Advances in Meteorology The latest articles from Hindawi © 2017 , Hindawi Limited . All rights reserved. An Efficient T-S Assimilation Strategy Based on the Developed Argo-Extending Algorithm Mon, 16 Oct 2017 08:44:37 +0000 Data assimilation is an efficient technique in the estimation of ocean state, by introducing the benefit of in situ measurements. Considering the insufficiency of the observations, the performance of assimilation with few temperature and salinity (T-S) profiles is not satisfied. To modify the situation, an extending algorithm based on the Argo temperature profile is developed and applied to present more reconstructed information. Meanwhile, when the reconstructed information is assimilated into the ocean model, the accuracy of the outcomes would obtain a notable enhancement. To validate it, an experiment including four cases is conducted based on Regional Ocean Modeling System (ROMS) and 4-dimensional variational method (4DVAR). The comparison with the EN4 dataset shows that the cases assimilated the Argo and the reconstructed temperature profiles are both promoted; the addition of reconstructed temperature profiles does enhance the accuracy; the impact of SST introduced in the extending algorithm process is negligible; the net enhancement of reconstructed temperature profiles is comparable with Argo T-S observations. Finally, the positive impact of the developed algorithm on data assimilation is validated. Chaojie Zhou, Xiaohua Ding, Jie Zhang, Jungang Yang, and Qiang Ma Copyright © 2017 Chaojie Zhou et al. All rights reserved. Composition and Thermal Structure of the Upper Troposphere and Lower Stratosphere in a Penetrating Mesoscale Convective Complex Determined by Satellite Observations and Model Simulations Mon, 16 Oct 2017 00:00:00 +0000 We describe here the composition and thermal structure of the upper troposphere and lower stratosphere during a penetrating mesoscale convective complex (MCC) event that occurred in southern China on 8 June 2009. Our results are based on satellite observations and Weather Research and Forecasting model simulations. Ice-rich and ozone-poor air reached as high as 17 km. The air was −5°C colder inside the mature MCC than outside at the first cold-point tropopause near 17 km, −2°C colder inside the mature MCC than outside at the second cold-point tropopause, and 3°C warmer inside the mature MCC than outside between the two cold-point tropopauses. Corresponding to the temperature structure, there were two lower water vapor contents inside the MCC than outside near 17 km and 19 km while there was a higher water vapor content inside the MCC than outside near 18 km. Chunhua Shi, Wenyi Cai, and Dong Guo Copyright © 2017 Chunhua Shi et al. All rights reserved. A Case Study of Offshore Advection of Boundary Layer Rolls over a Stably Stratified Sea Surface Sun, 15 Oct 2017 09:08:04 +0000 Streaky structures of narrow (8-9 km) high wind belts have been observed from SAR images above the Baltic Sea during stably stratified conditions with offshore winds from the southern parts of Sweden. Case studies using the WRF model and in situ aircraft observations indicate that the streaks originate from boundary layer rolls generated over the convective air above Swedish mainland, also supported by visual satellite images showing the typical signature cloud streets. The simulations indicate that the rolls are advected and maintained at least 30–80 km off the coast, in agreement with the streaks observed by the SAR images. During evening when the convective conditions over land diminish, the streaky structures over the sea are still seen in the horizontal wind field; however, the vertical component is close to zero. Thus advected feature from a land surface can affect the wind field considerably for long times and over large areas in coastal regions. Although boundary layer rolls are a well-studied feature, no previous study has presented results concerning their persistence during situations with advection to a strongly stratified boundary layer. Such conditions are commonly encountered during spring in coastal regions at high latitudes. Nina Svensson, Erik Sahlée, Hans Bergström, Erik Nilsson, Merete Badger, and Anna Rutgersson Copyright © 2017 Nina Svensson et al. All rights reserved. Spatiotemporal High-Resolution Cloud Mapping with a Ground-Based IR Scanner