A numerical study on impact of crop canopy on mesoscale climate

The impact of well watered mesoscale wheat planted on the mesoscale boundary layer structures of midlatitude arid area has been investigated by using a mesoscale biophysical meteorological model. The investigation indicates that mesoscale perturbations in temperature and specific humidity over crop area from the adjacent dry, bare soil, caused by the transpiration from the crop canopy and evaporation from underlying humid soil, result in a horizontal pressure gradient. A mesoscale circulation is forced by the pressure perturbation with a wind speed of about 5 m/s directing from the crop canopy to the bare soil in the lower boundary layer. In the daytime, the boundary layer structure over a complex terrain is determined by the interactions between upslope flow circulations and the circulations mentioned above when wheat crop canopies are located on plain and plateau. The impact of crop canopy scale on this thermally forced mesoscale circulation is also investigated.     

Agricultural Meteorology in Ireland – a historical perspective from the Irish Meteorological Service

Ireland has a temperate climate influenced by the Atlantic Gulf Stream. This, combined with fertile soils and adequate rainfall, provides an environment ideally suited for grass. Grass is an inexpensive, nutritious feed for livestock, giving Ireland a competitive advantage in this sector. Tillage farming is also an important sector for Ireland, and evidence of the Great Irish Famine of the mid-eighteen hundreds is still visible in the landscape. In this paper, we examine aspects of meteorological involvement in Irish agriculture, from the perspective of the Irish Meteorological Service. We examine the rise of agrometeorology in Ireland and take a look at the development of related services, including potato blight warnings. Two influential characters of Irish agrometeorological history, Austin Bourke and Tom Keane, are examined, as well as organisations such as the AGMET Group. The paper concludes with a brief snapshot of current Irish agrometeorological activities along with future ambitions.     

Southeast Alaska: oceanographic habitats and linkages

We provide an overview of the physical oceanographic and geological processes that affect marine biological habitats and production in the marine waters throughout the archipelago and continental shelf of Southeast Alaska. Given the paucity of regional data, our overview summarizes work done in adjacent regions of the Gulf of Alaska shelf and basin, and draws on research carried out in similar settings elsewhere. The geological setting, which critically influences the regional meteorology and oceanography, includes a narrow continental shelf, deep channels that permeate the archipelago, fjords, glaciers and a rugged, mountainous coast. The large-scale meteorology is influenced primarily by seasonal variations in the intensity and position of the Aleutian Low. Winds, freshwater runoff, tides and cross-shelf exchange control the regional oceanography. The large-scale flow field advects mass, heat, salt, nutrients and planktonic organisms northward from British Columbia (and even further south) to the northern Gulf of Alaska along the slope, shelf, and within the channels of Southeast Alaska. The deep channels permeating the island archipelago and narrow continental shelf facilitate communication between basin and interior waters. Water properties and flow fields are subject to large annual variations in response to similarly large variations in winds and coastal freshwater discharge. The complex geological setting leads to large spatial heterogeneity in the physical processes controlling the local circulation fields and mixing, thereby creating numerous and diverse marine biological habitats. These various circulation and mixing processes modify substantially Southeast Alaska water masses and thus influence marine ecosystem processes downstream over the northern and western Gulf of Alaska shelf.     

Assessing Tropical Forests' Climatic Sensitivities with Long‐term Data

Analyses relating long‐term records of tree growth to interannual climatic variation at La Selva, Costa Rica have revealed marked forest sensitivities to both temperature and dry‐season intensity ( Clark et al. 2010 ). The tropical‐forest biome is certain to become warmer, and many areas may become drier. Testing the generality of the La Selva findings with similar analyses of field data from diverse forests across the biome will be a valuable next step. Based on our experiences during the La Selva studies, we propose that such assessments will need to address three issues. One is the number of repeat forest measurements. Short series of re‐censuses can be an unreliable basis for assessing climatic sensitivities. For some key climatic factors (e.g., temperature), records consisting of fewer than 10–12 re‐censuses can span limited climatic ranges, producing erratic and largely nonsignificant correlations. Multiyear census intervals exacerbate these data limitations. Second, different types of forest‐growth data call for different analysis approaches. Cohort and tree‐ring records need to be adjusted for ontogenetic growth changes, while stand‐level data require taking into account potentially confounding influences from forest compositional changes, as from succession. Third, a reliable meteorological record is critical. Poor‐quality or internally inconsistent climatic records can fatally corrupt assessments of forest sensitivities. To be usable in such analyses, the meteorological record requires data quality control, gap filling, and adjustments to maintain the record's internal consistency in the face of commonly occurring methods changes (instruments, siting). We illustrate these issues using analyses of the long‐term La Selva records.     

Pollen grain viability in Parietaria judaica L. during the long blooming period and correlation with meteorological conditions and allergic diseases

Abstract

Pollen grain viability and starch presence in pollen were followed during the long blooming period (May-November) of Parietaria judaica, the most widespread pellitory in Italy, responsible for many cases of allergic diseases. Observations were carried out near Siena (Tuscany), in the years 1978 and 1979.

Viability is high in late spring and early autumn, and pollen grains are starchy. The presence of starchless grains is always related to low viability: a production of pollen with a low viability occurs at the beginning and end of blooming, and also in summer, during drought periods. Pollen grain viability varies widely during the blooming period, and its variations are correlated to meteorological conditions, mainly rainfall and temperature.

