Fernando Domínguez-Castro

Atlantic and Mediterranean synoptic drivers of central Spanish juniper growth

Atlantic and Mediterranean air masses influence the climate over the Iberian System mountain range. The relatively short instrumental records in central Spain though limit any long-term assessment of these synoptic systems. We here evaluate the potential to analyze such changes using ring width data from Juniperus thurifera trees growing in the northwestern and southeastern regions of the Iberian System, exposed to Atlantic and Mediterranean cyclonic activity, respectively. Comparison of tree rings with regional precipitation, temperature, and Palmer Drought Severity Index (PDSI) data indicates that juniper trees contain information on late spring and early summer drought conditions. Calibration trials using spatially resolved, gridded climate data reveal that the northwestern sampling site is predominantly controlled by Atlantic weather, while the southeastern site mainly reflects Mediterranean climate patterns. The strength and position of the blocking Azores high during spring to early summer is of particular importance for the distinct growth reactions in the Iberian System. The climate signal is remarkably strong in the southeastern site, where we developed the longest and best-replicated juniper tree ring record of the Iberian Peninsula. Data from this site allowed the reconstruction of May-June PDSI variability back to the early eighteenth century, indicating severe drought (PDSI < −9) in southeastern Spain in 1782, 1828, 1869, 1981, and 2005. The new PDSI record coheres well with historical rogation ceremony data from eastern Spain, indicating that common information on past drought events is inherent in both proxy archives.

Climatic potential of Islamic chronicles in Iberia: Extreme droughts (ad 711–1010)

From ad 711 to 1492, several regions in Iberia were under Muslim ruling. This Al-Andalus civilization generated a large amount of documentation during those centuries. Unfortunately, most of the documents are lost. The surviving Arabic documentary sources have never been studied from a climate perspective. In this paper, we present the first attempt to retrieve climate evidence from them. We studied all the Islamic chronicles (documents written by Islamic historians that narrate the social, political and religious history) available for the period ad 711–1010. It is shown that these sources recorded extreme events with a high temporal and spatial resolution. We identified three severe droughts, ad 748–754, ad 812–823 and ad 867–879, affecting Al-Andalus. We also noticed that the weather in Cordoba during the period ad 971–975 showed a higher frequency of snow and hail than current climate. The possibility of obtaining long continuous series from this type of source seems highly difficult.

The climate in Zafra from 1750 to 1840: precipitation

In this work, we present the construction of a rainfall index for Zafra (southwestern Spain) during the period 1750–1840 from documentary sources. For this purpose we used the correspondence of the Duke of Feria that contains a quasi-weekly report of the weather in Zafra. In order to check its reliability, the Zafra rainfall index was compared with the short rainfall series available from relatively close stations, including Lisbon, Mafra, Seville and Gibraltar, all of which show a similar pattern. We also studied the atmospheric circulation over North Atlantic and western Europe in the period 1750–1840 for the months characterized by extreme values of the percentage of rainy weeks in the period 1750–1840, specifically those months above the 95th percentile or below the 5th percentile. The average large-scale atmospheric circulation maps corresponding to the months with high percentages of rainy weeks have negative Sea Level Pressure (SLP) anomalies around southwestern Iberian Peninsula (IP) and higher than usual SLP around Iceland. On the other hand, the maps corresponding to the winter months with low percentages of rainy weeks are dominated by an anticyclonic circulation over the south Europe affecting southwestern IP. The monthly rainfall index anomalies for the study period were calculated and results show two wet period (from 1782 to 1789 and from 1799 to 1807) and two dry ones (from 1796 to 1799 and from 1816 to 1819) in accordance with other regional precipitation series available.

The climate in Zafra from 1750 to 1840: history and description of weather observations

Weather observations in Zafra during the period 1750 to 1840 have been compiled and studied. Zafra was the capital of the Duchy of Feria, located in the southwest of the Iberian Peninsula. The documentary sources used in this work are weekly reports submitted to the Duke (who lived in Madrid) that contain a section describing the weather of the preceding week or less. Regular and updated meteorological information was vital to the government of this Duchy as farming and ranching constituted the bases of the economic activity in this region, allowing the estimation of crop yield and quality and a better management of the trade of agricultural products. Therefore, this documentary source is exceptional to study the climate of SW Iberia due to its continuity, homogeneity and high temporal-resolution.

A possible case of Sporadic Aurora in 1843 from Mexico

In recent years, some authors have shown that some auroras can be observed at relatively low latitude when the geomagnetic activity is quiet or moderate. This very special type of aurora is called “sporadic aurora”. We present and analyze in this work a possible case of “sporadic aurora” observed in Mexico on the 19 April 1843. Moreover, we study the solar and auroral activity around this event.

