Influence of Soil Moisture and Surface Albedo Changes over the African Tropical Rain Forest on Summer Climate

Yamazaki, Koji; Tokioka, Tatsushi

doi:10.2151/jmsj1965.66.1_65

Cited by 28 publications

(18 citation statements)

References 31 publications

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“…This region corresponds to an arid or semi-arid region of Asia. The change in precipitation over equatorial and north Africa in the present experiment is very similar to that in the deforestation experiment in the African tropical rain forest by Kitoh et al (1988). In their AW run, the albedo between 0*N and 12*N over Africa is increased to 0.30 and the soil moisture capacity is reduced over the same region.…”

Section: Summersupporting

confidence: 78%

“…The increase in surface albedo causes the net cooling of the atmosphere and the descending motion which in turn reduces rainfall. This mechanism was tested and confirmed with the use of a GCM by Charney et al (1977) and others (e.g., Sud and Fennessy, 1982;Sud and Smith, 1985b;Laval and Picon, 1986;Kitoh et al, 1988;Sud and Molod, 1988). Another important factor which con-©1989, Meteorological Society of Japan trols climate is soil moisture.…”

Section: Introductionmentioning

confidence: 57%

“…16) is large over the Amazon and equatorial Africa. This mechanism is analyzed in detail for the African deforestation experiment by Kitoh et al (1988).…”

Section: Surface Albedo and Qround Wetness Effects On Summer Climatementioning

confidence: 99%

“…Another important factor which con-©1989, Meteorological Society of Japan trols climate is soil moisture. Many sensitivity experiments have been performed on it (e.g., Walker and Rowntree,1977;Shukla and Mintz,1982;Yeh et al, 1984;Sud and Fennessy, 1984;Sud and Smith, 1985b;Kitoh et al, 1988;Sud and Molod, 1988). The general conclusion of these experiments is that a reduced soil moisture causes a reduction in evaporation which in turn decreases rainfall.…”

Section: Introductionmentioning

confidence: 99%

“…The influence of surface albedo and soil moisture changes on early summer climate was investigated by Yamazaki (1986) using the MRI*GCM-I; it showed a large impact especially in arid and semi-arid regions. The influence of soil moisture and surface albedo changes over the African tropical rain forest on summer climate was investigated by Kitoh et al (1988).…”

Section: Introductionmentioning

confidence: 99%

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A Study of the Impact of Soil Moisture and Surface Albedo

Yamazaki¹

1989

Journal of the Meteorological Society of Japan

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The influence of changing soil moisture and surface albedo on climate is studied with an atmospheric general circulation model (MRI.GCM-I). In a control run (C run), a standard bucket model with a spatially uniform water holding capacity of 15g cm-2 is used for the ground hydrology. The surface albedo over bare land is specified as 0.14 and that over snow-covered land varies from 0.7 to 0.85 depending on the height of the ground surface. In the second run (AW run), the surface albedo and ground wetness are specified as the climate values. In the AW run, there is no snow-albedo feedback and the ground wetness is not predicted. Two additional runs are performed for separating the effect of albedo from that of ground wetness and for examining the effect of snow albedo.The results show that the atmospheric circulation in the Northern Hemisphere is very sensitive to the surface albedo specification in winter. In the C run, the Siberian high is stronger and extended southeastward compared with that in the AW run due to snow-albedo feedback in C. The Aleutian low in the C run is deeper and shifts eastward. On the other hand, the Icelandic low is deeper in the AW run than in the C run.It is found that snow albedo is an important factor which controls the northern summer climate. When snow albedo is low, snow melts earlier in spring and land becomes dry and warm in summer over the Eurasian arid region. Thus the summer precipitation is reduced there. Over the southeast Asia summer monsoon region in the model, however, moisture flux convergence is enhanced and the summer precipitation is increased. The increased precipitation makes soil wet, which in turn increases precipitation. In short, snow albedo affects summer climate significantly through the interaction of atmosphere and ground hydrological processes.Albedo of snow-free land also has a significant effect on climate particularly in low latitudes. High/low albedo produces less/much precipitation.

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Section: Summersupporting

confidence: 78%

Section: Introductionmentioning

confidence: 57%

“…16) is large over the Amazon and equatorial Africa. This mechanism is analyzed in detail for the African deforestation experiment by Kitoh et al (1988).…”

Section: Surface Albedo and Qround Wetness Effects On Summer Climatementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Study of the Impact of Soil Moisture and Surface Albedo

Yamazaki¹

1989

Journal of the Meteorological Society of Japan

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The influence of pre‐existing soil moisture content on Australian winter climate

Simmonds

Lynch

1992

Intl Journal of Climatology

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We have performed some experiments with the University of Melbourne General Circulation Model to determine the transient response of the climate system to the imposition of soil moisture anomalies over the Australian continent. Two sets of cases have been performed in which the soil over the entire continent was saturated and was completely dried on the first day of winter and then allowed to evolve normally for 4 months.The evaporation over most of the Australian continent in the 'saturated'case initially was significantly greater than that in the mean and this situation persisted for the 4 month's duration of the experiments, into the spring. A similar statement is true for the reduction of evaporation in the 'dry' experiments, although the magnitude was not as great. As dictated by surface energy considerations, the sensible heat fluxes over most of Australia assumed signs opposite to those of the evaporation and magnitudes somewhat smaller, but the residual differences were still significant in September. Other atmospheric parameters, such as precipitation, surface temperature and mean sea-level pressure tend to show much less persistence when averaged over Australia as a whole. However, many regions do show longer influence of the perturbed initial conditions.Of considerable interest to the value of Australian winter and spring crops is the finding that the soil moisture content still showed significant anomalies persisting into the fourth month, with an areal mean of 2.7 cm more than the control in the 'wet' case and 1.5 cm less in the 'dry'. This persistence of, albeit exaggerated, initial anomalies of winter soil moisture suggests that early winter soil moisture conditions may hold some potential for forecasting Australian winter crop productivity. We have found the 'halving time' of these large-scale soil moisture anomalies to be about 2 months and somewhat longer at higher latitudes. These findings are consistent with many other studies and are encouraging in that most of Australia's wheat is grown in that part of the continent.

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Land cover changes and their biogeophysical effects on climate

Mahmood

Pielke

Hubbard

et al. 2013

Intl Journal of Climatology

618

411

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Land cover changes (LCCs) play an important role in the climate system. Research over recent decades highlights the impacts of these changes on atmospheric temperature, humidity, cloud cover, circulation, and precipitation. These impacts range from the local-and regional-scale to sub-continental and global-scale. It has been found that the impacts of regional-scale LCC in one area may also be manifested in other parts of the world as a climatic teleconnection. In light of these findings, this article provides an overview and synthesis of some of the most notable types of LCC and their impacts on climate. These LCC types include agriculture, deforestation and afforestation, desertification, and urbanization. In addition, this article provides a discussion on challenges to, and future research directions in, assessing the climatic impacts of LCC.

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Influence of Soil Moisture and Surface Albedo Changes over the African Tropical Rain Forest on Summer Climate

Cited by 28 publications

References 31 publications

A Study of the Impact of Soil Moisture and Surface Albedo

A Study of the Impact of Soil Moisture and Surface Albedo

The influence of pre‐existing soil moisture content on Australian winter climate

Land cover changes and their biogeophysical effects on climate

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