Influences of local weather, large-scale climatic drivers, and the ca. 11 year solar cycle on lake ice breakup dates; 1905–2004

Spring freshet is the dominant annual discharge event in all major Arctic draining rivers with large contributions to freshwater inflow to the Arctic Ocean. Research has shown that the total freshwater influx to the Arctic Ocean has been increasing, while at the same time, the rate of change in the Arctic climate is significantly higher than in other parts of the globe. This study assesses the large-scale atmospheric and surface climatic conditions affecting the magnitude, timing and regional variability of the spring freshets by analyzing historic daily discharges from sub-basins within the four largest Arctic-draining watersheds (Mackenzie, Ob, Lena and Yenisei). Results reveal that climatic variations closely match the observed regional trends of increasing cold-season flows and earlier freshets. Flow regulation appears to suppress the effects of climatic drivers on freshet volume but does not have a significant impact on peak freshet magnitude or timing measures. Spring freshet characteristics are also influenced by El Niño-Southern Oscillation, the Pacific Decadal Oscillation, the Arctic Oscillation and the North Atlantic Oscillation, particularly in their positive phases. The majority of significant relationships are found in unregulated stations. This study provides a key insight into the climatic drivers of observed trends in freshet characteristics, whilst clarifying the effects of regulation versus climate at the sub-basin scale.

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Solar cycle changes of large-scale solar wind structure

Proceedings of the International Astronomical Union ◽

10.1017/s1743921309992912 ◽

2009 ◽

Vol 5 (S264) ◽

pp. 356-358 ◽

Cited By ~ 3

Author(s):

P. K. Manoharan

Keyword(s):

Solar Wind ◽

Solar Cycle ◽

Large Scale ◽

Interplanetary Space ◽

The Sun ◽

Wind Structure ◽

Level Of Activity ◽

Solar Wind Structure ◽

Current Minimum ◽

Inner Heliosphere

AbstractIn this paper, I present the results on large-scale evolution of density turbulence of solar wind in the inner heliosphere during 1985–2009. At a given distance from the Sun, the density turbulence is maximum around the maximum phase of the solar cycle and it reduces to ~70%, near the minimum phase. However, in the current minimum of solar activity, the level of turbulence has gradually decreased, starting from the year 2005, to the present level of ~30%. These results suggest that the source of solar wind changes globally, with the important implication that the supply of mass and energy from the Sun to the interplanetary space has significantly reduced in the present low level of activity.

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Solar Cycle Variation of Large Scale Plasma Flows

Astrophysics and Space Science Proceedings - Dynamics of the Sun and Stars ◽

10.1007/978-3-030-55336-4_20 ◽

2020 ◽

pp. 139-140

Author(s):

B. Lekshmi

Keyword(s):

Solar Cycle ◽

Large Scale ◽

Plasma Flows ◽

Solar Cycle Variation ◽

Cycle Variation

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Influence of large-scale variations in convective available potential energy (CAPE) and solar cycle over temperature in the tropopause region at Delhi (28.3°N, 77.1°E), Kolkata (22.3°N, 88.2°E), Cochin (10°N, 77°E), and Trivandrum (8.5°N, 77.0°E) using radiosonde during 1980–2005

Earth Planets and Space ◽

10.5047/eps.2009.09.001 ◽

2010 ◽

Vol 62 (3) ◽

pp. 319-331 ◽

Cited By ~ 12

Author(s):

S. K. Dhaka ◽

R. Sapra ◽

V. Panwar ◽

A. Goel ◽

R. Bhatnagar ◽

...

