The Variability of the Net Radiation Ratio

Prediction equations for estimating evaporation from bodies of water, often require values of net radiation. Solar radiation data are usually more accurate and more readily available than measurements of net radiation. Measured solar radiation and the mean ratio of net radiation to solar radiation have been used to estimate the net radiation levels required to predict evaporation rates. However, although the average net radiation ratio is relatively stable from year to year the effect of daily variation in the net radiation ratio on evaporation estimates has not been investigated. An empirical energy balance and measurements of pan evaporation and meteorological factors are used to examine the effect of the average daily variation on evaporation rates computed with the mean net radiation ratio. The results indicate that the average daily variation from the mean net radiation ratio may produce an error of approximately 13 per cent in an estimate of daily evaporation when the mean net radiation ratio is used. However, daily variability in the net radiation ratio has little influence on the regeneration of a large number of evaporation estimates. Estimated values of the net radiation ratio and its variability are compared with observed values from polar climates.

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Evapotranspiration at Two Mountain Sites During the Vegetation Period

Hydrology Research ◽

10.2166/nh.1981.0016 ◽

1981 ◽

Vol 12 (4-5) ◽

pp. 207-216 ◽

Cited By ~ 7

Author(s):

M. Staudinger ◽

H. Rott

Keyword(s):

Energy Balance ◽

Vegetation Period ◽

Test Site ◽

The Other ◽

Net Radiation ◽

Energy Fluxes ◽

Austrian Alps ◽

The Mean ◽

The Village ◽

Radiation Measurements

Hourly values of evapotranspiration (ET) for the months July to September 1976 and 1977 were calculated from energy balance measurements at two test sites near the village of Obergurgl in the Austrian Alps. One test site was situated at 1,960 m a.s.l. on a cultivated meadow near the timberline, the other test site at 2,580 m a.s.l. was covered with alpine sedges and grasses. Examples of the daily variations and daily sums of the energy fluxes are presented for clear and cloudy days. The mean daily courses of ET at the two test sites are shown for every month of the measurement periods; differences in ET between the two test sites are related to the decrease of transpirating leaf areas with altitude. Monthly sums of ET are presented in relation to net radiation and precipitation; on the average ET was about 30% lower at the higher elevated site. High correlations were found between the daily sums of net radiation and of ET at both sites. This relation can be used for calculating ET from radiation measurements.

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Mass and Energy Balance Estimation of Yala Glacier (2011–2017), Langtang Valley, Nepal

Water ◽

10.3390/w11010006 ◽

2018 ◽

Vol 11 (1) ◽

pp. 6 ◽

Cited By ~ 6

Author(s):

Anushilan Acharya ◽

Rijan Kayastha

Keyword(s):

Energy Balance ◽

Mass Balance ◽

Surface Albedo ◽

Surface Energy Balance ◽

Primary Energy ◽

Balance Model ◽

Net Radiation ◽

Temperature And Precipitation ◽

Physically Based ◽

The Mean

Six-year glaciological mass balance measurements, conducted at the Yala Glacier between November 2011 and November 2017 are presented and analyzed. A physically-based surface energy balance model is used to simulate summer mass and energy balance of the Yala Glacier for the 2012–2014 period. Cumulative mass balance of the Yala Glacier for the 2011–2017 period was negative at −4.88 m w.e. The mean annual glacier-wide mass balance was −0.81 ± 0.27 m w.e. with a standard deviation of ±0.48 m w.e. The modelled mass balance values agreed well with observations. Modelling showed that net radiation was the primary energy source for the melting of the glacier followed by sensible heat and heat conduction fluxes. Sensitivity of mass balance to changes in temperature, precipitation, relative humidity, surface albedo and snow density were examined. Mass balance was found to be most sensitive to changes in temperature and precipitation.

