GNSS remote sensing of the Australian tropopause

Radio occultation (RO) techniques that use signals transmitted by Global Navigation Satellite Systems (GNSS) have emerged over the past decade as an important tool for measuring global changes in tropopause temperature and height, a valuable capacity given the tropopause??s sensitivity to temperature variations. This study uses 45,091 RO data from the CHAMP (CHAllenging Minisatellite Payload, 80 months), GRACE (Gravity Recovery And Climate Experiment, 23 months) and COSMIC (Constellation Observing System for Meteorology, Ionosphere, and Climate, 20 months) satellites to analyse the variability of the tropopause??s height and temperature over Australia. GNSS RO temperature profiles from CHAMP, GRACE, and COSMIC are first validated using radiosonde observations provided by the Bureau of Meteorology (Australia). These are compared to RO soundings from between 2001 and 2007 that occurred within 3 h and 100 km of a radiosonde. The results indicate that RO soundings provide data of a comparable quality to radiosonde observations in the tropopause region, with temperature deviations of less than 0.5 ± 1.5 K. An analysis of tropopause height and temperature anomalies indicates a height increase over Australia as a whole of ca. 4.8 ± 1.3 m between September 2001 and April 2008, with a corresponding temperature decrease of ?0.019 ± 0.007 K. A similar pattern of increasing height/decreasing temperature was generally observed when determining the spatial distribution of the tropopause height and temperature rate of change over Australia. Although only a short period has been considered in this study, a function of the operating time of these satellites, the results nonetheless show an increase in the height of the tropopause over Australia during this period and thus may indicate regional warming. Several mechanisms could be responsible for these changes, such as an increase in the concentration of greenhouse gases in the atmosphere, and lower stratospheric cooling due to ozone loss, both of which have been observed during the last decades.     

Quantifying recent precipitation change and predicting lake expansion in the Inner Tibetan Plateau

Lake expansion since the middle of the 1990s is one of the most outstanding environmental change events in the Tibetan Plateau (TP). This expansion has mainly occurred in the Inner TP, a vast endorheic basin with an area of about 708,000 km² and containing about 780 lakes larger than 1 km². The total lake area of the Inner TP has increased from 24,930 km² in 1995 to 33,741 km² in 2015. The variability of the lake area in the coming decades is crucial for infrastructure planning and ecology policy for this remote region. In this study, a lake mass balance model was developed to describe the lake area response to climate change. First, the model was used to inversely estimate the change in precipitation from the change in lake volume. The result shows that precipitation has increased by about 21?±?7% since the middle of the 1990s, as seen in GPCC global data set. Then, the lake size in the coming two decades was predicted by the model driven with either current climate or a projected future climate, showing the lake area would expand continuously, but at a lower rate than before. Both predictions yield a total lake area of 36150?±?500 km² in 2025 and a rise of average lake level by about 6.6?±?0.3 m from 1995 to 2025. However, the two predictions become disparate in the second decade (2026–2035), as the future climate is more warming and wetting than the current climate. It is noted that the prediction of lake expansion is robust for the entire inner TP lake system but not always applicable to individual subregions or specific lakes due to their spatiotemporal heterogeneity.     

Changes of Terrestrial Water Storage in River Basins of China Projected by RegCM4

In this study, a historic simulation covering the period from 1951 to 2000 and three projected scenario simulations covering 2001-2050 were conducted employing the regional climate model RegCM4 to detect the changes of terrestrial water storage (TWS) in major river basins of China, using the Intergovernmental Panel on Climate Change (IPCC) Special Report on Emissions Scenarios (SRES): A1B, A2, and B1. The historic simulation revealed that the variations of TWS, which are dominated by precipitation in the basins, rely highly on their climatic features. Compared with the historic simulation, the changes of TWS in the scenario simulations showed strong regional differences. However, for all scenarios, TWS was found to increase most in Northeast China and surrounding mountains around the Tibetan Plateau, and decrease most in eastern regions of China. Unlike the low seasonal variations of TWS in arid areas, the TWS showed strong seasonal variations in eastern monsoon areas, with the maximum changes usually occurring in summer, when TWS increases most in a year. Among the three scenario simulations, TWS increased most in Songhua River Basin of B1 scenario, and de- creased most in Pearl River Basin of A2 scenario and Hai River Basin of A1B scenario, accompanied by different annual trends and seasonal variations.     

