Interactions between Taiwan’s Land-Use/Cover Change and Regional Atmospheric and Hydro-Meteorological Modeling and Large-Scale Climate Variability

Assist Prof. Chia-Jeng Chen

Significant land use/cover changes (LUCC), primarily induced by socioeconomic development (anthropogenic forcing) and global climatic/environmental change (natural forcing), could interact directly or indirectly with a region’s weather and climate phenomena. Some of the phenomena could develop into extreme events of which the likelihood could be further increased by continuous LUCC, potentially encumbering the sustainable management ideology of a nation. Taiwan is a representative country devoted to sustainable management, but meanwhile, it has been experiencing tremendous LUCC as well as notable increases in both frequency and severity of hydro-meteorological disasters (e.g., floods and droughts) since the last century. In this context, this research project intends to disclose the implicit interactions between Taiwan’s LUCC and regional atmospheric and hydro-meteorological conditions, and further, the large-scale climate variability by employing broad-spectrum analysis, including analytical, empirical/statistical, and dynamical modeling.

We plan on executing the project by three phases/years. In each phase, several research lines pertaining to distinct spatial and temporal scales will be developed separately; however, along with the progression of these three phases, the separate research lines will be united to answer the following questions:

  1. Has LUCC altered local/regional weather systems (e.g., convective systems in metropolitan areas)?
  2. What is the underlying mechanism of LUCC influenced atmospheric conditions and land-surface fluxes (and/or vice versa)?
  3. If any large-scale circulation patterns that correlate with LUCC-related variables (e.g., temperature, precipitation, sensible and latent heat, and vegetation index), potentially driving the long-term LUCC, can be identified?
  4. If it is possible to further hypothesize the influence of climate variability on LUCC could depict the trend and variation of those transient atmospheric processes in the long run?
  5. Is there any secondary or tertiary impact from LUCC to other environmental systems (e.g., watershed- and metro-scale hydrology)?
  6. Last but not least, to leverage the discussion and findings regarding the above questions to quantify the future interactions between land use/cover and atmospheric dynamics under climatic change.

To carry out the above discussion, this project comprises the following components that will be conducted.

In Phase I, 1) analytical and statistical analysis of the relationship between LUCC and the dynamics of thermal environment at target weather stations in Taiwan from the 1950s to 2010s; and 2) empirical analysis (e.g., EOF, SVD, and composites) of the correlation between climate indices (teleconnections) and the LUCC-related variables at the target stations and extended watersheds;

In Phase II, 3) similar empirical analysis to (2) but for the dynamic LUCC statistics provided by other sub-projects and discuss the inner correlation between the LUCC-related variables and LUCC statistics; and 4) preparation, offline (uncoupled, with prescribed forces) runs on WRF, Noah, WRF-Hydro, and SWMM for the understanding of the first-order impacts of LUCC on changes in surface temperature, precipitation, fluxes, and hydrological responses;

In Phase III, 5) coupled WRF-Noah, WRF-Hydro, and WRF-SWMM simulations to explore the relationships (and underlying mechanism) between LUCC, atmospheric convection (found from the statistical approach), and hydrological responses; and 6) integrated efforts based on Components 1–5 into the seamless prediction of future land use/cover and atmospheric dynamics.

台灣土地利用與覆蓋變遷與區域大氣與水文氣象及大尺度氣候變異之交互作用

由社會經濟發展與全球氣候及環境變遷而導致區域的土地利用與覆蓋變遷(Land Use/Cover Change, LUCC),可與該區域的氣象與氣候現象產生直接或間接的交互作用。本研究計畫欲探究台灣LUCC與區域大氣與水文氣象條件至大尺度氣候變異之間的交互作用,將利用多元的分析手段,包含解析函數、經驗或統計模式、以及動力模式等。

本計畫預計為三年期,為論證處於各種時空尺度的問題,將各期的研究子題大項設定為:於第一期,將進行1) 解析函數與統計分析用於探究長期LUCC與環境熱動力在台灣各氣象測站之關係;2) 經驗分析(如正交經驗函數、奇異值分解、與合成分析等)用於探究氣候遙相關(teleconnection)與LUCC關係變量於標的測站至延伸的集水區範圍之相關性;於第二期,3) 如2) 之經驗分析但針對由其他子計畫提供的動態LUCC統計量並探討其與LUCC關係變量之相關性;4) 各模式(WRF、Noah、WRF-Hydro、與SWMM)之預備與離線運行(offline;無耦合並給定驅動條件)用於瞭解第一階(first-order)的LUCC帶給地表溫度、降水、通量、與水文反饋之衝擊;於第三期,5) 各模式的耦合運行用於深度發掘LUCC、大氣對流、與水文反饋之間的交互作用及物理機制;6) 整合前五子題的結果運用於未來土地利用與覆蓋及大氣動力的無縫預報。

俟完成本研究計畫將帶給社經及科研領域正面影響,包含本計畫會1)啟發瞭解關於台灣土地利用與覆蓋變遷與水文氣象及全球大氣環流的多元物理機制、2)展現跨領域(包含氣象、水文、地理、水與環境、經濟、城鄉規劃、園藝等學者專家)的合作精神與成果、3)基於研究成果提供建議於未來國土發展與管理策略。