scholarly journals Temporal and Spatial Changes in Snow Cover and the Corresponding Radiative Forcing Analysis in Siberia from the 1970s to the 2010s

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Lingxue Yu ◽  
Tingxiang Liu ◽  
Shuwen Zhang
Keyword(s):  
Snow Cover ◽  
Vegetation Cover ◽  
Radiative Forcing ◽  
Global Climate ◽  
Regional Scale ◽  
Surface Radiation ◽  
Radiation Balance ◽  
Spatial Changes ◽  
Long Time ◽  
Temporal And Spatial

In the context of global climate change, the extent of snow cover in Siberia has significantly decreased since the 1970s, especially in spring. The changes of snow cover at middle and high latitudes have significant impacts on the meteorological and hydrological processes because the snow cover can affect the surface energy, water balance, and the development of the atmospheric boundary layer. In this paper, the temporal and spatial changes in snow cover were firstly estimated based on a long time series of remote sensing snow cover data, both showing a decreased trend. Based on this, we estimated the radiative forcing caused by the snow cover changes from the 1970s to the 2010s and compared it with the radiative forcing caused by the vegetation cover changes over the same time period in Siberia, indicating that the snow cover changes in Siberia can accelerate climate warming and the vegetation cover changes here have the opposite effect. Furthermore, the snow cover changes may play a more important role than the vegetation cover changes in regulating the surface radiation balance in Siberia on the regional scale.

Developing Best Practices for Observing Global Surface Shortwave and Longwave Radiation across the Land and Ocean

2020 ◽  
Author(s):  
Robert Weller ◽  
Christian Lanconelli ◽  
Martin Wild ◽  
Joerg Trenmann
Keyword(s):  
Climate Models ◽  
Global Climate ◽  
Surface Radiation ◽  
Global Ocean ◽  
Radiation Balance ◽  
Radiative Fluxes ◽  
Temporal Sampling ◽  
The Earth ◽  
Calibration Methods

<p>In-situ shortwave or solar radiation and longwave or thermal radiation are observed at the earth’s surface on both the land and the ocean.  In addition, satellites are used to develop fields of surface radiation balance.  Planning for the Global Ocean Observing System (GOOS) and the Global Climate Observing System (GCOS) has identified surface heat flux, including the radiative fluxes, as an Essential Ocean Variable (EOV) and Essential Climate Variable (ECV), respectively.  The GOOS and GCOS requirements for surface radiative fluxes (spatial and temporal sampling, accuracies) are summarized here.  Surface radiation sites will continue to be sparse in the future, especially in the ocean; and satellite-derived products developed in concert with in-situ observing system will be important.  To make better progress towards meeting those requirements, we propose the goal of establishing dialog across the different methods of in-situ observing surface radiation and with the remote sensing community.  Objectives of the effort would include sharing knowledge and experience of how to make the observations, documentation of calibration methods, and assessment of the uncertainties to be associated with the different observing methods.  The resulting metadata and quantitative understanding of the different approaches would support improved combination of surface radiation observations across land and sea into homogeneous products at global scale.  At the same time, improved in-situ sampling would help assess and validate climate models and contribute to our understanding of the earth’s energy balance.  We review here the different observing methods now in use on land and at sea and discuss the challenges faced in making the observations.  We also propose future field inter-comparison and standardization of calibration methods to better establish the accuracy and comparability of surface radiation observations on land and at sea.</p>

scholarly journals Influence of Twenty-First-Century Atmospheric and Sea Surface Temperature Forcing on West African Climate

2012 ◽  
Vol 25 (2) ◽  
pp. 527-542 ◽  
Author(s):  
Christopher B. Skinner ◽  
Moetasim Ashfaq ◽  
Noah S. Diffenbaugh
Keyword(s):  
West Africa ◽  
Radiative Forcing ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Regional Scale ◽  
Summer Precipitation ◽  
Global Scale ◽  
Boreal Summer ◽  
African Climate

