Satellite observations of snowfall regimes over the Greenland Ice Sheet
Satellite observations of snowfall regimes over the Greenland Ice Sheet
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格陵兰冰盖降雪状况的卫星观测
DOI：
10.5194/tc-2019-223
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
T. L’Ecuyer
中科院分区：
文献类型：
--
作者：
E. McIlhattan;C. Pettersen;N. Wood;T. L’Ecuyer
抽象的。格陵兰冰盖（GrIS）的质量正在减少，由于增加表面融化和冰动力。降雪既增加了GrIS的质量，又有能力通过增加表面亮度来减少表面融化，将额外的太阳辐射反射回太空。对GrIS当前和未来的质量平衡以及对未来海平面上升的潜在贡献进行建模，需要对当前降雪积累进行可靠的观测基准，以及单个降雪事件与产生它们的大规模大气环流模式之间的可靠联系。以前的工作使用地面观测表明，一个研究站上的GrIS，两个不同的降雪制度存在：那些与专门的冰相云过程（IC）和那些涉及混合相的过程表明存在过冷液态水（CLW）。这两种机制具有明显不同的积累特征和动力驱动因素。这项研究利用了两个卫星仪器之间的协同作用，CloudSat的云廓线雷达（CPR）和CALIPSO的正交偏振云气溶胶激光雷达（CALIOP），以确定整个GrIS的降雪情况，并将其划分为IC和CLW制度。我们发现，总的来说，大多数CPR观测的降雪在GrIS来自IC事件（70%），然而，在夏季的几个月里，近一半的雪观察到CLW事件（45%）。IC降雪在增加GrIS质量方面起着主导作用，产生了估计的399 Gt yr−1累积总量的约80%。除了定义降雪制度的云相之外，宏观物理云特征也是不同的;平均IC几何云深（104 km）比CLW几何云深（102 km）更深，与以前基于地面观测的研究一致。CPR反射率的垂直分布的二维直方图显示，IC事件表现出一致增加的反射率朝向表面，而CLW事件没有。ERA 5再分析表明，IC事件与气旋活动有关，CLW事件一般发生在GrIS大尺度异常高位势高度下。当与未来的气候预测相结合时，GrIS降雪特征的这一快照可能会揭示这种冰盖质量的来源如何在变暖的气候中对天气模式的变化做出反应。
Abstract. The mass of the Greenland Ice Sheet (GrIS) is decreasing due to increasing surface melt and ice dynamics. Snowfall both adds mass to the GrIS and has the capacity to reduce surface melt by increasing surface brightness, reflecting additional solar radiation back to space. Modeling the GrIS’s current and future mass balance and potential contribution to future sea level rise requires reliable observational benchmarks for current snowfall accumulation as well as robust connections between individual snowfall events and the large-scale atmospheric circulation patterns that produce them. Previous work using ground-based observations showed that, for one research station on the GrIS, two distinct snowfall regimes exist: those associated with exclusively ice-phase cloud processes (IC) and those involving mixed-phase processes indicated by the presence of supercooled liquid water (CLW). The two regimes have markedly different accumulation characteristics and dynamical drivers. This study leverages the synergy between two satellite instruments, CloudSat's Cloud Profiling Radar (CPR) and CALIPSO's Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP), to identify snowfall cases over the full GrIS and partition them into the IC and CLW regimes. We find that, overall, most CPR observations of snowfall over the GrIS come from IC events (70 %); however, during the summer months, close to half of the snow observed is produced in CLW events (45 %). IC snowfall plays a dominant role in adding mass to the GrIS, producing ∼ 80 % of the total estimated 399 Gt yr−1 accumulation. Beyond the cloud phase that defines the snowfall regimes, the macrophysical cloud characteristics are distinct as well; the mean IC geometric cloud depth (∼ 4 km) is deeper than the CLW geometric cloud depth (∼ 2 km), consistent with previous studies based on surface observations. Two-dimensional histograms of the vertical distribution of CPR reflectivities show that IC events demonstrate consistently increasing reflectivity toward the surface while CLW events do not. Analysis of ERA5 reanalyses shows that IC events are associated with cyclone activity and CLW events generally occur under large-scale anomalously high geopotential heights over the GrIS. When combined with future climate predictions, this snapshot of GrIS snowfall characteristics may shed light on how this source of ice sheet mass might respond to changing synoptic patterns in a warming climate.
影响因子：
5.2
作者：
Bamber, J. L.;Griggs, J. A.;Steinhage, D.
通讯作者：
Steinhage, D.
CloudSat 观测显示格陵兰岛降雪的时空变化
影响因子：
6.3
作者：
Bennartz, Ralf;Fell, Frank;Pettersen, Claire;Shupe, Matthew D.;Schuettemeyer, Dirk
通讯作者：
Schuettemeyer, Dirk
DOI：
10.1002/2014jd022079
发表时间：
2014-12
期刊：
Journal of Geophysical Research: Atmospheres
影响因子：
--
作者：
M. Maahn;C. Burgard;S. Crewell;I. Gorodetskaya;S. Kneifel;S. Lhermitte;K. Van Tricht;N. P. M. Lipzig
通讯作者：
M. Maahn;C. Burgard;S. Crewell;I. Gorodetskaya;S. Kneifel;S. Lhermitte;K. Van Tricht;N. P. M. Lipzig