Keyword(s):

Solar Cycle ◽

Potential Energy ◽

Large Scale ◽

Convective Available Potential Energy ◽

Available Potential Energy ◽

Tropopause Region

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Hotspots of extreme compound drought and heatwaves: Role of feedback and climate oscillations

10.5194/egusphere-egu21-11426 ◽

2021 ◽

Author(s):

Waqar Ul Hassan ◽

Munir Ahmad Nayak

Keyword(s):

Large Scale ◽

Southern Oscillation ◽

Standardized Precipitation Index ◽

Limited Attention ◽

Weather Events ◽

Excess Heat Factor ◽

Climatic Drivers ◽

Compound Events ◽

Positive And Negative Feedbacks

<p>Compound weather events arise from combination of multiple climatic drivers or hazards and often result in disastrous socio-economic impacts. Compound drought and heatwave (CDHE) events have received considerable attention in recent years, but limited attention is given towards the understanding of feedback relationships between droughts and heatwaves at global hotspots of the compound events. Here, we identify the potential hotspots of extreme compound drought and heatwaves (ECDH) over the globe using standardized precipitation index (SPI) and Excess heat factor (EHF) as metrics for droughts and heatwaves, respectively. Besides the well know positive feedback between droughts and heatwaves, i.e., heatwaves amplify droughts and vice-versa, we hypothesize and test the possibility of negative feedback at distinct hotspots where heatwaves tend to abate droughts. Multiple hotspots were identified with positive and negative feedbacks among drought and heatwave intensities, supporting our hypothesis. We also analyzed the role of different local and large-scale global drivers (such as El-Ni&#241;o Southern Oscillation) on the feedbacks at the hotspots. Our analysis has implications in predicting extreme compound droughts and heatwaves and provides new insights that will foster further research in this direction.</p>

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Reconstruction of Sun-as-Star Magnetic Field Structure and Evolution Using Filament Observations

International Astronomical Union Colloquium ◽

10.1017/s0252921100048156 ◽

1998 ◽

Vol 167 ◽

pp. 493-496

Author(s):

Dmitri I. Ponyavin

Keyword(s):

Magnetic Field ◽

Solar Cycle ◽

Large Scale ◽

Solar Magnetic Field ◽

Close Association ◽

Field Structure ◽

The Sun ◽

Magnetic Field Structure ◽

Large Scale Magnetic Field ◽

Field Organization

AbstractA technique is used to restore the magnetic field of the Sun viewed as star from the filament distribution seen on Hα photographs. For this purpose synoptic charts of the large-scale magnetic field reconstructed by the McIntosh method have been compared with the Sun-asstar solar magnetic field observed at Stanford. We have established a close association between the Sun-as-star magnetic field and the mean magnetic field inferred from synoptic magnetic field maps. A filtering technique was applied to find correlations between the Sun-as-star and large-scale magnetic field distributions during the course of a solar cycle. The correlations found were then used to restore the Sun-as-star magnetic field and its evolution in the late 1950s and 1960s, when such measurements of the field were not being made. A stackplot display of the inferred data reveals large-scale magnetic field organization and evolution. Patterns of the Sun-as-star magnetic field during solar cycle 19 were obtained. The proposed technique can be useful for studying the solar magnetic field structure and evolution during times with no direct observations.

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Solar cycle changes in the geo-effectiveness of small-scale solar wind turbulence measured by Wind and ACE at 1 AU

Annales Geophysicae ◽

10.5194/angeo-25-1183-2007 ◽

2007 ◽

Vol 25 (5) ◽

pp. 1183-1197 ◽

Cited By ~ 3

Author(s):

M. L. Parkinson ◽

R. C. Healey ◽

P. L. Dyson

Keyword(s):

