CiteULike: Tag albedo

Recovering Facial Shape Using a Statistical Model of Surface Normal Direction

WAP Smith — 2007-08-06T12:06:37-00:00

Pattern Analysis and Machine Intelligence, IEEE Transactions on, Vol. 28, No. 12. (2006), pp. 1914-1930.

In this paper, we show how a statistical model of facial shape can be embedded within a shape-from-shading algorithm. We describe how facial shape can be captured using a statistical model of variations in surface normal direction. To construct this model, we make use of the azimuthal equidistant projection to map the distribution of surface normals from the polar representation on a unit sphere to Cartesian points on a local tangent plane. The distribution of surface normal directions is captured using the covariance matrix for the projected point positions. The eigenvectors of the covariance matrix define the modes of shape-variation in the fields of transformed surface normals. We show how this model can be trained using surface normal data acquired from range images and how to fit the model to intensity images of faces using constraints on the surface normal direction provided by Lambert's law. We demonstrate that the combination of a global statistical constraint and local irradiance constraint yields an efficient and accurate approach to facial shape recovery and is capable of recovering fine local surface details. We assess the accuracy of the technique on a variety of images with ground truth and real-world images

Landsat Thematic Mapper: Detection of Shifts in Community Composition of Coral Reefs

Phillip Dustan — 2006-10-30T17:27:51-00:00

Conservation Biology, Vol. 15, No. 4. (2001), pp. 892-902.

We assembled a time series of 20 Landsat thematic mapper images from 1982 to 1996 for Key Largo, Florida, to ascertain whether satellite imagery can detect temporal changes in coral reef communities. Selected reef and control areas were examined for changes in brightness, spectral reflectance, band ratios, spatial texture, and temporal texture ( pixel-to-pixel change over time). We compared the data to known changes in the reef ecosystem of Carysfort Reef and terrestrial sample sites. Changes in image brightness and spectral-band ratios were suggestive of shifts from coral- to algal-dominated community structure, but the trends were not statistically significant. The spatial heterogeneity of the reef community decreased in the early 1980s at scales consistent with known ecological changes to the coral community on Carysfort Reef. An analysis of pixel-scale variation through time, termed temporal texture, revealed that the shallow reef areas are the most variable in regions of the reef that have experienced significant ecological decline. Thus, the process of reef degradation, which alters both the spatial patterning and variability of pixel brightness, can be identified in unclassified thematic mapper images. Mapeador Tematico Landsat: Deteccion de Desplazamientos en la Composicion de Comunidades en Arrecifes de Coral Resumen: Ensamblamos una serie de tiempo de 200 imagenes del mapeador tematico Landsat de 1982 a 1996 para Cayo Largo, Florida para determinar si las imagenes de satelite pueden detectar cambios temporales en las comunidades de arrecifes de coral. Los arrecifes de coral y las areas control fueron examinados para cambios en resplandor, reflectancia espacial, proporciones de las bandas, textura espacial y textura temporal (cambios pixel a pixel a traves del tiempo). Comparamos los datos de cambios conocidos en el ecosistema de arrecife de Carysfort y en muestras de sitios terrestres. Cambios en el resplandor de la imagen y en las proporciones de las bandas espectrales sugirieron desplazamientos en la estructura comunitaria dominante de coral a algas; sin embargo, las tendencias no fueron estadisticamente significativas. La heterogeneidad espacial de la comunidad de arrecifes disminuyo en los inicios de los anos 1980s en escalas consistentes con cambios ecologicos conocidos en la comunidad de coral del arrecife Carysfort. El analisis de la variacion a nivel de pixel a traves del tiempo, e identificado como textura temporal, revelo que las areas de arrecifes bajos son las mas variables en regiones donde el arrecife ha experimentado disminuciones ecologicas significativas. Por lo tanto, el proceso de degradacion, que altera tanto los patrones espaciales como la variabilidad del resplandor de pixeles, puede ser identificado en el Mapeador Tematico sin clasificar.

Vertical structure of recent Arctic warming

Rune Graversen — 2008-01-04T06:05:35-00:00

Nature, Vol. 451, No. 7174., pp. 53-56.

Global warming and climate forcing by recent albedo changes on Mars

Lori Fenton — 2007-04-05T10:04:24-00:00

Nature, Vol. 446, No. 7136., pp. 646-649.