关于我国北方干旱化及其转折性变化

过去半个世纪,中国经历了北方的"西湿东干"和东部的"南涝北旱"的降水分布格局。近十几年来,这种降水长期变化的分布格局是维持还是发生了变化?针对这个问题,本文基于年降水观测数据、自矫正的帕尔默干旱指数scPDSI、地表湿润指数SWI及GRACE（Gravity Recovery and Climate Experiment）卫星数据反演的陆地水储量（TWS）对中国区域干旱化问题进行了再分析。结果表明,近16年（2001~2016年）,中国东部地区（100°E以东）"南涝北旱"的格局正在发生显著的变化,长江上中游及江淮流域已转为显著的干旱化趋势,而华北地区的降水已转为增加趋势,东部"南旱北涝"的格局基本形成;北方过去的"西湿东干"也转变为"西干东湿"的空间分布特征。显然,中国区域的降水格局在2001年后发生了明显的年代尺度转折性变化,两种常用干旱指数scPDSI和SWI的分析也证明了这一点。但GRACE的陆地水储量（TWS）的分析却显示,最近16年来,中国东部"南涝北旱"的格局仍未发生变化,北方大部分地区仍然处于干旱化的时段,且有加剧的趋势,其原因有待于进一步研究。     

Climate change affecting temperature and aridity zones: a case study in Eastern Inner Mongolia, China from 1960–2008

Recent climate change is substantially affecting the spatial pattern of geographical zones, and the temporal and spatial inconsistency of climatic warming and drying patterns contributes to the complexity of the shifting of temperature and aridity zones. Eastern Inner Mongolia, China, located in the interface region of different biomes and ecogeographic zones, has experienced dramatic drying and warming over the past several decades. In this study, the annual accumulated temperature above 10 °C (AAT10) and the aridity index, two key indicators in geographical regionalization, are used to assess warming and drying processes and track the movements of temperature and aridity zones from 1960 to 2008. The results show a significant warming at the regional level from 1960 to 2008 with an AAT10 increase rate of 7.89 °C·d/year (p?<?0.001) in Eastern Inner Mongolia, while the drying trend was not significant during this period. Spatial heterogeneity of warming and drying distributions was also evident. Analysis of warming and drying via piecewise regression revealed two separate, specific trends between the first 31 years (1960–1990) and the subsequent 18 years (1991–2008). Generally, mild warming and very slight wetting occurred prior to 1990, while after 1991 both warming and drying were significant and enhanced. Continuous warming drove a northward shift of temperature zones from the 1960s to 2000s, while aridity zones displayed enhanced temporal and spatial variability. Climate change effects on temperature and aridity zones imply that the patterns of cropping systems, macro-ecosystems, and human land use modes are potentially undergoing migration and modification due to climate change.     

Understanding the impacts of climate change and human activities on streamflow: a case study of the Soan River basin,Pakistan

Urmia Lake, as one of the most valuable saline ecosystems in the world, has faced a sharp drop in the water level in recent years. The trend studies of climatic parameters can be effective in identifying the responsible factors and managing this crisis. This research investigated the frequency trend of daily precipitation in the ranges of less than 5 mm, 5–10 mm, 10–15 mm, 15–20 mm, and more than 20 mm in the Urmia Lake basin. The trend was assessed using Mann-Kendall, Spearman Rho and linear regression tests on 60 stations during a period of 30 years (1981 to 2011). The results showed that in all the three tests, the frequency of daily precipitation of less than 5 mm had a significant increase at 1% level. The 5–10 mm range displayed no significant trend, while the 10–15 mm range showed a significantly decreasing trend. The frequency in the 15–20 mm and above 20 mm ranges showed an insignificant falling trend. The analysis also indicated jumps in 1996 and 1999 (almost coinciding with the sharp drop in the lake’s water level). In other words, the frequency trends of daily precipitation with small amounts (as a result, high evapotranspiration loss) were increasing and with large amounts were decreasing. This can be a contributor to reduced run-off and, hence, decreased water entering the lake. The results emphasize the need for changes in the management and consumption of water resources in the basin, in order to adapt to the climatic change.     

