Unmasking Seasonal Cycles in Human Fertility: How holiday sex and fertility cycles shape birth seasonality

AbstractThe mechanisms of human birth seasonality have been debated for over 150 years. In particular, the question of whether sexual activity or fertility variations drive birth seasonality has remained open and difficult to test without large-scale data on sexual activity. Analyzing data from half-a-million users worldwide collected from the female health tracking app Clue in combination with birth records, we inferred that birth seasonality is primarily driven by seasonal fertility, yet increased sexual activity around holidays explains minor peaks in the birth curve. Our data came from locations in both the Northern Hemisphere (UK, US, and France) and the Southern Hemisphere (Brazil). We found that fertility peaks between the autumn equinox and winter solstice in the Northern Hemisphere locations and shortly following the winter solstice in the Southern Hemisphere locations.

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Predicting pregnancy using large-scale data from a women's health tracking mobile application

The World Wide Web Conference on - WWW '19 ◽

10.1145/3308558.3313512 ◽

2019 ◽

Cited By ~ 5

Author(s):

Bo Liu ◽

Shuyang Shi ◽

Yongshang Wu ◽

Daniel Thomas ◽

Laura Symul ◽

...

Keyword(s):

Women’S Health ◽

Women's Health ◽

Mobile Application ◽

Large Scale ◽

Large Scale Data ◽

Health Tracking ◽

Scale Data

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Simultaneous tracking of reconnected flux tubes: Cluster and conjugate SuperDARN observations on 1 April 2004

Annales Geophysicae ◽

10.5194/angeo-26-1545-2008 ◽

2008 ◽

Vol 26 (6) ◽

pp. 1545-1557 ◽

Cited By ~ 9

Author(s):

Q.-H. Zhang ◽

R. Y. Liu ◽

M. W. Dunlop ◽

J. Y. Huang ◽

H. Q. Hu ◽

...

Keyword(s):

Response Time ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

Large Scale ◽

Global Flow ◽

Local Response ◽

Polar Cap ◽

Flux Tubes ◽

North West ◽

The Third

Abstract. While the Cluster spacecraft were located near the high-latitude magnetopause, between 11:30–13:00 UT on 1 April 2004, a series of medium to large scale (40 nT, 0.6–1.2 Re) FTEs were observed. During this pass, simultaneous and conjugated SuperDARN measurements are available that show a global flow pattern which is consistent with the expected (mapped) north-west motion of (predominantly sub-solar) reconnected, magnetic flux at the magnetopause. We focus on analysing the local response of three FTEs, tracking their magnetopause motion via the four-spacecraft measurements together with their corresponding ground mapped motions. For two of these FTEs, where the tracking is strongly coordinated with the ionospheric flow at each footprint of the implied flux tubes in the Northern Hemisphere, conditions corresponded to stable, increasing (>100°) clock angle, while the third event, where the correspondence is less strong, coincided with low (<100°) clock angle. Flux tube motion, both measured and modeled from the inferred X-line, qualitatively matches the clear velocity enhancements in ionospheric convections with northward and westward flow at each location in the Northern Hemisphere, measured simultaneously by SuperDARN, and also roughly matches the observed, south-eastward ionospheric flow in the Southern Hemisphere at the time of these events. The time periods of these velocity enhancements infer that the evolution time of the FTEs is about 4–6 min from its origin on magnetopause to its addition to the polar cap. However, the ionospheric response time in the Southern Hemisphere might be 2 min longer for the 12:31 UT FTE (and 6 min longer for the 12:51 UT FTE) than the response time in the Northern Hemisphere.

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Hemispheric ozone variability indices derived from satellite observations and as diagnostics for coupled chemistry-climate models

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-6-5671-2006 ◽

2006 ◽

Vol 6 (3) ◽

pp. 5671-5709

Author(s):

T. Erbertseder ◽

V. Eyring ◽

M. Bittner ◽

M. Dameris ◽

V. Grewe

Keyword(s):