Satellite-based estimate of the direct and indirect aerosol climate forcing

Johannes Quaas — 2008-03-15T17:49:48-00:00

Journal of Geophysical Research, Vol. 113 (11 March 2008), D05204.

Separating the effects of albedo from eco-physiological changes on surface temperature along a successional chronosequence in the southeastern United States

Jehn-Yih Juang — 2007-12-13T15:00:50-00:00

Geophysical Research Letters, Vol. 34 (15 November 2007), L21408.

Southern Hemisphere and Deep-Sea Warming Led Deglacial Atmospheric CO2 Rise and Tropical Warming

Lowell Stott — 2007-09-28T14:46:52-00:00

Science (27 September 2007), 1143791.

Establishing what caused Earth's largest climatic changes in the past requires a precise knowledge of both the forcing and the regional responses. Here we establish the chronology of high and low latitude climate change at the last glacial termination by 14C dating benthic and planktonic foraminiferal stable isotope and Mg/Ca records from a marine core collected in the western tropical Pacific. Deep sea temperatures warmed by ~2oC between 19 and 17 ka B.P. (thousand years before present), leading the rise in atmospheric CO2 and tropical surface ocean warming by ~1000 years. The cause of this deglacial deep water warming does not lie within the tropics, nor can its early onset between 19-17 ka B.P. be attributed to CO2 forcing. Increasing austral spring insolation combined with sea-ice albedo feedbacks appear to be key factors responsible for this warming. 10.1126/science.1143791

Present-day springtime high-latitude surface albedo as a predictor of simulated climate sensitivity

Samuel Levis — 2007-09-07T14:03:53-00:00

Geophysical Research Letters, Vol. 34 (5 September 2007), L17703.

Seasonal and interannual variations of top-of-atmosphere irradiance and cloud cover over polar regions derived from the CERES data set

Seiji Kato — 2007-08-08T18:17:45-00:00

Geophysical Research Letters, Vol. 33 (2006), L19804.

Dynamical greenhouse-plus feedback and polar warming amplification. Part II: meridional and vertical asymmetries of the global warming

Cai — 2007-08-26T07:34:21-00:00

Climate Dynamics, Vol. 29, No. 4. (September 2007), pp. 375-391.

Arctic Air Pollution: Origins and Impacts

Kathy Law — 2007-03-20T19:16:34-00:00

Science, Vol. 315, No. 5818. (16 March 2007), pp. 1537-1540.

Notable warming trends have been observed in the Arctic. Although increased human-induced emissions of long-lived greenhouse gases are certainly the main driving factor, air pollutants, such as aerosols and ozone, are also important. Air pollutants are transported to the Arctic, primarily from Eurasia, leading to high concentrations in winter and spring (Arctic haze). Local ship emissions and summertime boreal forest fires may also be important pollution sources. Aerosols and ozone could be perturbing the radiative budget of the Arctic through processes specific to the region: Absorption of solar radiation by aerosols is enhanced by highly reflective snow and ice surfaces; deposition of light-absorbing aerosols on snow or ice can decrease surface albedo; and tropospheric ozone forcing may also be contributing to warming in this region. Future increases in pollutant emissions locally or in mid-latitudes could further accelerate global warming in the Arctic. 10.1126/science.1137695

Comparison of International Panel on Climate Change Fourth Assessment Report climate model simulations of surface albedo with satellite products over northern latitudes

Shusen Wang — 2008-01-08T17:14:15-00:00

Journal of Geophysical Research, Vol. 111 (8 November 2006), D21108.

A multi-data comparison of shortwave climate forcing changes

E Pallé — 2008-01-08T17:10:18-00:00

Geophysical Research Letters, Vol. 32 (2 November 2005), L21702.

Factors Affecting Climate Sensitivity in Global Coupled Models

Gerald Meehl — 2008-07-21T01:42:24-00:00

Journal of Climate, Vol. 17, No. 7. (1 April 2004), pp. 1584-1596.

