Comparison of algorithms for incoming atmospheric long‐wave radiation

Flerchinger, G. N.; Xaio, Wei; Marks, Danny; Sauer, T. J.; Yu, Qiang

doi:10.1029/2008wr007394

Cited by 145 publications

(149 citation statements)

References 41 publications

(63 reference statements)

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“…A variety of empirically derived formulas exist for calculating incoming longwave radiation under clear (L clear ) and cloudy skies at various sites throughout the world (Brutsaert, 1975;Sicart et al, 2004;Flerchinger et al, 2009). All derivations are variations of the general form of the StefanBoltzmann equation that relates clear sky incoming longwave radiation to atmospheric emissivity (ε clear ), the StefanBoltzman constant (σ ), and air temperature T air (K).…”

Section: Longwave Radiationmentioning

confidence: 99%

Forest impacts on snow accumulation and ablation across an elevation gradient in a temperate montane environment

Roth

Nolin

2017

Hydrol. Earth Syst. Sci.

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Abstract. Forest cover modifies snow accumulation and ablation rates via canopy interception and changes in subcanopy energy balance processes. However, the ways in which snowpacks are affected by forest canopy processes vary depending on climatic, topographic and forest characteristics. Here we present results from a 4-year study of snow-forest interactions in the Oregon Cascades. We continuously monitored snow and meteorological variables at paired forested and open sites at three elevations representing the Low, Mid, and High seasonal snow zones in the study region. On a monthly to bi-weekly basis, we surveyed snow depth and snow water equivalent across 900 m transects connecting the forested and open pairs of sites. Our results show that relative to nearby open areas, the dense, relatively warm forests at Low and Mid sites impede snow accumulation via canopy snow interception and increase sub-canopy snowpack energy inputs via longwave radiation. Compared with the Forest sites, snowpacks are deeper and last longer in the Open site at the Low and Mid sites (4-26 and 11-33 days, respectively). However, we see the opposite relationship at the relatively colder High sites, with the Forest site maintaining snow longer into the spring by 15-29 days relative to the nearby Open site. Canopy interception efficiency (C IE ) values at the Low and Mid Forest sites averaged 79 and 76 % of the total event snowfall, whereas C IE was 31 % at the lower density High Forest site. At all elevations, longwave radiation in forested environments appears to be the primary energy component due to the maritime climate and forest presence, accounting for 93, 92, and 47 % of total energy inputs to the snowpack at the Low, Mid, and High Forest sites, respectively. Higher wind speeds in the High Open site significantly increase turbulent energy exchanges and snow sublimation. Lower wind speeds in the High Forest site create preferential snowfall deposition. These results show the importance of understanding the effects of forest cover on subcanopy snowpack evolution and highlight the need for improved forest cover model representation to accurately predict water resources in maritime forests.

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Section: Longwave Radiationmentioning

confidence: 99%

Forest impacts on snow accumulation and ablation across an elevation gradient in a temperate montane environment

Roth

Nolin

2017

Hydrol. Earth Syst. Sci.

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“…Furthermore, by not perturbing the measured atmospheric emissivity used in the warmer scenarios, we may underestimate the longwave contribution to snowmelt. Atmospheric emissivity varies as a function of column-integrated temperature, specific humidity, and cloud structure above a site (Flerchinger et al, 2009). All of these interactions may be best characterized using GCM output dynamically downscaled to fine resolutions with regional climate models (e.g., Liu et al, 2017;Sun et al, 2016) or within a delta-change approach that considers the range of uncertainties in the climate change signal of different emissions scenarios (e.g., Marty et al, 2017).…”

Section: Sources Of Uncertainty and Caveatsmentioning

confidence: 99%

Snowmelt response to simulated warming across a large elevation gradient, southern Sierra Nevada, California