Sun, 15 Oct 2017 00:00:00 +0000 The high spatiotemporal variability of clouds requires automated monitoring systems. This study presents a retrieval algorithm that evaluates observations of a hemispherically scanning thermal infrared radiometer, the NubiScope, to produce georeferenced, spatially explicit cloud maps. The algorithm uses atmospheric temperature and moisture profiles and an atmospheric radiative transfer code to differentiate between cloudy and cloudless measurements. In case of a cloud, it estimates its position by using the temperature profile and viewing geometry. The proposed algorithm was tested with 25 cloud maps generated by the Fmask algorithm from Landsat 7 images. The overall cloud detection rate was ranging from 0.607 for zenith angles of 0 to 10° to 0.298 for 50–60° on a pixel basis. The overall detection of cloudless pixels was 0.987 for zenith angles of 30–40° and much more stable over the whole range of zenith angles compared to cloud detection. This proves the algorithm’s capability in detecting clouds, but even better cloudless areas. Cloud-base height was best estimated up to a height of 4000 m compared to ceilometer base heights but showed large deviation above that level. This study shows the potential of the NubiScope system to produce high spatial and temporal resolution cloud maps. Future development is needed for a more accurate determination of cloud height with thermal infrared measurements. Benjamin Brede, Boris Thies, Jörg Bendix, and Uwe Feister Copyright © 2017 Benjamin Brede et al. All rights reserved. A Case Study of Mass Transport during the East-West Oscillation of the Asian Summer Monsoon Anticyclone Tue, 10 Oct 2017 00:00:00 +0000 We use ERA-Interim reanalysis, MLS observations, and a trajectory model to examine the chemical transport and tracers distribution in the Upper Troposphere and Lower Stratosphere (UTLS) associated with an east-west oscillation case of the anticyclone in 2016. The results show that the spatial distribution of water vapor (H2O) was more consistent with the location of the anticyclone than carbon monoxide (CO) at 100 hPa, and an independent relative high concentration center was only found in H2O field. At 215 hPa, although the anticyclone center also migrated from the Tibetan Mode (TM) to the Iranian Mode (IM), the relative high concentration centers of both tracers were always colocated with regions where upward motion was strong in the UTLS. When the anticyclone migrated from the TM, air within the anticyclone over Tibetan Plateau may transport both westward and eastward but was always within the UTLS. The relative high concentration of tropospheric tracers within the anticyclone in the IM was from the east and transported by the westward propagation of the anticyclone rather than being lifted from surface directly. Air within the relative high geopotential height centers over Western Pacific was partly from the main anticyclone and partly from lower levels. Jiali Luo, Jiayao Song, Hongying Tian, Lei Liu, and Xinlei Liang Copyright © 2017 Jiali Luo et al. All rights reserved. Evaluating the Solar Slowly Varying Component at C-Band Using Dual- and Single-Polarization Weather Radars in Europe Sun, 08 Oct 2017 00:00:00 +0000 Six C-band weather radars located in Europe (Finland, Netherlands, and Switzerland) have been used to monitor the slowly varying solar emission, which is an oscillation with an amplitude of several decibels and a period of approximately 27 days. It is caused by the fact that the number of active regions that enhance the solar radio emission with respect to the quiet component, as seen from Earth, varies because of the Sun’s rotation about its axis. The analysis is based on solar signals contained in the polar volume data produced during the operational weather scan strategy. This paper presents hundreds of daily comparisons between radar estimates and the Sun’s reference signal, during the current active Sun period (year 2014). The Sun’s reference values are accurately measured by the Dominion Radio Astrophysical Observatory (DRAO) at S-band and converted to C-band using a standard DRAO formula. Vertical and horizontal polarization receivers are able to capture the monthly oscillation of the solar microwave signal: the standard deviation of the log-transformed ratio between radars and the DRAO reference ranges