Four global coupled climate models with different combinations of atmosphere, ocean, land surface, and sea ice components are compared in idealized forcing (1% CO2 increase) experiments. The four models are the Climate System Model (CSM), the Parallel Climate Model (PCM), the PCM/CSM Transition Model (PCTM), and the Community Climate System Model (CCSM). The hypothesis is posed that models with similar atmospheric model components should show a similar globally averaged dynamically coupled response to increasing CO2 in spite of different ocean, sea ice, and land formulations. Conversely, models with different atmospheric components should be most different in terms of the coupled globally averaged response. The two models with the same atmosphere and sea ice but different ocean components (PCM and PCTM) have the most similar response to increasing CO2, followed closely by CSM with comparable atmosphere and different ocean and sea ice from either PCM or PCTM. The fourth model, CCSM, has a different response from the other three and, in particular, is different from PCTM in spite of having the same ocean and sea ice but different atmospheric model component. These results support the hypothesis that, to a greater degree than the other components, the atmospheric model “manages” the relevant global feedbacks including sea ice albedo, water vapor, and clouds. The atmospheric model also affects the meridional overturning circulation in the ocean, as well as the ocean heat uptake characteristics. This is due to changes in surface fluxes of heat and freshwater that affect surface density in the ocean. For global sensitivity measures, the ocean, sea ice, and land surface play secondary roles, even though differences in these components can be important for regional climate changes.

Variability in global top-of-atmosphere shortwave radiation between 2000 and 2005

Norman Loeb — 2008-01-08T17:06:53-00:00

Geophysical Research Letters, Vol. 34 (8 February 2007), L03704.

Climate effects of global land cover change

S Gibbard — 2007-09-07T15:14:05-00:00

Geophysical Research Letters, Vol. 32 (8 December 2005), L23705.

Weak response of oceanic dimethylsulfide to upper mixing shoaling induced by global warming

SM Vallina — 2007-09-28T20:38:23-00:00

Proceedings of the National Academy of Sciences (27 September 2007), 0700843104.

Edited by Inez Y. Fung, University of California, Berkeley, CA, and approved June 26, 2007 (received for review February 1, 2007)The solar radiation dose in the oceanic upper mixed layer (SRD) has recently been identified as the main climatic force driving global dimethylsulfide (DMS) dynamics and seasonality. Because DMS is suggested to exert a cooling effect on the earth radiative budget through its involvement in the formation and optical properties of tropospheric clouds over the ocean, a positive relationship between DMS and the SRD supports the occurrence of a negative feedback between the oceanic biosphere and climate, as postulated 20 years ago. Such a natural feedback might partly counteract anthropogenic global warming through a shoaling of the mixed layer depth (MLD) and a consequent increase of the SRD and DMS concentrations and emission. By applying two globally derived DMS diagnostic models to global fields of MLD and chlorophyll simulated with an Ocean General Circulation Model coupled to a biogeochemistry model for a 50% increase of atmospheric CO2 and an unperturbed control run, we have estimated the response of the DMS-producing pelagic ocean to global warming. Our results show a net global increase in surface DMS concentrations, especially in summer. This increase, however, is so weak (globally 1.2%) that it can hardly be relevant as compared with the radiative forcing of the increase of greenhouse gases. This contrasts with the seasonal variability of DMS (10002000% summer-to-winter ratio). We suggest that the "planktonDMScloudsearth albedo feedback" hypothesis is less strong a long-term thermostatic system than a seasonal mechanism that contributes to regulate the solar radiation doses reaching the earth's biosphere. 10.1073/pnas.0700843104

Atmospheric science: Black carbon and brown clouds

John Seinfeld — 2008-04-25T01:13:33-00:00

Nature Geosci, Vol. 1, No. 1. (January 2008), pp. 15-16.

22 views of the global albedocomparison between 20 GCMs and two satellites

Frida Bender — 2006-04-08T19:51:24-00:00

Tellus A, Vol. 58, No. 3. (May 2006), pp. 320-330.

Forests and Climate Change: Forcings, Feedbacks, and the Climate Benefits of Forests

Gordon Bonan — 2008-06-13T13:17:39-00:00

Science, Vol. 320, No. 5882. (13 June 2008), pp. 1444-1449.

