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Quantifying the Role of Individual Surface Properties in Atmospheric Feedbacks and Land-atmosphere Interactions
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Quantifying the Role of Individual Surface Properties in Atmospheric Feedbacks and Land-atmosphere Interactions. |
| 개인저자 | Lague, Marysa M. |
| 단체저자명 | University of Washington. Atmospheric Sciences. |
| 발행사항 | [S.l.]: University of Washington., 2019. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2019. |
| 형태사항 | 228 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-04B. Dissertation Abstract International |
| ISBN | 9781687959294 |
| 학위논문주기 | Thesis (Ph.D.)--University of Washington, 2019. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-04, Section: B.
Advisor: Swann, Abigail LS. |
| 이용제한사항 | This item must not be sold to any third party vendors.This item must not be added to any third party search indexes. |
| 요약 | The land plays a critical role in the coupled Earth System. While it is intuitive to think of the impact of climate on the vegetated land surface, it is also true that changes in land surface properties can modify climate, on both local and global scales. Land surface properties such as albedo, evaporative resistance, and aerodynamic roughness modulate fluxes of energy to the atmosphere. Albedo controls how much incoming shortwave radiation is absorbed by the land surface, and thus how much energy must be either stored by the land surface, or returned to the atmosphere in the form of longwave radiation, sensible heat, or latent heat flux (evaporation). Evaporative resistance modifies the partitioning of turbulent energy fluxes between sensible and latent heat, thus modifying the amount of moisture fluxed from the land to the atmosphere. Aerodynamic resistance effects the efficiency of turbulent mixing with the atmosphere. While the general role of each of these surface properties in the surface energy budget is understood, it is not known which of these surface properties has the largest impact on the climate experienced by the land surface, or where each of these surface properties plays the largest role in influencing surface climate. Moreover, changes in any one of these surface properties can modify the climate experienced by the land surface both directly - that is, simply by changing the magnitude of individual surface energy fluxes - and indirectly, by driving atmospheric feedbacks. Atmospheric feedbacks are responses of the atmosphere to initial changes in surface fluxes, which can then feedback on the surface energy budget, both locally and remotely - that is, a change in the land surface in one location can modify the surface energy budget in remote regions, via ecoclimate teleconnections. In this dissertation, I separate and quantify the role of each of three individual surface properties associated with vegetation change - albedo, evaporative resistance, and aerodynamic resistance - using an idealized land surface model (the Simple Land Interface Model, SLIM) coupled to a complex Earth System Model. Additionally, I separate and quantify the magnitude of change in surface climate coming directly from the land surface, and the magnitude of change coming from atmospheric responses to those initial changes in the land surface. Albedo: I show that albedo has the largest direct impact on land surface temperatures and energy fluxes in regions that are sunny and dry, such as the sub-tropics. Albedo plays a less important direct role in high latitudes because there is less insolation (thus, the same change in albedo leads to a smaller change in absorbed energy than it would at a lower latitude). Albedo leads to increased energy absorption in the tropics, but does not directly lead to a large amount of warming, as the moist tropics can shed excess absorbed energy through evaporation (latent heat flux), rather than surface warming. Decreasing land albedo leads to more total energy absorbed by the land system, and thus released to the bottom of the atmosphere. As such, darkening the land surface leads to a net divergence of energy transport by the atmosphere away from the continents towards the ocean. In some regions, such as off the west coast of South America, this energy convergence over the oceans leads to increased low cloud cover. Historical changes in albedo resulting from vegetation change lead to both warming and cooling regional temperature signals, primarily resulting from afforestation of abandoned cropland in the mid-latitudes, and deforestation for agriculture in the tropics. Evaporative Resistance: Evaporative resistance does not directly control the total amount of energy absorbed by the land surface |
| 일반주제명 | Atmospheric sciences. Climate change. |
| 언어 | 영어 |
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