from 0.26 to 0.4 dB. A larger coefficient (and a different value for the quiet Sun component) in the standard formula improves the agreement. M. Gabella, A. Huuskonen, M. Sartori, I. Holleman, M. Boscacci, and U. Germann Copyright © 2017 M. Gabella et al. All rights reserved. Climatic Characteristics and Determination Method for Freezing Rain in China Sun, 08 Oct 2017 00:00:00 +0000 The climatic characteristics and temperature profiles of freezing rain in China are analyzed based on the observational data at 650 stations in China from 2000 to 2015. The freezing rain of China is generally in stripe-shape spatial distribution. The stations with freezing rain over 100 station-hours are mainly concentrated at the southeast areas of Southwest China and high-elevation mountainous areas of Eastern China. There are mainly two types of freezing rain temperature profiles, including single-warm-layer profile and double-warm-layer profile. The freezing rain profiles of mountainous area and urban area in Southwest China are similar to each other, and the freezing rain in Central and East China shares the similar single-warm-layer profile. The profiles in South China show the characteristics of freezing rain’s profile in both Southwest China and Central/East China as the position of stations. PA of freezing rain’s profiles is negatively correlated with NA, with correlation coefficients ranging from −0.36 to −0.70. The configuration of weak cold/warm layer (both smaller than 150°C·hPa) is one of major reasons causing frequent freezing rain at mountainous areas of Southwest China. The more obvious the change of NA with the variations of PA is, the more the freezing rain is likely to occur. Yue Zhou, Yanyu Yue, Zhengxu Gao, and Yuehua Zhou Copyright © 2017 Yue Zhou et al. All rights reserved. Climate Change Impact on Monthly Precipitation Wet and Dry Spells in Arid Regions: Case Study over Wadi Al-Lith Basin Wed, 04 Oct 2017 08:15:41 +0000 Durations of monthly precipitation wet and dry spells are calculated using historical records and regional climate model (RCM) simulations for the Wadi Al-Lith basin in western Saudi Arabia. The characteristics of durations of wet and dry spells are based on the 50% risk level corresponding to the monthly records for average regional precipitation. The duration of wet spells in the model data is compared with observations for the base period 1971–2000. The impact of climate change on the durations of wet and dry spells is obtained using three global climate models projections with RCP4.5 and RCP8.5 scenarios downscaled by RCM. The probability distribution functions (PDFs) of the climate model scenarios and the precipitation records for the base period prove that climate change has a clear impact on the durations of wet and dry spells over the study area. There is an increase in wet spells frequency in the far future (2070–2099) compared to the near future (2020–2049). The increase in wet spells can be partly explained by the increase in extreme rainfall events and by the decrease in dry spells expected to occur over the study area towards the end of 21st century. Mansour Almazroui, Khaled S. Balkhair, M. Nazrul Islam, and Zekai Şen Copyright © 2017 Mansour Almazroui et al. All rights reserved. Verification for Different Contrail Parameterizations Based on Integrated Satellite Observation and ECMWF Reanalysis Data Sun, 01 Oct 2017 10:58:35 +0000 Aviation induced cloud termed contrail plays a more and more important role in the climate change, which makes a significant contribution to anthropogenic climate forcing through impacting the coverage of cirrus in the intersection of troposphere and stratosphere. In this paper, we propose one novel automatic contrail detecting method based on Himawari-8 stationary satellite imagery and two kinds of potential contrail coverage (PCC1 and PCC2) from contrail parameterization in ECHAM4 and HadGEM2. In addition, we propose one new climatological index called contrail occurrence and persistence (COP). According to the algorithm identification (AI) and artificial visual inspection (AVI), COP measured from Himawari-8 stationary satellite imagery is related to upper tropospheric relative humidity over ice (RHI) computed with the ECMWF reanalysis data by simple linear regression. Similarly, we compared the linear correlation between COP and PCCs