiation, Support Vector Machine (SVM), Artificial Neural Network (ANN), and Extreme Learning Machine (ELM), aiming at the best prediction of daily solar irradiance in a São Paulo context. The largest dataset in Brazil for meteorological parameters, containing measurements from 1933 to 2014, was used to train and compare the results of the algorithms. The results showed good approximation between measured and predicted global solar radiation for the three algorithms; however, for São Paulo, the SVM produced a lower Root-Mean-Square Error (RMSE), and ELM, a faster training rate. Using all 10 meteorological parameters available for the site was the best approach for the three algorithms at this location.

Segmentation of Coronal Features to Understand the Solar EUV and UV Irradiance Variability III. Inclusion and Analysis of Bright Points

The study of solar irradiance variability is of great importance in heliophysics, Earth’s climate, and space weather applications. These studies require careful identifying, tracking and monitoring of features in the solar photosphere, chromosphere, and corona. Do coronal bright points contribute to the solar irradiance or its variability as input to the Earth atmosphere? We studied the variability of solar irradiance for a period of 10 years (May 2010 – June 2020) using the Large Yield Radiometer (LYRA), the Sun Watcher using APS and image Processing (SWAP) on board PROBA2, and the Atmospheric Imaging Assembly (AIA), and applied a linear model between the segmented features identified in the EUV images and the solar irradiance measured by LYRA. Based on EUV images from AIA, a spatial possibilistic clustering algorithm (SPoCA) is applied to identify coronal holes (CHs), and a morphological feature detection algorithm is applied to identify active regions (ARs), coronal bright points (BPs), and the quiet Sun (QS). The resulting segmentation maps were then applied on SWAP images, images of all AIA wavelengths, and parameters such as the intensity, fractional area, and contribution of ARs/CHs/BPs/QS features were computed and compared with LYRA irradiance measurements as a proxy for ultraviolet irradiation incident to the Earth atmosphere. We modeled the relation between the solar disk features (ARs, CHs, BPs, and QS) applied to EUV images against the solar irradiance as measured by LYRA and the F10.7 radio flux. A straightforward linear model was used and corresponding coefficients computed using a Bayesian method, indicating a strong influence of active regions to the EUV irradiance as measured at Earth’s atmosphere. It is concluded that the long- and short-term fluctuations of the active regions drive the EUV signal as measured at Earth’s atmosphere. A significant contribution from the bright points to the LYRA irradiance could not be found.

Stephan Prantner’s Sunspot Observations during the Dalton Minimum

Abstract In addition to regular Schwabe cycles (≈11 yr), solar variability also shows longer periods of enhanced or reduced activity. Of these, reconstructions of the Dalton Minimum provide controversial sunspot group numbers and limited sunspot positions, partially due to limited source record accessibility. In this context, we analyzed Stephan Prantner’s sunspot observations spanning from 1804 to 1844, the values of which had only been known through estimates despite their notable chronological coverage during the Dalton Minimum. We identified his original manuscript in Stiftsarchiv Wilten, near Innsbruck (Austria). We reviewed his biography (1782–1873) and located his observational sites at Wilten and Waidring, which housed the principal telescopes for his early and late observations: a 3.5 inch astronomical telescope and a Reichenbach 4 foot achromatic erecting telescope, respectively. We identified 215 days of datable sunspot observations, which is almost twice as much data as his estimated data in the existing databases (=115 days). In Prantner’s records, we counted up to seven to nine sunspot groups per day and measured sunspot positions, which show their distributions in both solar hemispheres. These results strikingly emphasize the difference between the Dalton Minimum and the Maunder Minimum as well as the similarity between the Dalton Minimum and the weak solar cycles in the modern observations.

Indian monsoon wind variability since ~11 kyr in the northwestern and northeastern Arabian Sea

• We studied varying monsoon wind stress in the Arabian Sea during the Holocene . • Surface productivity was high during the early Holocene . • Summer monsoon was weak and winter monsoon was strong in the middle Holocene. • Monsoon winds show high spatial variability in strength in the Arabian Sea. In this paper, we use planktic foraminifera and mixed-layer species from cores SK-240/327, SK-243/I- and ABP-25/03, northeastern Arabian Sea to investigate monsoon wind variability. Planktic foraminifera include Globigerina bulloides, a monsoon proxy and mixed-layer species Globigerinoides ruber, Gs. sacculifer, Gs. obliquus and Gs. extremus from cores SK-240/327, SK-243/I-1 and ABP-25/03 encompassing last ~11 calibrated kilo years before the Present (~11 cal kyr BP). The population abundances of Globigerina bulloides and mixed-layer species were compared with published Globigerina bulloides percentages from the western Arabian Sea Ocean Drilling Program Holes 723A, 724B and 727B, and eastern Arabian Sea core ABP-25, 02 to understand variations in Indian monsoon winds during the Holocene. In the eastern Arabian Sea, upwelling induced productivity was higher during 10–6.5 cal kyr BP which decreased during 6.5–3 cal kyr BP. In the northwestern Arabian Sea, we observe a similar scenario but not every site captured this change owing to spatial diverseness in monsoon wind stress. The productivity increased since 3 cal kyr BP due to intense summer monsoon winds in the northeastern Arabian Sea, whereas productivity began to increase at ~1.5 cal kyr BP in the northwestern Arabian Sea. The upwelling intensity shows large spatial and temporal variations in the eastern and western Arabian Sea, indicating varying monsoon wind strength across the Arabian Sea during the Holocene. The spectral analysis performed on Globigerina bulloides shows cyclicity which is associated with solar variability during the past 11 kyr record in the northeastern Arabian Sea.