2017

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Abstract. In a warmer climate, the fraction of annual meltwater produced at high melt rates in mountainous areas is projected to decline due to a contraction of the snow-cover season, causing melt to occur earlier and under lower energy conditions. How snowmelt rates, including extreme events relevant to flood risk, may respond to a range of warming over a mountain front is poorly known. We present a model sensitivity study of snowmelt response to warming across a 3600 m elevation gradient in the southern Sierra Nevada, USA. A snow model was run for three distinct years and verified against extensive ground observations. To simulate the impact of climate warming on meltwater production, measured meteorological conditions were modified by +1 to +6 • C. The total annual snow water volume exhibited linear reductions (−10 % • C −1 ) consistent with previous studies. However, the sensitivity of snowmelt rates to successive degrees of warming varied nonlinearly with elevation. Middle elevations and years with more snowfall were prone to the largest reductions in snowmelt rates, with lesser changes simulated at higher elevations. Importantly, simulated warming causes extreme daily snowmelt (99th percentiles) to increase in spatial extent and intensity, and shift from spring to winter. The results offer insight into the sensitivity of mountain snow water resources and how the rate and timing of water availability may change in a warmer climate. The identification of future climate conditions that may increase extreme melt events is needed to address the climate resilience of regional flood control systems.

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“…Sugitia and Brutsaert, 1993;Gabathuler et al, 2001) and for all cloudy sky conditions (Plüss and Ohmura, 1997;Crawford and Duchon, 1999;Pirazzini et al, 2000;Kjaersgaard et al, 20007;Sedlar and Hock, 2009;Staiger and Matzarakis, 2010). But only a few of them were carried out on highland sites (Iziomon et al, 2003;Lhomme et al, 2007;Flerchinger et al, 2009;Yang et al, 2010). Besides, the effect of clouds and stratification on atmospheric emissivity is highly dependent on regional factors, which may lead to the need for local expressions (e.g.…”

Section: Introductionmentioning

confidence: 99%

Parameterization of atmospheric longwave emissivity in a mountainous site for all sky conditions

Herrero

Polo

2012

Hydrol. Earth Syst. Sci.

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Abstract. Longwave radiation is an important component of the energy balance of the Earth's surface. The downward component, emitted by the clouds and aerosols in the atmosphere, is rarely measured, and is still not well understood. In mountainous areas, direct observations are even scarcer and the fitting of existing models is often subjected to local parameterization in order to surplus the particular physics of the atmospheric profiles. The influence of clouds makes it even harder to estimate for all sky conditions. This work presents a long-time continuous dataset of high-resolution longwave radiation measured in a weather station at a height of 2500 m a.s.l. in Sierra Nevada, Spain, together with the parameterization of the apparent atmospheric emissivity for clear and cloudy skies resulting from three different schemes. We evaluate the schemes of Brutsaert, and Crawford and Duchon with locally adjusted coefficients and compare them with a completely parametric expression adjusted for these data that takes into account three possible significant atmospheric states related to the cloud cover: clear, completely covered, and partly covered skies. All the parametric expressions are related to the screen-level values of temperature, relative humidity and solar radiation, which can be frequently found in standard weather stations. Unobserved cloudiness measurements needed for Brutsaert scheme for cloudy sky are also parameterized from screen-level measurements. The calibration performed for a 6-yr period at the study site resulted in satisfactory estimations of emissivity for all the analyzed schemes thanks to the local fitting of the parameterizations, with the best achievement found for the completely parametric expression. Further validation of the expressions in two alternative sites showed that the greater accuracy of the latter can also be found in very close sites, while a better performance of the Brutsaert scheme, with a more physical background and the successful parameterization of the clouds effect, is found in nearby sites outside the initial mountain range. The results show the feasibility for the local calibration of expressions to estimate instantaneous atmospheric emissivity for all sky conditions only using surface data, either with a completely parametric scheme if longwave data are available, or through obtaining of locally fitted coefficients for Brutsaert and derived schemes. Nevertheless, the best performance of the first approach would be at the expense of a reduced local applicability.

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Comparison of algorithms for incoming atmospheric long‐wave radiation

Cited by 145 publications

References 41 publications

Forest impacts on snow accumulation and ablation across an elevation gradient in a temperate montane environment

Forest impacts on snow accumulation and ablation across an elevation gradient in a temperate montane environment

Snowmelt response to simulated warming across a large elevation gradient, southern Sierra Nevada, California

Parameterization of atmospheric longwave emissivity in a mountainous site for all sky conditions

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