Linking two centuries of tree growth and glacier dynamics with climate changes in Kamchatka

Glaciers around the world retreated as the climate warmed substantially. For the majority of alpine and arctic areas, however, the lack of meteorological data over a long period makes it difficult to build long-term climate and glacial fluctuation relationships, emphasizing the importance of natural proxy archives. Here we use the 230-year record of stem radial growth of birch trees (Betula ermanii) from the treeline forests above the receding glaciers in eastern maritime Kamchatka to analyse temporal variations of climate as well as glacial advance and retreat. Glaciers in Kamchatka Peninsula represent the southern limit of glaciation in far eastern Eurasia, which makes them prone to global warming. Using instrumental climate data (1930–1996) from local meteorological stations, we find that the July temperature had most prominent positive impact on birch growth. On the contrary, smaller ring increments are associated with the positive summer and net annual ice mass balance of Koryto Glacier. The prevailing trend of higher summer temperatures and lower snowfall over the past 70 years has enhanced tree growth while causing the glacier’s surface to lower by about 35 m and its front to retreat by about 490 m. Assuming these same relationships between climate, tree growth, and glacier mass balance also existed in the past, we use tree rings as a proxy record of climatically induced temporary halts in the glacier’s retreat over the past two centuries, which in total was over 1,000 m. Both direct observations and tree ring proxies indicate several prolonged warm periods (1990s, 1960s, 1930–1940s, 1880–1900s) interspersed with cooler periods (1984–1985, 1970–1976, 1953–1957, 1912–1926, 1855–1875, 1830–1845, 1805–1820 and 1770–1780) when the glacier re-advanced, creating several consecutive terminal moraine ridges. We conclude that birch tree-rings are suitable for assessing tree growth/climate/glacial relationships over a longer timescale in maritime Kamchatka.     

Decadal variation of surface solar radiation in the Tibetan Plateau from observations, reanalysis and model simulations

In this study, the annual and seasonal variations of all-sky and clear-sky surface solar radiation (SSR) in the eastern and central Tibetan Plateau (TP) during the period 1960–2009 are investigated, based on surface observational data, reanalyses and ensemble simulations with the global climate model ECHAM5-HAM. The mean annual all-sky SSR series shows a decreasing trend with a rate of ?1.00 Wm^?2 decade^?1, which is mainly seen in autumn and secondly in summer and winter. A stronger decrease of ?2.80 Wm^?2 decade^?1 is found in the mean annual clear-sky SSR series, especially during winter and autumn. Overall, these results confirm a tendency towards a decrease of SSR in the TP during the last five decades. The comparisons with reanalysis show that both NCEP/NCAR and ERA-40 reanalyses do not capture the decadal variations of the all-sky and clear-sky SSR. This is probably due to a missing consideration of aerosols in the reanalysis assimilation model. The SSR simulated with the ECHAM5-HAM global climate model under both all-sky and clear-sky conditions reproduce the decrease seen in the surface observations, especially after 1980. The steadily increasing aerosol optical depth (AOD) at 550 nm over the TP in the ECHAM5-HAM results suggests transient aerosol emissions as a plausible cause.     