Abstract The persistence of extended drought events throughout West Africa during the twentieth century has motivated a substantial effort to understand the mechanisms driving African climate variability as well as the possible response to elevated greenhouse gas (GHG) forcing. An ensemble of global climate model experiments is used to examine the relative roles of future direct atmospheric radiative forcing and SST forcing in shaping potential future changes in boreal summer precipitation over West Africa. The authors find that projected increases in precipitation throughout the western Sahel result primarily from direct atmospheric radiative forcing. The changes in atmospheric forcing generate a slight northward displacement and weakening of the African easterly jet (AEJ), a strengthening of westward monsoon flow onto West Africa, and an intensification of the tropical easterly jet (TEJ). Alternatively, the projected decreases in precipitation over much of the Guinea Coast region are caused by SST changes induced by the atmospheric radiative forcing. The changes in SSTs generate a weakening of the monsoon westerlies and the TEJ as well as a decrease in low-level convergence and resultant rising air throughout the midlevels of the troposphere. Experiments suggest a potential shift in the regional moisture balance of West Africa should global radiative forcing continue to increase, highlighting the importance of climate system feedbacks in shaping the response of regional-scale climate to global-scale changes in radiative forcing.

scholarly journals Indigenous vegetation burning practices and their impact on the climate of the northern Australian monsoon region

2013 ◽  
Vol 10 (8) ◽  
pp. 10313-10332 ◽  
Author(s):  
K.-H. Wyrwoll ◽  
F. H. McRobie ◽  
M. Notaro ◽  
G. Chen
Keyword(s):  
Time Scales ◽  
Vegetation Cover ◽  
Large Scale ◽  
Climate Model ◽  
Global Climate ◽  
Global Climate Model ◽  
Regional Scale ◽  
Northern Australia ◽  
Monsoon Region ◽  
The Impact

Abstract. Here we pose the question: was there a downturn in summer monsoon precipitation over northern Australia due to Aboriginal vegetation practices over prehistoric time scales? In answering this question we consider the results from a global climate model incorporating ocean, land, ice, atmosphere and vegetation interactions, reducing the total vegetation cover over northern Australia by 20% to simulate the effects of burning. The results suggest that burning forests and woodlands in the monsoon region of Australia led to a shift in the regional climate, with a delayed monsoon onset and reduced precipitation in the months preceding the "full" monsoon. We place these results in a global context, drawing on model results from five other monsoon regions, and note that although the precipitation response is highly varied, there is a general but region specific climate response to reduced vegetation cover in all cases. Our findings lead us to conclude that large-scale vegetation modification over millennial time-scales due to indigenous burning practices, would have had significant impacts on regional climates. With this conclusion comes the need to recognise that the Anthropocene saw the impact of humans on regional-scale climates and hydrologies at much earlier times than generally recognized.

scholarly journals ARM Research In The Equatorial Western Pacific: A Decade And Counting

2013 ◽  
Vol 94 (5) ◽  
pp. 695-708 ◽  
Author(s):  
C. N. Long ◽  
S. A. McFarlane ◽  
A. Del Genio ◽  
P. Minnis ◽  
T. P. Ackerman ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Field Experiments ◽  
Global Climate ◽  
Western Pacific ◽  
Surface Radiation ◽  
Radiation Budget ◽  
Water Budgets ◽  
Model Studies ◽  
Cloud Properties ◽  
Tropical Clouds

The tropical western Pacific (TWP) is an important climatic region. Strong solar heating, warm sea surface temperatures, and the annual progression of the intertropical convergence zone (ITCZ) across this region generate abundant convective systems, which through their effects on the heat and water budgets have a profound impact on global climate and precipitation. In order to accurately evaluate tropical cloud systems in models, measurements of tropical clouds, the environment in which they reside, and their impact on the radiation and water budgets are needed. Because of the remote location, ground-based datasets of cloud, atmosphere, and radiation properties from the TWP region have come primarily from shortterm field experiments. While providing extremely useful information on physical processes, these short-term datasets are limited in statistical and climatological information. To provide longterm measurements of the surface radiation budget in the tropics and the atmospheric properties that affect it, the Atmospheric Radiation Measurement program established a measurement site on Manus Island, Papua New Guinea, in 1996 and on the island republic of Nauru in late 1998. These sites provide unique datasets now available for more than 10 years on Manus and Nauru. This article presents examples of the scientific use of these datasets including characterization of cloud properties, analysis of cloud radiative forcing, model studies of tropical clouds and processes, and validation of satellite algorithms. New instrumentation recently installed at the Manus site will provide expanded opportunities for tropical atmospheric science.

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