The effects of ozone and nitrogen oxides on cereal/aphid interactions

Imperial Users onl

Detection Thresholds of Falling Snow from Satellite-Borne Active and Passive Sensors

Precipitation, including rain and snow, is a critical part of the Earth's energy and hydrology cycles. In order to collect information on the complete global precipitation cycle and to understand the energy budget in terms of precipitation, uniform global estimates of both liquid and frozen precipitation must be collected. Active observations of falling snow are somewhat easier to estimate since the radar will detect the precipitation particles and one only needs to know surface temperature to determine if it is liquid rain or snow. The challenges of estimating falling snow from passive spaceborne observations still exist though progress is being made. While these challenges are still being addressed, knowledge of their impact on expected retrieval results is an important key for understanding falling snow retrieval estimations. Important information to assess falling snow retrievals includes knowing thresholds of detection for active and passive sensors, various sensor channel configurations, snow event system characteristics, snowflake particle assumptions, and surface types. For example, can a lake effect snow system with low (~2.5 km) cloud tops having an ice water content (Iwe) at the surface of 0.25 g m-3 and dendrite snowflakes be detected? If this information is known, we can focus retrieval efforts on detectable storms and concentrate advances on achievable results. Here, the focus is to determine thresholds of detection for falling snow for various snow conditions over land and lake surfaces. The analysis relies on simulated Weather Research Forecasting (WRF) simulations of falling snow cases since simulations provide all the information to determine the measurements from space and the ground truth. Results are presented for active radar at Ku, Ka, and W-band and for passive radiometer channels from 10 to 183 GHz (Skofronick-Jackson, et al. submitted to IEEE TGRS, April 2012). The notable results show: (1) the W-Band radar has detection thresholds more than an order of magnitude lower than the future GPM sensors, (2) the cloud structure macrophysics influences the thresholds of detection for passive channels, (3) the snowflake microphysics plays a large role in the detection threshold for active and passive instruments, (4) with reasonable assumptions, the passive 166 GHz channel has detection threshold values comparable to the GPM DPR Ku and Ka band radars with ~0.05 g m-3 detected at the surface, or an ~0.5-1 mm hr-l melted snow rate (equivalent to 0.5-2 cm hr-l solid fluffy snowflake rate)

Passive Microwave Remote Sensing of Falling Snow and Associated GPM Field Campaigns

Retrievals of falling snow from space represent one of the next important challenges for the atmospheric, hydrological, and energy budget scientific communities. Historically, retrievals of falling snow have been difficult due to the relative insensitivity of satellite rain-based channels as used in the past. We emphasize the use of high frequency passive microwave channels (85-200 GHz) since these are more sensitive to the ice in clouds and have been used to estimate falling snow from space. While satellite-based remote sensing provides global coverage of falling snow events and the science is relatively new, retrievals are still undergoing development with challenges remaining. There are several current satellite sensors, though not specifically designed for estimating falling snow, are capable of measuring snow from space. These include NOAA's AMSU-B, the MHS sensors, and CloudSat radar. They use high frequency (greater than 85 GHz) passive and active microwave and millimeter-wave channels that are sensitive to the scattering from ice and snow particles in the atmosphere. Sensors with water vapor channels near 183 GHz center line provide opaqueness to the Earth's surface features that can contaminate the falling snow signatures, especially over snow covered surface. In addition, the Global Precipitation Measurement (GPM) mission scheduled for launch in 2013 is specifically designed to measure both liquid rain and frozen snow precipitation. Since falling snow from space is the next precipitation measurement challenge from space, information must be determined in order to guide retrieval algorithm development for these current and future missions. This information includes thresholds of detection for various sensor channel configurations, snow event system characteristics, and surface types. For example, can a lake effect snow system with low cloud tops having an ice water content (IWC) at the surface of 1.0 gram per cubic meter be detected? If this information is known, we can focus retrieval efforts on detectable storms and concentrate advances on achievable results. In this work, the focus is to determine thresholds of detection for falling snow for various snow conditions over land and lake surfaces. The results rely on simulated Weather Research Forecasting (WRF) simulations of falling snow cases [9] since simulations provide all the information to determine the measurements from space and the ground truth. This analysis relies on data from the Canadian CloudSat/CALIPSO Validation Program (C3VP) field campaign held from October 31, 2006 through March 1, 2007. In January 2012 GPM will return to the C3VP area for the GPM Cold Precipitation Experiment (GCPEx). This presentation will describe the thresholds-of-detection procedure and results, as well as the field campaign details

Senior Recital: Lisa Mason, oboe

This recital is presented in partial fulfillment of requirements for the degree Bachelor of Music in Music Education. Ms. Mason studies oboe with Elizabeth Tiscione.https://digitalcommons.kennesaw.edu/musicprograms/1292/thumbnail.jp

Regulation and growth-oriented small businesses in North-West England

This paper examines the ways in which growth-oriented small and micro-businesses (SMBs) are affected by regulations. Case studies from North-West England are used to investigate the relationship between attitudes and responses to regulation and the characteristics of business growth. This research examines the relationship between regulation and growth using eight case studies of SMBs. The selected cases are proactive in seeking new market opportunities and innovative in terms of product development or business process. Case studies confirm that owner-managers of SMBs experience high levels of regulatory burden. However, some growth-oriented businesses also recognise the advantages in being proactive in seeking regulatory knowledge. These advantages were particularly prevalent in cases where growth is driven by product innovation in relatively new product-markets. The study is based on a limited number of case studies in one region of England. Even so, interviews facilitate probing to increase understanding of the underlying reasons for attitudes towards regulation. The cases demonstrate that even very small businesses can use regulatory knowledge as a basis for business growth. The findings suggest that networking in order to engage with regulatory regimes can generate competitive advantages and open up new market opportunities for small businesses. This research contributes towards the debate on the impact of regulations on the economy at the micro level and in so doing highlights important nuances in the relationship between business growth and the regulatory environment

