Solar Reflectance Measurements Research Articles

Adsorption of natural dye phycocyanin by means of Laponite®: Synthesis and characterization of the hybrid obtained

This work addresses the use of Laponite® clay in various applications, focusing on its adsorption capacity and improvement of properties in water-based products. It describes the synthesis of Laponite® hybrids with the pigmented cyanobacterium phycocyanin (PC) to evaluate the adsorption capacity of the dye. This research addresses the importance of Laponite® clay in improving rheological properties of water-based products due to its ability to interact with components in aqueous solutions. Laponite® can be effectively dispersed in water, enhancing the dispersion of other elements in solution and preventing aggregation of solids. The structure and properties of synthetic Laponite® are described, highlighting its use in the textile industry as an additive for pigments and the formation of gels. Experimentally, Laponite® is used to adsorb phycocyanin, a cyanobacterial pigment, with the aim of achieving maximum adsorption. A design of experiments with different experimental conditions, including pH, addition of silane and surfactant, is used. A detailed analysis of the characterization of the resulting hybrids is presented, including colour, total solar reflectance (TSR), thermal analysis (TGA), EDS, FTIR and X-ray diffraction (XRD) measurements. The results show successful adsorption of the pigment in all experiments, with adsorption percentages above 97%. The colour of the hybrids is evaluated and the total solar reflectance is analyzed, highlighting their importance in applications such as coatings and printed textiles. Infrared spectroscopy and X-ray diffraction are used to study the structural properties of the hybrids. For future work, it is intended to be able to apply the hybrids obtained on an industrial scale in the colouring of textiles and plastic polymers.

A cost-effective intense blue colour inorganic pigment for multifunctional cool roof and anticorrosive coatings

An enormous attention has been paid to cobalt aluminate (CoAl2O4) blue pigments owing to their significant hue of blue colour. Nevertheless, several serious disadvantages, such as high cost due to the high cobalt consumption and poor solar reflectance, are associated with this pigment. Therefore, the development of cost effective and sustainable blue pigments with reduced Co content and improved solar reflectivity is a major focused area in pigment research. Herein, a new series of multifunctional blue coloured inorganic pigments with low cobalt content were prepared via the solid-state method. The structural and spectroscopic evaluations were indicated that the strong blue colour could be generated because of the distorted tetrahedrally organized cobalt chromophore. This structural distortion of the chromophore geometry was linked to the covalency and electron affinity factors. Colour (b* = −59.21) and solar reflectance (R* = 64%) measurements of the optimized composition (NaZn0.9Co0.1PO4) was observed to be superior than the commercially available CoAl2O4 blue pigment. Meanwhile, the optimized pigment loaded epoxy coated steel substrate in marine medium exhibited impressive corrosion resistance properties. The anticorrosive mechanism, further established through the XPS results, validated that the phosphatized inhibitive film served as the barrier for corrosion. The estimated Co content in NaZn0.9Co0.1PO4 was found to be around 10 times lower than the CoAl2O4 blue pigment indicating the cost-effective nature. The optimized pigment was able to retain its optical properties in the prepared acrylic coatings on Al sheet and concrete block. Further, the temperature shielding studies ensured a reduction of ~4 °C in comparison with CoAl2O4 coatings. Therefore, the developed multifunctional blue pigment could be employed for the economic production of blue exterior paint for anticorrosive cool roof coatings.

