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Simulating propagation of sound and audio rendering can improve the sense of realism and the immersion both in complex acoustic environments and dynamic virtual scenes. In studies of sound auralization, the focus has always been on room acoustics modeling, but most of the same methods are also applicable in the construction of virtual environments such as those developed to facilitate computer gaming, cognitive research, and simulated training scenarios. This paper is a review of state-of-the-art techniques that are based on acoustic principles that apply not only to real rooms but also in 3D virtual environments. The paper also highlights the need to expand the field of immersive sound in a web based browsing environment, because, despite the interest and many benefits, few developments seem to have taken place within this context. Moreover, the paper includes a list of the most effective algorithms used for modelling spatial sound propagation and reports their advantages and disadvantages. Finally, the paper emphasizes in the evaluation of these proposed works. [ABSTRACT FROM AUTHOR]

Introduction: EGFR (epidermal growth factor receptor), cyclin D1 and Akt/mTOR pathways are active in head and neck cancer. The aim of this study was to explore biomarker expression, their correlations with clinicopathological parameters and their prognostic utility in a cohort of patients with localized squamous laryngeal carcinoma.Patients and Methods: We assessed relative messenger RNA expression of EGFR, Akt1, 2, and 3, mTOR and CCND1, copy number variants of the EGFR and CCND1 genes and immunohistochemical protein expression of EGFR, p-Akt308, p-Akt473, pmTOR, PTEN, p53 and cyclin D1 in paraffin-embedded tissue samples of localized laryngeal carcinomas.Results: In 289 patients with T3-4 (77.8%), node-negative (84.1%) tumors of the larynx, high EGFR and CCND1 mRNA correlated with no or ex-smoking, (p = 0.003 and p = 0.029, respectively), while low Akt3 mRNA correlated with alcohol abuse, N0 stage, total laryngectomy, and absence of neck dissection. At a median follow-up of 74.5 months, high mTOR mRNA expression was marginally associated with shorter disease-free survival (hazard ratio [HR] = 1.54; p = 0.093) and high Akt3 mRNA with shorter overall survival (HR = 1.49; p = 0.0786), in univariate analysis. In multivariate analysis, node-positive status, subglottic-transglottic location, surgery other than total laryngectomy and mTOR/CCND1 mRNA interaction with a hazard ratio of 2.16 (p value for interaction:  0.0010) were independent predictors of relapse, while node-positive status and subglottic-transglottic location were associated with higher risk for death.Conclusion: In localized laryngeal cancer, clinicopathological parameters and an interaction of high mTOR and CCND1 mRNA expression were found to be associated with poor patient outcome. [ABSTRACT FROM AUTHOR]

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The article presents a study which analyzes the excision repair cross-complementation group 1 (ERCC-1) expression in patients with epithelial ovarian cancer (EOC). It examines the correlation of ERCC-1 expression results with the immunohistochemical expression of p53, bcl-2 and bax. It defines EOC as the most common cause of death among women who develop gynecologic cancer.

We model the Penman potential evaporation (PE) over all land areas of the globe for the 25-yr period 1983-2008, relying on radiation transfer models (RTMs) for the shortwave and longwave fluxes. Penman's PE is determined by two factors: available energy for evaporation and ground to atmosphere vapour transfer. Input to the PE model and RTMs comprises satellite cloud and aerosol data, as well as data from reanalyses. PE is closely linked to pan evaporation, whose trends have sparked controversy in the community, since the factors responsible for the observed pan evaporation trends are not determined with consensus. Our particular interest is the temporal evolution of PE, and the provided insight to the observed trends of pan evaporation. We examine the decadal trends of PE and various related physical quantities, such as net solar flux, net longwave flux, water vapour saturation deficit and wind speed. Our findings are the following: Global warming has led to a larger water vapour saturation deficit. The periods 1983-1989, 1990-1999, and 2000-2008 were characterised by decreasing, increasing, and slightly decreasing PE, respectively. In these last 25 yr, global dimming/brightening cycles generally increased the available energy for evaporation. PE trends seem to follow more closely the trends of energy availability than the trends of the atmospheric capability for vapour transfer, at most locations on the globe, with trends in the Northern hemisphere significantly larger than in the Southern. These results support the hypothesis that global potential evaporation trends are attributed primarily to secular changes in the radiation fluxes, and secondarily to vapour transfer considerations. [ABSTRACT FROM AUTHOR]

