152 research outputs found
The global monsoon system: research and forecast
The main objective of this workshop was to provide a forum for discussion between researchers and forecasters on the current status of monsoon forecasting and on priorities and opportunities for monsoon research. WMO hopes that through this series of quadrennial workshops, the following goals can be accomplished: (a) to update forecasters on the latest reseach findings and forecasting technology; (b) to update researchers on monsoon analysis and forecasting; (c) to identify basic and applied research priorities and opportunities; (d) to identify opportunities and priorities for acquiring observations; (e) to discuss the approach of a web-based training document in order to update forecasters on developments of direct relevance to monsoon forecasting
The WWRP Polar Prediction Project (PPP)
Mission statement: āPromote cooperative international research enabling development of improved weather and environmental prediction services for the polar regions, on time scales from hours to seasonalā. Increased economic, transportation and research activities in polar regions are leading to more demands for sustained and improved availability of predictive weather and climate information to support decision-making. However, partly as a result of a strong emphasis of previous international efforts on lower and middle latitudes, many gaps in weather, sub-seasonal and seasonal forecasting in polar regions hamper reliable decision making in the Arctic, Antarctic and possibly the middle latitudes as well.
In order to advance polar prediction capabilities, the WWRP Polar Prediction Project (PPP) has been established as one of three THORPEX (THe Observing System Research and Predictability EXperiment) legacy activities. The aim of PPP, a ten year endeavour (2013-2022), is to promote cooperative international research enabling development of improved weather and environmental prediction services for the polar regions, on hourly to seasonal time scales. In order to achieve its goals, PPP will enhance international and interdisciplinary collaboration through the development of strong linkages with related initiatives; strengthen linkages between academia, research institutions and operational forecasting centres; promote interactions and communication between research and stakeholders; and foster education and outreach.
Flagship research activities of PPP include sea ice prediction, polar-lower latitude linkages and the Year of Polar Prediction (YOPP) - an intensive observational, coupled modelling, service-oriented research and educational effort in the period mid-2017 to mid-2019
Associations of interannual variation in summer tropospheric ozone with the Western Pacific Subtropical High in China from 1999 to 2017
Associations between tropospheric ozone (O3) and climate variations have been extensively investigated worldwide. However, given the lack of historical O3 monitoring data, the knowledge gaps regarding the influences of climate variations on long-term O3 trends in China remain. The present study used a tropospheric O3 dataset from the summers of 1999 to 2017 simulated by an atmospheric chemistry model to explore the linkage between summer O3 and a dominant atmospheric circulation system ā the Western Pacific Subtropical High (WPSH) pressure ā on an interannual basis in China. During this period, both WPSH strength and O3 concentrations in eastern and central China illustrated a growing trend. An EOF analysis was conducted to examine significant summer O3 characteristics and patterns and their potential connections with the WPSH. We find that the correlation between the first principal component of summer ozone concentration in the EOF analysis and the WPSH reached 0.56 (Pā¤0.01) in China from 1999 to 2017. We show that the WPSH determines interannual fluctuations of summer O3, whereas O3 precursor emissions contribute primarily to the O3 long-term trend. Our results reveal that the WPSH plays a vital role in O3 perturbation in the eastern seaboard regions and inland China. Precursor emissions made more significant contributions of up to 60ā% to increasing O3 trends in the inland urban agglomerations than coastal regions in eastern and southern China. The strongest contribution of meteorological conditions associated with the WPSH to summer O3 occurred in the Yangtze River Delta (YRD), accounting for over 9ā% to ozone perturbations from 1999 to 2017. We find that the effect of the WPSH on regional O3 depends on the spatial proximity to the WPSH. We attributed the effects of the WPSH on O3 interannual variations to the changes in air temperature, precipitation, and winds associated with the WPSH's intensity and positions.</p
Electromagnetic Radiation
The application of electromagnetic radiation in modern life is one of the most developing technologies. In this timely book, the authors comprehensively treat two integrated aspects of electromagnetic radiation, theory and application. It covers a wide scope of practical topics, including medical treatment, telecommunication systems, and radiation effects. The book sections have clear presentation, some state of the art examples, which makes this book an indispensable reference book for electromagnetic radiation applications
Coupling between surface ozone and leaf area index in a chemical transport model: strength of feedback and implications for ozone air quality and vegetation health
Tropospheric ozone is an air pollutant that substantially harms vegetation
and is also strongly dependent on various vegetation-mediated processes. The
interdependence between ozone and vegetation may constitute feedback
mechanisms that can alter ozone concentration itself but have not been
considered in most studies to date. In this study we examine the importance
of dynamic coupling between surface ozone and leaf area index (LAI) in
shaping ozone air quality and vegetation. We first implement an empirical
scheme for ozone damage on vegetation in the Community Land Model (CLM) and
simulate the steady-state responses of LAI to long-term exposure to a range
of prescribed ozone levels (from 0 to 100 ppb). We find that most plant
functional types suffer a substantial decline in LAI as ozone level
increases. Based on the CLM-simulated results, we develop and implement in
the GEOS-Chem chemical transport model a parameterization that computes
fractional changes in monthly LAI as a function of local mean ozone levels.
By forcing LAI to respond to ozone concentrations on a monthly timescale, the
model simulates ozoneāLAI coupling dynamically via biogeochemical processes
including biogenic volatile organic compound (VOC) emissions and dry
deposition, without the complication from meteorological changes. We find
that ozone-induced damage on LAI can lead to changes in ozone concentrations
by ā1.8 to +3 ppb in boreal summer, with a corresponding ozone feedback
factor of ā0.1 to +0.6 that represents an overall self-amplifying effect
from ozoneāLAI coupling. Substantially higher simulated ozone due to strong
positive feedbacks is found in most tropical forests, mainly due to the
ozone-induced reductions in LAI and dry deposition velocity, whereas reduced
isoprene emission plays a lesser role in these low-NOx
environments. In high-NOx regions such as the eastern US,
Europe,
and China, however, the feedback effect is much weaker and even negative in
some regions, reflecting the compensating effects of reduced dry deposition
and reduced isoprene emission (which reduces ozone in
high-NOx environments). In remote, low-LAI regions, including
most of the Southern Hemisphere, the ozone feedback is generally slightly
negative due to the reduced transport of NOxāVOC reaction
products that serve as NOx reservoirs. This study represents
the first step to accounting for dynamic ozoneāvegetation coupling in a chemical
transport model with ramifications for a more realistic joint assessment of
ozone air quality and ecosystem health.</p
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