Albedo feedbacks to future climate via climate change impacts on dryland biocrusts

Drylands represent the planet’s largest terrestrial biome and evidence suggests these landscapes have large potential for creating feedbacks to future climate. Recent studies also indicate that dryland ecosystems are responding markedly to climate change. Biological soil crusts (biocrusts) ‒ soil surface communities of lichens, mosses, and/or cyanobacteria ‒ comprise up to 70% of dryland cover and help govern fundamental ecosystem functions, including soil stabilization and carbon uptake. Drylands are expected to experience significant changes in temperature and precipitation regimes, and such alterations may impact biocrust communities by promoting rapid mortality of foundational species. In turn, biocrust community shifts affect land surface cover and roughness—changes that can dramatically alter albedo. We tested this hypothesis in a full-factorial warming (+4 °C above ambient) and altered precipitation (increased frequency of 1.2 mm monsoon-type watering events) experiment on the Colorado Plateau, USA. We quantified changes in shortwave albedo via multi-angle, solar-reflectance measurements. Warming and watering treatments each led to large increases in albedo (>30%). This increase was driven by biophysical factors related to treatment effects on cyanobacteria cover and soil surface roughness following treatment-induced moss and lichen mortality. A rise in dryland surface albedo may represent a previously unidentified feedback to future climate.

The global surface temperatures of the Moon as measured by the Diviner Lunar Radiometer Experiment

The Diviner Lunar Radiometer Experiment onboard the Lunar Reconnaissance Orbiter (LRO) has been acquiring solar reflectance and mid-infrared radiance measurements nearly continuously since July of 2009. Diviner is providing the most comprehensive view of how regoliths on airless bodies store and exchange thermal energy with the space environment. Approximately a quarter trillion calibrated radiance measurements of the Moon, acquired over 5.5 years by Diviner, have been compiled into a 0.5° resolution global dataset with a 0.25h local time resolution. Maps generated with this dataset provide a global perspective of the surface energy balance of the Moon and reveal the complex and extreme nature of the lunar surface thermal environment. Our achievable map resolution, both spatially and temporally, will continue to improve with further data acquisition.Daytime maximum temperatures are sensitive to the albedo of the surface and are ∼387–397K at the equator, dropping to ∼95K just before sunrise, though anomalously warm areas characterized by high rock abundances can be > 50K warmer than the zonal average nighttime temperatures. An asymmetry is observed between the morning and afternoon temperatures due to the thermal inertia of the lunar regolith with the dusk terminator ∼30K warmer than the dawn terminator at the equator. An increase in albedo with incidence angle is required to explain the observed decrease in temperatures with latitude. At incidence angles exceeding ∼40°, topography and surface roughness influence temperatures resulting in increasing scatter in temperatures and anisothermality between Diviner channels.Nighttime temperatures are sensitive to the thermophysical properties of the regolith. High thermal inertia (TI) materials such as large rocks, remain warmer during the long lunar night and result in anomalously warm nighttime temperatures and anisothermality in the Diviner channels. Anomalous maximum and minimum temperatures are highlighted by subtracting the zonal mean temperatures from maps. Terrains can be characterized as low or high reflectance and low or high TI. Low maximum temperatures result from high reflectance surfaces while low minimum temperatures from low-TI material. Conversely, high maximum temperatures result from dark surface, and high minimum temperatures from high-TI materials.Impact craters are found to modify regolith properties over large distances. The thermal signature of Tycho is asymmetric, consistent with an oblique impact coming from the west. Some prominent crater rays are visible in the thermal data and require material with a higher thermal inertial than nominal regolith. The influence of the formation of the Orientale basin on the regolith properties is observable over a substantial portion of the western hemisphere despite its age (∼3.8Gyr), and may have contributed to mixing of highland and mare material on the southwest margin of Oceanus Procellarum where the gradient in radiative properties at the mare-highland contact is broad (∼200km).

Optic-Energy Performance of Innovative and Traditional Materials for Roof Covering in Commercial Buildings in Central Italy

Innovative and traditional solutions for roof coating and urban paving are under development in order to study their effect both as passive cooling strategies for buildings and as effective tools for urban heat island mitigation. This paper deals with the optic-energy in-lab and numerical analysis of three materials used for roof covering and urban paving in Italy. Bitumen covering, cool painting and natural gravel covering are taken into account. Solar reflectance measurements shows that gravel optimize this property by more than 20% with respect to the bitumen covering of classic streets paving. The three materials are also evaluated in terms of roof covering in commercial buildings with flat roofs. Dynamic simulation results demonstrated that innovative cool membranes are able to optimize building year-round energy efficiency by 19.3%. Nevertheless, natural gravel covering produce important energy saving (15.6%) with respect to bitumen roof membrane configuration.