The Hidden Role of Women in Monitoring Nineteenth-Century African Weather: Instrumental Observations in Equatorial Guinea

Abstract Some of the first systematic meteorological observations in Africa were made by two women in Equatorial Guinea in 1875. Sisters Isabel and Juliana Urquiola, together with Manuel Iradier, Isabels husband, built a meteorological observatory on Little Elobey Island (0°59′46″N, 9°32′14″E), off the tiny nations western coast. From 1 June to 31 December 1875, the sisters took subdaily readings (6, 12, 15, and 18 h past midnight local time) of humidity, temperature, precipitation, and wind direction and speed. To evaluate the quality of these historical observations, the authors have compared them with equivalent modern meteorological data from Cocobeach (the modern meteorological station nearest to Little Elobey). The monthly-mean distributions of maximum and minimum temperature are similar to those of Cocobeach, but minimum temperatures are 2.4°C higher than Cocobeach values. Despite this difference, the observations of the Urquiola sisters were found to be far better and more consistent than other ...

The climate in Zafra from 1750 to 1840: temperature indexes from documentary sources

This article shows the first monthly series of a temperature index for the region of Zafra, located in the southwest of Spain, during the period 1750–1840 using weekly weather descriptions. Three different index categories are established (−1, 0, and 1). We compare the index series of temperature in Zafra with the early instrumental data available in the southwest of Iberian Peninsula in order to assess the quality of these indices series. In addition, we characterize the synoptic situation over the North Atlantic region during the period 1750–1840 for the seasons with highest seasonal percentages of cold and warm weeks in each season. The overall configuration of the particularly cold (warm) weeks is seasonally dependent and makes sense from a synoptic perspective. Finally, we analyze the effects on climate in Zafra of important eruptions which took place during the period 1750–1840.

Recent changes of relative humidity: regional connections with land and ocean processes

We analyzed changes in surface relative humidity (RH) at the global scale from 1979 to 2014 using both observations and the ERA-Interim dataset. We compared the variability and trends in RH with those of land evapotranspiration and ocean evaporation in moisture source areas across a range of selected regions worldwide. The sources of moisture for each particular region were identified by integrating different observational data and model outputs into a Lagrangian approach. The aim was to account for the possible role of changes in air temperature over land, in comparison to sea surface temperature (SST), but also the role of land evapotranspiration and the ocean evaporation on RH variability. The results demonstrate that the patterns of the observed trends in RH at the global scale cannot be linked to a particular individual physical mechanism. Our results also stress that the different hypotheses that may explain the decrease in RH under a global warming scenario could act together to explain recent RH trends. Albeit with uncertainty in establishing a direct causality between RH trends and the different empirical moisture sources, we found that the observed decrease in RH in some regions can be linked to lower water supply from land evapotranspiration. In contrast, the empirical relationships also suggest that RH trends in other target regions are mainly explained by the dynamic and thermodynamic mechanisms related to the moisture supply from the oceanic source regions. Overall, while this work gives insights into the connections between RH trends and oceanic and continental processes at the global scale, further investigation is still desired to assess the contribution of both dynamic and thermodynamic factors to the evolution of RH over continental regions.

The first meteorological observations at a tropical high elevation site: Antisana, 1846

Antisana is a stratovolcano with an associated glacier located in the Ecuadorian Andes. Dr Aguirre made meteorological readings every day, at every hour from sunrise to sunset, from December 1845 to December 1846, at Antisana using a meteorological station at 4060 mamsl (meters above mean sea level). Unfortunately, only the monthly average data have been preserved. These meteorological data are here studied and compared with the closest modern stations for monthly values of temperature, rainfall, and pressure. According to these comparisons, the year 1846 was rainy and cold in comparison with the current climate. Moreover, these observations have been useful to help resolve a debate about a possible El Niño event in 1846 with the high precipitation in Antisana and Quito in 1846 discarding the occurrence of an El Niño event. The probable occurrence of a La Niña event is discussed. These data are the earliest known systematic instrumental meteorological observations taken at above 4000 mamsl.

Early meteorological records from Latin-America and the Caribbean during the 18th and 19th centuries

This paper provides early instrumental data recovered for 20 countries of Latin-America and the Caribbean (Argentina, Bahamas, Belize, Brazil, British Guiana, Chile, Colombia, Costa Rica, Cuba, Ecuador, France (Martinique and Guadalupe), Guatemala, Jamaica, Mexico, Nicaragua, Panama, Peru, Puerto Rico, El Salvador and Suriname) during the 18th and 19th centuries. The main meteorological variables retrieved were air temperature, atmospheric pressure, and precipitation, but other variables, such as humidity, wind direction, and state of the sky were retrieved when possible. In total, more than 300,000 early instrumental data were rescued (96% with daily resolution). Especial effort was made to document all the available metadata in order to allow further post-processing. The compilation is far from being exhaustive, but the dataset will contribute to a better understanding of climate variability in the region, and to enlarging the period of overlap between instrumental data and natural/documentary proxies.