World distribution of solar radiation

Löf, G.O.G.; Duffie, John A.; Smith, Calvin

doi:10.1016/0038-092x(66)90069-7

Cited by 134 publications

(14 citation statements)

References 5 publications

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“…Löf et al, 1966;Rietveld, 1978;Hay, 1979;Iqbal, 1979;Benson et al, 1984;Ahmad et al, 1991;Hamdan and Al-Sayeh, 1991). Indeed, one of the most probable causes of trends in solar radiation is a change in the amount of cloud cover (Stanhill and Cohen, 2001).…”

Section: Sunshine Durationmentioning

confidence: 99%

Solar radiation climate change over southern Africa and an assessment of the radiative impact of volcanic eruptions

Power

Mills²

2005

Int. J. Climatol.

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Spatial and temporal variability in global, diffuse, and horizontal direct irradiance and sunshine duration has been evaluated at eight stations in South Africa and two stations in Namibia where the time series range between 21 and 41 years. Global and direct irradiance and sunshine duration decrease from northwest to southeast; diffuse irradiance increases toward the east. Annually averaged global irradiance G a decreased between 1.3% (2.8 W m −2 ) and 1.7% (4.4 W m −2 ) per decade at Bloemfontein, Cape Town, Durban, Pretoria, and Upington. Annually averaged diffuse irradiance D a decreased 5.2% (3.0 W m −2 ) per decade at Grootfontein and 4.2% (3.1 W m −2 ) per decade at Port Elizabeth. Annual direct irradiance B a decreased 2.1% (3.5 W m −2 ) per decade at Cape Town and 2.8% (5.7 W m −2 ) per decade at Alexander Bay. A simultaneous decrease in annually averaged daily sunshine duration S a may have contributed to the decrease in B a at Alexander Bay and the decrease in G a at Pretoria. Increases in aerosols may have contributed to the observed decrease in G a at Cape Town and Durban, and the decrease in D a at Grootfontein may be due to a decrease in aerosols. On average, variability in S a explains 89.0%, 50.4%, and 89.5% of the variance in G a , D a , and B a respectively. The radiative response to changes in sunshine duration is greater for direct irradiance than for global and diffuse. In the 2 years following the 1963 Mount Agung eruption in Indonesia, changes in global irradiance over southern Africa were small and inconsistent. At eight stations, diffuse irradiance increased 21.9% (13.3 W m −2 ) on average and direct irradiance decreased 8.7% (15.5 W m −2 ). After the 1982 El Chichón eruption in Mexico, global irradiance increased at two stations and decreased at seven stations. Eight stations witnessed an increase in diffuse irradiance averaging 7.2% (4.0 W m −2 ) and a decrease in direct irradiance of 5.0% (9.0 W m −2 ). The contribution of changes in cloud cover to the observed changes in irradiances appears to be small. Following the 1991 Mount Pinatubo eruption in the Philippines, diffuse irradiance increased an average of 18.8% (10.0 W m −2 ) at three stations and direct irradiance decreased by 7.2% (13.0 W m −2 ).

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Section: Sunshine Durationmentioning

confidence: 99%

Solar radiation climate change over southern Africa and an assessment of the radiative impact of volcanic eruptions

Power

Mills²

2005

Int. J. Climatol.

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“…The annual rainfall in Namibia is 50 − 600 mm (Bethune et al, 2005) but the seasonal wetlands formed during the rainy season due to flooded water from Angola, have high rice productivity. Some of the semi-arid regions also have a high potential for rice production because of a strong radiative environment (Löf et al, 1966), which increases the yield of rice (Namba, 2003). However, water is still limited in semi-arid regions, and thus it is important to develop water saving techniques that are adoptable for such semi-arid regions with minimum water resources but without an irrigation system.…”

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confidence: 99%

Role of Canopy Coverage in Water Use Efficiency of Lowland Rice in Early Growth Period in Semi-Arid Region