Trastuzumab (T) is effective in metastatic breast cancer (MBC) with HER2 overexpression and/or amplification, but resistance to T develops in a significant number of HER2-positive patients. Understanding the mechanisms of resistance is critical to the care of these patients. Formalin-fixed paraffin-embedded tumor tissue samples were collected from 256 patients with T-treated MBC. Clinical information was collected retrospectively from the patients' medical records. Central review of HER2 status by fluorescent in situ hybridization (FISH) and/or immunohistochemistry (IHC) revealed that of the 227 eligible patients only 139 (61%) were truly HER2-positive. PTEN, ER, PgR, and Ki67 were evaluated by IHC, while PTEN status was evaluated by FISH as well. PIK3CA mutations were identified with single nucleotide polymorphism (SNP) genotyping. Median time to progression (TTP) was 14.4 months for the HER2-positive and 10.3 for the HER2-negative patients (log-rank, P = 0.22). Survival from the initiation of T (survivalT) was 50.4 months for the HER2-positive and 35.3 for the HER2-negative subgroups ( P = 0.006). Higher risk of progression was associated with HER2-positive status and the presence of PIK3CA mutations ( P = 0.014). PTEN loss, as determined by IHC, was associated with lower survivalT in the whole population ( P = 0.029) and in the HER2-positive population ( P = 0.017). PIK3CA mutations and/or PTEN loss status were evaluated together as a single parameter, to estimate the impact of activation of the PI3K/AKT molecular pathway, and it was significantly associated with both decreased TTP ( P = 0.003 in the total population, P = 0.004 in HER2-positive patients) and survival (survivalT, P = 0.011 in total, P = 0.006 in HER2-positive). In this trastuzumab-treated breast cancer population, PIK3CA activating mutations were associated with shorter TTP and PTEN loss with decreased survival. The activation of the PI3K/AKT pathway from either defect was associated with both TTP and survival, indicating the adverse effect of this pathway's status on trastuzumab efficacy. [ABSTRACT FROM AUTHOR]

We model the Penman potential evaporation (PE) over all land areas of the globe for the 25-year period 1983-2008, relying on radiation transfer models (RTMs) for the shortwave and longwave fluxes. Penman's PE is determined by two factors: available energy for evaporation and ground to atmosphere vapour transfer. Input to the PE model and RTMs comprises satellite cloud and aerosol data, as well as data from reanalyses. PE is closely linked to pan evaporation, whose trends have sparked controversy in the community, since the factors responsible for the observed pan evaporation trends are not determined with consensus. Our particular interest is the temporal evolution of PE, and the provided insight to the observed trends of pan evaporation. We examine the interannual trends of PE and various related physical quantities, such as net solar flux, net longwave flux, water vapour saturation deficit and wind speed. Our findings are the following: Global warming has led to a larger water vapour saturation deficit. Global dimming/brightening cycles in the last 25 years slightly increased the available energy for evaporation. PE trends seem to follow closely the trends of energy availability and not the trends of the atmospheric capability for vapour transfer, almost everywhere on the globe, with trends in the Northern hemisphere significantly larger than in the Southern. These results support the hypothesis that secular changes in the radiation fluxes, and not vapour transfer considerations, are responsible for potential evaporation trends. [ABSTRACT FROM AUTHOR]

We estimate the effect of the Arctic sea ice on the absorbed (net) solar flux using a radiative transfer model. Ice and cloud input data to the model come from satellite observations, processed by the International Satellite Cloud Climatology Project (ISCCP) and span the period July 1983- June 2007. The sea-ice effect on the solar radiation fluctuates seasonally with the solar flux and decreases interannually in synchronisation with the decreasing sea-ice extent. A disappearance of the Arctic ice cap during the sunlit period of the year would radically reduce the local albedo and cause an annually averaged 19.7Wm-2 increase in absorbed solar flux at the Arctic Ocean surface, or equivalently an annually averaged 0.55Wm-2 increase on the planetary scale. In the clear-sky scenario these numbers increase to 34.9 and 0.97Wm-2, respectively. A meltdown only in September, with all other months unaffected, increases the Arctic annually averaged solar absorption by 0.32Wm-2. We examined the net solar flux trends for the Arctic Ocean and found that the areas absorbing the solar flux more rapidly are the North Chukchi and Kara Seas, Baffin and Hudson Bays, and Davis Strait. The sensitivity of the Arctic absorbed solar flux on sea-ice extent and cloud amount was assessed. Although sea ice and cloud affect jointly the solar flux, we found little evidence of strong non-linearities. [ABSTRACT FROM AUTHOR]

