Performance of surface radiation products of Greenland Ice Sheet using in-situ measurements

Radiation is the direct energy source of the surface natural environment and the main driving force of climate change.It has increasingly become an important meteorological factor affecting the surface heat exchange and glacier mass balance,especially in the glacier changes of the Greenland Ice Sheet(Gr IS).Due to the harsh climatic conditions of Gr IS and sparse observed data,it has become an important way to obtain radiation data from reanalysis datasets.However,the applicability of these radiation data on Gr IS is uncertain and worth exploring.In this work,we evaluate five reanalysis datasets(the fifth generation of European Centre for Medium-Range Weather Forecasts(ERA5),European Centre for Medium-Range Weather Forecasts Interim Reanalysis(ERA-Interim),Japanese 55-year Reanalysis(JRA55),National Centers for Environmental Prediction Reanalysis II(NCEP2)and Modern-Era Retrospective analysis for Research and Applications,Version 2(MERRA-2))during 1997-2022 using observations from 26 Program for Monitoring the Greenland Ice Sheet(PROMICE)automatic weather stations(AWSs)and 3 K-transect AWSs on Gr IS.The conclusions are as follows:ERA5 has the best performances in downward shortwave radiation(SWD)as well as downward and upward longwave radiation(LWD and LWU),but the performance is not the best in upward shortwave radiation(SWU).Based on the radiation budget analysis with ERA5 during 1979-2022,the fluctuation of longwave radiation is greater than that of shortwave radiation.The seasonal variation of shortwave radiation is obvious,while that of longwave radiation is small.The increasing trend of longwave radiation may result from global warming,in which ice sheets absorb more solar radiation and the surface heats up significantly,emitting more LWU.

Spatial variability of glacial changes and their effects on water resources in the Chinese Tianshan Mountains during the last five decades

Changes in glaciers in the Chinese Tianshan Mountains have been analyzed previously. However, most previous studies focused on individual glaciers and/or decentralized glacial basins. Moreover, a majority of these studies were published only in Chinese, which limited their usefulness at the international level. With this in mind, the authors reviewed the previous studies to create an overview of glacial changes in the Chinese Tianshan Mountains over the last five decades and discussed the effects of glacial changes on water resources. In response to climate change, glaciers in the Tianshan Mountains are shrinking rapidly and are ca. 20% smaller on average in the past five decades. Overall, the area reduction of glacial basins in the central part of the Chinese Tianshan Mountains is larger than that in the eastern and western parts. The spatial differentiation in glacial changes are caused by both differences in regional climate and in glacial factors. The effects of glacial changes on water resources vary in different river basins due to the differences in glacier distribution, characteristics of glacial change and proportion of the glacier meltwater in river runoff.

RS analysis of glaciers change in the Heihe River Basin, Northwest China, during the recent decades

Heihe 河盆是在西北中国的第二最大的内陆河盆，它也是在干旱水文学，水资源和在冷区域的研究的另外的方面的一个热点。另外， Heihe 河盆有完全的风景，中等分水岭尺寸，和典型社会生态的环境问题。到目前为止，没有对整个河盆的冰河变化信息的详细评价。地志的地图数据， Landsat TM/ETM+ 遥感图象和数字举起建模的 1:50,000 数据在这研究被使用。通过综合计算机自动解释和视觉解释方法，面向对象的图象特征抽取方法被使用提取冰河轮廓信息。冰河变化数据从分析被导出，并且到气候的冰河变化和它的反应在时期 1956/19632007/2011 变化也被分析。结果显示出那：(1 ) 在时期 1956/19632007/2011， Heihe 河盆冰河有一个明显的撤退趋势，冰河的全部的区域从 361.69 km 减少了 < 啜 class= “ a-plus-plus ” > 2 到 231.17 km < 啜 class= “ a-plus-plus ” > 2 ；以 36.08% 的率缩小，与平均单个冰河区域减少 0.14 km < 啜 class= “ a-plus-plus ” > 2 ；冰河的全部的数字从 967 ～ 800 减少了。(2 ) 在这盆的冰河主要在 43004400 m， 44004500 m 和 45004600 m 的举起被散布；并且在冰河分发和冰河变化有重要地区性的差别。(3 ) 与另外的西方的山冰河相比，在 Heihe 河盆的冰河撤退有更高的率。(4 ) 六个气象学的车站的分析从 1960 ～ 2010 的年度平均温度和降水数据建议吝啬的年度温度显著地增加了，年度降水也显示出一个增加的趋势。冰河收缩是密切相关的，而且，温度升起，这被结束冰河融化由增加的降水由比冰河团供应大的升起的温度引起了到某程度。

How do GPM and TRMM precipitation products perform in alpine regions?A case study in northwestern China's Qilian Mountains

Satellite technologies provide valuable areal precipitation datasets in alpine mountains.However,coarse resolution still limits the use of satellite precipitation datasets in hydrological and meteorological research.We evaluated different time scales and precipitation magnitudes of Tropical Rainfall Measurement Mission 3B43 V7(TRMM)and Global Precipitation Measurement(GPM)products for alpine regions using ground precipitation datasets from January 2015 to June 2019 obtained from 25 national meteorological stations and 11 sets of T-200B weighing precipitation gauges in the Qilian Mountains.The results indicated that GPM outperformed TRMM at all temporal scales at an elevation<3500 m with a higher probability of detection(POD),false alarm ratio(FAR),and frequency bias index(FBI)and performed best at 3000 m;TRMM performed better than GPM at an elevation>3500 m,with the best performance at 4000 m.GPM and TRMM had the best estimation accuracy in areas with monthly precipitation of 30 mm and 40 mm,respectively.Both TRMM and GPM products underestimated mid to large daily precipitation and overestimated light daily precipitation averaging<2 mm/d.This research not only emphasizes the superiority of GPM/TRMM in different regions but also indicates the limitations of precipitation algorithms.