Quantification of Land-surface Heterogeneity
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| Title: | Main Title: Quantification of Land-surface Heterogeneity |
| Description: | Abstract: Land-surface heterogeneity plays an important role in the exchanges between the atmosphere and the land surface. How heterogeneity should be represented in land-surface parameterizations remains a problem that is yet to be satisfactorily solved. It has been identified in earlier studies (Avissar and Pielke 1989), (Shao, et al. 2001) that heterogeneity has both “aggregation effect” and “dynamic effect” on the computation of surface fluxes. The aggregation effect occurs because the fluxes estimated using spatially averaged state variables differ from spatially averaged fluxes as a consequence of the non-linear relationships between the fluxes and the state variables. The dynamic effect arises because land-surface heterogeneity can generate turbulence which contributes to turbulent exchanges, but are not accounted for in the parameterizations. The most widely used method for the treatment of land-surface heterogeneity in land-surface schemes is so far the “mosaic” method (Avissar and Pielke 1989), (Koster 1992) in which land-surface cells with the same properties are grouped into patches for which the fluxes are then computed. By using this method, the importance of the land-surface properties is recognised, but the spatial variations of the atmospheric variables and the dynamic effects associated with land-surface heterogeneity are neglected. More recently, a down-scaling technique (Schomburg, et al. 2010) has been developed to account for the effect of land-surface heterogeneity on the atmosphere. However, this technique is mainly a statistical manipulation of the data and is not sufficient to well represent the dynamic effect. What is then land-surface heterogeneity and how can it be quantified? These questions must be first clarified to study the heterogeneity influences on the atmospheric motions. The meaning of heterogeneity is often not exactly clear when the word is used. Nevertheless, several methods have been proposed to quantify land-surface heterogeneity, including spectral analysis [e.g. (Wu 2004)] and wavelets analysis (Brunsell 2011). While these methods are useful in quantifying some aspects of land-surface heterogeneity, they have in each of them critical deficits. In this study, we will first provide a systematic review of the methods used so far for the characterization of land-surface heterogeneity. We will then propose a new method for the quantification of land-surface heterogeneity, which combines the ideas of Shannon entropy and wavelet analysis. We show that to this end more than one parameter is needed. A closely related question to land-surface heterogeneity is how heterogeneity propagates in the atmosphere and which scales of heterogeneity are important. Some work has been done in this regard by several research groups [e.g. (Huang and Margulis 2009), (Brunsell 2011) and (Liu, et al. 2012)]. However, this question should not be the focus of this paper, but will be investigated in detail in a study to follow. |
Responsible Party
| Creator: | Michael Hintz (Author) |
| Publisher: | CRC/TR32 Database (TR32DB) |
| Publication Year: | 2013 |
Topic
| TR32 Topic: | Atmosphere |
| Related Subproject: | D6 |
| Subject: | Keyword: PhD Report |
File Details
| Filename: | Report3_Hintz_2012.pdf |
| Data Type: | Text - Text |
| File Size: | 1.2 MB |
| Date: | Available: 30.09.2012 |
| Mime Type: | application/pdf |
| Data Format: | |
| Language: | English |
| Status: | Completed |
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| Download Permission: | Only Project Members |
| General Access and Use Conditions: | According to the TR32DB data policy agreement. |
| Access Limitations: | According to the TR32DB data policy agreement. |
| Licence: | [TR32DB] Data policy agreement |
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Specific Information - Report
| Report Date: | 30th of September, 2012 |
| Report Type: | PhD Report |
| Report City: | Cologne, Germany |
| Report Institution: | Institute of Geophysics and Meteorology, University Cologne |
| Number of Pages: | 12 (1 - 12) |
| Further Information: | TR32 Student Report Phase II |
Metadata Details
| Metadata Creator: | Michael Hintz |
| Metadata Created: | 04.12.2013 |
| Metadata Last Updated: | 04.12.2013 |
| Subproject: | D6 |
| Funding Phase: | 2 |
| Metadata Language: | English |
| Metadata Version: | V50 |
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| Page Visits: | 626 |
| Metadata Downloads: | 0 |
| Dataset Downloads: | 1 |
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