We estimate the effect of the Arctic sea ice on the absorbed (net) solar flux using a radiation transfer model. Ice and cloud input data to the model come from satellite observations, processed by the International Satellite Cloud Climatology Project (ISCCP) and span the period July 1983-June 2007. The sea-ice effect on the solar radiation fluctuates seasonally with the solar flux and decreases interannually in synchronisation with the decreasing sea-ice extent. A disappearance of the Arctic ice cap during the sunlit period of the year would radically reduce the local albedo and cause a 19.7 Wm-2 increase in absorbed solar flux at the Arctic Ocean surface, or equivalently a 0.55 Wm-2 increase on the planetary scale. In the clear-sky scenario these numbers increase to 34.9 and 0.97 Wm-2, respectively. A meltdown only in September, with all other months unaffected, increases the Arctic annually averaged solar absorption by 0.32 Wm-2. We examined the net solar flux trends for the Arctic Ocean and found that the areas absorbing the solar flux more rapidly are the North Chukchi and Kara Seas, Buffin and Hudson Bays, and Davis Strait. The sensitivity of the Arctic absorbed solar flux on sea-ice extent and cloud amount was assessed. Although sea ice and cloud affect jointly the solar flux, we found little evidence of strong non-linearities. [ABSTRACT FROM AUTHOR]

We have studied the spatial and temporal variation of the downward shortwave radiation (DSR) at the surface of the Earth during ENSO events for a 21-year period over the tropical and subtropical Pacific Ocean (40° S-40° N, 90° E-75° W). The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite data from the ISCCP-D2 database, reanalysis data from NCEP/NCAR for the key atmospheric and surface input parameters, and aerosol parameters from GADS (acronyms explained in main text). A clear anti-correlation was found between the downward shortwave radiation anomaly (DSR-A) time-series, in the region 7° S-5° N 160° E-160°W located west of the Niño-3.4 region, and the Niño-3.4 index time-series. In this region where the highest in absolute value DSR anomalies are observed, the mean DSR anomaly values range from -45 Wm-2 during El Niño episodes to +40 Wm-2 during La Niña events. Within the Niño-3.4 region no significant DSR anomalies are observed during the cold ENSO phase in contrast to the warm ENSO phase. A high correlation was also found over the western Pacific (10° S-5° N, 120-140° E), where the mean DSR anomaly values range from +20 Wm-2 to -20 Wm-2 during El Niño and La Niña episodes, respectively. There is also convincing evidence that the time series of the mean downward shortwave radiation anomaly in the off-equatorial western Pacific region 7- 15° N 150-170° E, precedes the Ni&x00F1;o-3.4 index time-series by about 7 months and the pattern of this anomaly is indicative of ENSO operating through the mechanism of the western Pacific oscillator. Thus, the downward shortwave radiation anomaly is a complementary index to the SST anomaly for the study of ENSO events and can be used to assess whether or not El Niño or La Niña conditions prevail. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the patterns of renal function recovery during partial nephrectomy (PN) on an experimental solitary kidney rabbit model and establish the upper tolerable time limits of applied ischemia. Forty-eight New Zealand rabbits underwent an open right nephrectomy and after 30 days, the animals were clustered into five groups (A, B, C, D, E). The first four groups received an open left PN, under different types of ischemia. Groups A ( n = 8) and B ( n = 10) were subjected to 90 and 60 min of warm ischemia (WI), respectively, while groups C ( n = 10) and D ( n = 10) received 90 and 120 min of cold ischemia (CI) with ice-slush cooling. Group E ( n = 10) served as sham group. Serum determinations of creatinine (SCr) and BUN were recorded preoperatively and on postoperative days (POD) 1, 3, 6 and 15. The animals were euthanized and the remaining kidneys were harvested and evaluated microscopically. The type and duration of ischemia were statistically significant parameters ( P < 0.001). Groups B, C and D exhibited a similar pattern of recovery from trial initiation to the 15th POD ( P = 0.788 and P = 0.068, respectively). Group A was extremely differentiated, with 100% mortality caused by uremia. The microscopic findings were consistent to the serum biochemistry. In our solitary kidney rabbit model, the upper limits of tolerable WI seem to be set on 60 min. CI can safely preserve the model’s renal function—even up to 120 min. [ABSTRACT FROM AUTHOR]

