We present an analysis of surface fluxes and cloud forcing from data obtained during the Surface Heat Budget of the Arctic Ocean (SHEBA) experiment, conducted in the Beaufort and Chuchki Seas and the ...Arctic Ocean from November 1997 to October 1998. The measurements used as part of this study include fluxes from optical radiometer sets, turbulent fluxes from an instrumented tower, cloud fraction from a depolarization lidar and ceilometer, and atmospheric temperature and humidity profiles from radiosondes. Clear‐sky radiative fluxes were modeled in order to estimate the cloud radiative forcing since direct observation of fluxes in cloud‐free conditions created large statistical sampling errors. This was particularly true during summer when cloud fractions were typically very high. A yearlong data set of measurements, obtained on a multiyear ice floe at the SHEBA camp, was processed in 20‐day blocks to produce the annual evolution of the surface cloud forcing components: upward, downward, and net longwave and shortwave radiative fluxes and turbulent (sensible and latent heat) fluxes. We found that clouds act to warm the Arctic surface for most of the annual cycle with a brief period of cooling in the middle of summer. Our best estimates for the annual average surface cloud forcings are −10 W m−2 for shortwave, 38 W m−2 for longwave, and −6 W m−2 for turbulent fluxes. Total cloud forcing (the sum of all components) is about 30 W m−2 for the fall, winter, and spring, dipping to a minimum of −4 W m−2 in early July. We compare the results of this study with satellite, model, and drifting station data.
An annual cycle of cloud and radiation measurements made as part of the Surface Heat Budget of the Arctic (SHEBA) program are utilized to determine which properties of Arctic clouds control the ...surface radiation balance. Surface cloud radiative forcing (CF), defined as the difference between the all-sky and clear-sky net surface radiative fluxes, was calculated from ground-based measurements of broadband fluxes and results from a clear-sky model. Longwave cloud forcing (CFLW) is shown to be a function of cloud temperature, height, and emissivity (i.e., microphysics). Shortwave cloud forcing (CFSW) is a function of cloud transmittance, surface albedo, and the solar zenith angle. The annual cycle of Arctic CF reveals cloud-induced surface warming through most of the year and a short period of surface cooling in the middle of summer, when cloud shading effects overwhelm cloud greenhouse effects. The sensitivity of CFLWto cloud fraction is about 0.65 W m−2per percent cloudiness. The sensitivity of CFSWto cloud fraction is a function of insolation and ranges over 0–1.0 W m−2per percent cloudiness for the sun angles observed at SHEBA. In all seasons, liquid-containing cloud scenes dominate both LW and SW radiative impacts on the surface. The annual mean CFLW(CFSW) for liquid-containing and ice-only cloud scenes is 52 (−21) and 16 (−3) W m−2, respectively. In the LW, 95% of the radiatively important cloud scenes have bases below 4.3 km and have base temperatures warmer than −31°C. The CFLWis particularly sensitive to LWP for LWP < 30 g m−2, which has profound implications in the winter surface radiation balance. The CFSWbecomes more negative as surface albedo decreases and at higher sun elevations. Overall, low-level stratiform liquid and mixed-phase clouds are found to be the most important contributors to the Arctic surface radiation balance, while cirrus clouds and diamond dust layers are found to have only a small radiative impact on the Arctic surface.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract To the central nervous system (CNS) belong a heterogeneous group of glial and non glial rare cancers. The aim of the present study was to estimate the burden (incidence, prevalence, survival ...and proportion of cured) for the principal CNS cancers in Europe (EU27) and in European regions using population-based data from cancer registries participating in the RARECARE project. We analysed 44,947 rare CNS cancers diagnosed from 1995 to 2002 (with follow up at 31st December 2003): 86.0% astrocytic (24% low grade, 63% high grade and 13% glioma NOS), 6.4% oligodendroglial (74% low grade), 3.6% ependymal (85% low grade), 4.1% Embryonal tumours and 0.1% choroid plexus carcinoma. Incidence rates vary widely across European regions especially for astrocytic tumours ranging from 3/100,000 in Eastern Europe to 5/100,000 in United Kingdom and Ireland. Overall, about 27,700 new rare CNS cancers were estimated every year in EU27, for an annual incidence rate of 4.8 per 100,000 for astrocytic, 0.4 for oligodendroglial, 0.2 for ependymal and embryonal tumours and less than 0.1 for choroid plexus carcinoma. More than 154,000 persons with rare CNS were estimated alive (prevalent cases) in the EU at the beginning of 2008. Five-year relative survival was 14.5% for astrocytic tumours (42.6% for low grade, 4.9% for high grade and 17.5% for glioma NOS), 54.5% for oligodendroglial (64.9% high grade and 29.6% low grade), 74.2% for ependymal (80.4% low grade and 36.6% high grade), 62.8% for choroid plexus carcinomas and 56.8% for embryonal tumours. Survival rates for astrocytic tumours were relatively higher in Northern and Central Europe than in Eastern Europe and in UK and Ireland. The different availability of diagnostic imaging techniques and/or radiation therapy equipment across Europe may contribute to explain the reported survival differences. The estimated proportion of cured patients was 7.9% for the ‘glial’ group to which belong astrocytic tumours. Overall results are strongly influenced by astrocytic tumours that are the most common type. This is the first study to delineate the rare CNS cancer burden in Europe by age, sex and European region.
