An Indirect Data Assimilation Scheme for Deep Soil Temperature in the Pleim-Xiu Land Surface Model
An Indirect Data Assimilation Scheme for Deep Soil Temperature in the Pleim-Xiu Land Surface Model
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DOI：
10.1175/2009jamc2053.1
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发表时间：
2009-07-01
影响因子：
3
通讯作者：
Gilliam, Robert
中科院分区：
文献类型：
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作者：
Pleim, Jonathan E.;Gilliam, Robert
Pleim-Xiu陆面模式（PX LSM）通过增加第二个间接资料同化方案而得到改进。第一，这是前面所描述的，是一种技术，其中土壤水分是轻推根据2米的空气温度和相对湿度之间的模型和观测分析的偏差。新技术涉及轻推深层土壤温度的土壤温度力恢复（FR）模型根据模型偏差在2米的空气温度只有在夜间。虽然FR技术是计算效率高，非常准确的特殊条件下，它是派生，它是非常依赖于深层土壤温度，驱动表层土壤温度方程的恢复项。因此，深层土壤温度的调整，以优化2米的空气温度在夜间，当表面强迫是最小的，提供了显着的优势，比其他方法的深层土壤水分初始化。天气研究和预报模型（WRF）的模拟使用PX LSM与和没有新的深层土壤温度轻推计划证明了新的计划，减少误差和偏差的2米的空气温度的实质性好处。新的推动计划的影响是最明显的冬季（2006年1月），在此期间，模型的冷偏差大大减少。在夏季模拟（2006年8月）中，气温误差和偏差也有所减少，在植被较少和干旱地区受益最大。因此，深层温度推动方案补充了土壤水分推动方案，因为它在土壤水分方案效果最差的条件下最有效，也就是说，当蒸散不重要时（冬季和干旱气候）。
The Pleim-Xiu land surface model (PX LSM) has been improved by the addition of a second indirect data assimilation scheme. The first, which was described previously, is a technique in which soil moisture is nudged according to the biases in 2-m air temperature and relative humidity between the model-and observation-based analyses. The new technique involves nudging the deep soil temperature in the soil temperature force restore (FR) model according to model bias in 2-m air temperature only during nighttime. While the FR technique is computationally efficient and very accurate for the special conditions for which it was derived, it is very dependent on the deep soil temperature that drives the restoration term of the surface soil temperature equation. Thus, adjustment of the deep soil temperature to optimize the 2-m air temperature during the night, when surface forcing is minimal, provides significant advantages over other methods of deep soil moisture initialization. Simulations of the Weather Research and Forecasting Model (WRF) using the PX LSM with and without the new deep soil temperature nudging scheme demonstrate substantial benefits of the new scheme for reducing error and bias of the 2-m air temperature. The effects of the new nudging scheme are most pronounced in the winter (January 2006) during which the model's cold bias is greatly reduced. Air temperature error and bias are also reduced in a summer simulation (August 2006) with the greatest benefits in less vegetated and more arid regions. Thus, the deep temperature nudging scheme complements the soil moisture nudging scheme because it is most effective for conditions in which the soil moisture scheme is least effective, that is, when evapotranspiration is not important (winter and arid climates).