We used a spectral radiative transfer model to compute the direct radiative effect (DRE) of natural plus anthropogenic aerosols in the solar near-infrared (IR), between 0.85-10µm, namely, their effect on the outgoing near- IR radiation at the top of atmosphere (TOA, ΔFTOA), on the atmospheric absorption of near-IR radiation (ΔFatmab) and on the surface downward and absorbed near-IR radiation (ΔFsurf, and ΔFsurfnet, respectively). The computations were performed on a global scale (over land and ocean) under all-sky conditions, using detailed spectral aerosol optical properties taken from the Global Aerosol Data Set (GADS) supplemented by realistic data for the rest of surface and atmospheric parameters. The computed aerosol DRE, averaged over the 12-year period 1984-1995 for January and July, shows that on a global mean basis aerosols produce a planetary cooling by increasing the scattered near-IR radiation back to space by 0.48Wm-2, they warm the atmosphere by 0.37Wm-2 and cool the surface by decreasing the downward and absorbed near-IR radiation at surface by 1.03 and 0.85Wm-2, respectively. The magnitude of the near-IR aerosol DRE is smaller than that of the combined ultraviolet (UV) and visible DRE, but it is still energetically important, since it contributes to the total shortwave (SW) DRE by 22-31%. The aerosol-produced near-IR surface cooling combined with the atmospheric warming, may affect the thermal dynamics of the Earth-atmosphere system, by increasing the atmospheric stability, decreasing thus cloud formation, and precipitation, especially over desertification threatened regions such as the Mediterranean basin. This, together with the fact that the sign of near-IR aerosol DRE is sometimes opposite to that of UV-visible DRE, demonstrates the importance of performing detailed spectral computations to provide estimates of the climatic role of aerosols for the Earth-atmosphere system. This was demonstrated by sensitivity tests revealing very large differences (up to 300%) between aerosol DREs computed using detailed spectral and spectrally-averaged aerosol optical properties. Our model results indicate thus that the aerosol direct radiative effect on the near-IR radiation is very sensitive to the treatment of the spectral dependence of aerosol optical properties and solar radiation. [ABSTRACT FROM AUTHOR]

A global estimate of the seasonal direct radiative effect (DRE) of natural plus anthropogenic aerosols on solar radiation under all-sky conditions is obtained by combining satellite measurements and reanalysis data with a spectral radiative transfer model and spectral aerosol optical properties taken from the Global Aerosol Data Set (GADS). The estimates are obtained with detailed spectral model computations separating the ultraviolet (UV), visible and near-infrared wavelengths. The global distribution of spectral aerosol optical properties was taken from GADS whereas data for clouds, water vapour, ozone, carbon dioxide, methane and surface albedo were taken from various satellite and reanalysis datasets. Using these aerosol properties and other related variables, we generate climatological (for the 12-year period 1984-1995) monthly mean aerosol DREs. The global annual mean DRE on the outgoing SW radiation at the top of atmosphere (TOA, ΔFTOA) is -1.62Wm-2 (with a range of -15 to 10Wm-2, negative values corresponding to planetary cooling), the effect on the atmospheric absorption of SW radiation (ΔFatmab) is 1.6Wm-2 (values up to 35Wm-2, corresponding to atmospheric warming), and the effect on the surface downward and absorbed SW radiation (ΔFsurf, and ΔFsurfnet, respectively) is -3.93 and -3.22Wm-2 (values up to -45 and -35Wm-2, respectively, corresponding to surface cooling). According to our results, aerosols decrease/increase the planetary albedo by -3 to 13% at the local scale, whereas on planetary scale the result is an increase of 1.5%. Aerosols can warm locally the atmosphere by up to 0.98K day-1, whereas they can cool the Earth's surface by up to -2.9K day-1. Both these effects, which can significantly modify atmospheric dynamics and the hydrological cycle, can produce significant planetary cooling on a regional scale, although planetary warming can arise over highly reflecting surfaces. The aerosol DRE at the Earth's surface compared to TOA can be up to 15 times larger at the local scale. The largest aerosol DRE takes place in the northern hemisphere both at the surface and the atmosphere, arising mainly at ultraviolet and visible wavelengths. [ABSTRACT FROM AUTHOR]