Characteristics of Atmospheric Heat Sources in the Tibetan Plateau-Tropical Indian Ocean Region

Investigating the temporal and spatial distributions of the atmospheric heat sources(AHS) over the Tibetan Plateau-Tropical Indian Ocean(TP-TIO) region is of great importance for the understanding of the evolution and development of the South Asian summer monsoon(SASM). This study used the Japanese 55-year Reanalysis(JRA-55) data from 1979 to 2016 and adopted statistical methods to study the characteristics of the AHS between the TP and TIO, and theirs link to the SASM on an interannual scale. The results indicated that the monthly variations of the AHS in the two regions were basically anti-phase, and that the summer AHS in the TP was obviously stronger than that in the TIO. There were strong AHS and atmospheric moisture sink(AMS) centers in both the eastern and western TP in summer. The AHS center in the east was stronger than that in the west, and the AMS centers showed the opposite pattern. In the TIO, a strong AHS center in the northwest-southeast direction was located near 10°S, 90°E.Trend analysis showed that summer AHS in the TIO was increasing significantly, especially before 1998, whereas there was a weakening trend in the TP. The difference of the summer AHS between the TP and TIO(hereafter IQ)was used to measure the thermal contrast between the TP and the TIO. The IQ showed an obvious decreasing trend.After 1998, there was a weak thermal contrast between the TP and the TIO, which mainly resulted from the enhanced AHS in the TIO. The land-sea thermal contrast, the TIO Hadley circulation in the southern hemisphere and the SASM circulation all weakened, resulting in abnormal circulation and abnormal precipitation in the Bay of Bengal(BOB).     

基于多种资料的青藏高原地表感热的对比分析

青藏高原地表感热通量是高原热源的主要分量之一,对高原局地天气系统、我国天气气候以及亚洲季风等都有着重要影响。选取1980～2016年青藏高原的站点资料和ERA-Interim、NCEP1、NCEP2再分析资料,计算高原地表感热通量的分布状况和时间变化特征并对不同资料得到的结果进行比较分析,结果表明:4种资料在夏季的空间分布、年际变化,高原中部的年际变化,以及长期变化趋势上具有较好的一致性,其中ERA-Interim感热资料较优于其他两种再分析资料。青藏高原的地表感热通量分布呈西高东低的特征,年均最大值出现在柴达木盆地,最小值位于贡山;区域平均值春季最大,冬季最小。感热逐月变化呈单峰型分布,不同分区的年际变化均在2001年或2003年由减弱趋势转变为增强趋势。      

Projection of snow cover changes over China under RCP scenarios

Snow cover changes in the middle (2040–2059) and end (2080–2099) of the twenty-first century over China were investigated with a regional climate model, nested within the global model BCC_CSM1.1. The simulations had been conducted for the period of 1950–2099 under the RCP4.5 and RCP8.5 scenarios. Results show that the model perform well in representing contemporary (1986–2005) spatial distributions of snow cover days (SCDs) and snow water equivalent (SWE). However, some differences between observation and simulation were detected. Under the RCP4.5 scenarios, SCDs are shortened by 10–20 and 20–40 days during the middle and end of the twenty-first century, respectively. Whereas simulated SWE is lowered by 0.1–10 mm in most areas over the Tibetan Plateau (TP). On the other hand, the spatial distributions of SWE are reversed between the middle and end terms in the northeast China. Furthermore, compared with the changes of RCP4.5 scenario, SCDs are reduced by 5–20 days in the middle period under RCP8.5 scenario with even larger decreasing amplitude in the end term. SWE was lowered by 0.1–2.5 mm in most areas except the northeast of China in middle term under RCP8.5 scenario. The great center of SCDs and SWE changes are always located over TP. The regional mean of SCDs and SWE for the TP and for China display a declining trend from 2006 to 2099 with more pronounced changes in the TP than in China as a whole. Under the RCP8.5 scenario, the changes are enhanced compared to those under RCP4.5.     

