An uncommon period of cold and change of lapse rate in the Rocky Mountains of Colorado and Wyoming

EXTRACT (SEE PDF FOR FULL ABSTRACT): Temperature and lapse rate show extreme departures from mean values for May 1981 through October 1986 at the high-elevation station D1 on Niwot Ridge in the Front Range, Colorado. If the D1 record is accurate, this period may present an opportunity to identify factors that influence temperature at high elevations, but not necessarily at low elevations. This paper focuses on four questions: (1) Is the D1 temperature record accurate? (2) What is the geographical extent of this anomalous cold period? (3) Are there any identifiable contributing factors or physical events relating to this period? (4) Is there evidence of a similar anomalous period in the past?

A late-Holocene pollen record from Lower Pahrangat Lake, southern Nevada, USA: high resolution paleoclimatic records and analysis of environmental responses to climate change

EXTRACT (SEE PDF FOR FULL ABSTRACT): High resolution paleobotanical records provide sufficient detail to correlate events regionally. Once correlated events can be examined in tandem to determine the underlying inputs that fashioned them. Several localities in the Great Basin have paleobotanical records of sufficient detail to generate regional reconstructions of vegetation changes for the last 2 ka and provide conclusions as to the climates that caused them.

High-speed wavelength conversion utilizing birefringence in semiconductor optical amplifiers

This paper describes a novel technique whereby a mixture of cross-phase and cross-gain modulation effects in an SOA causes polarization rotation of a cw probe beam in the presence of a signal pulse, enabling the transmission of the probe through a polarizer to be controlled. The benefits of this approach are: 1) Very high extinction ratios present in the wavelength converted signal (>30 achieved); 2) A non-inverted wavelength converted signal, which is advantageous for chirp-compensation;2 3) A simple and stable experimental set-up, 4) Converted pulses which can be shaped to be faster than the input pulses.

Chirp limitation on high-speed wavelength conversion using semiconductor optical amplifiers

The cross-gain-saturation effect in SOAs, has been shown to enable robust high-speed wavelength conversion. Under strong electrical and optical pumping, conversion speeds in excess of 20 Gbit/s have been illustrated. However, the effect of chirp on transmission distance at such ultrahigh bit rates has not been studied theoretically in detail. This paper considers the chirp introduced on conversion, employing cross-gain saturation, and studies its dependence on amplifier drive current and signal power. It further shows how an increase in injected cw optical power can reduce chirp while improving conversion speed.

East African Freshwater Fisheries Research Organization Annual Report 1972

Feeding habits of many animals have been used widely in animal classifications. This is so, because the type of diet an organism requires demands structural specialisation which will utilise the available resource. Many animals may however have many structural modifications to enable them to be described as omnivourous or generalised feeders such as H. empodisma and H. riponianus (GREENWOOD 1960) which may show varying degrees of structural and adaptational intermediacy between two trophic groups. Generally, however, the diet of many animals including fish changes as the animal grow larger. The change in structural modifications is usually correlated with changes in the diet. In fishes the change may involve change from tricuspid to biscuspid and finally to unicuspid type of teeth. The degree of modification in the structure depends on the diet, thus Haplochromis that feeds on soft tissues of snails only requires modifications in oral dentition while Haplochromis that feeds on both soft tissues and shells of snails require modification in the lower pharyngeal bone for grinding purposes. Other modifications connected with food utilisation may be located in the alimentary canal. (I) The fish species that are commercially exploited are Protopterus aethiopicus, Clarias mossambicus, Tilapia esculenta, Tilapia amphimelas and Tilapia hybrids. The other fish species present in the lake but not commercially exploited are: Gnathonemus sp. Alestes sp. Labeo sp., Barbus paludinoses, Barbus jacksoni, Barbus lineomaculatus, Barbus regersi, Leptogrlanis sp., Schilbe sp., Haplochromis spp. and Hemihaplochromis sp. (2) Protopterus sp. and Clarias sp. are mostly caught with hooks on long lines. There has been a steady increase in number of hooks on the lake. Since the stocks of Protopterus and C/arias in the lake have a limit, we should control the number of hooks used by each of the fishermen in order to avoid overharvesting. (3) All the previous studies on Lake Kitangiri fisheries suggested the use of gill nets with mesh size greater than 88.9 mm in order to avoid the capture of immature Ti/apia spp. But if the fishermen are to obtain economic gains from the fishery, the optimum mesh size for use is 88.9 -101.6 mm. (4) The gillnet is a passive gear with very beneficial selective characteristics. Unfortunately the drive-in fishery which exists on Lake Kitangiri more or less destroys the gillnet selectivity characteristics. It is therefore recommended that the beating of water with poles be discouraged and stopped. (5) There is need for provision of stable fishing canoes to replace the unstable bottle palm dug-out canoes which are currently being used and which are very risky to operate. (6) The fish processing facilities on Lake Kitangiri are still inadequate. Most of the fish is sun dried, Since sun drying is very difficult during the rainy season, most fishermen carry out intensive fishing during the dry season, Concentrating most of the fishing effort in anyone season instead of spreading evenly this effort over the whole year could damage the age structure of the exploitable stocks. (7) There are considerable fluctuations in the volume of water of the lake. The feasibility of regulating the water loss through the effluent Sibiti river should be investigated by the Water Development Department. (8) Damming the Sibiti river is an expensive undertaking and therefore, the Rural Development Bank of Tanzania should be asked to assess the economic feasibility of such a project.