We have studied the spatial and temporal variation of the surface longwave radiation (downwelling and net) over a 21-year period in the tropical and subtropical Pacific Ocean (40 S-40 N, 90 E-75 W). The fluxes were computed using a deterministic model for atmospheric radiation transfer, along with satellite data from the ISCCP-D2 database and reanalysis data from NCEP/NCAR (acronyms explained in main text), for the key atmospheric and surface input parameters. An excellent correlation was found between the downwelling longwave radiation (DLR) anomaly and the Niño-3.4 index time-series, over the Niño-3.4 region located in the central Pacific. A high anti-correlation was also found over the western Pacific (15-0 S, 105-130 E). There is convincing evidence that the time series of the mean downwelling longwave radiation anomaly in the western Pacific precedes that in the Niño-3.4 region by 3-4 months. Thus, the downwelling longwave radiation anomaly is a complementary index to the SST anomaly for the study of ENSO events and can be used to asses whether or not El Niño or La Niña conditions prevail. Over the Niño-3.4 region, the mean DLR anomaly values range from +20Wm-2 during El Niño episodes to -20Wm-2 during La Niña events, while over the western Pacific (15-0 S, 105-130 E) these values range from -15Wm-2 to +10Wm-2, respectively. The long- term average (1984-2004) distribution of the net downwelling longwave radiation at the surface over the tropical and subtropical Pacific for the three month period November-December-January shows a net thermal cooling of the ocean surface. When El Niño conditions prevail, the thermal radiative cooling in the central and south-eastern tropical Pacific becomes weaker by 10 Wm-2 south of the equator in the central Pacific (7-0 S, 160-120 W) for the three-month period of NDJ, because the DLR increase is larger than the increase in surface thermal emission. In contrast, the thermal radiative cooling over Indonesia is enhanced by 10Wm-2 during the early (August-September-October) El Niño phase. [ABSTRACT FROM AUTHOR]

A global estimate of the seasonal direct radiative effect (DRE) of natural plus anthropogenic aerosols on solar radiation under all-sky conditions is obtained by combining satellite measurements and reanalysis data with a spectral radiative transfer model. The estimates are obtained with detailed spectral model computations separating the ultraviolet (UV), visible and near-infrared wavelengths. The global distribution of spectral aerosol optical properties was taken from the Global Aerosol Data Set (GADS) whereas data for clouds, water vapour, ozone, carbon dioxide, methane and surface albedo were taken from various satellite and reanalysis datasets. Using these aerosol properties and other related variables, we generate climatological (for the 12-year period 1984-1995) monthly mean aerosol DREs. The global annual mean DRE on the outgoing SW radiation at the top of atmosphere (TOA, ΔFTOA) is 1.62Wm-2 (with a range of -10 to 15Wm-2, positive values corresponding to planetary cooling), the effect on the atmospheric absorption of SW radiation (ΔFatmab) is 1.6Wm-2 (values up to 35Wm-2, corresponding to atmospheric warming), and the effect on the surface downward and absorbed SW radiation (ΔFsurf, and ΔFsurfnet, respectively) is -3.93 and -3.22Wm-2 (values up to -45 and -35Wm-2, respectively, corresponding to surface cooling.) According to our results, aerosols decrease/increase the planetary albedo by -3 to 13% at the local scale, whereas on planetary scale the result is an increase of 1.5%. Aerosols can warm locally the atmosphere by up to 0.98 K day-1, whereas they can cool the Earth's surface by up to -2.9 K day-1. Both these effects, which can significantly modify atmospheric dynamics and the hydrological cycle, can produce significant planetary cooling on a regional scale, although planetary warming can arise over highly reflecting surfaces. The aerosol DRE at the Earth's surface compared to TOA can be up to 15 times larger at the local scale. The largest aerosol DRE takes place in the northern hemisphere both at the surface and the atmosphere, arising mainly at ultraviolet and visible wavelengths. [ABSTRACT FROM AUTHOR]

In this study, we investigate the aerosol optical properties, namely aerosol extinction optical thickness (AOT), Angström parameter and size distribution over the Eastern Mediterranean Basin, using spectral measurements from the recently established FORTH (Foundation for Research and Technology-Hellas) AERONET station in Crete, for the two-year period 2003-2004. The location of the FORTH-AERONET station offers a unique opportunity to monitor aerosols from different sources. Maximum values of AOT are found primarily in spring, which together with small values of the Angström parameter indicate dust transported from African deserts, whereas the minimum values of AOT occur in winter. In autumn, large AOT values observed at near-infrared wavelengths arise also from dust transport. In summer, large AOT values at ultraviolet (340 nm) and visible wavelengths (500 nm), together with large values of the Angström parameter, are associated with transport of fine aerosols of urban/industrial and biomass burning origin. The Angström parameter values vary on a daily basis within the range 0.05-2.20, and on a monthly basis within the range 0.68-1.9. This behaviour, together with broad frequency distributions and back-trajectory analyses, indicates a great variety of aerosol types over the study region including dust, urban-industrial and biomass-burning pollution, and maritime, as well as mixed aerosol types. Large temporal variability is observed in AOT, Angström parameter, aerosol content and size. The fine and coarse aerosol modes persist throughout the year, with the coarse mode dominant except in summer. The highest values of AOT are related primarily to southeasterly winds, associated with coarse aerosols, and to a less extent to northwesterly winds associated with fine aerosols. The results of this study show that the FORTH AERONET station in Crete is well suited for studying the transport and mixing of different types of aerosols from a variety of sources, especially those associated with major dust events from the Sahara. [ABSTRACT FROM AUTHOR]

