Assimilation of Satellite-Derived Soil Moisture for Improved Forecasts of the Great Plains Low-Level Jet
Assimilation of Satellite-Derived Soil Moisture for Improved Forecasts of the Great Plains Low-Level Jet
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DOI：
10.1175/mwr-d-20-0185.1
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发表时间：
2020-11
影响因子：
3.2
通讯作者：
C. Ferguson;S. Agrawal;M. Beauharnois;G. Xia;D. Burrows;L. Bosart
中科院分区：
文献类型：
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作者：
C. Ferguson;S. Agrawal;M. Beauharnois;G. Xia;D. Burrows;L. Bosart
在预测具有社会影响的大平原低空急流 (GPLLJ) 的背景下，卫星土壤湿度 (SM) 数据同化 (DA) 的潜在附加值很高。 GPLLJ 对区域土壤湿度梯度和恶劣天气（包括中尺度对流系统）的频繁驱动因素都很敏感。一个未经检验的假设是，SM DA 在预测弱天气强迫或非耦合 GPLLJ 方面比在预测气旋引起的耦合 GPLLJ 方面更有效。使用 NASA 统一天气研究和预报 (NU-WRF) 模型，在使用和不使用 NASA 土壤湿度主动被动 SM DA 的情况下，以 9 公里分辨率模拟 75 个 GPLLJ。对大平原中南部的单个急流和急流类型事件子集以及每个 GPLLJ 扇区（入口、核心和出口）的建模 SM、表面感热 (SH) 和潜热 (LH) 通量、2 米温度 (T2)、2 米湿度 (Q2)、PBL 高度 (PBLH) 和 850 hPa 风速 (W850) 的差异进行了量化。在 GPLLJ 核心，SM 中高达 5.4 kg m−2 的 DA 相关变化可导致 T2、Q2、LH、SH、PBLH 和 W850 差异分别为 0.68°C、0.71 g kg−2、59.9 W m−2、52.4 W m−2、240 m 和 4 m s−1。 W850 差异集中在喷流轴上，并且从南向北趋于增加。射流类型差异在 GPLLJ 出口处最为明显，其中 DA 分别增加和减少非耦合和耦合 GPLLJ 中的 W850。数据同化略微减少了所有喷流的负风速偏差，但正如假设的那样，对于非耦合 GPLLJ 的修正更大。
In the context of forecasting societally impactful Great Plains low-level jets (GPLLJs), the potential added value of satellite soil moisture (SM) data assimilation (DA) is high. GPLLJs are both sensitive to regional soil moisture gradients and frequent drivers of severe weather, including mesoscale convective systems. An untested hypothesis is that SM DA is more effective in forecasts of weakly synoptically forced, or uncoupled GPLLJs, than in forecasts of cyclone-induced coupled GPLLJs. Using the NASA Unified Weather Research and Forecasting (NU-WRF) Model, 75 GPLLJs are simulated at 9-km resolution both with and without NASA Soil Moisture Active Passive SM DA. Differences in modeled SM, surface sensible (SH) and latent heat (LH) fluxes, 2-m temperature (T2), 2-m humidity (Q2), PBL height (PBLH), and 850-hPa wind speed (W850) are quantified for individual jets and jet-type event subsets over the south-central Great Plains, as well as separately for each GPLLJ sector (entrance, core, and exit). At the GPLLJ core, DA-related changes of up to 5.4 kg m−2in SM can result in T2, Q2, LH, SH, PBLH, and W850 differences of 0.68°C, 0.71 g kg−2, 59.9 W m−2, 52.4 W m−2, 240 m, and 4 m s−1, respectively. W850 differences focus along the jet axis and tend to increase from south to north. Jet-type differences are most evident at the GPLLJ exit where DA increases and decreases W850 in uncoupled and coupled GPLLJs, respectively. Data assimilation marginally reduces negative wind speed bias for all jets, but the correction is greater for uncoupled GPLLJs, as hypothesized.