Suzuki

Ohta

Izumi

et al. 2013

Plant Production Science

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An appropriate combination of rice cultivar and cropping system that maximizes water use efficiency (WUE) may improve yield of rainfed lowland rice. In the paddy field, a large amount of water is consumed by evaporation during the early growth period, and it can be reduced by canopy coverage especially in semi-arid regions. Therefore, we evaluated the role of canopy coverage in WUE of rice in the early growth period in semi-arid region. A pot experiment was conducted in Namibia to investigate the genotypic and species difference in WUE, and another pot and a field experiment were conducted to investigate the effects of planting density on WUE. Although no significant difference was observed among species, the mean WUE was in the decreasing order of Oryza sativa, and Oryza glaberrima followed by the interspecific progenies including NERICA. In contrast, there was a significant difference in WUE at the genotypic level. Highly tillering genotypes such as WAB1159-2-12-11-5-1 and WITA 2 showed a high WUE. Furthermore, WUE was significantly correlated with the number of tillers (R 2 = 0.453), and higher planting density resulted in a higher WUE. In contrast, stomatal conductance had no significant correlation with WUE (R 2 = 0.081). Thus, the physical conditions affected by number of tillers and planting density had greater impacts on WUE than physiological characteristics such as stomatal conductance. The suppression of surface water evaporation by coverage was significant, probably contributing to WUE improvement. To increase WUE in semi-arid regions, we recommend the increase of canopy coverage and higher planting density.

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“…Many meteorological observatories around the world took this opportunity to begin pyranometer observations. The global surface shortwave irradiance map has been investigated using pyranometer measurements as well as sunshine duration measurements (Löf et al 1966). More recently, studies on surface shortwave irradiance have focused mainly not on decadal or secular variations but on a global map, i.e., the geographical distribution of the downward shortwave irradiance.…”

Section: Introductionmentioning

confidence: 99%

The Long-term Variation in Surface Shortwave Irradiance in China and Japan: A Review

Hayasaka

2016

Journal of the Meteorological Society of Japan

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We reviewed the long-term trends and inter-annual variations in the surface shortwave irradiance in China and Japan. Pyranometer observations revealed decreases followed by increases in the shortwave irradiance in China and Japan between the 1960s and 2000s, while obvious long-term trends were not evident in the satellite observations after 1983. In China, surface shortwave irradiance decreased from 1961 until around 1990, but then began to increase. In Japan, on the contrary, the decreasing trend stopped in the 1960s, with little inter-annual variation during the 1970s and 1980s, and an increase began around 1990. The causes of the differences between the shortwave irradiance trends in China and Japan were ascribed to an increase in light-absorbing aerosols in China that began in the 1960s and a decrease in absorbing aerosols in Japan that began in the late 1970s. Absorbing aerosols decrease both direct and diffuse radiation, while non-absorbing aerosols decrease direct radiation but increase diffuse radiation. Although these aerosol influences are generally found under clear sky conditions, absorbing aerosols could have direct effects even under cloudy sky conditions. The trends of surface shortwave irradiance in China and Japan are in line with the so-called global dimming and brightening dimming processes, although the phases of the minimum periods in the two regions slightly differed. An increase in anthropogenic aerosol was responsible for the variation in the shortwave irradiance through the direct radiative effect of aerosol in the polluted area, while indirect radiative effects, i.e., changes in cloud cover due to an increase in cloud condensation nuclei, dominated in pristine areas. The effects of other factors, such as variations in water vapor and natural aerosol levels, appear to be small compared to the effects of cloud and anthropogenic aerosols.

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World distribution of solar radiation

Cited by 134 publications

References 5 publications

Solar radiation climate change over southern Africa and an assessment of the radiative impact of volcanic eruptions

Solar radiation climate change over southern Africa and an assessment of the radiative impact of volcanic eruptions

Role of Canopy Coverage in Water Use Efficiency of Lowland Rice in Early Growth Period in Semi-Arid Region

The Long-term Variation in Surface Shortwave Irradiance in China and Japan: A Review

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