In this study, we investigate the aerosol optical properties, namely aerosol extinction optical thickness (AOT), Angström parameter and size distribution over the Eastern Mediterranean Basin, using spectral measurements from the recently established FORTH (Foundation for Research and Technology-Hellas) AERONET station in Crete, for the two-year period 2003-2004. The location of the FORTH-AERONET station offers a unique opportunity to monitor aerosols from different sources. Maximum values of AOT are found primarily in spring, which together with small values of the Angströmeter indicate dust transported from African deserts, whereas the minimum values of AOT occur in winter. In autumn, large AOT values observed at near-infrared wavelengths arise also from dust transport. In summer, large AOT values at ultraviolet (340 nm) and visible wavelengths (500 nm), together with large values of the Angström parameter, are associated with transport of fine aerosols of urban/industrial and biomass burning origin. The Angström parameter values vary on a daily basis within the range 0.05-2.20, and on a monthly basis within the range 0.68-1.9. This behaviour, together with broad frequency distributions and back-trajectory analyses, indicates a great variety of aerosol types over the study region including dust, urban-industrial and biomass-burning pollution, and maritime, as well as mixed aerosol types. Large temporal variability is observed in AOT, Angström parameter, aerosol content and size. The fine and coarse aerosol modes persist throughout the year, with the coarse mode dominant except in summer. The highest values of AOT are related primarily to southeasterly winds, associated with coarse aerosols, and to a less extent to northwesterly winds associated with fine aerosols. The results of this study show that the FORTH AERONET station in Crete is well suited for studying the transport and mixing of different types of aerosols from a variety of sources, especially those associated with major dust events from the Sahara. [ABSTRACT FROM AUTHOR]

A decadal-scale trend in the tropical radiative energy budget has been observed recently by satellites, which however is not reproduced by climate models. In the present study, we have computed the outgoing shortwave radiation (OSR) at the top of atmosphere (TOA) at 2.5° longitude-latitude resolution and on a mean monthly basis for the 17-year period 1984-2000, by using a deterministic solar radiative transfer model and cloud climatological data from the International Satellite Cloud Climatology Project (ISCCP) D2 database. Atmospheric temperature and humidity vertical profiles, as well as other supplementary data, were taken from the National Centers for Environmental Prediction -- National Center for Atmospheric Research (NCEP/NCAR) and the European Center for Medium-Range Weather Forecasts (ECMWF) Global Reanalysis Projects, while other global databases, such as the Global Aerosol Data Set (GADS) for aerosol data, were also used. Anomaly time series for the mean monthly pixel-level OSR fluxes, as well as for the key physical parameters, were constructed. A significant decreasing trend in OSR anomalies, starting mainly from the late 1980s, was found in tropical and subtropical regions (30° S-30° N), indicating an increase in solar planetary heating equal to 3.2±0.5Wm-2 over the 17-year time period from 1984 to 2000 or 1.9±0.3Wm-2/decade, reproducing well the features recorded by satellite observations, in contrast to climate model results. The model computed trend is in good agreement with the corresponding linear decrease of 3.7±0.5Wm-2 (or 2.5±0.4Wm-2/decade) in tropical mean OSR anomalies derived from ERBE S-10N non-scanner data. An attempt was made to identify the physical processes responsible for the decreasing trend in tropical mean OSR. A detailed correlation analysis using pixel-level anomalies of OSR flux and ISCCP cloud cover over the entire tropical and subtropical region (30° S-30° N), gave a correlation coefficient of 0.79, indicating that decreasing cloud cover is the main reason for the tropical OSR trend. According to the ISCCP-D2 data derived from the combined visible/infrared (VIS/IR) analysis, the tropical cloud cover has decreased by 6.6±0.2% per decade, in relative terms. A detailed analysis of the inter-annual and long-term variability of the various parameters determining the OSR at TOA, has shown that the most important contribution to the observed OSR trend comes from a decrease in low-level cloud cover over the period 1984-2000, followed by decreases in middle and high-level cloud cover. Opposite but small trends are introduced by increases in cloud scattering optical depth of low and 5 middle clouds. [ABSTRACT FROM AUTHOR]