In February and March of 2011, the Global Hawk unmanned aircraft system (UAS) was deployed over the Pacific Ocean and the Arctic during the Winter Storms and Pacific Atmospheric Rivers (WISPAR) field ...campaign. The WISPAR science missions were designed to (1) mprove our understanding of Pacific weather systems and the polar atmosphere; (2) evaluate operational use of unmanned aircraft for investigating these atmospheric events; and (3) demonstrate operational and research applications of a UAS dropsonde system at high latitudes. Dropsondes deployed from the Global Hawk successfully obtained high-resolution profiles of temperature, pressure, humidity, and wind information between the stratosphere and surface. The 35 m wingspan Global Hawk, which can soar for ~ 31 h at altitudes up to ~ 20 km, was remotely operated from NASA's Dryden Flight Research Center at Edwards Air Force Base (AFB) in California. During the 25 h polar flight on 9–10 March 2011, the Global Hawk released 35 sondes between the North Slope of Alaska and 85° N latitude, marking the first UAS Arctic dropsonde mission of its kind. The polar flight transected an unusually cold polar vortex, notable for an associated record-level Arctic ozone loss, and documented polar boundary layer variations over a sizable ocean–ice lead feature. Comparison of dropsonde observations with atmospheric reanalyses reveal that, for this day, large-scale structures such as the polar vortex and air masses are captured by the reanalyses, while smaller-scale features, including low-level jets and inversion depths, are mischaracterized. The successful Arctic dropsonde deployment demonstrates the capability of the Global Hawk to conduct operations in harsh, remote regions. The limited comparison with other measurements and reanalyses highlights the potential value of Arctic atmospheric dropsonde observations where routine in situ measurements are practically nonexistent.
Complete cancer prevalence data in Europe have never been updated after the first estimates provided by the EUROPREVAL project and referred to the year 1993. This paper provides prevalence estimates ...for 16 major cancers in Europe at the beginning of the year 2003.
We estimated complete prevalence by the completeness index method. We used information on cancer patients diagnosed in 1978–2002 with vital status information available up to 31 December 2003, from 76 European cancer registries.
About 11.6 millions of Europeans with a history of one of the major considered cancers were alive on 1 January 2003. For breast and prostate cancers, about 1 out of 73 women and 1 out of 160 men were living with a previous diagnosis of breast and prostate cancers, respectively. The demographic variations alone will increase the number of prevalent cases to nearly 13 millions in 2010.
Several factors (early detection, population aging and better treatment) contribute to increase cancer prevalence and push for the need of a continuous monitoring of prevalence indicators to properly plan needs, resource allocation to cancer and for improving health care programs for cancer survivors. Cancer prevalence should be included within the EU official health statistics.
The New England Air Quality Study (NEAQS) was a regional portion of the International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) planned by groups in North America ...and Europe to develop a better understanding of the factors that shape air quality in their respective regions and the remote North Atlantic. The NOAA research vessel Ronald H. Brown was only one of a number of platforms given the task of monitoring the emissions of aerosol and ozone precursors and the atmosphere in which they reside. Two remote and one in situ sensor were used to measure wind profiles. A radar wind profiler (RWP) permanently deployed on the ship and corrected in real time for ship motion provided continuous hourly profiles at 60‐ and 100‐m vertical resolutions. A high‐resolution Doppler lidar (HRDL) was also operated during the experiment and provided continuous low‐level wind profiles. Rawinsondes were launched 4–6 times daily and provided a detailed profile of winds. Initial results show that the RWP, HRDL, and rawinsonde data compare very well. The ability of HRDL to monitor low‐level winds below the minimum range gate of the RWP, while the RWP wind data extend to a much greater height than can be reached by HRDL, make the two systems complementary. Single merged profiles were generated using the RWP and HRDL data, which in turn were used to calculate trajectories to help better understand the transport of pollutants within the Gulf of Maine.
Atmospheric observations from active remote sensors and surface observers, obtained in the western Arctic Ocean between November 1997 and May 1998, were analyzed to determine the physical ...characteristics and to assess the surface radiative contribution of diamond dust. The observations showed that diamond dust contributed only a negligible radiative effect to the sea ice surface. Surface radiative fluxes and radiative forcing values during diamond dust events were similar in magnitude when compared to observed clear-sky periods. Combined information from lidar, radar, and surface observers showed that diamond dust occurred ∼13% of the time between November and mid-May over the Arctic Ocean and was not observed between mid-May and October. Diamond dust vertical depths, derived from lidar measurements, varied between 100 and 1000 m but were most often observed to be about 250 m.