fractions and found that PCC1 has better correspondence with COP than PCC2. Jinglin Zhang, Jian Shang, and Guoyu Zhang Copyright © 2017 Jinglin Zhang et al. All rights reserved. Comparison of the Long-Range Climate Memory in Outgoing Longwave Radiation over the Tibetan Plateau and the Indian Monsoon Region Thu, 28 Sep 2017 12:54:35 +0000 Based on the detrended fluctuation analysis (DFA) method, scaling behaviors of the daily outgoing longwave radiation (OLR) from 1979 to 2015 over the Tibetan Plateau (TP) and the Indian Monsoon Region (IMR) are analyzed. The results show that there is long-term memory for the OLR time series over the TP and IMR. The long-range memory behaviors of OLR over TP are stronger than those over IMR. The averaged values of the scaling exponents over TP and IMR are 0.71 and 0.64; the maximum values in the two regions are 0.81 and 0.75; the minimum values are 0.59 and 0.58. The maximum frequency counts for scaling exponents occur in the range of 0.625 and 0.675 both in TP and in IMR. The spatial distribution of the scaling exponents of the OLR sequence is closely related to the conditions of climatic high cloud cover in the two areas. The high cloud cover over TP is obviously less than that of IMR. In addition, the scaling behaviors of OLR over TP and IMR are caused by the fractal characteristics of time series, which is further proved by randomly disrupting the time series to remove trends and correlation. Zhongping Shen, Jun Shi, and Yadong Lei Copyright © 2017 Zhongping Shen et al. All rights reserved. Evaluation of the Impact of Argo Data on Ocean Reanalysis in the Pacific Region Thu, 28 Sep 2017 08:57:34 +0000 Observing System Simulation Experiments (OSSEs) have been conducted to evaluate the effect of Argo data assimilation on ocean reanalysis in the Pacific region. The “truth” is obtained from a 5-year model integration from 2003 to 2007 based on the MIT general circulation model with the truly varying atmospheric forcing. The “observations” are the projections of the truth onto the observational network including ocean station data, CTD, and various BTs and Argo, by adding white noise to simulate observational errors. The data assimilation method employed is a sequential three-dimensional variational (3D-Var) scheme within a multigrid framework. Results show the interannual variability of temperature, salinity, and current fields can be reconstructed fairly well. The spread of temperature anomalies in the tropical Pacific region is also able to be reflected accurately when Argo data is assimilated, which may provide a reliable initial field for the forecast of temperature and currents for the subsurface in the tropical Pacific region. The adjustment of salinity by using T-S relationship is vital in the tropical Pacific region. However, the adjustment of salinity is almost meaningless in the northwest Pacific if Argo data is included during the reanalysis. Xuefeng Zhang, Chaohui Sun, Chang Liu, Lianxin Zhang, Caixia Shao, Xiaoshuang Zhang, and Yuxin Zhao Copyright © 2017 Xuefeng Zhang et al. All rights reserved. A New Method for Evaporation Modeling: Dynamic Evolving Neural-Fuzzy Inference System Wed, 27 Sep 2017 09:06:23 +0000 Evaporation estimation is very essential for planning and development of water resources. The study investigates the ability of new method, dynamic evolving neural-fuzzy inference system (DENFIS), in modeling monthly pan evaporation. Monthly maximum and minimum temperatures, solar radiation, wind speed, and relative humidity data obtained from two stations located in Turkey are used as inputs to the models. The results of DENFIS method were compared with the classical adaptive neural-fuzzy inference system (ANFIS) by using root mean square error (RMSE), mean absolute relative error (MARE), and Nash-Sutcliffe Coefficient (NS) statistics. Cross validation was applied for better comparison of the models. The results indicated that DENFIS models increased the accuracy of ANFIS models to some extent. RMSE, MARE, and NS of the ANFIS model were increased by 11.13, 11.45, and 6.83% for the Antalya station and 20.11, 12.94%, and 8.29% for the Antakya station using DENFIS. Ozgur Kisi, Iman Mansouri, and Jong Wan Hu Copyright © 2017 Ozgur Kisi et al. All rights reserved. Downscaling of Open Coarse Precipitation Data through Spatial and Statistical