On characterization and measurement of average solar field mirror reflectance in utility-scale concentrating solar power plants

Due to the emerging need for the development of acceptance test codes for commercial concentrating solar power (CSP) plants, an effort is made here to develop a mirror reflectance model suitable for CSP applications as well as a general procedure to measure the average mirror reflectance of a solar field. Typically, a utility-scale solar field includes hundreds of thousands of mirror panels (if not more), and their reflectance is subject to many factors, such as weather and planned washing schedule. The newly developed mirror reflectance model can be used to characterize different types of mirror materials and can be directly used to perform optical performance evaluation of solar collectors. The newly proposed procedure for average solar field reflectance measurements includes a baseline comprehensive measurement and an individual factor measurement: the former allows a comprehensive survey of mirror reflectance across the whole solar field, and the latter can provide correcting factors for selected individual factors to further improve the accuracy of the baseline measurements. A detailed test case implementing the general procedure is applied to a state-of-the-art commercial parabolic trough plant and validates the proposed mirror reflectance model and average reflectance measurement procedure. In the test case, the plant-wide reflectance measurements at a commercial utility-scale solar plant were conducted and can shed light on relevant analysis of CSP applications. The work can also be naturally applied to other types of solar plants, such as power towers and linear Fresnel plants.

Systematic and random errors between collocated satellite ice water path observations

AbstractThere remains large disagreement between ice‐water path (IWP) in observational data sets, largely because the sensors observe different parts of the ice particle size distribution. A detailed comparison of retrieved IWP from satellite observations in the Tropics (±30° latitude) in 2007 was made using collocated measurements. The radio detection and ranging(radar)/light detection and ranging (lidar) (DARDAR) IWP data set, based on combined radar/lidar measurements, is used as a reference because it provides arguably the best estimate of the total column IWP. For each data set, usable IWP dynamic ranges are inferred from this comparison. IWP retrievals based on solar reflectance measurements, in the moderate resolution imaging spectroradiometer (MODIS), advanced very high resolution radiometer–based Climate Monitoring Satellite Applications Facility (CMSAF), and Pathfinder Atmospheres‐Extended (PATMOS‐x) datasets, were found to be correlated with DARDAR over a large IWP range (~20–7000 g m‐2). The random errors of the collocated data sets have a close to lognormal distribution, and the combined random error of MODIS and DARDAR is less than a factor of 2, which also sets the upper limit for MODIS alone. In the same way, the upper limit for the random error of all considered data sets is determined. Data sets based on passive microwave measurements, microwave surface and precipitation products system (MSPPS), microwave integrated retrieval system (MiRS), and collocated microwave only (CMO), are largely correlated with DARDAR for IWP values larger than approximately 700 g m‐2. The combined uncertainty between these data sets and DARDAR in this range is slightly less MODIS‐DARDAR, but the systematic bias is nearly an order of magnitude.

Using passive remote sensing to retrieve the vertical variation of cloud droplet size in marine stratocumulus: An assessment of information content and the potential for improved retrievals from hyperspectral measurements