Lidar and radar measurements were analyzed to assess if precipitation from boundary layer clouds was present during times when surface observers reported diamond dust. This analysis revealed that surface observers had incorrectly coded diamond dust events ∼45% of the time. The miscoded events occurred almost exclusively under conditions with limited or no illumination (December–March). In 95% of the miscoded reports, lidar measurements revealed the presence of thin liquid water clouds precipitating ice crystals down to the surface.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Cloud and boundary layer variables from the European Centre for Medium‐Range Weather Forecasts (ECMWF) forecast model were compared with measurements made from surface instruments and from upward ...looking 8 mm wavelength radar and lidar at the Surface Heat Budget of the Arctic Ocean (SHEBA) ice camp during November and December of 1997. The precipitation accumulation, near‐surface winds, and surface downward longwave irradiance predicted by the model were in good agreement with SHEBA observations during this period. However, surface downward longwave irradiance was underestimated by 10 W m−2 on average when low clouds were present in the model and observations. The model demonstrated considerable skill in predicting the occurrence and vertical extent of cloudiness over SHEBA, with some tendency to overestimate the frequency of clouds below 1 km. A synthetic radar reflectivity estimated from the ECMWF model variables was compared with 8 mm wavelength radar measurements. The two were broadly consistent only if the assumed snowflake size distribution over SHEBA had a smaller proportion of large flakes than was found in previous studies at lower latitudes. The ECMWF model assumes a temperature‐dependent partitioning of cloud condensate between water and ice. Lidar depolarization measurements at SHEBA indicate that both liquid and ice phase clouds occurred over a wide range of temperatures throughout the winter season, with liquid occurring at temperatures as low as 239 K. A much larger fraction of liquid water clouds was observed than the ECMWF model predicted. The largest discrepancies between the ECMWF model and the observations were in surface temperature (up to 15 K) and turbulent sensible heat fluxes (up to 60 W m−2). These appear to be due at least partially to the ECMWF sea ice model, which did not allow surface temperatures to respond nearly as rapidly to changing atmospheric conditions as was observed.
Surface Heat Budget of the Arctic Ocean Uttal, Taneil; Curry, Judith A.; McPhee, Miles G. ...
Bulletin of the American Meteorological Society,
02/2002, Letnik:
83, Številka:
2
Journal Article
Recenzirano
Odprti dostop
A summary is presented of the Surface Heat Budget of the Arctic Ocean (SHEBA) project, with a focus on the field experiment that was conducted from October 1997 to October 1998. The primary objective ...of the field work was to collectocean, ice, and atmospheric datasets over a full annual cycle that could be used to understand the processes controlling surface heat exchanges—in particular, the ice-albedo feedback and cloud-radiation feedback. This information is being used to improve formulations of arctic ice-ocean-atmosphere processes in climate models and thereby improve simulations of present and future arctic climate. The experiment was deployed from an ice breaker that was frozen into the ice packand allowed to drift for the duration of the experiment. This research platform allowed the use of an extensive suite of instruments that directly measured ocean, atmosphere, and ice properties from both the ship and the ice pack in the immediate vicinity of the ship. This summary describes the project goals, experimental design, instrumentation, and the resulting datasets. Examples of various data products available from the SHEBA project are presented.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The variability of precipitation and water supply along the U.S. West Coast creates major challenges to the region’s economy and environment, as evidenced by the recent California drought. This ...variability is strongly influenced by atmospheric rivers (ARs), which deliver much of the precipitation along the U.S. West Coast and can cause flooding, and by aerosols (from local sources and transported from remote continents and oceans) that modulate clouds and precipitation. A better understanding of these processes is needed to reduce uncertainties in weather predictions and climate projections of droughts and floods, both now and under changing climate conditions.
To address these gaps, a group of meteorologists, hydrologists, climate scientists, atmospheric chemists, and oceanographers have created an interdisciplinary research effort, with support from multiple agencies. From 2009 to 2011 a series of field campaigns California Water Service (CalWater) 1 collected atmospheric chemistry, cloud microphysics, and meteorological measurements in California and associated modeling and diagnostic studies were carried out. Based on the remaining gaps, a vision was developed to extend these studies offshore over the eastern North Pacific and to enhance land-based measurements from 2014 to 2018 (CalWater-2). The dataset and selected results from CalWater-1 are summarized here. The goals of CalWater-2, and measurements to date, are then described.
CalWater is producing new findings and exploring new technologies to evaluate and improve global climate models and their regional performance and to develop tools supporting water and hydropower management. These advances also have potential to enhance hazard mitigation by improving near-term weather prediction and subseasonal and seasonal outlooks.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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