Future change in the frequency of warm and cold spells over Pakistan simulated by the PRECIS regional climate model

Climate change caused by anthropogenic activities has generated a variety of research focusing on investigating the past climate, predicting the future climate and quantifying the change in climate extreme events by using different climate models. Climate extreme events are valuable to evaluate the potential impact of climate change on human activities, agriculture and economy and are also useful to monitor the climate change on global scale. Here, a Regional Climate Model (RCM) simulation is used to study the future variations in the temperature extreme indices, particularly change in frequency of warm and cold spells duration over Pakistan. The analyses are done on the basis of simulating two 30 years simulations with the Hadley Center’s RCM PRECIS, at a horizontal resolution of 50 km. Simulation for the period 1961–1990 represents the recent climate and simulation for the period 2071–2100 represents the future climate. These simulations are driven by lateral boundary conditions from HadAM3P GCM of Hadley centre UK. For the validation of model, observed mean, maximum and minimum temperatures for the period 1961–1990 at all the available stations in Pakistan are first averaged and are then compared with the PRECIS averaged grid-box data. Also the observed monthly gridded data set of Climate Research Unit (UK) data is used to validate the model. Temperature indices in the base period as well as in future are then calculated and the corresponding change is observed. Percentile based spatial change of temperature shows that in summer, increase in daily minimum temperature is more as compared to the increase of daily maximum temperature whereas in winter, the change in maximum temperature is high. The occurrence of annual cold spells shows significantly decreasing trend while for warm spells there is slight increasing trend over Pakistan.     

A mechanism for Atlantic multidecadal variability in the Kiel Climate Model

Atlantic Multidecadal Variability (AMV) is investigated in a millennial control simulation with the Kiel Climate Model (KCM), a coupled atmosphere–ocean–sea ice model. An oscillatory mode with approximately 60 years period and characteristics similar to observations is identified with the aid of three-dimensional temperature and salinity joint empirical orthogonal function analysis. The mode explains 30 % of variability on centennial and shorter timescales in the upper 2,000 m of the North Atlantic. It is associated with changes in the Atlantic Meridional Overturning Circulation (AMOC) of ±1–2 Sv and Atlantic Sea Surface Temperature (SST) of ±0.2 °C. AMV in KCM results from an out-of-phase interaction between horizontal and vertical ocean circulation, coupled through Irminger Sea convection. Wintertime convection in this region is mainly controlled by salinity anomalies transported by the Subpolar Gyre (SPG). Increased (decreased) dense water formation in this region leads to a stronger (weaker) AMOC after 15 years, and this in turn leads to a weaker (stronger) SPG after another 15 years. The key role of salinity variations in the subpolar North Atlantic for AMV is confirmed in a 1,000 year long simulation with salinity restored to model climatology: No low frequency variations in convection are simulated, and the 60 year mode of variability is absent.     

Estimates of twenty-first century sea-level changes for Norway

In this work we establish a framework for estimating future regional sea-level changes for Norway. Following recently published works, we consider how different physical processes drive non-uniform sea-level changes by accounting for spatial variations in (1) ocean density and circulation (2) ice and ocean mass changes and associated gravitational effects on sea level and (3) vertical land motion arising from past surface loading change and associated gravitational effects on sea level. An important component of past and present sea-level change in Norway is glacial isostatic adjustment. Central to our study, therefore, is a reassessment of vertical land motion using a far larger set of new observations from a permanent GNSS network. Our twenty-first century sea-level estimates are split into two parts. Firstly, we show regional projections largely based on findings from the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4) and dependent on the emission scenarios A2, A1B and B1. These indicate that twenty-first century relative sea-level changes in Norway will vary between ?0.2 to 0.3 m (1-sigma ± 0.13 m). Secondly, we explore a high-end scenario, in which a global atmospheric temperature rise of up to 6 °C and emerging collapse for some areas of the Antarctic ice sheets are assumed. Using this approach twenty-first century relative sea-level changes in Norway are found to vary between 0.25 and 0.85 m (min/max ± 0.45 m). We attach no likelihood to any of our projections owing to the lack of understanding of some of the processes that cause sea-level change.     