Allergic diseases due to pellitory, however, are mainly reported between April and July, and on the other hand a small amount of patients states that they suffer all the year round. The discrepancies between the periods of viable pollen production and of declared symptoms by patients, are discussed.     

Airborne Ericaceae Pollen Grains in the Atmosphere of Vigo （Northwest Spain） and Its Relationship with Meteorological Factors

Abstract: Several species of the Erica genus are broadly represented in northwest Spain, being among the shrubs that form the substitution stage following forest degradation as a result of human activity, caused mainly by fire or other antrophic causes. Therefore airborne pollen from Erica is frequent. From 1995 to 2002, an aerobiological study of Ericaceae family pollen was undertaken in the atmosphere of the city of Vigo (Northwest Spain) using a Lanzoni VPPS 2000 (Lanzoni srl, Bologna, Italy) sampler placed in the left margin of the Vigo fiord (42°14'15 "N, 8°43'30" W). Despite being a taxon of eminently entomophillous pollination, the pollen of Ericaceae was well represented in the atmosphere above the study zone. Erica arborea L. is the main species represented in the annual pollen curve. This taxon shows a long main pollen season and higher pollen concentrations were recorded during the months of April and May, which is why beekeepers place their beehives at specific locations in April to ensure a considerable contribution from this pollen to the composition of the honey. The maximum daily average concentration was detected in 1997, with a concentration of 156 grains/m³. Throughout the day, maximum values occur at 5/6 h and between 17:00 and 18:00 h. Finally, correlation statistical analyses were developed in order to determine the degree of association between the daily average of meteorological parameters and daily mean airborne pollen concentrations. Rainfall exerts a clear influence on Ericaceae pollen season characteristics, with precipitation registered in March being responsible for the decrease in total annual pollen values.
(Managing editor: Ya-Qin HAN)     

Ragweed and mugwort pollen in Szczecin, Poland

Ragweed (genus Ambrosia) and mugwort (Artemisia vulgaris) pollen grains are known to be very potent aeroallergens, often noted to enter into cross reactions. The aim of the study was to analyse ragweed and mugwort pollen release in Szczecin (western Poland) during the period 2000–2003. Measurements were performed by the volumetric and gravimetric method. Pollen seasons were defined as the periods of 90% of the total catch. Of the 4 years studied, the lowest concentration of ragweed pollen was observed in 2000. In 2000, the annual ragweed pollen count was very high, threefold higher than in 2001. There was a high Ambrosia pollen count in 2003, with the highest daily value of 84 grains/m³. The mugwort pollen season started in the third 10-day period of July and lasted to the end of August in all of the years studied. Analysis of pollen deposition from different Szczecin city’s districts showed that the highest exposure to ragweed pollen allergens occurred in the Majowe district, which is related to the presence of numerous plants of Ambrosia in that district. The mugwort pollen deposition was more abundant in the Żelechowa district, which is an area with villas and gardens. Statistically significant correlations were found between the ragweed pollen count in the air and the maximum wind speed, air temperature and relative humidity and between the mugwort pollen count in the air and air temperature and relative humidity.     

Relevance of individual and environmental drivers of movement of Golden Eagles

An animal's movement is expected to be governed by an interplay between goals determined by its internal state and energetic costs associated with navigating through the external environment. Understanding this ecological process is challenging when an animal moves in two dimensions and even more difficult for birds that move in a third dimension. To understand the dynamic interaction between the internal state of an animal and the variable external environment, we evaluated hypotheses explaining association of different covariates of movement and the trade-offs birds face as they make behavioural decisions in a fluctuating landscape. We used ~870 000 GPS telemetry data points collected from 68 Golden Eagles Aquila chrysaetos to test demographic, diel, topographic and meteorological hypotheses to determine (1) the probability that these birds would be in motion and (2), once in motion, their flight speed. A complex and sometimes interacting set of potential internal and external factors determined movement behaviour. There was good evidence that reproductive state, manifested as age, sex and seasonal effects, had a significant influence on the probability of being in motion and, to a lesser extent, on speed of motion. Likewise, movement responses to the external environment were often unexpectedly strong. These responses, to northness of slope, strength of orographic updraft and intensity of solar radiation, were regionally and temporally variable. In contrast to previous work showing the role of a single environmental factor in determining movement decisions, our analyses support the hypothesis that multiple factors simultaneously interact to influence animal movement. In particular they highlighted how movement is influenced by the interaction between the individual's internal reproductive state and the external environment, and that, of the environmental factors, topographic influences are often more relevant than meteorological influences in determining patterns of flight behaviour. Further disentangling of how these internal and externals states jointly affect movement will provide additional insights into the energetic costs of movement and benefits associated with achieving process-driven goals.     

不同放牧压力下草地微气象的变化与草地荒漠化的发生

过度放牧是我国半干旱地区荒漠化的主要成因之一。作者在内蒙古奈曼进行了草地放牧试验,目的在于探明荒漠化的发生机制。试验分为４个小区,即无牧区,轻牧区,中牧区和重牧区。每个小区的牧羊数分别为０,３,６和９。从１９９１至１９９４年,在试验区进行了微气象观测,并运用波文化热量平衡法和空气动力学梯度法分析了观测数据。