The monthly mean shortwave (SW) radiation budget at the Earth's surface (SRB) was computed on 2.5-degree longitude-latitude resolution for the 17-year period from 1984 to 2000, using a radiative transfer model accounting for the key physical parameters that determine the surface SRB, and long-term climatological data from the International Satellite Cloud Climatology Project (ISCCP-D2). The model input data were supplemented by data from the National Centers for Environmental Prediction - National Center for Atmospheric Research (NCEP-NCAR) and European Center for Medium Range Weather Forecasts (ECMWF) Global Reanalysis projects, and other global data bases such as TIROS Operational Vertical Sounder (TOVS) and Global Aerosol Data Set (GADS). The model surface radiative fluxes were validated against surface measurements from 22 stations of the Baseline Surface Radiation Network (BSRN) covering the years 1992-2000, and from 700 stations of the Global Energy Balance Archive (GEBA), covering the period 1984-2000. The model is in good agreement with BSRN and GEBA, with a negative bias of 14 and 6.5 Wm14, respectively. The model is able to reproduce interesting features of the seasonal and geographical variation of the surface SW fluxes at global scale. Based on the 17-year average model results, the global mean SW downward surface radiation (DSR) is equal to 171.6 Wm14, whereas the net downward (or absorbed) surface SW radiation is equal to 149.4 Wm14, values that correspond to 50.2 and 43.7% of the incoming SW radiation at the top of the Earth's atmosphere. These values involve a long-term surface albedo equal to 12.9%. Significant increasing trends in DSR and net DSR fluxes were found, equal to 4.1 and 3.7 Wm14, respectively, over the 1984-2000 period (equivalent to 2.4 and 2.2 Wm14 per decade), indicating an increasing surface solar radiative heating. This surface SW radiative heating is primarily attributed to clouds, especially low-level, and secondarily to other parameters such as total precipitable water. The surface solar heating occurs mainly in the period starting from the early 1990s, in contrast to decreasing trend in DSR through the late 1980s. The computed global mean DSR and net DSR flux anomalies were found to range within ±8 and ±6 Wm14, respectively, with signals from El Niño and La Niña events, and the Pinatubo eruption, whereas significant positive anomalies have occurred in the period 1992-2000. [ABSTRACT FROM AUTHOR]

The monthly mean shortwave (SW) radiation budget at the Earth's surface (SRB) was computed on 2.5-degree longitude-latitude resolution for the 17-year period from 1984 to 2000, using a radiative transfer model accounting for the key physical parameters that determine the surface SRB, and long-term climatological data from the International Satellite Cloud Climatology Project (ISCCP-D2). The model input data were supplemented by data from the National Centers for Environmental Prediction -- National Center for Atmospheric Research (NCEP-NCAR) and European Center for Medium RangeWeather Forecasts (ECMWF) Global Reanalysis projects, and other global data bases such as TIROS Operational Vertical Sounder (TOVS) and Global Aerosol Data Set (GADS). The model surface radiative fluxes were validated against surface measurements from 22 stations of the Baseline Surface Radiation Network (BSRN) covering the years 1992-2000, and from 700 stations of the Global Energy Balance Archive (GEBA), covering the period 1984-2000. The model is in very good agreement with BSRN and GEBA, with a negative bias of 14 and 6.5Wm-2, respectively. The model is able to reproduce interesting features of the seasonal and geographical variation of the surface SW fluxes at global scale, which is not possible with surface measurements. Based on the 17-year average model results, the global mean SW downward surface radiation (DSR) is equal to 171.6Wm-2, whereas the net downward (or absorbed) surface SW radiation is equal to 149.4Wm-2, values that correspond to 50.2 and 43.7% of the incoming SW radiation at the top of the Earth's atmosphere. These values involve a long-term surface albedo equal to 12.9%. Significant increasing trends in DSR and net DSR fluxes were found, equal to 4.1 and 3.7Wm-2, respectively, over the 1984-2000 period (equivalent to 2.4 and 2.2Wm-2 per decade), indicating an increasing surface solar radiative heating. This surface SW radiative heating is primarily attributed to clouds, especially low-level, and secondarily to other parameters such as total precipitable water. The surface solar heating occurs mainly in the period starting from the early 1990s, in contrast to the commonly reported decreasing trend in DSR through the late 1980s, found also in our study. The computed global mean DSR and net DSR flux anomalies were found to range within ±8 and ±6Wm-2, respectively, with signals from El Niño and La Niña events, and the Pinatubo eruption, whereas significant positive anomalies have occurred in the period 1992-2000. [ABSTRACT FROM AUTHOR]