Bi-annual environment monitoring technical report for the SON cage fish culture site at Bugungu, Napoleon Gulf, northern Lake Victoria, December 2012

The first year-round quarterly surveys were completed for the year 2011. For the year 2012, SON management decided to change the frequency of the surveys from quarterly to biannual and the first such survey, was undertaken in June 2012. The second survey was undertaken in December 2012 and is the subject of this report: Results/observations made are presented in this technical report along with a scientific interpretation and discussion of the results with reference to possible impacts of the cage facilities to the water environment and aquatic biota. SON cage study sites were coded as downstream of cages (DSC), within cages (WIC) and upstream of cages (USC). Physical-chemical parameters (water column temperature, dissolved oxygen, pH, conductivity, were measured in-situ with a pre-calibrated hydrolab at each site. A digital Echo Sounder was used to determine the total water column depth at each site. A black and white Secchi disc was used to determine water column transparency. Coordinate locations were determined with a GPS device.

SON bi‐annual environment monitoring technical report for the cage culture site at Bugungu, northern Lake Victoria, June 2012

Source of the Nile Fish farm (SON) is located at Bugungu area in Napoleon Gulf, northern Lake Victoria. The proprietors of the farm requested NaFIRRI to provide technical assistance to undertake regular environment monitoring of the cage site as is mandatory under the NEMA conditions. NAFIRRI agreed to undertake regular environment surveys in the cage area covering selected physical‐chemical factors i.e. water column depth, water transparency, water column temperature, dissolved oxygen, pH, conductivity, redox potential and turbidity; nutrient status, algal and invertebrate communities (micro‐invertebrates/zooplankton and macro‐invertebrates/macro‐benthos) as well as fish community. The first year‐round quarterly surveys were completed for the year 2011. It was decided by SON management to change the frequency of the monitoring surveys to biannual starting in the year 2012 and the first such survey, which is the subject of this report, was undertaken in June 2012. Results/observations made are presented in this technical report along with a scientific interpretation and discussion of the results with reference to possible impacts of the cage facilities to the water environment and aquatic biota. SON

Spatio-temporal changes in annual accumulated temperature in China and the effects on cropping systems, 1980s to 2000

Change in thermal conditions can substantially affect crop growth, cropping systems, agricultural production and land use. In the present study, we used annual accumulated temperatures > 10 degrees C (AAT10) as an indicator to investigate the spatio-temporal changes in thermal conditions across China from the late 1980s to 2000, with a spatial resolution of 1 x 1 km. We also investigated the effects of the spatio-temporal changes on cultivated land use and cropping systems. We found that AAT10 has increased on a national scale since the late 1980s, Particularly, 3.16 x 10(5) km(2) of land moved from the spring wheat zone (AAT10: 1600 to 3400 degrees C) to the winter wheat zone (AAT10: 3400 to 4500 degrees C). Changes in thermal conditions had large influences on cultivated land area and cropping systems. The areas of cultivated land have increased in regions with increasing AAT10, and the cropping rotation index has increased since the late 1980s. Single cropping was replaced by 3 crops in 2 years in many regions, and areas of winter wheat cultivation were shifted northward in some areas, such as in the eastern Inner Mongolia Autonomous Region and in western Liaoning and Jilin Provinces.