Surface and Atmospheric Contributions to Passive Microwave Brightness Temperatures

Physically-based passive microwave precipitation retrieval algorithms require a set of relationships between satellite observed brightness temperatures (TB) and the physical state of the underlying atmosphere and surface. These relationships are typically non-linear, such that inversions are ill-posed especially over variable land surfaces. In order to better understand these relationships, this work presents a theoretical analysis using brightness temperature weighting functions to quantify the percentage of the TB resulting from absorption/emission/reflection from the surface, absorption/emission/scattering by liquid and frozen hydrometeors in the cloud, the emission from atmospheric water vapor, and other contributors. The results are presented for frequencies from 10 to 874 GHz and for several individual precipitation profiles as well as for three cloud resolving model simulations of falling snow. As expected, low frequency channels (<89 GHz) respond to liquid hydrometeors and the surface, while the higher frequency channels become increasingly sensitive to ice hydrometeors and the water vapor sounding channels react to water vapor in the atmosphere. Low emissivity surfaces (water and snow-covered land) permit energy downwelling from clouds to be reflected at the surface thereby increasing the percentage of the TB resulting from the hydrometeors. The slant path at a 53deg viewing angle increases the hydrometeor contributions relative to nadir viewing channels and show sensitivity to surface polarization effects. The TB percentage information presented in this paper answers questions about the relative contributions to the brightness temperatures and provides a key piece of information required to develop and improve precipitation retrievals over land surfaces

Business perceptions of regulatory burden

Document submitted to the UK Department for Business, Innovation and Skills. The purpose of this project is to explore business perceptions of regulatory burden and to investigate the characteristics of the social processes that influence these perceptions. The project seeks to understand the process of communication of regulatory change and to establish how, and to what extent, the nature of media coverage can affect business’ perceptions of burden. Recent political comment has drawn considerable attention to the perception of regulatory burden in the UK. This has been intensified by the economic downturn and its impacts on business growth and survival. The debate surrounding regulatory burden on business has also been conducted in the media spotlight. This not only reflects the views of business but can also exercise considerable influence over the strength of feeling about this issue. The research methodology is designed to examine the general hypothesis that the manner in which regulatory changes are reported or communicated will tend to exaggerate the perception of regulatory burden on businesses. This assertion is tested using available evidence from existing research, supplemented by case studies and international comparisons based on secondary sources

Evaluation of Precipitation Detection over Various Surfaces from Passive Microwave Imagers and Sounders

During the middle part of this decade a wide variety of passive microwave imagers and sounders will be unified in the Global Precipitation Measurement (GPM) mission to provide a common basis for frequent (3 hr), global precipitation monitoring. The ability of these sensors to detect precipitation by discerning it from non-precipitating background depends upon the channels available and characteristics of the surface and atmosphere. This study quantifies the minimum detectable precipitation rate and fraction of precipitation detected for four representative instruments (TMI, GMI, AMSU-A, and AMSU-B) that will be part of the GPM constellation. Observations for these instruments were constructed from equivalent channels on the SSMIS instrument on DMSP satellites F16 and F17 and matched to precipitation data from NOAA's National Mosaic and QPE (NMQ) during 2009 over the continuous United States. A variational optimal estimation retrieval of non-precipitation surface and atmosphere parameters was used to determine the consistency between the observed brightness temperatures and these parameters, with high cost function values shown to be related to precipitation. The minimum detectable precipitation rate, defined as the lowest rate for which probability of detection exceeds 50%, and the detected fraction of precipitation, are reported for each sensor, surface type (ocean, coast, bare land, snow cover) and precipitation type (rain, mix, snow). The best sensors over ocean and bare land were GMI (0.22 mm/hr minimum threshold and 90% of precipitation detected) and AMSU (0.26 mm/hr minimum threshold and 81% of precipitation detected), respectively. Over coasts (0.74 mm/hr threshold and 12% detected) and snow-covered surfaces (0.44 mm/hr threshold and 23% detected), AMSU again performed best but with much lower detection skill, whereas TMI had no skill over these surfaces. The sounders (particularly over water) benefited from the use of re-analysis data (vs. climatology) to set the a-priori atmospheric state and all instruments benefit from the use of a conditional snow cover emissivity database over land. It is recommended that real-time sources of these data be used in the operational GPM precipitation algorithms

A comparative case study of the strategies used by grade one teachers who teach through the medium of English

This research project begins by exploring the problems surrounding the implementation of the 1997 Language in Education Policy (LiEP), and offers insight into why some schools, despite the promotion of additive bilingualism, choose English as the primary medium of instruction. It is a comparative case study of two Grade 1 classes in different situational contexts, which highlights the teaching strategies and language practices of teachers who teach predominantly non-English speakers through the medium of English. Research carried out through this case study illustrates the use of a wide range of teaching strategies, which assist young learners when learning through an additional language. In School A, thematic linking between different learning areas to maximise vocabulary development in both the mother tongue and the additional language, as well as repetition, recycling, scaffolding and contextualisation of content were found to be important. In addition, the use of questioning to elicit understanding, as well as classroom organisation and code-switching were strategies which assisted both the teacher and learners in this multilingual environment. In School B, class size, group work and the inclusion into the timetable of a wide range of diverse activities over and above the main learning areas, which provided opportunities for language development, were important considerations. In addition, routine, predictability and an attention to detail, in keeping with a form-focussed approach, aided the children in understanding the mechanics of literacy and guiding them towards becoming phonologically aware