Momentum and Energy Budgets in the High‐Latitude Lower Thermospheric Wind System

2021 ◽  
pp. 19-40
Author(s):  
Young‐Sil Kwak ◽  
Arthur D. Richmond
Keyword(s):  
High Latitude ◽  
Energy Budgets ◽  
Wind System ◽  
Thermospheric Wind

scholarly journals What Do the New 2018 HIWIND Thermospheric Wind Observations Tell Us About High‐Latitude Ion‐Neutral Coupling During Daytime?

2019 ◽  
Vol 124 (7) ◽  
pp. 6173-6181 ◽  
Author(s):  
Qian Wu ◽  
Delores Knipp ◽  
Jing Liu ◽  
Wenbin Wang ◽  
Ingemar Häggström ◽  
...  
Keyword(s):  
High Latitude ◽  
Thermospheric Wind

scholarly journals High latitude cooling associated with landscape changes from North American boreal forest fires

2012 ◽  
Vol 9 (9) ◽  
pp. 12087-12136 ◽  
Author(s):  
B. M. Rogers ◽  
J. T. Randerson ◽  
G. B. Bonan
Keyword(s):  
Boreal Forest ◽  
High Latitude ◽  
Forest Fires ◽  
Boreal Forests ◽  
Regional Climate ◽  
Forest Composition ◽  
Energy Budgets ◽  
Surface Cooling ◽  
Functional Variation ◽  
Greenhouse Gasses

Abstract. Fires in the boreal forests of North America are generally stand-replacing, killing the majority of trees and initiating succession that may last over a century. Functional variation during succession can affect local surface energy budgets and, potentially, regional climate. Burn area across Alaska and Canada has increased in the last few decades and is projected to be substantially higher by the end of the 21st century because of a warmer climate with longer growing seasons. Here we simulated the changes in forest composition due to altered burn area using a stochastic model of fire occurrence, historical fire data from national inventories, and succession trajectories derived from remote sensing. When coupled to an Earth system model, younger vegetation from increased burning cooled the high-latitude atmosphere, primarily in the winter and spring, with noticeable feedbacks from the ocean and sea ice. Results from multiple scenarios suggest that a doubling of burn area would result in surface cooling of 0.23 ± 0.09 °C and 0.43 ± 0.12 °C for winter–spring and February–April time periods, respectively. This could provide a negative feedback to high-latitude terrestrial warming during winter on the order of 4–6% for a doubling, and 14–23% for a quadrupling, of burn area. Further work is needed to integrate all the climate drivers from boreal forest fires, including aerosols and greenhouse gasses.

scholarly journals High-latitude cooling associated with landscape changes from North American boreal forest fires

2013 ◽  
Vol 10 (2) ◽  
pp. 699-718 ◽  
Author(s):  
B. M. Rogers ◽  
J. T. Randerson ◽  
G. B. Bonan
Keyword(s):  
North America ◽  
Boreal Forest ◽  
High Latitude ◽  
Forest Fires ◽  
Boreal Forests ◽  
Regional Climate ◽  
Forest Composition ◽  
Energy Budgets ◽  
Functional Variation ◽  
Greenhouse Gasses

Abstract. Fires in the boreal forests of North America are generally stand-replacing, killing the majority of trees and initiating succession that may last over a century. Functional variation during succession can affect local surface energy budgets and, potentially, regional climate. Burn area across Alaska and Canada has increased in the last few decades and is projected to be substantially higher by the end of the 21st century because of a warmer climate with longer growing seasons. Here we simulated changes in forest composition due to altered burn area using a stochastic model of fire occurrence, historical fire data from national inventories, and succession trajectories derived from remote sensing. When coupled to an Earth system model, younger vegetation from increased burning cooled the high-latitude atmosphere, primarily in the winter and spring, with noticeable feedbacks from the ocean and sea ice. Results from multiple scenarios suggest that a doubling of burn area would cool the surface by 0.23 ± 0.09 °C across boreal North America during winter and spring months (December through May). This could provide a negative feedback to winter warming on the order of 3–5% for a doubling, and 14–23% for a quadrupling, of burn area. Maximum cooling occurs in the areas of greatest burning, and between February and April when albedo changes are largest and solar insolation is moderate. Further work is needed to integrate all the climate drivers from boreal forest fires, including aerosols and greenhouse gasses.

scholarly journals IMF dependence of high-latitude thermospheric wind pattern derived from CHAMP cross-track measurements

2008 ◽  
Vol 26 (6) ◽  
pp. 1581-1595 ◽  
Author(s):  
M. Förster ◽  
S. Rentz ◽  
W. Köhler ◽  
H. Liu ◽  
S. E. Haaland
Keyword(s):  
Southern Hemisphere ◽  
High Latitude ◽  
Polar Regions ◽  
High Latitudes ◽  
Plasma Convection ◽  
Thermospheric Wind ◽  
Wind Pattern ◽  
Magnetospheric Convection ◽  
Cross Track ◽  
The Imf

Abstract. Neutral thermospheric wind pattern at high latitudes obtained from cross-track acceleration measurements of the CHAMP satellite above both North and South polar regions are statistically analyzed in their dependence on the Interplanetary Magnetic Field (IMF) direction in the GSM y-z plane (clock angle). We compare this dependency with magnetospheric convection pattern obtained from the Cluster EDI plasma drift measurements under the same sorting conditions. The IMF-dependency shows some similarity with the corresponding high-latitude plasma convection insofar that the larger-scale convection cells, in particular the round-shaped dusk cell for ByIMF+ (ByIMF−) conditions at the Northern (Southern) Hemisphere, leave their marks on the dominant general transpolar wind circulation from the dayside to the nightside. The direction of the transpolar circulation is generally deflected toward a duskward flow, in particular in the evening to nighttime sector. The degree of deflection correlates with the IMF clock angle. It is larger for ByIMF+ than for ByIMF− and is systematically larger (~5°) and appear less structured at the Southern Hemisphere compared with the Northern. Thermospheric cross-polar wind amplitudes are largest for BzIMF−/ByIMF− conditions at the Northern Hemisphere, but for BzIMF−/ByIMF+ conditions at the Southern because the magnetospheric convection is in favour of largest wind accelerations over the polar cap under these conditions. The overall variance of the thermospheric wind magnitude at Southern high latitudes is larger than for the Northern. This is probably due to a larger "stirring effect" at the Southern Hemisphere because of the larger distance between the geographic and geomagnetic frameworks.

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