Industrial development and land use/cover change and their effects on local environment: a case study of Changshu in eastern coastal China

The interactions among industrial development, land use/cover change (LUCC), and environmental effects in Changshu in the eastern coastal China were analyzed using high-resolution Landsat TM data in 1990, 1995, 2000, and 2006, socio-economic data and water environmental quality monitoring data from research institutes and governmental departments. Three phases of industrial development in Changshu were examined (i.e., the three periods of 1990 to 1995, 1995 to 2000, and 2000 to 2006). Besides industrial development and rapid urbanization, land use/cover in Changshu had changed drastically from 1990 to 2006. This change was characterized by major replacements of farmland by urban and rural settlements, artificial ponds, forested and constructed land. Industrialization, urbanization, agricultural structure adjustment, and rural housing construction were the major socio-economic driving forces of LUCC in Changshu. In addition, the annual value of ecosystem services in Changshu decreased slightly during 1990-2000, but increased significantly during 2000-2006. Nevertheless, the local environmental quality in Changshu, especially in rural areas, has not yet been improved significantly. Thus, this paper suggests an increased attention to fully realize the role of land supply in adjustment of environment-friendly industrial structure and urban-rural spatial restructuring, and translating the land management and environmental protection policies into an optimized industrial distribution and land-use pattern.

Diurnal, seasonal and annual variation in net ecosystem CO2 exchange of an alpine shrubland on Qinghai-Tibetan plateau

Thus far, grassland ecosystem research has mainly been focused on low-lying grassland areas, whereas research on high-altitude grassland areas, especially on the carbon budget of remote areas like the Qinghai-Tibetan plateau is insufficient. To address this issue, flux of CO2 were measured over an alpine shrubland ecosystem (37 degrees 36'N, 101 degrees 18'E; 325 above sea level [a. s. l.]) on the Qinghai-Tibetan Plateau, China, for 2 years (2003 and 2004) with the eddy covariance method. The vegetation is dominated by formation Potentilla fruticosa L. The soil is Mol-Cryic Cambisols. To interpret the biotic and abiotic factors that modulate CO2 flux over the course of a year we decomposed net ecosystem CO2 exchange (NEE) into its constituent components, and ecosystem respiration (R-eco). Results showed that seasonal trends of annual total biomass and NEE followed closely the change in leaf area index. Integrated NEE were -58.5 and -75.5 g C m(-2), respectively, for the 2003 and 2004 years. Carbon uptake was mainly attributed from June, July, August, and September of the growing season. In July, NEE reached seasonal peaks of similar magnitude (4-5 g C m(-2) day(-1)) each of the 2 years. Also, the integrated night-time NEE reached comparable peak values (1.5-2 g C m(-2) day(-1)) in the 2 years of study. Despite the large difference in time between carbon uptake and release (carbon uptake time < release time), the alpine shrubland was carbon sink. This is probably because the ecosystem respiration at our site was confined significantly by low temperature and small biomass and large day/night temperature difference and usually soil moisture was not limiting factor for carbon uptake. In general, R-eco was an exponential function of soil temperature, but with season-dependent values of Q(10). The temperature-dependent respiration model failed immediately after rain events, when large pulses of R-eco were observed. Thus, for this alpine shrubland in Qinghai-Tibetan plateau, the timing of rain events had more impact than the total amount of precipitation on ecosystem R-eco and NEE.