Snow cover validation and sensitivity to CO2 in the UVic ESCM

Abstract

The University of Victoria's (UVic) Earth System Climate model is used to conduct equilibrium atmospheric CO₂ sensitivity experiments over the range 200–1600 ppm in order to explore changes in northern hemisphere snow cover and feedbacks on terrestrial surface air temperature (SAT). Simulations of warmer climates predict a retreat of snow cover over northern continents, in a northeasterly direction. The decline in northern hemisphere global snow mass is estimated to reach 33% at 600 ppm and 54% at 1200 ppm. In the most northerly regions, annual mean snow depth increases for simulations with CO₂ levels higher than present day. The shift in the latitude of maximum snowfall is estimated to be inversely proportional to the CO₂ concentration. The northern hemisphere net shortwave radiation changes are found to be greater over land than over the ocean, suggesting a stronger albedo feedback from changes in terrestrial snow cover than from changes in sea ice. Results also reveal high sensitivity of the snow mass balance under low CO₂ conditions. The amplification feedback (defined as the zonal SAT anomaly caused by doubling CO₂ divided by the equatorial anomaly) is greatest for scenarios with less than 300 ppm, reaching 1.9 at the pole for 250 ppm. The stronger feedback is attributed to the significant albedo changes over land areas. The simulation with 200 ppm triggers continuous accumulation of snow ('glaciation') in regions which, according to paleo‐reconstructions, were covered by ice during the last glacial cycle (the Canadian Arctic, Scandinavia, and the Taymir Peninsula).     

Moisture variability across China and Mongolia: 1951–2005

Moisture variability across China and Mongolia (hereafter, CM) during 1951–2005 was investigated using the recently developed monthly Palmer Drought Severity Index (PDSI) dataset. In total there are 206 PDSI grid points across CM, based on a 2.5° × 2.5° gridding system. For CM as a whole a significant decreasing trend in mean moisture availability was observed during 1951–2005, but with strong decadal (17.1-year) and interannual (5.0-year, 3.2-year, 2.4–2.8 year) variations. The areas affected by moderate and severe moisture deficit over CM have increased significantly since the mid-1950s. In contrast, there is a significant decreasing trend for areas affected by moderate wetness since the mid-1950s, and no significant trend was found for the areas affected by severe wetness. Ten moisture-related spatial patterns were objectively defined for CM using rotated Empirical Orthogonal Function (REOF) analysis. These patterns are related to distinct geographical areas and are associated with distinct temporal variations. Four of these patterns, in Northeast China (NE), North China (NC), Central China (CC), and East China (EC), generally demonstrate a significant decreasing trend in moisture availability. Two patterns located in western areas of Northwest China (NW) and the Tibetan Plateau (TP) show a significant moisture increase, while four patterns in Mongolia (MN), far western China (FW), South China (SC), and Southwest China (SW) do not have significant moisture trends during 1951–2005. Based on REOF results we propose that CM should be divided into ten coherent moisture divisions. Moisture variations within each division are generally coherent, but may show either similar or contrasting covariability with adjacent divisions.     

Systematic Hydrological Evaluation of the Noah-MP Land Surface Model over China

We evaluate water budget components—namely, soil moisture, runoff, evapotranspiration, and terrestrial water storage (TWS)—simulated by the Noah land surface model with multi-parameterization options (Noah-MP) in China, a large geographic domain challenging for hydrological modeling due to poor observational data and a lack of one single parameterization that can fit for complex hydrological processes. By comparing the model simulations with multi-source reference data, we show that Noah-MP can generally reproduce the overall spatiotemporal patterns of runoff and evapotranspiration over six major river basins, with the annual correlation coefficients generally greater than 0.8 and the Nash–Sutcliffe model efficiency coefficient exceeding 0.5. Among the six basins evaluated, the best model performance is seen over the Huaihe River basin. The temporal trend of the modeled TWS anomalies agrees well with GRACE (Gravity Recovery and Climate Experiment) observations, capturing major flood and drought events in different basins. Experiments with 12 selected physical parameterization options show that the runoff parameterization has a stronger impact on the simulated soil moisture–runoff–evapotranspiration relationships than the soil moisture factor for stomatal resistance schemes, a result consistent with previous studies. Overall, Noah-MP driven by GLDAS forcing simulates the hydrological variables well, except for the Songliao basin in northeastern China, likely because this is a transitional region with extensive freeze–thaw activity, while representations of human activities may also help improve the model performance.     

