Estimating long‐wave radiation at the Earth's surface from measurements of specific humidity

Rosa, Ricardo D.; Stanhill, G.

doi:10.1002/joc.3793

Cited by 8 publications

(5 citation statements)

References 18 publications

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“…Our result fits well the relationships between specific humidity and incoming longwave radiation obtained from the analysis of measurement data from BSRN as well as some other actinometrical stations (Ruckstuhl et al, 2007;Stanhill, 2011;Rosa and Stanhill, 2014). A slightly different result from our Eq.…”

Section: Factors Affecting Downwelling Longwave Radiationsupporting

confidence: 85%

Longwave radiation at the earth’s surface in Estonia

Russak¹,

Niklus²

2015

Proc. Estonian Acad. Sci.

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Solar radiation has been continuously measured in Estonia since 1950, but the recordings of longwave radiation began only about ten years ago. This paper presents the first description of the characteristic features of up-and downwelling longwave radiation in the Baltic Sea region. In the radiation balance the longwave fluxes have an important role. In the annual totals of radiation incident upon the ground surface in Estonia, the longwave atmospheric downwelling radiation L l  exceeds the direct solar radiation E g  about three times, and this ratio has an essential seasonal run. In the total upwelling radiation L l , the infrared part is still greater, up to 92%. Comparing the measured and calculated (according to the Stefan-Boltzmann law) hourly totals of L l  for snow (emissivity ε = 0.85) we found a good linear relationship (R 2 = 0.96). However, the measured totals systematically exceeded the calculated values (on average by 18%). Dependence of the downwelling infrared radiation L l  on the near-surface water vapour pressure e is approximated by a power function (R 2 = 0.73). This is in good accordance with the results of studies carried out at other geographical sites. The influence of clouds on the fitted power function is noteworthy. Separate analysis of the hours with full cloudiness of low clouds and the cloudless hours confirmed the validity of the power function. However, a difference was found in their parameters (for overcast sky the exponent b = 0.20, R 2 = 0.91 and for cloudless sky b = 0.25 and R 2 = 0.93).

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Section: Factors Affecting Downwelling Longwave Radiationsupporting

confidence: 85%

Longwave radiation at the earth’s surface in Estonia

Russak¹,

Niklus²

2015

Proc. Estonian Acad. Sci.

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“…This uncertainty was not reduced by using seasonally changing parameters in the sunshine duration to global radiation relationship [Sanchez-Lorenzo and Wild, 2012]: there was no evidence of a significant time trend in the parameters of the equation during the 76 years of measurement. Monthly values of E lH2O↓ estimated with the power relationship measured at Lindenberg (Figure 2) have a RMSE of 12.8 W m À2 or 4%; the parameters of the power relationship are similar to those of the pooled relationship derived from the data of the 42 globally distributed BSRN stations [Rosa and Stanhill, 2013].The uncertainty in the small correction to the values of E lH2O↓ for the effect of changing concentrations of anthropogenic gases in the atmosphere has been estimated at 10% [Ramaswamy et al, 2001].…”

Section: Accuracy Of Estimates Of Radiation Fluxesmentioning

confidence: 60%

“…Monthly values of E lH2O↓ estimated with the power relationship measured at Lindenberg (Figure ) have a RMSE of 12.8 W m −2 or 4%; the parameters of the power relationship are similar to those of the pooled relationship derived from the data of the 42 globally distributed BSRN stations [ Rosa and Stanhill , ].The uncertainty in the small correction to the values of E lH2O↓ for the effect of changing concentrations of anthropogenic gases in the atmosphere has been estimated at 10% [ Ramaswamy et al , ].…”

Section: Discussionmentioning

confidence: 99%

Radiative forcing and temperature change at Potsdam between 1893 and 2012

Stanhill

Ahiman

2014

JGR Atmospheres

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Radiative forcing in both the short and long-wave lengths reaching the Earth's surface accounted for more than 80% of the inter-annual variations in the mean yearly temperatures measured at Potsdam, Germany, during the last 120 years. Three quarters of the increase in the long-wave flux was due to changes in the water content of the lower atmosphere; the remainder was attributed to increases in CO 2 and other anthropogenic , radiatively active gases. Over the period radiative forcing in the short-wave flux slightly exceeded that in the long wave, but its effect on air temperature was much less as the climate sensitivity to atmospheric radiation, 0.187°C per W m À2, was three times greater than to short-wave global radiation. This anomalous finding, similar to that previously reported at two coastal sites, awaits explanation as does the complex interaction existing between radiative forcing and advection in determining temperature change.