Interannual Variability ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

Total Ozone ◽

Large Scale ◽

Model Simulation ◽

Polar Vortex ◽

Satellite Observations ◽

Ozone Hole ◽

Wave Number

Abstract. Dynamics and chemistry of the lower and middle stratosphere are characterized by manifold processes on different scales in time and space. The total column density of ozone, measured by numerous instruments, can be used to trace the resulting variability. In particular, satellite-borne spectrometers allow global observation of the total ozone distribution with proven accuracy and high temporal and spatial resolution. In order to analyse the zonal and hemispherical ozone variability a spectral statistical Harmonic Analysis is applied to multi-year total ozone observations from the Total Ozone Monitoring Spectrometer (TOMS). As diagnostic variables we introduce the hemispheric ozone variability indices one and two. They are defined as the hemispheric means of the amplitudes of the zonal waves number one and two, respectively, as traced by the total ozone field. In order to demonstrate the capability of the diagnostic for intercomparison studies we apply the hemispheric ozone variability indices to evaluate total ozone fields of the coupled chemistry-climate model ECHAM4.L39(DLR)/CHEM (hereafter: E39/C) against satellite observations. Results of a multi-year model simulation representing ''2000" climate conditions with an updated version of E39/C and corresponding total ozone data of TOMS from 1996 to 2004 (Version 8.0) are used. It is quantified to what extent E39/C is able to reproduce the zonal and hemispherical large scale total ozone variations. The different representations of the hemispheric ozone variability indices are discussed. Summarizing the main differences of model and reference observations, we show that both indices, one and two, in E39/C are preferably too high in the Northern Hemisphere and preferably too low in the Southern Hemisphere. In the Northern Hemisphere, where the coincidence is generally better, E39/C produces a too strong planetary wave one activity in winter and spring as well as a too high interannual variability. For the Southern Hemisphere we conclude that model and observations differ significantly during the ozone hole season. In October and November amplitudes of wave number one and two are underestimated. This explains that E39/C exhibits a too stable polar vortex and a too low interannual variability of the ozone hole. Further, a strong negative bias of wave number one amplitudes in the tropics and subtropics from October to December is identified, which may also contribute to the zonal-symmetric polar vortex. The lack of wave two variability in October and November leads to weak vortex elongation and eventually a too late final warming. Contrary, too high wave number two amplitudes in July and August indicate why the polar vortex is formed too late in season by E39/C. In general, the hemispheric ozone variability indices can be regarded as a simple and robust approach to quantify differences in total ozone variability on a monthly mean basis. Therefore, the diagnostic represents a core diagnostic for model intercomparisons within the CCM Validation Activity for WCRP's (World Climate Research Programme) SPARC (Stratospheric Processes and their Role in Climate) regarding stratospheric dynamics.

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Terrestrial evaporation and global climate: lessons from Northland, a planet with a hemispheric continent

Journal of Climate ◽

10.1175/jcli-d-20-0452.1 ◽

2020 ◽

pp. 1-64

Author(s):

Marysa M. Laguë ◽

Marianne Pietschnig ◽

Sarah Ragen ◽

Timothy A. Smith ◽

David S. Battisti

Keyword(s):

Water Vapor ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

Land Surface ◽

Large Scale ◽

Climate Model ◽

Global Climate ◽

Atmospheric Water Vapor ◽

Atmospheric Water ◽

Local Warming

AbstractMotivated by the hemispheric asymmetry of land distribution on Earth, we explore the climate of Northland, a highly idealized planet with a Northern Hemisphere continent and a Southern Hemisphere ocean. The climate of Northland can be separated into four distinct regions: the Southern Hemisphere ocean, the seasonally wet tropics, the mid-latitude desert, and the Great Northern Swamp. We evaluate how modifying land surface properties on Northland drives changes in temperatures, precipitation patterns, the global energy budget, and atmospheric dynamics. We observe a surprising response to changes in land-surface evaporation, where suppressing terrestrial evaporation in Northland cools both land and ocean. In previous studies, suppressing terrestrial evaporation has been found to lead to local warming by reducing latent cooling of the land surface. However, reduced evaporation can also decrease atmospheric water vapor, reducing the strength of the greenhouse effect and leading to large-scale cooling. We use a set of idealized climate model simulations to show that suppressing terrestrial evaporation over Northern Hemisphere continents of varying size can lead to either warming or cooling of the land surface, depending on which of these competing effects dominate. We find that a combination of total land area and contiguous continent size controls the balance between local warming from reduced latent heat flux and large-scale cooling from reduced atmospheric water vapor. Finally, we demonstrate how terrestrial heat capacity, albedo, and evaporation all modulate the location of the ITCZ both over the continent and over the ocean.