Vulnerability and adaptation to climate change in Guam – a case-study of the perceptions, attitudes, behaviors, and knowledge of a small rural community towards their watershed

This thesis argues that examining the attitudes, perceptions, behaviors, and knowledge of a community towards their specific watershed can reveal their social vulnerability to climate change. Understanding and incorporating these elements of the human dimension in coastal zone management will lead to efficient and effective strategies that safeguard the natural resources for the benefit of the community. By having healthy natural resources, ecological and community resilience to climate change will increase, thus decreasing vulnerability. In the Pacific Ocean, climate and SLR are strongly modulated by the El Niño Southern Oscillation. SLR is three times the global average in the Western Pacific Ocean (Merrifield and Maltrud 2011; Merrifield 2011). Changes in annual rainfall in the Western North Pacific sub‐region from 1950-2010 show that islands in the east are getting much less than in the past, while the islands in the west are getting slightly more rainfall (Keener et al. 2013). For Guam, a small island owned by the United States and located in the Western Pacific Ocean, these factors mean that SLR is higher than any other place in the world and will most likely see increased precipitation. Knowing this, the social vulnerability may be examined. Thus, a case-study of the community residing in the Manell and Geus watersheds was conducted on the island of Guam. Measuring their perceptions, attitudes, knowledge, and behaviors should bring to light their vulnerability to climate change. In order to accomplish this, a household survey was administered from July through August 2010. Approximately 350 surveys were analysed using SPSS. To supplement this quantitative data, informal interviews were conducted with the elders of the community to glean traditional ecological knowledge about perceived climate change. A GIS analysis was conducted to understand the physical geography of the Manell and Geus watersheds. This information about the human dimension is valuable to CZM managers. It may be incorporated into strategic watershed plans, to better administer the natural resources within the coastal zone. The research conducted in this thesis is the basis of a recent watershed management plan for the Guam Coastal Management Program (see King 2014).

Coordinated analysis of delayed sprites with high-speed images and remote electromagnetic fields

Simultaneous measurements of high-altitude optical emissions and magnetic fields produced by sprite-associated lightning discharges enable a close examination of the link between low-altitude lightning processes and high-altitude sprite processes. We report results of the coordinated analysis of high-speed sprite video and wideband magnetic field measurements recorded simultaneously at Yucca Ridge Field Station and Duke University. From June to August 2005, sprites were detected following 67 lightning strokes, all of which had positive polarity. Our data showed that 46% of the 83 discrete sprite events in these sequences initiated more than 10 ms after the lightning return stroke, and we focus on these delayed sprites in this work. All delayed sprites were preceded by continuing current moments that averaged at least 11 kA km between the return stroke and sprites. The total lightning charge moment change at sprite initiation varied from 600 to 18,600 C km, and the minimum value to initiate long-delayed sprites ranged from 600 for 15 ms delay to 2000 C km for more than 120 ms delay. We numerically simulated electric fields at altitudes above these lightning discharges and found that the maximum normalized electric fields are essentially the same as fields that produce short-delayed sprites. Both estimated and simulation-predicted sprite initiation altitudes indicate that long-delayed sprites generally initiate around 5 km lower than short-delayed sprites. The simulation results also reveal that slow (5-20 ms) intensifications in continuing current can play a major role in initiating delayed sprites. Copyright 2008 by the American Geophysical Union.

Annual westward propagating anomalies near 26 degrees N and eddy generation south of the Canary Islands: remote sensing (altimeter/SeaWIFS) and in situ measurement

Seasonal changes in altimeter data are derived for the North Atlantic Ocean. Altimeter data are then used to examine annually propagating structure along 26 degree N. By averaging the altimeter data into monthly values or by Fourier analysis, a positive anomaly can be followed from 17 degree W to similar to 50 degree W along similar to 26 degree N. The methods give a westward travel speed of 1 degree of longitude a month and a half-life of one year for the average decaying structure. At similar to 50 degree W 26 degree N, the average structure is about 2.8 years old with an elevation signal of similar to 1 cm, having gravelled similar to 3300 km westward. The mean positive anomaly results from the formation of anticyclonic eddies which are generally formed annually south of the Canary Islands by late summer and which then travel westward near 26 degree N. Individual eddy structure along 26 degree N is examined and related to in situ measurements and anomalies in the annual seasonal concentration cycle of SeaWiFS chlorophyll-a.