Solar Wind ◽

Solar Cycle ◽

Solar Minimum ◽

Large Scale ◽

Small Scale ◽

Scaling Exponent ◽

Mhd Turbulence ◽

Scaling Exponents ◽

Solar Wind Turbulence ◽

Wind Turbulence

Abstract. Multi-scale structure of the solar wind in the ecliptic at 1 AU undergoes significant evolution with the phase of the solar cycle. Wind spacecraft measurements during 1995 to 1998 and ACE spacecraft measurements during 1997 to 2005 were used to characterise the evolution of small-scale (~1 min to 2 h) fluctuations in the solar wind speed vsw, magnetic energy density B2, and solar wind ε parameter, in the context of large-scale (~1 day to years) variations. The large-scale variation in ε most resembled large-scale variations in B2. The probability density of large fluctuations in ε and B2 both had strong minima during 1995, a familiar signature of solar minimum. Generalized Structure Function (GSF) analysis was used to estimate inertial range scaling exponents aGSF and their evolution throughout 1995 to 2005. For the entire data set, the weighted average scaling exponent for small-scale fluctuations in vsw was aGSF=0.284±0.001, a value characteristic of intermittent MHD turbulence (>1/4), whereas the scaling exponents for corresponding fluctuations in B2 and ε were aGSF=0.395±0.001 and 0.334±0.001, respectively. These values are between the range expected for Gaussian fluctuations (1/2) and Kolmogorov turbulence (1/3). However, the scaling exponent for ε changed from a Gaussian-Kolmogorov value of 0.373±0.005 during 1997 (end of solar minimum) to an MHD turbulence value of 0.247±0.004 during 2003 (recurrent fast streams). Changes in the characteristics of solar wind turbulence may be reproducible from one solar cycle to the next.

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Observed Tropospheric Temperature Response to 11-yr Solar Cycle and What It Reveals about Mechanisms

Journal of the Atmospheric Sciences ◽

10.1175/jas-d-12-0214.1 ◽

2013 ◽

Vol 70 (1) ◽

pp. 9-14 ◽

Cited By ~ 9

Author(s):

Jiansong Zhou ◽

Ka-Kit Tung

Keyword(s):

Solar Cycle ◽

Large Scale ◽

Stratospheric Ozone ◽

Statistical Significance ◽

Temperature Response ◽

Polar Regions ◽

Tropospheric Temperature ◽

Tropical Ocean ◽

Global Data ◽

Difference Projection

Abstract Using 54 yr of NCEP reanalysis global data from 1000 to 10 hPa, this study establishes the existence and the statistical significance of the zonal-mean temperature response to the 11-yr solar cycle throughout the troposphere and parts of the lower stratosphere. Two types of statistical analysis are used: the composite-mean difference projection method, which tests the existence of the solar cycle signal level by level, and the adaptive AR(p)-t test, which tells if a particular local feature is statistically significant at the 95% confidence level. A larger area of statistical significance than that in previous published work is obtained, due to the longer record and a better trend removal process. It reveals a spatial pattern consistent with a “bottom up” mechanism, involving evaporative feedback near the tropical ocean surface and tropical vertical convection, latent heating of the tropical upper troposphere, and poleward large-scale heat transport to the polar regions. It provides an alternative to the currently favored “top down” mechanism involving stratospheric ozone heating.

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Solar Irradiance: Instrument-Based Advances

Proceedings of the International Astronomical Union ◽

10.1017/s1743921319004605 ◽

2018 ◽

Vol 14 (A30) ◽

pp. 354-357

Author(s):

Greg Kopp

Keyword(s):

Solar Cycle ◽

Solar Flares ◽

Solar Irradiance ◽

Large Scale ◽

Total Solar Irradiance ◽

Climate Forcing ◽

Solar Cycles ◽

Climate Stability ◽

Measurement Results ◽

Measuring Space

AbstractVariations of the total solar irradiance (TSI) over long periods of time provide natural Earth-climate forcing and are thus important to monitor. Variations over a solar cycle are at the 0.1 % level. Variations on multi-decadal to century timescales are (fortunately for our climate stability) very small, which drives the need for highly-accurate and stable measurements over correspondingly long periods of time to discern any such irradiance changes. Advances to TSI-measuring space-borne instruments are approaching the desired climate-driven measurement accuracies and on-orbit stabilities. I present a summary of the modern-instrument improvements enabling these measurements and present some of the solar-variability measurement results from recent space-borne instruments, including TSI variations on timescales from solar flares and large-scale convection to solar cycles.

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