Monitoring Earth'S Vital Signs

King, Michael D.; Herring, David

doi:10.1038/scientificamerican0400-92

Cited by 25 publications

(13 citation statements)

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“…Satellite estimates of biomass changes can be an important component of carbon accounting (4,24) for verification of compliance, if the uncertainty of these estimates can be further reduced. Improved observations of greenness levels from a new generation of spacecraft sensors such as the moderate-resolution imaging spectroradiometer and multiangle imaging spectroradiometer (30), and possibly direct biomass measurements with lidars, offer promise for the future. …”

Section: Discussionmentioning

confidence: 99%

A large carbon sink in the woody biomass of Northern forests

Myneni

Dong

Tucker

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

591

413

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The terrestrial carbon sink, as of yet unidentified, represents 15-30% of annual global emissions of carbon from fossil fuels and industrial activities. Some of the missing carbon is sequestered in vegetation biomass and, under the Kyoto Protocol of the United Nations Framework Convention on Climate Change, industrialized nations can use certain forest biomass sinks to meet their greenhouse gas emissions reduction commitments. Therefore, we analyzed 19 years of data from remote-sensing spacecraft and forest inventories to identify the size and location of such sinks. The results, which cover the years 1981-1999, reveal a picture of biomass carbon gains in Eurasian boreal and North American temperate forests and losses in some Canadian boreal forests. For the 1.42 billion hectares of Northern forests, roughly above the 30th parallel, we estimate the biomass sink to be 0.68 ؎ 0.34 billion tons carbon per year, of which nearly 70% is in Eurasia, in proportion to its forest area and in disproportion to its biomass carbon pool. The relatively high spatial resolution of these estimates permits direct validation with ground data and contributes to a monitoring program of forest biomass sinks under the Kyoto protocol.

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Section: Discussionmentioning

confidence: 99%

A large carbon sink in the woody biomass of Northern forests

Myneni

Dong

Tucker

et al. 2001

Proc. Natl. Acad. Sci. U.S.A.

591

413

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“…The Moderate Resolution Imaging Spectroradiometer (MODIS; Platnick et al 2003;King et al 2003King et al , 2004; see also information online at http://modis.gsfc.nasa.gov) is uniquely designed with wide spectral range, high spatial and spectral resolution, and near-daily global coverage. Upwelling radiation in several narrow spectral channels at a resolution of 1 km in a 2300-km swath under the satellite track is measured by MODIS and converted into cloud properties using various algorithms (King et al 1992(King et al , 1997(King et al , 2004Platnick et al 2003;Minnis et al 1995Minnis et al , 1998Minnis et al , 2002. Because of the complex physical processes that relate the retrieved parameters to the upwelling radiances, the error characteristics of the retrievals need to be thoroughly understood before the retrieval results can be used quantitatively to improve our understanding of the role of cirrus in the climate system or to use this knowledge to develop cloud parameterizations for models.…”

Section: Introductionmentioning

confidence: 99%

“…In order to build a longterm global dataset, the National Aeronautics and Space Administration's (NASA) Earth Observing System (EOS) project launched its first spacecraft (Terra) on 18 December 1999 (King and Herring 2000). The Moderate Resolution Imaging Spectroradiometer (MODIS; Platnick et al 2003;King et al 2003King et al , 2004; see also information online at http://modis.gsfc.nasa.gov) is uniquely designed with wide spectral range, high spatial and spectral resolution, and near-daily global coverage.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of Cirrus Cloud Properties Derived from MODIS Data Using Cloud Properties Derived from Ground-Based Observations Collected at the ARM SGP Site