Analysis, Integrating NDVI, NDWI, Elevation, and Distance from Sea Wed, 27 Sep 2017 00:00:00 +0000 This study aims to improve the statistical spatial downscaling of coarse precipitation (TRMM 3B43 product) and also to explore its limitations in the Mediterranean area. It was carried out in Morocco and was based on an open dataset including four predictors (NDVI, NDWI, DEM, and distance from sea) that explain TRMM 3B43 product. For this purpose, four groups of models were established based on different combinations of the four predictors, in order to compare from one side NDVI and NDWI based models and the other side stepwise with multiple regression. The models that have given rise to the best approximations and best fits were used to downscale TRMM 3B43 product. The resulting downscaled and calibrated precipitations were validated by independent RGS. Aside from that, the limitations of the proposed approach were assessed in five bioclimatic stages. Furthermore, the influence of the sea was analyzed in five classes of distance. The findings showed that the models built using NDVI and NDWI have a high correlation and therefore can be used to downscale precipitation. The integration of elevation and distance improved the correlation models. According to , RMSE, bias, and MAE, the study revealed that there is a great agreement between downscaled precipitations and RGS measurements. In addition, the analysis showed that the contribution of the variable (distance from sea) is evident around the coastal area and decreases progressively. Likewise, the study demonstrated that the approach performs well in humid and arid bioclimatic stages compared to others. Hicham Ezzine, Ahmed Bouziane, Driss Ouazar, and Moulay Driss Hasnaoui Copyright © 2017 Hicham Ezzine et al. All rights reserved. Impact of Ozone Valley over the Tibetan Plateau on the South Asian High in CAM5 Tue, 26 Sep 2017 09:13:54 +0000 Local climate effects of Tibetan Plateau Ozone Valley (OVTP) were investigated by numerical simulations using Community Atmosphere Model version 5.1.1 (CAM5). After a 20-year spin-up period, two additional 10-year experiments were conducted. CAM5 was driven by monthly mean climatological ozone in control experiment (CE) and OVTP in the sensitivity experiment (SE) was removed from May to September. After the removal of OVTP, South Asian High (SAH) becomes more robust and colder from June to August, especially in June. The reason for enhancement of SAH is that removal of OVTP increasing ozone in 200–30 hPa leads to significant enhancement of longwave and shortwave radiative heating rate in SAH region in June, and then enhancement of horizontal divergence resulting from the radiative warming leads to strengthening of SAH influenced by the Coriolis force, while the colder SAH is primarily caused by dynamic processes. Adiabatic expansion and ascending movement mainly bring about temperature decrease in SAH after OVTP removal, but the thermodynamic process related to radiative heating offsets part of the cooling response. Zhenkun Li, Hao Qin, Dong Guo, Shunwu Zhou, Ying Huang, Yucheng Su, Linwei Wang, and Yang Sun Copyright © 2017 Zhenkun Li et al. All rights reserved. Separation of the Climatic and Land Cover Impacts on the Flow Regime Changes in Two Watersheds of Northeastern Tibetan Plateau Tue, 26 Sep 2017 07:29:10 +0000 Assessment of the effects of climate change and land use/cover change (LUCC) on the flow regimes in watershed regions is a fundamental research need in terms of the sustainable water resources management and ecosocial developments. In this study, a statistical and modeling integrated method utilizing the Soil and Water Assessment Tool (SWAT) has been adopted in two watersheds of northeastern Tibetan Plateau to separate the individual impacts of climate and LUCC on the flow regime metrics. The integrated effects of both LUCC and climate change have led to an increase in the annual streamflow in the Yingluoxia catchment (YLC) region and a decline in the Minxian catchment (MXC) region by 3.2% and 4.3% of their total streamflow, respectively. Climate change has shown an increase in streamflow in YLC and a decline in MXC region, occupying 107.3% and 93.75% of the total streamflow changes, respectively, a reflection of climatic latitude effect on streamflow. It is thus construed that the climatic factors contribute