Effect of land cover classification map resolution in land surface modeling studies

2007-12-10
Yılmaz, Mustafa Tuğrul
Shrestha, Roshan
Evapotranspiration, soil moisture and surface temperature are the key variables controlling the partitioning of energy and water fluxes at the land surface. Over the last two decades, satellite data have been used to constrain these variables in land surface models using data assimilation and parameter calibration methods. For example, the Noah land surface model uses satellite-based land cover information to estimate vegetation parameters and improve its predictions. For simplicity, coarse resolution land cover maps are often used across a range of model resolutions. This study focused on the effect of using coarse spatial resolution land cover classification (LCC) remote- sensing images in land surface models. It was hypothesized that a scaling-threshold exists where high resolution variability is averaged out that can result in significant model prediction errors. To test this hypothesis, a 1 km resolution University of Maryland LCC map was rescaled into several coarser resolution images. Each LCC map was used in a separate Noah model run within the Land Information System modeling framework to estimate evapotranspiration, bare soil evaporation, soil moisture and upper layer soil temperature. Model results were compared using three methods: (1) observing the direct differences; (2) decomposition of the differences into long term, cyclic and random components; and (3) quantifying the overall root mean square error. The direct difference method revealed that increasing biases were introduced as LCC maps were rescaled to coarser resolutions. The decomposition method showed that the magnitude and the sign of the seasonal and annual variations of time series differences are linked to climatological variables like temperature and precipitation. Both methods also showed that land cover sub-pixel variations have strong effects on the direction of the bias introduced by increased heterogeneity. Root mean square error method showed rescaling to coarser resolution increased the overall bias. The hypothesized scaling-threshold was not found. However all methods showed the resulting biases increases as the LCC map rescaling factors increased.

Suggestions

Impacts of climatic variables on water-level variations in two shallow Eastern Mediterranean lakes
Yagbasan, Ozlem; Yazıcıgil, Hasan; Demir, Vahdettin (2017-08-01)
Variations in temperature and precipitation have direct impacts on the physical, chemical and biological characteristics of the shallow lakes. This paper examines the possible linkages between climate variables and the water levels of shallow interconnected Lakes Mogan and Eymir, located 20 km south of Ankara in Central Anatolia. The variations in the lakes' water levels during 1996-2015 are studied and the impacts of climate variables on the lake levels are assessed to address the long-term consequences. T...
Enhancing model-based land surface temperature estimates using multiplatform microwave observations
Holmes, Thomas R. H.; Crow, Wade T.; Yılmaz, Mustafa Tuğrul; Jackson, Thomas J.; Basara, Jeffrey B. (2013-01-01)
Land surface temperature plays an important role in surface processes and is a key input for physically based retrieval algorithms of soil moisture and evaporation. This study presents a framework for using independent estimates of land surface temperature from five microwave satellite sensors to improve the accuracy of land surface temperature output from a numerical weather prediction system in an off-line (postprocessing) analysis. First, structural differences in timing and amplitude of the temperature ...
Effect of Gas Diffusion Layer Characteristics and Addition of Pore-Forming Agents on the Performance of Polymer Electrolyte Membrane Fuel Cells
Senguel, Erce; Erkan, Serdar; Eroğlu, İnci; BAÇ, NURCAN (Informa UK Limited, 2009-01-01)
The performance of five layer membrane electrode assemblies having different characteristics of gas diffusion layers was determined at 70 degrees C cell temperature and ambient pressure. The maximum power density at 0.6 V was 0.36 W/cm(2) for the membrane electrode assembly prepared with the gas diffusion layer having minimum thickness (SGL BC 30 type). On the other hand, the maximum power density at 0.5 V was 0.44 W/cm(2) for the membrane electrode assembly prepared with SGL BC 34 type gas diffusion layer....
Investigation of the impact of the nonlinear relations among soil moisture products over data fusion process
Afshar, Mehdi; Bulut, Burak; Yılmaz, Mustafa Tuğrul (2017-04-28)
Soil moisture is one of the terrestrial essential climate variables that has critical role in the water, energy, and carbon cycles. There are different ways available for the retrieval of this essential variable (e.g., remote sensing, hydrological models, insitu measurements, and etc.). However, the time series of these retrievals often contain systematic differences, which need to be removed via different rescaling approaches before these data sets could be used in data fusion type studies. In this study, ...
Impact of Model Relative Accuracy in Framework of Resealing Observations in Hydrological Data Assimilation Studies
Yılmaz, Mustafa Tuğrul; Ryu, D. (American Meteorological Society, 2016-08-01)
Soil moisture datasets vary greatly with respect to their time series variability and signal-to-noise characteristics. Minimizing differences in signal variances is particularly important in data assimilation to optimize the accuracy of the analysis obtained after merging model and observation datasets. Strategies that reduce these differences are typically based on resealing the observation time series to match the model. As a result, the impact of the relative accuracy of the model reference dataset is of...
Citation Formats
M. T. Yılmaz and R. Shrestha, “Effect of land cover classification map resolution in land surface modeling studies,” presented at the American Geophysical Union Fall Meeting 2007, (10-14 Aralık 2007), 2007, Accessed: 00, 2021. [Online]. Available: https://hdl.handle.net/11511/73781.