We present a theoretical study into the information content of solar reflectance measurements at multiple near‐infrared wavelengths in the context of deriving the vertical variation of cloud droplet size from marine stratocumulus. We employ a Bayesian optimal estimation approach to retrieve a profile of droplet effective radius as a function of optical depth in the cloud. This allows an assessment of the information content of the measurement of reflectance at different wavelengths and the potential for a new generation of hyperspectral sensors to improve the retrieval. Our results show that using the three absorbing near‐infrared channels of the Moderate Resolution Imaging Spectroradiometer (MODIS) centered at 1.6, 2.1 and 3.7 μm a retrieval of droplet sizes lower in the cloud is highly sensitive to small changes in reflectance. Consequently instrument and modeling errors must be reduced to <1% in order to gain a useful uncertainty constraint on droplet size near to cloud base. By introducing many high spectral resolution wavelength channels, such as those available from hyperspectral sensors, we find that the information content pertaining to all retrieval variables increases significantly. This results in a reduction in the uncertainty estimates on all retrieved quantities. We also test the ability of a vertical profile retrieval to provide improved liquid water path estimates by using several in situ profiling measurements of marine stratocumulus in the South‐East Pacific region. We find that a vertical profile retrieval significantly improves the liquid water path estimate when compared to a two‐band lookup table retrieval.

Lunar equatorial surface temperatures and regolith properties from the Diviner Lunar Radiometer Experiment

The Diviner Lunar Radiometer Experiment onboard the Lunar Reconnaissance Orbiter has measured solar reflectance and mid‐infrared radiance globally, over four diurnal cycles, at unprecedented spatial and temporal resolution. These data are used to infer the radiative and bulk thermophysical properties of the near‐surface regolith layer at all longitudes around the equator. Normal albedos are estimated from solar reflectance measurements. Normal spectral emissivities relative to the 8‐μm Christiansen Feature are computed from brightness temperatures and used along with albedos as inputs to a numerical thermal model. Model fits to daytime temperatures require that the albedo increase with solar incidence angle. Measured nighttime cooling is remarkably similar across longitude and major geologic units, consistent with the scarcity of rock exposures and with the widespread presence of a near‐surface layer whose physical structure and thermal response are determined by pulverization through micrometeoroid impacts. Nighttime temperatures are best fit using a graded regolith model, with a ∼40% increase in bulk density and an eightfold increase in thermal conductivity (adjusted for temperature) occurring within several centimeters of the surface.

A case for natural colour imagery from geostationary satellites, and an approximation for the GOES-R ABI

‘Natural’ (or ‘true’) colour imagery, so-called for its qualitative likeness to colour photography, is one of the most visually intuitive and readily communicable forms of satellite information. It is constructed by combining solar reflectance measurements from three narrow spectral bands defining the red, green and blue wavelengths of visible light. Natural colour facilitates the interpretation of multiple components in the complex earth/atmosphere scene and, therefore, it is widely used by experts and non-experts alike to visualize many forms of geophysical phenomena. Although sensors on board low-Earth-orbiting (LEO) satellites have long-demonstrated the superior quality of natural colour imagery over various other ‘false colour’ renditions, similar capabilities currently do not exist on sensors operating in geostationary orbits that offer distinct advantages over LEO in terms of high temporal refresh. The Advanced Baseline Imager (ABI) of the next-generation Geostationary Operational Environmental Satellite (GOES)-R series will include the blue and red bands, but is missing the 0.55 μm green band necessary for producing natural colour. The emphases of this article are twofold. First, we consider the merits of natural colour imagery from the standpoints of both science and operational users, and the philosophical roadblocks of a system definition process that seems inherently ill-equipped to consider qualitative user requirements. Second, we present a mitigation strategy for GOES-R ABI that entails synthesizing the missing ABI green band information via its correlation with spectrally adjacent available bands, with a first-order account for surface type dependencies. The technique is developed, demonstrated and evaluated here using Moderate-resolution Imaging Spectroradiometer (MODIS) data.

Light emitting diode as sensor for miniature multispectral radiometer

A methodology is proposed for studying the suitability of the light emitting diode (LED) as the optical sensor of a miniature multispectral radiometer. The optoelectronic properties of three commercially available LEDs of three different wavebands were standardized by measuring the open-circuit voltage and short-circuit currents at different light intensities and different wavelengths of incident radiation. A photoconductive measurement was found to be more useful for obtaining the appropriate optical response and was suggested as the suitable mode of sensing. The sensor performances were demonstrated for both solar photometry and surface reflectance measurements.

