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Retrieval of geophysical and thermod...

Hwang, Byong Jun.

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Retrieval of geophysical and thermodynamic state information from time series microwave radiometry in the fall and spring periods over Arctic sea ice.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Retrieval of geophysical and thermodynamic state information from time series microwave radiometry in the fall and spring periods over Arctic sea ice./
作者:	Hwang, Byong Jun.
面頁冊數:	334 p.
附註:	Source: Dissertation Abstracts International, Volume: 69-01, Section: B, page: 0194.
Contained By:	Dissertation Abstracts International69-01B.
標題:	Atmospheric Sciences. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NR36265
ISBN:	9780494362655

Retrieval of geophysical and thermodynamic state information from time series microwave radiometry in the fall and spring periods over Arctic sea ice.
Hwang, Byong Jun.

Retrieval of geophysical and thermodynamic state information from time series microwave radiometry in the fall and spring periods over Arctic sea ice. - 334 p.

Source: Dissertation Abstracts International, Volume: 69-01, Section: B, page: 0194.

Thesis (Ph.D.)--University of Manitoba (Canada), 2008.

The Arctic is regarded as a herald to global climate mainly because of strong interactions between the Arctic sea ice and the climate system. Understanding the roles of sea ice in the climate system is therefore critical in improving our knowledge of past and future climate changes on our planet. The primary objective of my dissertation is to investigate the utility of microwave radiometry in understanding how sea ice in the marine cryosphere evolves seasonally and how it responds to climate forcing. I conducted intensive field measurements of sea ice microwave and thermophysical/radiative properties during fall 2003 and spring 2004 in the southern Beaufort Sea and the Amundsen Gulf. The field data were carefully analyzed to address (1) surface-scale interactions between passive microwave signatures and thermophysical/radiative properties of snow/sea ice during fall and spring periods, and (2) spatial scaling issues associated with large footprint sizes of satellite microwave radiometers. The surface-scale fall studies revealed three significant correlations between microwave brightness temperature ratios and thermophysical/radiative properties of newly formed sea ice: microwave-ice thickness, microwave-brine volume and microwave-albedo. The first correlation confirmed the robustness of a previously reported thin ice thickness algorithm. The second correlation was found between microwave emissivity and brine volume on bare thin ice (R2&sim;0.8, p-value<0.05). The physical causes for these two correlations were attributed to changes in ice salinity and temperature (i.e., changes in brine volume) and their significant controls on microwave brightness temperatures. A strong correlation between microwave PR(19) and sea ice albedo (R2&sim;0.96) was found, which has never been reported in the literature. The surface-scale spring study showed the five events ('brine-rich', 'blowing snow', 'melt onset', 'funicular' and 'freezing') that significantly affected microwave-thermophysical interactions. I found that melt onset signals can easily get confused with the signals from 'brine-rich' and 'blowing-snow' events when using melt detection indices (i.e., DeltaTB(H) and XPGR). The results indicated an additional index (i.e., TB(19H)) would be useful to detect melt onset without ambiguity. From spatial scaling studies, I found significant errors in estimating sea ice concentrations occurred over homogeneous thin ice types, even before considering the effects of spatial heterogeneity. In comparative studies between surface-scale and satellite-scale measurements, I found that the linear mixing rule used in sea ice algorithms might not be valid to account for the satellite-scale brightness temperatures over mixed areas of open water and ice. Comparative studies between aircraft-scale and satellite-scale data showed the microwave brightness temperatures over thin ice dominant areas could not be distinguished from those over heterogeneous areas of open water and thicker ice. The studies also showed the difference in spatial resolution between AMSR-E and SSM/I became large in heterogeneous surfaces, which might be useful in estimating spatial heterogeneity at the surface. The results of my dissertation refined the extents and limitations of the utility of microwave radiometry in monitoring the fall/spring ice evolution processes in seasonal ice zones. To maximize the utility of microwave radiometry, however, new approaches should be considered, which include a combination of microwave radiometry and numerical climate/sea ice models.

ISBN: 9780494362655Subjects--Topical Terms:

1019179
Atmospheric Sciences.

Retrieval of geophysical and thermodynamic state information from time series microwave radiometry in the fall and spring periods over Arctic sea ice.
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502 $a Thesis (Ph.D.)--University of Manitoba (Canada), 2008.
520 $a The Arctic is regarded as a herald to global climate mainly because of strong interactions between the Arctic sea ice and the climate system. Understanding the roles of sea ice in the climate system is therefore critical in improving our knowledge of past and future climate changes on our planet. The primary objective of my dissertation is to investigate the utility of microwave radiometry in understanding how sea ice in the marine cryosphere evolves seasonally and how it responds to climate forcing. I conducted intensive field measurements of sea ice microwave and thermophysical/radiative properties during fall 2003 and spring 2004 in the southern Beaufort Sea and the Amundsen Gulf. The field data were carefully analyzed to address (1) surface-scale interactions between passive microwave signatures and thermophysical/radiative properties of snow/sea ice during fall and spring periods, and (2) spatial scaling issues associated with large footprint sizes of satellite microwave radiometers. The surface-scale fall studies revealed three significant correlations between microwave brightness temperature ratios and thermophysical/radiative properties of newly formed sea ice: microwave-ice thickness, microwave-brine volume and microwave-albedo. The first correlation confirmed the robustness of a previously reported thin ice thickness algorithm. The second correlation was found between microwave emissivity and brine volume on bare thin ice (R2&sim;0.8, p-value<0.05). The physical causes for these two correlations were attributed to changes in ice salinity and temperature (i.e., changes in brine volume) and their significant controls on microwave brightness temperatures. A strong correlation between microwave PR(19) and sea ice albedo (R2&sim;0.96) was found, which has never been reported in the literature. The surface-scale spring study showed the five events ('brine-rich', 'blowing snow', 'melt onset', 'funicular' and 'freezing') that significantly affected microwave-thermophysical interactions. I found that melt onset signals can easily get confused with the signals from 'brine-rich' and 'blowing-snow' events when using melt detection indices (i.e., DeltaTB(H) and XPGR). The results indicated an additional index (i.e., TB(19H)) would be useful to detect melt onset without ambiguity. From spatial scaling studies, I found significant errors in estimating sea ice concentrations occurred over homogeneous thin ice types, even before considering the effects of spatial heterogeneity. In comparative studies between surface-scale and satellite-scale measurements, I found that the linear mixing rule used in sea ice algorithms might not be valid to account for the satellite-scale brightness temperatures over mixed areas of open water and ice. Comparative studies between aircraft-scale and satellite-scale data showed the microwave brightness temperatures over thin ice dominant areas could not be distinguished from those over heterogeneous areas of open water and thicker ice. The studies also showed the difference in spatial resolution between AMSR-E and SSM/I became large in heterogeneous surfaces, which might be useful in estimating spatial heterogeneity at the surface. The results of my dissertation refined the extents and limitations of the utility of microwave radiometry in monitoring the fall/spring ice evolution processes in seasonal ice zones. To maximize the utility of microwave radiometry, however, new approaches should be considered, which include a combination of microwave radiometry and numerical climate/sea ice models.
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