A decadal-scale trend in the tropical radiative energy budget has been observed recently by satellites, which however is not reproduced by climate models. In the present study, we have computed the outgoing shortwave radiation (OSR) at the top of atmosphere (TOA) at 2.5° longitude-latitude resolution and on a mean monthly basis for the 17- year period 1984.2000, by using a deterministic solar radiative transfer model and cloud climatological data from the International Satellite Cloud Climatology Project (ISCCP) D2 database. Anomaly time series for the mean monthly pixel-level OSR fluxes, as well as for the key physical parameters, were constructed. A significant decreasing trend in OSR anomalies, starting mainly from the late 1980s, was found in tropical and subtropical regions (30° S- 30° N), indicating a decadal increase in solar planetary heating equal to 1.9±0.3Wm-2/decade, reproducing well the features recorded by satellite observations, in contrast to climate model results. This increase in solar planetary heating, however, is accompanied by a similar increase in planetary cooling, due to increased outgoing longwave radiation, so that there is no change in net radiation. The model computed OSR trend is in good agreement with the corresponding linear decadal decrease of 2.5±0.4Wm-2/decade in tropical mean OSR anomalies derived from ERBE S-10N nonscanner data (edition 2). An attempt was made to identify the physical processes responsible for the decreasing trend in tropical mean OSR. A detailed correlation analysis using pixel-level anomalies of model computed OSR flux and ISCCP cloud cover over the entire tropical and subtropical region (30° S-30° N), gave a correlation coefficient of 0.79, indicating that decreasing cloud cover is the main reason for the tropical OSR trend. According to the ISCCP-D2 data derived from the combined visible/infrared (VIS/IR) analysis, the tropical cloud cover has decreased by 6.6±0.2% per decade, in relative terms. A detailed analysis of the interannual and long-term variability of the various parameters determining the OSR at TOA, has shown that the most important contribution to the observed OSR trend comes from a decrease in low-level cloud cover over the period 1984-2000, followed by decreases in middle and high-level cloud cover. Note, however, that there still remain some uncertainties associated with the existence and magnitude of trends in ISCCP-D2 cloud amounts. Opposite but small trends are introduced by increases in cloud scattering optical depth of low and middle clouds. [ABSTRACT FROM AUTHOR]

A decadal-scale trend in the tropical radiative energy budget has been observed recently by satellites, which however is not reproduced by climate models. In the present study, we have computed the outgoing shortwave radiation (OSR) at the top of atmosphere (TOA) at 2.5° longitude-latitude resolution and on a mean monthly basis for the 17-year period 1984-2000, by using a deterministic solar radiative transfer model and cloud climatological data from the International Satellite Cloud Climatology Project (ISCCP) D2 database. Atmospheric temperature and humidity vertical profiles, as well as other supplementary data, were taken from the National Centers for Environmental Prediction - National Center for Atmospheric Research (NCEP/NCAR) and the European Center for Medium-Range Weather Forecasts (ECMWF) Global Reanalysis Projects, while other global databases, such as the Global Aerosol Data Set (GADS) for aerosol data, were also used. Anomaly time series for the mean monthly pixel-level OSR fluxes, as well as for the key physical parameters, were constructed. A significant decreasing trend in OSR anomalies, starting mainly from the late 1980s, was found in tropical and subtropical regions (30° S-30° N), indicating an increase in solar planetary heating equal to 3.2±0.5Wm-2 over the 17-year time period from 1984 to 2000 or 1.9±0.3Wm-2/decade, reproducing well the features recorded by satellite observations, in contrast to climate model results. The model computed trend is in good agreement with the corresponding linear decrease of 3.7±0.5Wm-2 (or 2.5±0.4Wm-2/decade) in tropical mean OSR anomalies derived from ERBE S-10N non-scanner data. An attempt was made to identify the physical processes responsible for the decreasing trend in tropical mean OSR. A detailed correlation analysis using pixel-level anomalies of OSR flux and ISCCP cloud cover over the entire tropical and subtropical region (30° S-30° N), gave a correlation coefficient of 0.79, indicating that decreasing cloud cover is the main reason for the tropical OSR trend. According to the ISCCP-D2 data derived from the combined visible/infrared (VIS/IR) analysis, the tropical cloud cover has decreased by 6.6±0.2% per decade, in relative terms. A detailed analysis of the inter-annual and long-term variability of the various parameters determining the OSR at TOA, has shown that the most important contribution to the observed OSR trend comes from a decrease in low-level cloud cover over the period 1984-2000, followed by decreases in middle and high-level cloud cover. Opposite but small trends are introduced by increases in cloud scattering optical depth of low and 5 middle clouds. [ABSTRACT FROM AUTHOR]

The study of the dynamics of ionization fronts has moved far since Franz Kahn helped define the field in the 1950s. Nevertheless, the stability of the fronts and the nature of elephant trunks and bright rims in HII regions remain contentious issues. [ABSTRACT FROM AUTHOR]