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The recent retreat of Mexican glaciers on Citlaltépetl Volcano detected using ASTER data

The Cryosphere Discussions ◽

10.5194/tcd-6-3149-2012 ◽

2012 ◽

Vol 6 (4) ◽

pp. 3149-3176 ◽

Cited By ~ 4

Author(s):

J. Cortés-Ramos ◽

H. Delgado-Granados

Keyword(s):

Energy Balance ◽

Surface Energy ◽

Satellite Imagery ◽

Surface Energy Balance ◽

Meteorological Data ◽

Radiation Balance ◽

Net Radiation ◽

Glacial Retreat ◽

Radiation Data ◽

Close Relationship

Abstract. Satellite imagery and net radiation data collected between 2001 and 2007 for Citlaltépetl Volcano confirm the dramatic shrinkage of Glaciar Norte and the elimination of Jamapa and Chichimeco glacier tongues. The Glaciar Norte rapidly retreated between 2001 and 2002 while for 2007 this retreat decreases considerably. Jamapa and Chichimeco tongues disappeared by 2001 as compared to the geometry shown for 1958. The Glaciar Norte lost about 72% of its surface area between 1958 and 2007. Recently, the ice loss appears to be accelerating as evidenced by the 33% areal loss in just 6 yr between 2001 and 2007. At this shrinkage rate the glaciers would be gone from the volcano by the year 2020, which is decades earlier than previously estimated. The net radiation from ASTER images and the energy fluxes calculated via the meteorological data at the glacial surface show the close relationship between glacial shrinkage and surface energy balance. The magnitude of changes in the net radiation balance allows improved understanding of glacial retreat in Mexico.

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High-Precision Solar Radiation Data for λλ3300–12500Å

Symposium - International Astronomical Union ◽

10.1017/s0074180900079250 ◽

1985 ◽

Vol 111 ◽

pp. 473-474

Author(s):

Heinz Neckel ◽

Dietrich Labs

Keyword(s):

Fourier Transform ◽

High Resolution ◽

Solar Radiation ◽

Disk Center ◽

Central Intensity ◽

Radiation Data ◽

Precise Data ◽

Spectral Bands ◽

The Mean ◽

Fourier Transform Spectra

Very precise data on the solar radiation has been obtained by merging: (1) the absolute integrals of the disk-center intensity for 20Å-wide spectral bands, observed in the 1960's by Labs and Neckel (1962, 1963, 1967); (2) the ratios of the mean-to-central intensity following from observations of the center-to-limb variation of (a) all 20Å bands below 6600Å (Neckel and Labs 1984), and (b) the intensities at selected continuum wavelengths (Pierce and Slaughter 1977a, b); and (3) the high-resolution Fourier transform spectra (FTS) obtained by J. Brault at Kitt Peak for the center of the disk and for the irradiance.

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Inconsistency in Chinese solar radiation data caused by instrument replacement: Quantification based on pan evaporation observations

Journal of Geophysical Research Atmospheres ◽

10.1002/2014jd023015 ◽

2015 ◽

Vol 120 (8) ◽

pp. 3191-3198 ◽

Cited By ~ 4

Author(s):

Hanbo Yang ◽

Zhe Li ◽

Mingliang Li ◽

Dawen Yang

Keyword(s):

Solar Radiation ◽

Pan Evaporation ◽

Radiation Data

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Meteorological factors associated with the timing and abundance of Hymenoscyphus fraxineus spore release

International Journal of Biometeorology ◽

10.1007/s00484-021-02211-z ◽

2021 ◽

Author(s):

Paul Burns ◽

Volkmar Timmermann ◽

Jon M. Yearsley

Keyword(s):

Meteorological Factors ◽

Additive Model ◽

Net Radiation ◽

Generalised Additive Model ◽

Exponential Increase ◽

Hymenoscyphus Fraxineus ◽

Spore Release ◽

Novel Method ◽

The Mean ◽

High Level

AbstractThe ascomycete Hymenoscyphus fraxineus has spread across most of the host range of European ash with a high level of mortality, causing important economic, cultural and environmental effects. We present a novel method combining a Monte-Carlo approach with a generalised additive model that confirms the importance of meteorology to the magnitude and timing of H. fraxineus spore emissions. The variability in model selection and the relative degree to which our models are over- or under-fitting the data has been quantified. We find that both the daily magnitude and timing of spore emissions are affected by meteorology during and prior to the spore emission diurnal peak. We found the daily emission magnitude has the strongest associations to weekly average net radiation and leaf moisture before the emission, soil temperature during the day before emission and net radiation during the spore emission. The timing of the daily peak in spore emissions has the strongest associations to net radiation both during spore emission and in the day preceding the emission. The seasonal peak in spore emissions has a near-exponential increase/decrease, and the mean daily emission peak is approximately Gaussian.

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