to more significant influence than LUCC on the magnitude, variability, duration, and component of the flow regimes, implying that the climate certainly dominates the flow regime changes in northeastern Tibetan Plateau. Linshan Yang, Qi Feng, Zhenliang Yin, Ravinesh C. Deo, Xiaohu Wen, Jianhua Si, and Changbin Li Copyright © 2017 Linshan Yang et al. All rights reserved. Impacts of Microphysics Schemes and Topography on the Prediction of the Heavy Rainfall in Western Myanmar Associated with Tropical Cyclone ROANU (2016) Mon, 25 Sep 2017 00:00:00 +0000 The impacts of different microphysics and boundary schemes and terrain settings on the heavy rainfall over western Myanmar associated with the tropical cyclone (TC) ROANU (2016) are investigated using the Weather Research and Forecasting (WRF) model. The results show that the microphysics scheme of Purdue Lin (LIN) scheme produces the strongest cyclone. Six experiments with various combinations of microphysics and boundary schemes indicated that a combination of WRF Single-Moment 6-class (WSM6) scheme and Mellor-Yamada-Janjic (MYJ) best fits to the Joint Typhoon Warning Center (JTWC) data. WSM6-MYJ also performs the best for the track and intensity of rainfall and obtains the best statistics skill scores in the range of maximum rainfall intensity for 48-h. Sensitivity experiments on different terrain settings with Normal Rakhine Mountain (NRM), with Half of Rakhine Mountain (HRM), and Without Rakhine Mountain (WoRM) are designed with the use of WSM6-MYJ scheme. The track of TC ROANU moved northwestward in WoRM and HRM. Due to the presence of Rakhine Mountain, TC track moved into Myanmar and the peak rainfall occurred on the leeward side of the Mountain. In the absence of Rakhine Mountain, a shift in peak rainfall was observed in north side of the Mountain. Khin Win Maw and Jinzhong Min Copyright © 2017 Khin Win Maw and Jinzhong Min. All rights reserved. Probabilistic Interval Forecasts: An Individual Differences Approach to Understanding Forecast Communication Sun, 24 Sep 2017 10:46:34 +0000 Predictive interval forecasts, showing a range of values with specified probability, have the potential to improve decisions compared to point estimates. The research reported here demonstrates that this advantage extends from college undergraduates to a wide user group and does not depend on education. In two experiments, participants made decisions based on predictive intervals or point estimates and answered questions about them. In Experiment , they also completed numeracy and working memory span tests. Those using predictive intervals were better able to identify situations requiring precautionary action. Nonetheless, two errors were noted: (1) misinterpreting predictive intervals as diurnal fluctuation (deterministic construal errors) and (2) judging the probability of events within and beyond the interval, when asked about them separately, as greater than 100%. These errors were only partially explained by WMS and numeracy. Importantly, omitting visualizations eliminated deterministic construal errors and overestimation of percent chance was not consistently related to decision quality. Thus, there may be important benefits to predictive interval forecasts that are not dependent on a full understanding of the theoretical principles underlying them or an advanced education, making them appropriate for a broad range of users with diverse backgrounds, weather concerns, and risk tolerances. Margaret A. Grounds, Susan Joslyn, and Kyoko Otsuka Copyright © 2017 Margaret A. Grounds et al. All rights reserved. Comparison of Chebyshev and Legendre Polynomial Expansion of Phase Function of Cloud and Aerosol Particles Mon, 18 Sep 2017 00:00:00 +0000 Chebyshev and Legendre polynomial expansion is used to reconstruct the Henyey-Greenstein phase function and the phase functions of spherical and nonspherical particles. The result of Legendre polynomial expansion is better than that of Chebyshev polynomial for around 0-degree forward angle, while Chebyshev polynomial expansion produces more accurate results in most regions of the phase function. For large particles like ice crystals, the relative errors of Chebyshev polynomial can be two orders of magnitude less than those of Legendre polynomial. Feng Zhang, Kun Liu, Quan Yang, Kun Wu, and Jian-Qi Zhao Copyright © 2017 Feng