The world's forests influence climate through physical, chemical, and biological processes that affect planetary energetics, the hydrologic cycle, and atmospheric composition. These complex and nonlinear forest-atmosphere interactions can dampen or amplify anthropogenic climate change. Tropical, temperate, and boreal reforestation and afforestation attenuate global warming through carbon sequestration. Biogeophysical feedbacks can enhance or diminish this negative climate forcing. Tropical forests mitigate warming through evaporative cooling, but the low albedo of boreal forests is a positive climate forcing. The evaporative effect of temperate forests is unclear. The net climate forcing from these and other processes is not known. Forests are under tremendous pressure from global change. Interdisciplinary science that integrates knowledge of the many interacting climate services of forests with the impacts of global change is necessary to identify and understand as yet unexplored feedbacks in the Earth system and the potential of forests to mitigate climate change. 10.1126/science.1155121

On the climate forcing consequences of the albedo continuum between cloudy and clear air

Robert Charlson — 2007-08-15T02:25:28-00:00

Tellus B, Vol. 59, No. 4. (September 2007), pp. 715-727.

Fine-scale processes regulate the response of extreme events to global climate change

Noah Diffenbaugh — 2008-08-18T16:21:24-00:00

Proceedings of the National Academy of Sciences of the United States of America, Vol. 102, No. 44. (1 November 2005), pp. 15774-15778.

10.1073/pnas.0506042102 We find that extreme temperature and precipitation events are likely to respond substantially to anthropogenically enhanced greenhouse forcing and that fine-scale climate system modifiers are likely to play a critical role in the net response. At present, such events impact a wide variety of natural and human systems, and future changes in their frequency and/or magnitude could have dramatic ecological, economic, and sociological consequences. Our results indicate that fine-scale snow albedo effects influence the response of both hot and cold events and that peak increases in extreme hot events are amplified by surface moisture feedbacks. Likewise, we find that extreme precipitation is enhanced on the lee side of rain shadows and over coastal areas dominated by convective precipitation. We project substantial, spatially heterogeneous increases in both hot and wet events over the contiguous United States by the end of the next century, suggesting that consideration of fine-scale processes is critical for accurate assessment of local- and regional-scale vulnerability to climate change.

Evaluation of surface albedo and snow cover in AR4 coupled climate models

A Roesch — 2007-08-13T13:56:54-00:00

Journal of Geophysical Research, Vol. 111 (15 August 2006), D15111.

Passing through a giant molecular cloud: “Snowball” glaciations produced by interstellar dust

Alexander Pavlov — 2005-02-14T19:31:50-00:00

Geophysical Research Letters, Vol. 32 (4 February 2005), L03705.

In its motion through the Milky Way galaxy, the solar system encounters an average -density (≥330 H atoms cm−3) giant molecular cloud (GMC) approximately every 108 years, a dense (∼2 × 103 H atoms cm−3) GMC every ∼109 years and will inevitably encounter them in the future [ <cite-ref bib="talb77"> Talbot and Newman, 1977 </cite-ref>]. However, there have been no studies linking such events with severe (snowball) glaciations in Earth history. Here we show that dramatic climate change can be caused by interstellar dust accumulating in Earth's atmosphere during the solar system's immersion into a dense (∼2 × 103 H atoms cm−3) GMC. The stratospheric dust layer from such interstellar particles could provide enough radiative forcing to trigger the runaway ice-albedo feedback that results in global snowball glaciations. We also demonstrate that more frequent collisions with less dense GMCs could cause moderate ice ages.

Single scattering albedo of aerosols over the central India: Implications for the regional aerosol radiative forcing

Dilip Ganguly — 2005-09-20T22:51:54-00:00

Geophysical Research Letters, Vol. 32 (17 September 2005), L18803.

Extensive measurements of various aerosol parameters including single scattering albedo (SSA) were made at various locations over the central Indian region during February 2004 to study their impact on the regional aerosol radiative forcing. An overall increase in the measured value of SSA is noticed (0.75 to 0.9) over the period of this campaign, indicating unequal changes in source strength or removal processes of absorbing and scattering types of aerosols. Diurnally averaged value of direct SW radiative forcing for the region is in the range of −15 to −40 W/m2 at the surface, about 15% lower compared to that over the Bay of Bengal region and 22% higher than over the Arabian Sea. TOA forcing is in the range of +0.7 to −11 W/m2, about 50% lower compared to both these regions. This results in a heating rate of nearly 0.8 K/day for the first 2km in the atmosphere.

Land-cover change and vegetation dynamics across Africa

Marc Linderman — 2005-06-30T18:43:14-00:00

Journal of Geophysical Research, Vol. 110 (17 June 2005), D12104.

