Circulation changes in the winter lower atmosphere and long-lasting solar/geomagnetic activity

The paper describes the association between high long-lasting solar/geomagnetic activity and geopotential height (GPH) changes in the winter lower atmosphere, based on their development in the Northern Hemisphere in the winter periods (December–March) of 1950–1969 and 1970–2002. Solar/geomagnetic activity is characterised by the 60-day mean of the sunspot number R/by the 60-day mean of the daily sum of the Kp index. The GPH distributions in the lower atmosphere are described by 60-day anomalies from their long-term daily average at 20 hPa/850 hPa. The data have been adopted from the NCEP/NCAR reanalysis. The 60-day mean values of solar/geomagnetic activity and GPH anomalies were calculated in five-day steps over the whole winter period. The analysis was carried out using composite maps which represent their distribution of the GPH anomalies during high solar activity (R ≥ 100) and high geomagnetic activity (ΣKp ≥ 20). Analysis has shown that the distribution of GPH anomalies depends on solar activity, geomagnetic activity and the phase of winter period (early or late winter). The nature of this relationship then depends on the time interval involved, i.e. 1950–1969 or 1970–2002. Positive anomalies in the polar stratosphere (20 hPa) were detected during the whole winter periods of the years 1950–1969. Significant anomalies were detected in the lower troposphere (850 hPa) during the second half of the winter period. The distribution of GPH anomalies on the maps compiled with regard to solar activity was similar to the distribution on maps compiled with regard to geomagnetic activity. In the interval 1970–2002, significant negative GPH anomalies were detected in the stratosphere at high latitudes, and positive anomalies were detected in the region of low latitudes. The distribution of GPH anomalies in the lower troposphere was substantially affected by situations in which, together with high solar activity, also high geomagnetic activity occurred

Exploring associations of maternal exposure to ambient temperature with duration of gestation and birth weight: a prospective study

Abstract Background Evidence suggests the possible impact of ambient high temperature on fetal growth and birth outcomes. However, little is known about the relative impact of exposure to heat and cold and the possible vulnerable window during pregnancy. Methods Data on a total of 237,585 pregnant women from January 1st, 2001 to December 31st, 2010 were acquired from the Queensland Health, Australia. Daily data on meteorological factors, including ambient temperature, relative humidity, barometric pressure, and air pollutants, such as PM10, SO2, NO2, and O3, were obtained from relevant government agencies. This study was to examine the associations of maternal exposure to ambient temperature (high and low temperatures, in early vs. late pregnancy) with the duration of gestation and birth weight. Results A J-shaped association between minimum temperature at conception and duration of gestation was observed after adjusting for seasonality and other confounders. Compared to women who were exposed to the minimum temperature of 15–20 °C in the first gestational week, exposure to the minimum temperature of > 20 °C significantly increased the duration of gestation by 0.029 weeks (95% CI: 0.008, 0.049). A cumulative effect was found when exposure across the first four weeks was examined. There was an inverted U-shaped relationship between minimum temperature at delivery and the duration of gestation. Compared to women exposed to 15–20 °C, exposure to minimum temperature of > 20 °C and ≤ 10 °C was associated with a shortened gestation by 0.030 weeks (95% CI: -0.052, − 0.008) and 0.018 weeks (95% CI: -0.057, − 0.004), respectively. By contrast, an inverse relationship between maximum temperature and birth weight was observed. Compared to exposure to the maximum temperature of > 30 °C in the last week of pregnancy, maternal exposure to 20–25 °C and < 20 °C significantly increased birth weight by 0.011 kg (95% CI: 0.008, 0.018) and 0.018 kg (95% CI: 0.010, 0.031), respectively. Similarly, a mild cumulative effect was observed when maximum temperature exposure across the four weeks before delivery was evaluated. Conclusions The finding emphasized the importance of keeping an optimal temperature range during pregnancy for reducing the risk of preterm birth and low birthweight