Mace

Zhang

Platnick

et al. 2005

Journal of Applied Meteorology and Climatology

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The Moderate Resolution Imaging Spectroradiometer (MODIS) on board the NASA Terra satellite has been collecting global data since March 2000 and the one on the Aqua satellite since June 2002. In this paper, cirrus cloud properties derived from ground-based remote sensing data are compared with similar cloud properties derived from MODIS data on Terra. To improve the space-time correlation between the satellite and ground-based observations, data from a wind profiler are used to define the cloud advective streamline along which the comparisons are made. In this paper, approximately two dozen cases of cirrus are examined and a statistical approach to the comparison that relaxes the requirement that clouds occur over the ground-based instruments during the overpass instant is explored. The statistical comparison includes 168 cloudy MODIS overpasses of the Southern Great Plains (SGP) region and approximately 300 h of ground-based cirrus observations. The physical and radiative properties of cloud layers are derived from MODIS data separately by the MODIS Atmospheres Team and the Clouds and the Earth's Radiant Energy System (CERES) Science Team using multiwavelength reflected solar and emitted thermal radiation measurements. Using two ground-based cloud property retrieval algorithms and the two MODIS algorithms, a positive correlation in the effective particle size, the optical thickness, the ice water path, and the cloud-top pressure between the various methods is shown, although sometimes there are significant biases. Classifying the clouds by optical thickness, it is demonstrated that the regionally averaged cloud properties derived from MODIS are similar to those diagnosed from the ground. Because of a conservative approach toward identifying thin cirrus pixels over this region, the area-averaged cloud properties derived from the MODIS Atmospheres MOD06 product tend to be biased slightly toward the optically thicker pixels. This bias tendency has implications for model validation and parameterization development applied to thin cirrus retrieved over SGP-like land surfaces. A persistent bias is also found in the derived cloud tops of thin cirrus with both satellite algorithms reporting cloud top several hundred meters less than that reported by the cloud radar. Overall, however, it is concluded that the MODIS retrieval algorithms characterize with reasonable accuracy the properties of thin cirrus over this region.

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“…We will examine the sensitivity of reflected solar radiation over a wide range of viewing angles and azimuthal directions using reflectance measurements obtained with the cloud absorption radiometer (CAR) during the Smoke, Clouds, and Radiation-Brazil (SCAR-B) Experiment conducted in 1995 [20]. Variations of zenith angle across images and between images occur naturally due to a wide swath width in satellite imagery, and these spectral reflectance properties of natural surfaces need to be accurately assessed in retrieving aerosol optical thickness over land using a global dataset such as the moderate resolution imaging spectroradiometer (MODIS) on the Terra platform [21]. MODIS images the Earth's surface across track with a swath width of 2330 km, with the view zenith angle varying between 55 , or about 61 at the surface.…”

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confidence: 99%

Sensitivity of off-nadir zenith angles to correlation between visible and near-infrared reflectance for use in remote sensing of aerosol over land

Gatebe

King

Tsay

et al. 2001

IEEE Trans. Geosci. Remote Sensing

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Abstract-Cloud absorption radiometer (CAR) multispectral and multiangular data, collected during the Smoke, Clouds, and Radiation-Brazil (SCAR-B) Experiment, was used to examine the ratio technique, the official method for remote sensing of aerosols over land from the moderate resolution imaging spectroradiometer (MODIS) data, for view angles from nadir to 65 off-nadir. The strategy we used is to first select a pristine, low aerosol optical thickness flight, and we then computed ratios of reflectance at 0.47 and 0.68 m to corresponding values at 2.20 m, separately for backward and forward scattering directions. Similarly, we analyzed data from high turbidity flights for comparison purposes. For both flights, we removed the effects of atmospheric absorption and scattering using 6S, a radiative transfer code, and then recomputed the ratios again for different values of aerosol optical thickness. Finally, we analyzed bidirectional reflection function (BRF) data to examine the dependence of the ratio technique on the relative azimuth angle. Results of this analysis show that a relationship between visible reflectance and near infrared (IR) reflectance exists for view angles from nadir to 40 off-nadir, and that simple parametric relationships can be derived. In spite of these observed relationships, the relationship 0 47 = 2 20 4, used in remote sensing of aerosol over land, does not seem to hold for the cases tested, both in the forward and backward scattering directions and that 0 68 = 2 20 2 seems to hold for view angles from nadir to 45 off-nadir but only in the backward scattering direction. These ratios show little variation with azimuth view angle and this seems to hold well for backward scattering directions over dark targets.

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Monitoring Earth'S Vital Signs

Cited by 25 publications

References 0 publications

A large carbon sink in the woody biomass of Northern forests

A large carbon sink in the woody biomass of Northern forests

Evaluation of Cirrus Cloud Properties Derived from MODIS Data Using Cloud Properties Derived from Ground-Based Observations Collected at the ARM SGP Site

Sensitivity of off-nadir zenith angles to correlation between visible and near-infrared reflectance for use in remote sensing of aerosol over land

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