Challenges In Reanalysis Products To Assess Extreme Weather Impacts On Yield Underestimate Drought

The incidence of dry or wet day sequences has a great influence on crops management and development. The lack of spatialized observed data with appropriate temporal resolution to investigate the changes that has occurred during the last century regarding the length and frequencies of those sequences has led to reliance on reanalysis products. However, the question can be raised about the suitability of those products when evaluating such climate indices and their impacts on crop production. Different products are here investigated to evaluate the way that succession of dry and wet days are depicted. We showed clearly that the frequency and intensity of dry and wet spells returned can differ widely between products. For instance, number of dry spell events can range from 1 to 11 over the same decade for two different products. This divergence in representation of spells could generate substantial differences in impact analysis of crop yields in agricultural modeling.

Simulating Properties of “Seasonal” Variability in Solar Activity and Space Weather Impacts

Solar short-term, quasi-annual variability within a decadal sunspot-cycle has recently been observed to strongly correlate with major class solar flares, resulting into quasi-periodic space weather “seasons.” In search for the origin of this quasi-periodic enhanced activity bursts, significant researches are going on. In this article we show, by employing a 3D thin-shell shallow-water type model, that magnetically modified Rossby waves can interact with spot-producing toroidal fields and create certain quasi-periodic spatio-temporal patterns, which plausibly cause a season of enhanced solar activity followed by a relatively quiet period. This is analogous to the Earth’s lower atmosphere, where Rossby waves and jet streams are produced and drive global terrestrial weather. Shallow-water models have been applied to study terrestrial Rossby waves, because their generation layer in the Earth’s lower atmospheric region has a much larger horizontal than vertical scale, one of the model-requirements. In the Sun, though Rossby waves can be generated at various locations, particularly favorable locations are the subadiabatic layers at/near the base of the convection zone where the horizontal scale of the fluid and disturbances in it can be much larger than the vertical scale. However, one important difference with respect to terrestrial waves is that solar Rossby waves are magnetically modified due to presence of strong magnetic fields in the Sun. We consider plausible magnetic field configurations at the base of the convection zone during different phases of the cycle and describe the properties of energetically active Rossby waves generated in our model. We also discuss their influence in causing short-term spatio-temporal variability in solar activity and how this variability could have space weather impacts. An example of a possible space weather impact on the Earth’s radiation belts are presented.

Timelines as a Tool for Learning about Space Weather Storms

Space weather storms typically have solar, interplanetary, geophysical and societal-effect components that overlap in time, making it hard for students and novices to determine cause-and-effect relationships and relative timing. To address this issue, we use timelines to provide context for space weather storms of different intensities. First, we present a timeline and tabular description for the great auroral storms of the last 500 years as an example for space climate. The graphical summary for these 14 events suggests that they occur about every 40-60 years, although the distribution of such events is far from even. One outstanding event in 1770 may qualify as a one-in-500-year auroral event, based on duration. Additionally, we present two examples that describe space weather storms using solar, geospace and effects categories. The first of these is for the prolonged storm sequence of late January1938 that produced low-latitude auroras and space weather impacts on mature technology (telegraphs) and on high frequency radio communication for aviation, which was a developing technology. To illustrate storm effects in the space-age, we produce a detailed timeline for the strong December 2006 geomagnetic storm that impacted numerous space-based technologies for monitoring space weather and for communication and navigation. During this event there were numerous navigations system disturbances and hardware disruptions. We adopt terminology developed in many previous space weather studies and blend it with historical accounts to create graphical timelines to help organize and disentangle the events presented herein.

Using mobile phone data to examine weather impacts on recreational ecosystem services in an urban protected area

Mobile phone big data can offer new opportunities for identifying weather impacts on recreational ecosystem services in protected areas. This could be useful to assess how climate change could affect recreational ecosystem services. To explore these opportunities, we utilize mobile phone data and examine impacts of tropical weather (temperature, rainfall, and wind) and holidays on visitor numbers and stay time in an urban protected area in Singapore. These impacts were analyzed by visitors’ home regions and ethnic groups as well. The study results showed that rising temperatures below 31.7 °C had positive impacts on visitor numbers, in contrast to the common perception that cooler temperatures would be always preferred for outdoor activities in a tropical region. Meanwhile, these rising temperatures reduced visitor stay time in the protected area. Rain and wind had limited impacts on visitors. Compared to the weather variables, holidays had bigger impacts on visitors, particularly the Chinese group and those visitors living not close to the protected area. The study results highlight several advantages of mobile phone data application to analyzing weather impacts on public use of urban protected areas.

Geomagnetic activity effects on CO2‐driven trend in the thermosphere and ionosphere: ideal model experiments with GAIA

<p>We examine impacts of geomagnetic activity on CO<sub>2</sub>-driven trend in the Ionosphere and Thermosphere (IT) using the GAIA whole atmosphere model. The model reveals three salient features. (1) Geomagnetic activities usually weakens the CO<sub>2</sub>-driven trend at a fixed altitude. Among the IT parameters analyzed, the thermosphere mass density is the most robust indicator for CO<sub>2</sub> cooling effect even with geomagnetic activity influences. (2) Geomagnetic activities can either strengthen or weaken the CO<sub>2</sub>-driven trend in hmF2 and NmF2, depending on local time and latitudes. This renders the widely used linear fitting methods invalid for removing geomagnetic effects from observations. (3) An interdependency exists between the efficiency of CO<sub>2</sub> forcing and geomagnetic forcing, with the former enhances at lower geomagnetic activity level, while the latter enhances at higher CO<sub>2</sub> concentration. This could imply that the CO<sub>2</sub>-driven trend would accelerate in periods of declining geomagnetic activity, while magnetic storms may have larger space weather impacts in the future with increasing CO<sub>2</sub>. These findings provide a preliminary model framework to understand interactions between the CO<sub>2</sub> forcing from below and the geomagnetic forcing from above.</p>