MODIS observations of enhanced clear sky reflectance near clouds

Several recent studies have found that the brightness of clear sky systematically increases near clouds. Understanding this increase is important both for a correct interpretation of observations and for improving our knowledge of aerosol‐cloud interactions. However, while the studies suggested several processes to explain the increase, the significance of each process is yet to be determined. This study examines one of the suggested processes—three‐dimensional (3‐D) radiative interactions between clouds and their surroundings—by analyzing a large dataset of MODIS (Moderate Resolution Imaging Spectroradiometer) observations over the Northeast Atlantic Ocean. The results indicate that 3‐D effects are responsible for a large portion of the observed increase, which extends to about 15 km away from clouds and is stronger (i) at shorter wavelengths (ii) near optically thicker clouds and (iii) near illuminated cloud sides. This implies that it is important to account for 3‐D radiative effects in the interpretation of solar reflectance measurements over clear regions in the vicinity of clouds.

Scanning Imaging Absorption Spectrometer for Atmospheric Chartography carbon monoxide total columns: Statistical evaluation and comparison with chemistry transport model results

This paper presents a detailed statistical analysis of one year (September 2003 to August 2004) of global Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) carbon monoxide (CO) total column retrievals from the Iterative Maximum Likelihood Method (IMLM) algorithm, version 6.3. SCIAMACHY provides the first solar reflectance measurements of CO and is uniquely sensitive down to the boundary layer. SCIAMACHY measurements and chemistry transport model (CTM) results are compared and jointly evaluated. Significant improvements in agreement occur, especially close to biomass burning emission regions, when the new Global Fire Emissions Database version 2 (GFEDv2) is used with the CTM. Globally, the seasonal variation of the model is very similar to that of the SCIAMACHY measurements. For certain locations, significant differences were found, which are likely related to modeling errors due to CO emission uncertainties. Statistical analysis shows that differences between single SCIAMACHY CO total column measurements and corresponding model results are primarily explained by random instrument noise errors. This strongly suggests that the random instrument noise errors are a good diagnostic for the precision of the measurements. The analysis also indicates that noise in single SCIAMACHY CO measurements is generally greater than actual variations in total columns. It is thus required to average SCIAMACHY data over larger temporal and spatial scales to obtain valuable information. Analyses of monthly averaged SCIAMACHY measurements over 3° × 2° geographical regions indicates that they are of sufficient accuracy to reveal valuable information about spatial and temporal variations in CO columns and provide an important tool for model validation. A large spatial and temporal variation in instrument noise errors exists which shows a close correspondence with the spatial distribution of surface albedo and cloud cover. This large spatial variability is important for the use of monthly and annual mean SCIAMACHY CO total column measurements. The smallest instrument noise errors of monthly mean 3° × 2° SCIAMACHY CO total columns measurements are 0.01 × 1018 molecules/cm2 for high surface albedo areas over the Sahara. Errors in SCIAMACHY CO total column retrievals due to errors other than instrument noise, like cloud cover, calibration, retrieval uncertainties and averaging kernels are estimated to be about 0.05–0.1 × 1018 molecules/cm2 in total. The bias found between model and observations is around 0.05–0.1 1018 molecules/cm2 (or about 5%) which also includes model errors. This thus provides a best estimate of the currently achievable measurement accuracy for SCIAMACHY CO monthly mean averages.