Zhang et al. All rights reserved. Cloud Base Height Estimation from ISCCP Cloud-Type Classification Applied to A-Train Data Thu, 14 Sep 2017 07:12:22 +0000 Cloud base height (CBH) is an important cloud macro parameter that plays a key role in global radiation balance and aviation flight. Building on a previous algorithm, CBH is estimated by combining measurements from CloudSat/CALIPSO and MODIS based on the International Satellite Cloud Climatology Project (ISCCP) cloud-type classification and a weighted distance algorithm. Additional constraints on cloud water path (CWP) and cloud top height (CTH) are introduced. The combined algorithm takes advantage of active and passive remote sensing to effectively estimate CBH in a wide-swath imagery where the cloud vertical structure details are known only along the curtain slice of the nonscanning active sensors. Comparisons between the estimated and observed CBHs show high correlation. The coefficient of association () is 0.8602 with separation distance between donor and recipient points in the range of 0 to 100 km and falls off to 0.5856 when the separation distance increases to the range of 401 to 600 km. Also, differences are mainly within 1 km when separation distance ranges from 0 km to 600 km. The CBH estimation method was applied to the 3D cloud structure of Tropical Cyclone Bill, and the method is further assessed by comparing CTH estimated by the algorithm with the MODIS CTH product. Yao Liang, Xuejin Sun, Steven D. Miller, Haoran Li, Yongbo Zhou, Riwei Zhang, and Shaohui Li Copyright © 2017 Yao Liang et al. All rights reserved. Error Analysis and Evaluation of the Latest GSMap and IMERG Precipitation Products over Eastern China Wed, 06 Sep 2017 10:47:03 +0000 The present study comprehensively analyzes error characteristics and performance of the two latest GPM-era satellite precipitation products over eastern China from April 2014 to March 2016. Analysis results indicate that the two products have totally different spatial distributions of total bias. Many of the underestimations for the GSMap-gauged could be traced to significant hit bias, with a secondary contribution from missed precipitation. For IMERG, total bias illustrates significant overestimation over most of the eastern part of China, except upper reaches of Yangtze and Yellow River basins. GSMap-gauged tends to overestimate light precipitation (<16 mm/day) and underestimate precipitation with rain rate larger than 16 mm/day; however, IMERG underestimates precipitation at rain rate between 8 and 64 mm/day and overestimates precipitation at rain rate more than 64 mm/day. IMERG overestimates extreme precipitation indices (RR99P and R20TOT), with relative bias values of 17.9% and 11.5%, respectively. But GSMap-gauged shows significant underestimation of these indices. In addition, both products performed well in the Huaihe, Liaohe, and Yangtze River basins for extreme precipitation detection. At basin scale comparisons, the GSMap-gauged data has a relatively higher accuracy than IMERG, especially at the Haihe, Huaihe, Liaohe, and Yellow River basins. Shaowei Ning, Fan Song, Parmeshwar Udmale, Juliang Jin, Bhesh Raj Thapa, and Hiroshi Ishidaira Copyright © 2017 Shaowei Ning et al. All rights reserved. Extreme Precipitation and Floods: Monitoring, Modelling, and Forecasting Wed, 30 Aug 2017 06:34:43 +0000 Zheng Duan, Hongkai Gao, and Mouleong Tan Copyright © 2017 Zheng Duan et al. All rights reserved. The Relationship between Polar Vortex and Ozone Depletion in the Antarctic Stratosphere during the Period 1979–2016 Tue, 29 Aug 2017 08:19:29 +0000 As the most prominent feature of the polar stratosphere, polar vortex results in widespread changes in the climate system, especially in the ozone variation. In this study, the linkage between polar vortex and ozone depletion in Antarctic stratosphere during the period 1979–2016 is investigated; we calculated the averaged total column ozone within the polar vortex based on the vortex edge (−28.8 PVU PV contour) instead of the geographical region defined by latitude and longitude. Results from the spatial patterns of ozone and polar vortex suggest that the morphological changes of polar vortex can impact the horizontal distribution of ozone and the ozone within the polar vortex experiences a severe depletion in spring. The negative relationship