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“…Albedo changes with reservoir surface cover (i.e., snow, ice, and water), snow depth, and ice depth (Duguay et al, 2003). Incoming long-wave radiation is determined using a power function of the specific humidity (Rosa and Stanhill, 2014), while outgoing long-wave radiation from the reservoir is calculated using the Stefan-Biogeosciences Discuss., doi: 10.5194/bg-2016-100, 2016 Manuscript under review for journal Biogeosciences Published: 11 April 2016 c Author(s) 2016. CC-BY 3.0 License.…”

Section: Thermal Dynamic and Water Mixingmentioning

confidence: 99%

Integrating aquatic and terrestrial biogeochemical model to predict effects of reservoir creation on CO2 emissions

Wang

Roulet

Kim

et al. 2016

Preprint

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There is considerable debate on the role of hydroelectric reservoirs for the emission of CO2 and other greenhouse gases. To quantify CO2 emissions from a newly created reservoir that was formed by flooding the boreal landscape we developed a daily time-step reservoir model by integrating a terrestrial and an aquatic ecosystem model. We calibrated the model using the measurements of dissolved organic and inorganic carbon (C) in a ~ 600 km2 boreal hydroelectric reservoir, Eastmain-1, in northern Quebec, Canada. A major constraint we dealt with is the dearth of basic environmental data for the Boreal region so we took a parsimonious approach for required inputs. We then evaluated the model performance against observed CO2 fluxes data from an eddy covariance tower in the middle of the EM-1 reservoir for the period from 2006 to 2012 and compared internal variables such as water column respiration, chlorophyll-a concentration, and sedimentation rate to measurements from field campaigns during 2006–2008. The model predicted the seasonal and inter-annual variability of CO2 emissions reasonably well compared to the observations. Discrepancies between simulation results and observations usually occurred near ice-off dates when there was large amount of dissolved CO2 under ice-cover. We applied the model to assess the effects of reservoir creation on C dynamics over the estimated “engineering” reservoir lifetime (i.e., 100 years). We found that the reservoir acts as a net C source over its lifetime and simulated CO2 fluxes were 204 g C m−2 yr−1 in the first year after flooding, steeply declined in the first three years, and then steadily decreased to ~110 g C m−2 yr−1 with increasing reservoir age. Sensitivity analyses revealed that the amount of terrestrial organic C flooded and oxygen effects can positively enhance benthic respiration and CO2 fluxes across air–water interface, but the effects on CO2 emissions were not significant. Higher temperatures dramatically stimulate CO2 emissions by enhancing CO2 production in both the water column and the sediment, and extending the duration of the open water period over which emissions can occur. Changing wind speeds had large uncertainties on annual CO2 emissions, given that wind speeds not only affect the gas transfer rate but also the open water period by affecting the surface energy balance. The model is useful for the estimation of CO2 emissions from reservoirs to the atmosphere and could be used to assist the hydro-power industry and others interested in emissions evaluate the role of boreal reservoirs as sources of greenhouse gas emissions.

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Estimating long‐wave radiation at the Earth's surface from measurements of specific humidity

Cited by 8 publications

References 18 publications

Longwave radiation at the earth’s surface in Estonia

Longwave radiation at the earth’s surface in Estonia

Radiative forcing and temperature change at Potsdam between 1893 and 2012

Integrating aquatic and terrestrial biogeochemical model to predict effects of reservoir creation on CO<sub>2</sub> emissions

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Estimating long‐wave radiation at the Earth's surface from measurements of specific humidity

Cited by 8 publications

References 18 publications

Longwave radiation at the earth’s surface in Estonia

Longwave radiation at the earth’s surface in Estonia

Radiative forcing and temperature change at Potsdam between 1893 and 2012

Integrating aquatic and terrestrial biogeochemical model to predict effects of reservoir creation on CO&lt;sub&gt;2&lt;/sub&gt; emissions

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Integrating aquatic and terrestrial biogeochemical model to predict effects of reservoir creation on CO<sub>2</sub> emissions