Variability in surface BRDF at different spatial scales (30m–500m) over a mixed agricultural landscape as retrieved from airborne and satellite spectral measurements

Román, M. O.; Gatebe, Charles K.; Schaaf, Crystal B.; Poudyal, R.; Wang, Zhuosen; King, Michael D.

doi:10.1016/j.rse.2011.04.012

Cited by 103 publications

(56 citation statements)

References 77 publications

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“…on the anisotropy of the reflectance field, which affects the overall albedo. Thus, when using the tower measurements to characterize the albedo of the larger spatial area, information on the bidirectional reflectance function at "landscape-level" scales (90 m) from aircraft measurements should also be included (Román et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility

et al. 2011

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Abstract. We present a method for identifying dominant surface type and estimating high spectral resolution surface albedo at the Atmospheric Radiation Measurement (ARM) facility at the Southern Great Plains (SGP) site in Oklahoma for use in radiative transfer calculations. Given a set of 6-channel narrowband visible and near-infrared irradiance measurements from upward and downward looking multi-filter radiometers (MFRs), four different surface types (snow-covered, green vegetation, partial vegetation, non-vegetated) can be identified. A normalized difference vegetation index (NDVI) is used to distinguish between vegetated and non-vegetated surfaces, and a scaled NDVI index is used to estimate the percentage of green vegetation in partially vegetated surfaces. Based on libraries of spectral albedo measurements, a piecewise continuous function is developed to estimate the high spectral resolution surface albedo for each surface type given the MFR albedo values as input. For partially vegetated surfaces, the albedo is estimated as a linear combination of the green vegetation and non-vegetated surface albedo values. The estimated albedo values are evaluated through comparison to high spectral resolution albedo measurements taken during several Intensive Observational Periods (IOPs) and through comparison of the integrated spectral albedo values to observed broadband albedo measurements. The estimated spectral albedo values agree well with observations for the visible wavelengths constrained by the MFR measurements, but have larger biases and variability at longer wavelengths. Additional MFR channels at 1100 nm and/or 1600 nm would help constrain the high resolution spectral albedo in the near infrared region.

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Section: Discussionmentioning

confidence: 99%

Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility

et al. 2011

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“…We estimate an uncertainty of 20 % in the MODIS BRDF product for both accuracy and precision, based on comparisons between MODIS BRDF-derived reflectance and aircraft observations at a similar spatial scale to the GeoTASO 250 m × 250 m observations (Román et al, 2011). The resultant uncertainty in the AMF is about 10 % for polluted scenes and 5 % for clean scenes.…”

Section: Air Mass Factor and Model Uncertaintiesmentioning

confidence: 99%

Nitrogen dioxide observations from the Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument: Retrieval algorithm and measurements during DISCOVER-AQ Texas 2013

et al. 2016

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Abstract. The Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument is a test bed for upcoming air quality satellite instruments that will measure backscattered ultraviolet, visible and near-infrared light from geostationary orbit. GeoTASO flew on the NASA Falcon aircraft in its first intensive field measurement campaign during the Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) Earth Venture Mission over Houston, Texas, in September 2013. Measurements of backscattered solar radiation between 420 and 465 nm collected on 4 days during the campaign are used to determine slant column amounts of NO 2 at 250 m × 250 m spatial resolution with a fitting precision of 2.2 × 10 15 molecules cm −2 . These slant columns are converted to tropospheric NO 2 vertical columns using a radiative transfer model and trace gas profiles from the Community Multiscale Air Quality (CMAQ) model. Total column NO 2 from GeoTASO is well correlated with ground-based Pandora observations (r = 0.90 on the most polluted and cloud-free day of measurements and r = 0.74 overall), with GeoTASO NO 2 slightly higher for the most polluted observations. Surface NO 2 mixing ratios inferred from GeoTASO using the CMAQ model show good correlation with NO 2 measured in situ at the surface during the campaign (r = 0.85). NO 2 slant columns from GeoTASO also agree well with preliminary retrievals from the GEO-CAPE Airborne Simulator (GCAS) which flew on the NASA King Air B200 (r = 0.81, slope = 0.91). Enhanced NO 2 is resolvable over areas of traffic NO x emissions and near individual petrochemical facilities.

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“…MODIS BRDF comparisons with aircraft observations of the surface indicate an uncertainty in the MODIS BRDF product of 20 % for both accuracy and precision (Román et al, 2011) at GCAS spatial resolutions. We estimate the impact of those uncertainties from the MODIS surface BRDF on our individual AMFs to be 10 % for polluted observations and 5 % for 25 clean observations.…”

Section: Air Mass Factor Uncertaintiesmentioning

confidence: 99%

Nitrogen dioxide and formaldehyde measurements from the GEOstationary Coastal and Air Pollution Events (GEO-CAPE) Airborne Simulator over Houston, Texas

Nowlan¹,

Liu²,

Janz³

et al. 2018

Preprint

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Abstract. The GEOstationary Coastal and Air Pollution Events (GEO-CAPE) Airborne Simulator (GCAS) was developed in support of NASA's decadal survey GEO-CAPE geostationary satellite mission. GCAS is an airborne pushbroom remote sensing instrument, consisting of two channels which make hyperspectral measurements in the ultraviolet/visible (optimized for air quality observations) and the visible/near-infrared (optimized for ocean color observations). The GCAS instrument participated in its first intensive field campaign during the Deriving Information on Surface Conditions from Column and Ver- Texas. We present GCAS trace gas retrievals of nitrogen dioxide (NO 2 ) and formaldehyde (CH 2 O), and compare these results with trace gas columns derived from coincident in situ profile measurements of NO 2 and CH 2 O made by instruments on a P-3B aircraft, and with NO 2 observations from ground-based Pandora spectrometers operating in direct sun and scattered light 10 modes. GCAS tropospheric column measurements correlate well spatially and temporally with columns estimated from the P-3B measurements for both NO 2 (r

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Variability in surface BRDF at different spatial scales (30m–500m) over a mixed agricultural landscape as retrieved from airborne and satellite spectral measurements

Cited by 103 publications

References 77 publications

Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility

Development of a high spectral resolution surface albedo product for the ARM Southern Great Plains central facility

Nitrogen dioxide observations from the Geostationary Trace gas and Aerosol Sensor Optimization (GeoTASO) airborne instrument: Retrieval algorithm and measurements during DISCOVER-AQ Texas 2013

Nitrogen dioxide and formaldehyde measurements from the GEOstationary Coastal and Air Pollution Events (GEO-CAPE) Airborne Simulator over Houston, Texas

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