Examination of long-wave radiative bias in general circulation models over North Africa during May-July
Examination of long-wave radiative bias in general circulation models over North Africa during May-July
复制标题
5-7月北非大气环流模型中长波辐射偏差的检验
DOI：
10.1002/qj.717
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发表时间：
2010
影响因子：
8.9
通讯作者：
Allan R
中科院分区：
文献类型：
--
作者：
Allan R
通过一系列气候模式和英国气象局全球数值天气预报（NWP）模式模拟，卫星数据被用于量化和检验5 - 7月北非上空发射的长波（LW）辐射的偏倚。与2000年5月至7月在西撒哈拉部分地区的云和地球辐射能系统（CERES）的观测结果相比，基于多个气候模式的集合平均值的模拟高估了晴空长波辐射（LWc），高估了20 W m−2以上，北非地区（20°W - 30°E, 10-40°N）高估了9 W m−2。使用高分辨率哈德利中心全球环境模型（HiGEM）的大气版本进行的实验表明，包括矿物粉尘辐射效应可以消除这种偏差。此外，只有将表面温度和发射率降低到不切实际的程度，才有可能解释偏差的大小。将英国气象局NWP模式的模拟结果与地球同步地球辐射收支（GERB）仪器的卫星观测结果进行比较，表明该模式将北非夏季的LW高估了20-40 W m−2。偏差在2003-2008年期间下降，尽管这可能与模式的改进和卫星时间序列的不均匀性有关。LWc的偏差与臭氧监测仪器（OMI）估计的高气溶胶粉尘负荷一致，包括在GERBILS野外活动期间（2007年6月18日至28日），在20°N， 0-20°W附近，LWc的模式高估大于20 W m - 2， OMI估计的气溶胶光学深度（AOD）大于0.8。在2007年6月18日至21日期间，模式-负- GERB LW偏差约为30 wm - 2，与高AOD一致，尽管云量的差异也影响模式- GERB的差异。版权所有©英国皇家气象学会和英国皇家版权所有，2010
Satellite data are used to quantify and examine the bias in the outgoing long‐wave (LW) radiation over North Africa during May–July simulated by a range of climate models and the Met Office global numerical weather prediction (NWP) model. Simulations from an ensemble‐mean of multiple climate models overestimate outgoing clear‐sky long‐wave radiation (LWc) by more than 20 W m−2relative to observations from Clouds and the Earth's Radiant Energy System (CERES) for May–July 2000 over parts of the west Sahara, and by 9 W m−2for the North Africa region (20°W–30°E, 10–40°N). Experiments with the atmosphere‐only version of the High‐resolution Hadley Centre Global Environment Model (HiGEM), suggest that including mineral dust radiative effects removes this bias. Furthermore, only by reducing surface temperature and emissivity by unrealistic amounts is it possible to explain the magnitude of the bias.Comparing simulations from the Met Office NWP model with satellite observations from Geostationary Earth Radiation Budget (GERB) instruments suggests that the model overestimates the LW by 20–40 W m−2during North African summer. The bias declines over the period 2003–2008, although this is likely to relate to improvements in the model and inhomogeneity in the satellite time series. The bias in LWc coincides with high aerosol dust loading estimated from the Ozone Monitoring Instrument (OMI), including during the GERBILS field campaign (18–28 June 2007) where model overestimates in LWc greater than 20 W m−2and OMI‐estimated aerosol optical depth (AOD) greater than 0.8 are concurrent around 20°N, 0–20°W. A model‐minus‐GERB LW bias of around 30 W m−2coincides with high AOD during the period 18–21 June 2007, although differences in cloud cover also impact the model–GERB differences. Copyright © Royal Meteorological Society and Crown Copyright, 2010