Using improved metrics and recently available MODerate resolution Imaging Spectrometer (MODIS) data, we examined the magnitude, extent, and nature of changes in photosynthetic activity and its timing across Sub-Saharan Africa. Changes in overall vegetation activity and shifts in its timing have considerable implications for a variety of processes including surface-atmosphere energy exchanges, terrestrial sources and sinks of carbon, the contribution of local evapotranspiration to the water cycle, disturbance regimes such as fires and pests, and the food security of societies using these ecosystems. While previous studies have examined broad-scale trends in phenology or provided more detailed estimates of land-cover conversion in the tropics, less is known of the year-to-year dynamics of vegetation. Here we quantified the overall changes in vegetation activity for each year between 2000 and 2004 and examined the proportion linked to differences in phenology and overall photosynthetic activity. In addition, we examined the nature of these changes in terms of frequency and duration, the proportion per ecosystem, identified areas of intensive change, and discuss the potential consequences of these changes. We found that most interannual change was not from shifts in timing or phenology, but rather largely due to differences in the amount of annual photosynthetic activity. In fact, there was as much as a 5% annual difference in vegetation activity across the continent. The changes were likely climate driven with particular vegetation types most susceptible to interannual change with high spatial and temporal variability found across the continent.

Climate response of fossil fuel and biofuel soot, accounting for soot's feedback to snow and sea ice albedo and emissivity

Mark Jacobson — 2005-01-12T19:17:17-00:00

Journal of Geophysical Research, Vol. 109 (6 November 2004), D21201.

The first three-dimensional global model in which time-dependent spectral albedos and emissivities over snow and sea ice are predicted with a radiative transfer solution, rather than prescribed, is applied to study the climate response of fossil fuel plus biofuel black carbon plus organic matter (ff+bf BC+OM) when BC absorption in snow and sea ice is accounted for. The model treats the cycling of size-resolved BC+OM between emission and removal by dry deposition and precipitation from first principles. Particles produce and enter size-resolved clouds and precipitation by nucleation scavenging and aerosol-hydrometeor coagulation. Removal brings BC to the surface, where internally and externally mixed BC in snow and sea ice affects albedo and emissivity through radiative transfer. Climate response simulations were run with a ff+bf BC+OC emission inventory lower than that used in a previous study. The 10-year, globally averaged ff+bf BC+OM near-surface temperature response due to all feedbacks was about +0.27 K (+0.32 in the last 3 years), close to those from the previous study (5-year average of +0.3 K and fifth-year warming of +0.35 K) and its modeled range (+0.15 to +0.5 K) because warming due to soot absorption in snow and sea ice here (10-year average of +0.06 K with a modeled range of +0.03 to +0.11 K) offset reduced warming due to lower emission. BC was calculated to reduce snow and sea ice albedo by ∼0.4% in the global average and 1% in the Northern Hemisphere. The globally averaged modeled BC concentration in snow and sea ice was ∼5 ng/g; that in rainfall was ∼22 ng/g. About 98% of BC removal from the atmosphere was due to precipitation; the rest was due to dry deposition. The results here support previous findings that controlling ff+bf BC+OM and CO2 emission may slow global warming.

Climate dynamics of a hard snowball Earth

RT Pierrehumbert — 2005-01-15T00:21:20-00:00

Journal of Geophysical Research, Vol. 110 (15 January 2005), D01111.

The problem of deglaciating a globally ice-covered (“hard snowball”) Earth is examined using a series of general circulation model simulations. The aim is to determine the amount of CO 2 that must be accumulated in the atmosphere in order to trigger deglaciation. Prior treatments of this problem have been limited to energy balance models, which are incapable of treating certain crucial physical processes that turn out to strongly affect the conditions under which deglaciation can occur. CO 2 concentrations up to .2 bars are considered in the general circulation model simulations, and even at such high CO 2 content the model radiation code is found to perform well in comparison with codes explicitly designed for high CO 2. In contrast to prevailing expectations, the hard snowball Earth is found to be nearly 30 K short of deglaciation, even at .2 bars. The very cold climates arise from a combination of the extreme seasonal and diurnal cycle, lapse rate effects, snow cover, and weak cloud effects. Several aspects of the atmospheric dynamics are examined in detail. The simulations indicate that the standard scenario, wherein snowball termination occurs after a few tenths of a bar of CO 2 has built up following cessation of weathering, is problematic. However, the climate was found to be sensitive to details of a number of parameterized physical processes, notably clouds and heat transfer through the stable boundary layer. It is not out of the question that other parameterization suites might permit deglaciation. The results should not be construed as meaning that the hard snowball state could not have occurred, but only that deglaciation requires the operation of as-yet undiscovered processes that would enhance the climate sensitivity. A brief survey of some of the possibilities is provided.

