Temporal variation of “solar dimming” induced by composite and carbonaceous aerosols: Observations from mineral‐rich eastern Indian region
Temporal variation of “solar dimming” induced by composite and carbonaceous aerosols: Observations from mineral‐rich eastern Indian region
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DOI：
10.1002/2014jd021483
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发表时间：
2014-05
期刊：
影响因子：
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通讯作者：
R. Latha;B. S. Murthy;K. Lipi;Manoj Kumar;Subrata Kumar Das;N. Mahanti
中科院分区：
文献类型：
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作者：
R. Latha;B. S. Murthy;K. Lipi;Manoj Kumar;Subrata Kumar Das;N. Mahanti
利用太阳天空辐射计和辐射传输模型获得的平均光学特性，计算了2011年2月至2012年1月印度东部兰契地区（23.5°N，85.3°E）月尺度和季节尺度的复合气溶胶和碳气溶胶辐射强迫（RF）。Ranchi位于Chotanagpur高原，平均海拔650米;该地区拥有密集的开放式活动矿山，是煤和石灰石等具有相反光学特性的矿物气溶胶的来源。在0.3-3.0 µm的光谱波段，地面的日平均复合气溶胶RF从冬季（12月、1月、2月）到季风前（3月、4月、5月）增加，3月气溶胶RF最大（−65 Wm−2），与最高的黑碳（BC）气溶胶光学厚度（AOD）0.05相关。7月是气溶胶RF最小值，气溶胶光学厚度和气溶胶光学厚度最小。大气层顶部的气溶胶RF在4月最大（-17 Wm−2），3月为正值（+1.2 Wm−2）。平均而言，含碳气溶胶（BC）贡献约8.8%的总AOD和约60%的总大气吸收。BC在后季风期间迅速增加，9月为1.0 µg m−3，10月为3.0 µg m−3。气溶胶引起的太阳变暗约占地面辐射的9.4%（季风前），7.0%（季风），10.6%（季风后）和10.2%（冬季）。季节平均气溶胶加热率在季风前（~1.15°K/d−1）最大，其次是季风后，而冬季和季风经历最小（~0.45°K/d−1）加热，假设模式的典型气溶胶廓线。
Composite and carbonaceous aerosol radiative forcing (RF) over Ranchi (23.5°N, 85.3°E) in eastern India at monthly and seasonal scales during February 2011 to January 2012 is derived from mean optical properties obtained from Sun‐sky radiometer and a radiative transfer model. Ranchi is located on the Chotanagpur plateau at 650 m above mean sea level; the region is unique with dense open active mines, a source of mineral aerosols with opposing optical properties such as coal and limestone. Diurnal mean composite aerosol RF at the surface, in the spectral band 0.3–3.0 µm increases from winter (December, January, February) to premonsoon (March, April, May) with maximum (−65 Wm−2) aerosol RF in March that is associated with highest black carbon (BC) aerosol optical depth (AOD), 0.05. Minimum surface aerosol RF occurs in July with minimum values of AOD and AODBC. Aerosol RF at top of the atmosphere is maximum (−17 Wm−2) in April, and is positive (+1.2 Wm−2) in March. On an average, carbonaceous aerosols (BC) contribute ~8.8% to total AOD and about 60% to total atmospheric absorption. A rapid increase of BC is seen in the postmonsoon with 1.0 µg m−3 in September to 3.0 µg m−3 in October. Aerosol‐induced solar dimming is about 9.4% (premonsoon), 7.0% (monsoon), 10.6% (postmonsoon), and 10.2% (winter) of the surface radiation. Seasonal mean aerosol heating rate is observed to be maximum in premonsoon (~1.15°K/d−1), followed by postmonsoon, while winter and monsoon experience minimum (~0.45°K/d−1) heating, assuming typical aerosol profiles of the model.