Inversion of satellite ocean colour imagery and geoacoustic characterization of seabed properties: Variational data inversion using a semi-automatic adjoint approach

In this paper a semi-automatic adjoint approach for variational data inversion is proposed. To demonstrate the effectiveness of the approach two illustrative examples are presented: the geoacoustic characterization of a Mediterranean shallow water environment using realistic experimental conditions and the estimation of oceanic and atmospheric constituents from satellite ocean colour imagery. In the first case geoacoustic parameters of the seabed (density, sound speed and attenuation) are determined from long/medium range underwater acoustic propagation data in the water column. In the second case the aerosol optical thickness in the atmosphere and the phytoplankton concentration in the ocean (chlorophyll- a) are estimated from solar reflectance measurements obtained with ocean colour sensors on board satellites. The general methodology for both applications is based on a modular graph concept that allows a straightforward adjoint computation by means of gradient backpropagation. Generation and coding of the adjoint models in both cases are accomplished with an algorithmic tool.

A solar reflectance method for retrieving the optical thickness and droplet size of liquid water clouds over snow and ice surfaces

Cloud optical thickness and droplet effective radius retrievals from solar reflectance measurements are traditionally implemented using a combination of spectral channels that are absorbing and nonabsorbing for water particles. Reflectances in nonabsorbing channels (e.g., 0.67, 0.86, 1.2 μm spectral window bands) are largely dependent on cloud optical thickness, while longer‐wavelength absorbing channels (1.6, 2.1, and 3.7 μm window bands) provide cloud particle size information. Cloud retrievals over ice and snow surfaces present serious difficulties. At the shorter wavelengths, ice is bright and highly variable, both characteristics acting to significantly increase cloud retrieval uncertainty. In contrast, reflectances at the longer wavelengths are relatively small and may be comparable to that of dark open water. A modification to the traditional cloud retrieval technique is presented. The new algorithm uses only a combination of absorbing spectral channels for which the snow/ice albedo is relatively small. Using this approach, retrievals have been made with the MODIS airborne simulator (MAS) imager flown aboard the high‐altitude NASA ER‐2 from May to June 1998 during the Arctic FIRE‐ACE field deployment. Data from several coordinated ER‐2 and in situ University of Washington Convair‐580 aircraft observations of liquid water stratus clouds are examined. MAS retrievals of optical thickness, droplet effective radius, and liquid water path are shown to be in good agreement with in situ measurements. The initial success of the technique has implications for future operational satellite cloud retrieval algorithms in polar and wintertime regions.

Vertical photon transport in cloud remote sensing problems

Photon transport in plane‐parallel, vertically inhomogeneous clouds is investigated and applied to cloud remote sensing techniques that use solar reflectance or transmittance measurements for retrieving droplet effective radius. Transport is couched in terms of weighting functions which approximate the relative contribution of individual layers to the overall retrieval. Two vertical weightings are investigated, including one based on the average number of scatterings encountered by reflected and transmitted photons in any given layer. A simpler vertical weighting, based on the maximum penetration of reflected photons, proves useful for solar reflectance measurements. These weighting functions are highly dependent on droplet absorption and solar/viewing geometry. A superposition technique, using adding/doubling radiative transfer procedures, is used to accurately determine both weightings, avoiding time‐consuming Monte Carlo methods. Effective radius retrievals from modeled vertically structured liquid water clouds are then made using the standard near‐infrared bands and compared with size estimates based on the proposed weighting functions. Agreement between the two methods is generally within several tenths of a micrometer, much better than expected retrieval accuracy. Though the emphasis is on photon transport in clouds, the derived weightings can be applied to any multiple‐scattering plane‐parallel radiative transfer problem, including arbitrary combinations of cloud, aerosol, and gas layers.

A superposition technique for deriving mean photon scattering statistics in plane-parallel cloudy atmospheres

Photon transport in a multiple scattering medium is critically dependent on scattering statistics, in particular the average number of scatterings. A superposition technique is derived to accurately determine the average number of scatterings encountered by reflected and transmitted photons within arbitrary layers in plane-parallel, vertically inhomogeneous clouds. As expected, the resulting scattering number profiles are highly dependent on cloud particle absorption and solar/viewing geometry. The technique uses efficient adding and doubling radiative transfer procedures, avoiding traditional time-intensive Monte Carlo methods. Derived superposition formulae are applied to a variety of geometries and cloud models, and selected results are compared with Monte Carlo calculations. Cloud remote sensing techniques that use solar reflectance or transmittance measurements generally assume a homogeneous plane-parallel cloud structure. The scales over which this assumption is relevant, in both the vertical and horizontal, can be obtained from the superposition calculations. Though the emphasis is on photon transport in clouds, the derived technique is applicable to any multiple scattering plane-parallel radiative transfer problem, including arbitrary combinations of cloud, aerosol, and gas layers in the atmosphere.