Observation of new particle formation and growth under cloudy conditions at Gosan Climate Observatory,Korea

Under cloudy conditions at the Gosan Climate Observatory (GCO), Korea, we observed distinct new particle formation and growth (NPF) events from simultaneous co-located measurements of aerosol and cloud profiles, cloud cover, shortwave radiation, and the number concentration and size distribution of aerosols. The high frequency of NPF was observed at GCO under decreased downwelling solar radiation caused by clouds. Although we observed about 15 and 40 % decreases in downwelling surface shortwave radiations, in the presence of thick mid-level (low-level) clouds, on January 28 and 30, 2012, respectively, distinct NPFs with a growth rate of 3.3 (3.9) nm h^?1 were observed. We examined a 4-year series (May 2008 to April 2012) of continuous measurements of the size distribution of aerosol numbers and visually observed cloud cover. We found that approximately 13 % (i.e., 35 days out of 280 days) of total NPF events were observed under cloud-free conditions (i.e., cloud cover of 0/10). About 20 % (i.e., 57 days out of 280 days) of total NPF events occurred under mostly overcast conditions (i.e., cloud cover of 9/10–10/10). Although NPF events occurring under cloudy conditions were also found elsewhere, the frequency of NPF occurring at GCO seems much higher. The average value of relative humidity for the strong-NPF event days is lower than that of the weak and non-NPF event days for all cloud categories. No significant difference in the condensation sink was found among strong-, weak-, and non-NPF days, but the condensation sink showed a slight decreasing tendency with increasing cloudiness. Further investigations on precursor gases and preexisting aerosols under cloudy conditions are needed.     

Precipitation climatically features over the Huai River Basin,China

The temporal and spatial characteristics of precipitation in the HRB (Huai River Basin) were studied using the observation data of monthly precipitation provided by the National Climate Center from 1961–2016 and the NCEP/NCAR global monthly reanalysis data. The results showed that: (1) The precipitation was mainly concentrated in summer, accounting for 52% of the total annual precipitation; there was more precipitation in the south, less in the north, and more in the coastal areas, less in the inland in summer; (2) The precipitation showed obvious decadal variations, especially in summer; the range of variation of most regions is above 140 mm; and significant decadal abrupt changes of precipitation from “abnormally less” to “abnormally more” appeared around 1979.     

Changing inland lakes responding to climate warming in Northeastern Tibetan Plateau

The main portion of Tibetan Plateau has experienced statistically significant warming over the past 50 years, especially in cold seasons. This paper aims to identify and characterize the dynamics of inland lakes that located in the hinterland of Tibetan Plateau responding to climate change. We compared satellite imageries in late 1970s and early 1990s with recent to inventory and track changes in lakes after three decades of rising temperatures in the region. It showed warm and dry trend in climate with significant accelerated increasing annual mean temperature over the last 30 years, however, decreasing periodically annual precipitation and no obvious trend in potential evapotranspiration during the same period. Our analysis indicated widespread declines in inland lake??s abundance and area in the whole origin of the Yellow River and southeastern origin of the Yangtze River. In contrast, the western and northern origin of the Yangtze River revealed completely reverse change. The regional lake surface area decreased by 11,499 ha or 1.72% from the late 1970s to the early 1990s, and increased by 6,866 ha or 1.04% from the early 1990s to 2004. Shrinking inland lakes may become a common feature in the discontinuous permafrost regions as a consequence of warming climate and thawing permafrost. Furthermore, obvious expanding were found in continuous permafrost regions due to climate warming and glacier retreating. The results may provide information for the scientific recognition of the responding events to the climate change recorded by the inland lakes.