Modelling of strong heterogeneities in aerosol single scattering albedos over a polluted region

M Mallet — 2005-05-12T18:37:58-00:00

Geophysical Research Letters, Vol. 32 (11 May 2005), L09807.

To date, most models dedicated to the investigation of aerosol direct or semi-direct radiative forcings have assumed the various aerosol components to be either completely externally mixed or homogeneously internally mixed. Some recent works have shown that a core-shell treatment of particles should be more realistic, leading to significant differences in the radiative impact as compared to only externally or well-internally mixed states. To account for these studies, an optical module, ORISAM-RAD, has been developed for computing aerosol radiative properties under the hypothesis of internally mixed particles with a n-layer spherical concentric structure. Mesoscale simulations using ORISAM-RAD, coupled with the 3D mesoscale model Meso-NH-C, have been performed for one selected day (06/24/2001) during the ESCOMPTE experiment in the Marseilles-Fos/Berre region, which illustrate the ability of this new module to reproduce spatial heterogeneities of measured single scattering albedo (ω o ), due to industrial and/or urban pollution plumes.

Distant origins of Arctic black carbon: A Goddard Institute for Space Studies ModelE experiment

Dorothy Koch — 2005-02-25T19:49:44-00:00

Journal of Geophysical Research, Vol. 110 (25 February 2005), D04204.

Black carbon (BC) particles, derived from incomplete combustion of fossil fuels and biomass, may have a severe impact on the sensitive Arctic climate, possibly altering the temperature profile, cloud temperature and amount, the seasonal cycle, and the tropopause level and accelerating polar ice melting. We use the Goddard Institute for Space Studies general circulation model to investigate the origins of Arctic BC by isolating various source regions and types. The model suggests that the predominant sources of Arctic soot today are from south Asia (industrial and biofuel emissions) and from biomass burning. These are the primary global sources of BC (approximately 20% and 55%, respectively, of the global emissions), and BC aerosols in these regions are readily lofted to high altitudes where they may be transported poleward. According to the model the Arctic BC optical thickness is mostly from south Asia (30%) and from biomass (28%) (with slightly more than half of biomass coming from north of 40°N); North America, Russia, and Europe each contribute 10–15%. Russia, Europe, and south Asia each contribute about 20–25% of BC to the low-altitude springtime “Arctic haze.” In the Arctic upper troposphere/lower stratosphere during the springtime, south Asia (30–50%) and low-latitude biomass (20–30%) are dominant, with a significant aircraft contribution (10–20%). Industrial S emissions are estimated to be weighted relatively more toward Russia and less toward south Asia (compared with BC). As a result, Russia contributes the most to Arctic sulfate optical thickness (24%); however, the south Asian contribution is also substantial (17%). Uncertainties derive from source estimates, model vertical mixing, and aerosol removal processes. Nevertheless, our results suggest that distant sources contribute more to Arctic pollution than is generally assumed.

Approaches to Modelling the Surface Albedo of a High Arctic Glacier

A Arendt — 2006-08-28T18:00:17-00:00

Geografiska Annaler, Vol. 81A, pp. 477-487.

Broadband surface albedo measurements, made during the summer melt season at three weather stations on John Evans Glacier (79°40 N, 74°00 W), varied strongly with the solar zenith angle (z). Tests were carried out to assess the impact of diurnal variations in surface albedo on seasonal net shortwave radiation (K* ) totals. Removing the diurnal signal from albedo measurements by daily averaging of hourly measurements, or by applying midday measurements to all hours of the day, changed K* by up to 16%. Ignoring measurements made at z & 75°, to account for measurement (cosine) error at high z , decreased K* by between 5 and 18%. Given the sensitivity of K* to diurnal patterns in surface albedo, experiments were carried out with two albedo models. One model accounted for albedo variations with z and one did not. The model driven by z , when implemented within a surface energy balance model for John Evans Glacier, produced better melt estimates. This suggests that diurnal variations in surface albedo should be accounted for in energy balance models of glacier melt.