Remote sensing of optical and microphysical properties of cirrus clouds using Moderate‐Resolution Imaging Spectroradiometer channels: Methodology and sensitivity to physical assumptions

A methodology for the retrieval of cirrus cloud microphysical and optical properties based on observations of reflected sunlight is introduced. The retrieval method is based on correlation of the bidirectional reflectance of three channels, 0.65, 1.6, and 2.2 μm, that are available onboard Earth Observing System (EOS) Moderate‐Resolution Imaging Spectroradiometer (MODIS). Validation studies using microphysical measurements and MODIS airborne simulator (MAS) observations illustrate the nature of the potential errors associated with the retrieved optical depth and mean effective ice crystal size. The effects of the physical assumptions involving ice crystal size distribution and shape employed in the algorithm are subsequently assessed. In terms of the microphysical models used for radiation calculations the ice crystal shape assumption is found to have the most significant impact on the retrieved parameters. The effect of the background surface reflectance on the retrieval results is further examined, and we show that in order to reliably infer nonblack cirrus parameters from solar reflectance measurements it is essential to properly account for the background radiation over both land and ocean surfaces. Finally, we present the measured ice microphysical data for tropical cirrus as a function of cloud development and ambient temperature to illustrate the importance of vertical inhomogeneity for validation studies.

Intercomparison of cloud liquid water path derived from the GOES 9 imager and ground based microwave radiometers for continental stratocumulus

Solar reflectance measurements (0.6 and 3.9 μm) from 15‐min Geostationary Operational Environmental Satellite (GOES) 9 imager data were used to estimate cloud liquid water path (LWP) for an extensive stratocumulus system over Oklahoma on May 2, 1996. The objective was to determine the consistency between these satellite estimates and retrievals from high temporal resolution (20 s) surface microwave radiometer (SMWR) measurements. The SMWRs were located at the Atmospheric Radiation Measurement (ARM) program cloud and radiation test bed (CART) sites at Morris and Purcell in Oklahoma. Results show that while the comparisons are in favorable agreement at both sites in the morning and early afternoon (root‐mean‐square difference of 17 g m−2 and correlation of 0.94), large cloud LWP maxima in the midafternoon as measured by the SMWR at the Morris site are not captured by the satellite retrievals. On the basis of indirect evidence (in situ microphysical measurements were unavailable), it is hypothesized that the discrepancies may be the result of the formation of light drizzle in the middle to lower portions of the cloud, unseen at visible and near‐infrared wavelengths from space but easily sensed by microwave radiometry. These results demonstrate that extra care must be taken in future efforts to validate satellite derived cloud properties on a routine basis using SMWR data. Additional information about the cloud microphysical properties may also be required to help properly interpret the comparisons, particularly in the later stages of development of stratocumulus.

Predicting maximum field service temperatures from solar reflectance measurements of vinyl

AbstractVinyl products continue penetrating Western U. S. markets. Vinyl products may show unacceptable heat distribution when installed in Western environments even after demonstrating a long tradition of acceptable heat build performance in Eastern U. S. environments. This paper presents a methodology for predicting maximum field service temperatures from solar reflectance measurements. Solar reflectance data (ASTM E‐903 and E‐892), field measurement data and a predictive model for a variety of vinyl systems are shown. This methodology may be used in addition to ASTM D‐4803 and is not limited to vinyl materials.