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Hemispheric shift of the zonal mean ITCZ during the last deglaciation

10.5194/egusphere-egu21-13976 ◽

2021 ◽

Author(s):

Chetankumar Jalihal ◽

Uwe Mikolajewicz ◽

Marie-Luise Kapsch

Keyword(s):

Southern Hemisphere ◽

Northern Hemisphere ◽

Large Scale ◽

Vertical Motion ◽

Moist Static Energy ◽

Last Deglaciation ◽

Max Planck ◽

The Last Deglaciation ◽

Moist Static Energy Budget ◽

Static Energy

<div> <p>The zonal-annual mean inter-hemispheric convergence zone (ITCZ) is located in the northern hemisphere in the modern climate. A transient simulation of the last deglaciation using the Max Planck Institute Earth System Model (MPI-ESM), suggests that the ITCZ was located in the southern hemisphere 14 kyrs ago. This shift is due to a substantial cooling of the northern hemisphere relative the southern hemisphere, after the release of melt water pulse 1a. The ITCZ compensates for these changes in the surface temperature by shifting south, thereby leading to a northward atmospheric heat transport away from the southern hemisphere. Along with the southward shift, the intensity of the precipitation within the ITCZ decreases. These changes in the intensity of precipitation can be explained by using a framework based on the moist static energy budget. We find that these changes are primarily related to the changes in the large-scale vertical motion of the atmosphere in the tropics. This affects the vertical transport of the moist static energy, and hence total gross moist stability (TGMS).&#160;</p> </div>

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Alpha-Effect, Current and Kinetic Helicities for Magnetically Driven Turbulence, and Solar Dynamo

International Astronomical Union Colloquium ◽

10.1017/s0252921100064885 ◽

2000 ◽

Vol 179 ◽

pp. 387-388

Author(s):

Gaetano Belvedere ◽

V. V. Pipin ◽

G. Rüdiger

Keyword(s):

Southern Hemisphere ◽

Northern Hemisphere ◽

Convection Zone ◽

Solar Surface ◽

Momentum Transport ◽

Angular Momentum Transport ◽

Magnetic Buoyancy ◽

Alpha Effect ◽

Current Helicity

Extended AbstractRecent numerical simulations lead to the result that turbulence is much more magnetically driven than believed. In particular the role ofmagnetic buoyancyappears quite important for the generation ofα-effect and angular momentum transport (Brandenburg & Schmitt 1998). We present results obtained for a turbulence field driven by a (given) Lorentz force in a non-stratified but rotating convection zone. The main result confirms the numerical findings of Brandenburg & Schmitt that in the northern hemisphere theα-effect and the kinetic helicityℋkin= 〈u′ · rotu′〉 are positive (and negative in the northern hemisphere), this being just opposite to what occurs for the current helicityℋcurr= 〈j′ ·B′〉, which is negative in the northern hemisphere (and positive in the southern hemisphere). There has been an increasing number of papers presenting observations of current helicity at the solar surface, all showing that it isnegativein the northern hemisphere and positive in the southern hemisphere (see Rüdigeret al. 2000, also for a review).

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The Hemispheric Sign Rule of Current Helicity during the Rising Phase of Cycle 23

International Astronomical Union Colloquium ◽

10.1017/s0252921100064721 ◽

2000 ◽

Vol 179 ◽

pp. 303-306

Author(s):

S. D. Bao ◽

G. X. Ai ◽

H. Q. Zhang

Keyword(s):

Solar Cycle ◽

Southern Hemisphere ◽

Northern Hemisphere ◽

Active Regions ◽

Hemispheric Preference ◽

Current Helicity

AbstractWe compute the signs of two different current helicity parameters (i.e., αbestandHc) for 87 active regions during the rise of cycle 23. The results indicate that 59% of the active regions in the northern hemisphere have negative αbestand 65% in the southern hemisphere have positive. This is consistent with that of the cycle 22. However, the helicity parameterHcshows a weaker opposite hemispheric preference in the new solar cycle. Possible reasons are discussed.

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