Retrieval error estimation of surface albedo derived from geostationary large band satellite observations: Application to Meteosat-2 and Meteosat-7 data

YM Govaerts — 2007-03-05T06:57:13-00:00

Journal of Geophysical Research, Vol. 112 (1 March 2007), D05102.

Atmospheric correction of visible to middle-infrared EOS-MODIS data over land surfaces: Background, operational algorithm and validation

EF Vermote — 2008-01-30T18:50:43-00:00

Journal of Geophysical Research, Vol. 102, No. D14. (1997), pp. 17131-17141.

The NASA moderate resolution imaging spectroradiometer (MODIS) instrument will provide a global and improved source of information for the study of land surfaces with a spatial resolution of up to 250 m. Prior to the derivation of various biophysical parameters based on surface reflectances, the top of the atmosphere signals need to be radiometrically calibrated and corrected for atmospheric effects. The present paper describes in detail the state of the art techniques that will be used for atmospheric correction of MODIS bands 1 through 7, centered at 648, 858, 470, 555, 1240, 1640, and 2130 nm, respectively. Previous operational correction schemes have assumed a standard atmosphere with zero or constant aerosol loading and a uniform, Lambertian surface. The MODIS operational atmospheric correction algorithm, reported here, uses aerosol and water vapor information derived from the MODIS data, corrects for adjacency effects and takes into account the directional properties of the observed surface. This paper also describes the operational implementation of these techniques and its optimization. The techniques are applied to remote sensing data from the Landsat Thematic Mapper (TM), the NOAA advanced very high resolution radiometer (AVHRR), and the MODIS airborne simulator (MAS) and validated against ground-based measurements from the Aerosol Robotic Network (AERONET).

Determination of an effective spectral surface albedo from ground-based global and direct UV irradiance measurements

A Kylling — 2007-12-04T18:02:15-00:00

Journal of Geophysical Research, Vol. 105, No. D4. (2000), pp. 4949-4960.

Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes

Johannes Cornelissen — 2007-06-02T15:12:27-00:00

Ecology Letters, Vol. 10, No. 7. (July 2007), pp. 619-627.

Wetland restoration response analysis using MODIS and groundwater data

AM Melesse — 2007-11-28T15:45:03-00:00

Sensors, Vol. 7, No. 9. (2007), pp. 1916-1933.

Vegetation cover and groundwater level changes over the period of restoration are the two most important indicators of the level of success in wetland ecohydrological restoration. As a result of the regular presence of water and dense vegetation, the highest evapotranspiration (latent heat) rates usually occur within wetlands. Vegetation cover and evapotranspiration of large areas of restoration like that of Kissimmee River basin, South Florida will be best estimated using remote sensing technique than point measurements. Kissimmee River basin has been the area of ecological restoration for some years. The current ecohydrological restoration activities were evaluated through fractional vegetation cover (FVC) changes and latent heat flux using Moderate Resolution Imaging Spectroradiometer (MODIS) data. Groundwater level data were also analyzed for selected eight groundwater monitoring wells in the basin. Results have shown that the average fractional vegetation cover and latent heat along 10 km buffer of Kissimmee River between Lake Kissimmee and Lake Okeechobee was higher in 2004 than in 2000. It is evident that over the 5-year period of time, vegetated and areas covered with wetlands have increased significantly especially along the restoration corridor. Analysis of groundwater level data (2000-2004) from eight monitoring wells showed that, the average monthly level of groundwater was increased by 20 cm and 34 cm between 2000 and 2004, and 2000 and 2003, respectively. This change was more evident for wells along the river. © 2007 by MDPI.

Surface Contribution to Planetary Albedo Variability in Cryosphere Regions

Xin Qu — 2006-04-17T21:17:54-00:00

Journal of Climate, Vol. 18, No. 24. (2005), pp. 5239-5252.

Climatological planetary albedo obtained from the International Satellite Cloud Climatology Project (ISCCP) D-series flux dataset is broken down into contributions from the surface and atmosphere in cryosphere regions. The atmosphere accounts for much more of climatological planetary albedo (