between ozone and polar vortex in terms of vortex area, strength, and breakup time is significant with the correlation coefficients of −0.57, −0.68, and −0.76, respectively. The breakup time of polar vortex plays an important role in the relation between polar vortex and ozone depletion with the highest-value correlation coefficient among three polar vortex parameters. Furthermore, the possible mechanism for this relationship is also discussed in this article. Yu Zhang, Jing Li, and Libo Zhou Copyright © 2017 Yu Zhang et al. All rights reserved. Vegetation Dynamics and Their Response to Climatic Variability in China Tue, 29 Aug 2017 07:23:41 +0000 Based on SPOT VEGETATION data and meteorological data, NDVI (Normalized Difference Vegetation Index) and its response to temperature and precipitation in China and its different regions were investigated over the period 1998–2013 by using the maximum value composite and linear regression methods. The results showed that NDVI presented significant increase (0.0046/a) for all of China and all the regions over the last 16 years. Meanwhile, annual mean temperature of China presented a slightly increasing trend, while the annual precipitation showed a slightly decreasing trend over the last 16 years. Nevertheless, there were differences between temperature and precipitation in the subregions of China. The Annual NDVI had better relationships with precipitation () compared to temperature (), and NDVI also had a good correlation with precipitation rather than temperature in different subregions of China. Additionally, human activities also made a difference to the trends of NDVI in some regions. This study is conductive to the effects of climate change on vegetation activity in future research. Bowen Zhang, Linli Cui, Jun Shi, and Peipei Wei Copyright © 2017 Bowen Zhang et al. All rights reserved. Intercomparing the Response of Tropospheric and Stratospheric Temperature to Two Types of El Niño Onset Sun, 27 Aug 2017 00:00:00 +0000 Based on Remote Sensing Systems-retrieved temperature data in the period of January 1979 to February 2016, the response of stratospheric and tropospheric temperature in boreal winter to two previously defined types of El Niño [spring (SP) and summer (SU)] is investigated. The results show that, the response of temperature under SP onset involves a significant positive anomaly, with a symmetric distribution about the equator over the Indian Ocean region in the lower troposphere (850 hPa) and a negative anomaly in the lower stratosphere (50 hPa). Meanwhile, in the area 30°N and 30°S of the equator, most parts of the lower stratosphere feature a positive anomaly. This indicates that SP El Niño events are more conducive than SU events to warming the lower stratosphere. The atmospheric circulation structure over the tropical Indian Ocean is beneficial to the upward transfer of warm air to the upper layer. In contrast, the structure over the tropical Pacific Ocean favors the warming of upper air. On the other hand, the Eliassen–Palm (EP) flux is small and the heat flux is negative during SP-type events. Thus, the EP flux and Brewer–Dobson circulation decrease, making the temperature higher in the upper troposphere-lower stratosphere region at low latitudes. Shujie Chang, Min Shao, Chunhua Shi, and Hua Xu Copyright © 2017 Shujie Chang et al. All rights reserved. Quantifying Spatiotemporal Dynamics of Solar Radiation over the Northeast China Based on ACO-BPNN Model and Intensity Analysis Thu, 24 Aug 2017 10:11:07 +0000 Reliable information on the spatiotemporal dynamics of solar radiation plays a crucial role in studies relating to global climate change. In this study, a new backpropagation neural network (BPNN) model optimized with an Ant Colony Optimization (ACO) algorithm was developed to generate the ACO-BPNN model, which had demonstrated superior performance for simulating solar radiation compared to traditional BPNN modelling, for Northeast China. On this basis, we applied an intensity analysis to investigate the spatiotemporal variation of solar radiation from 1982 to 2010 over the study region at three levels: interval, category, and conversion. Research findings revealed that () the solar radiation resource in the study region increased from the 1980s to the 2000s and the average annual rate of variation from the 1980s to the 1990s was lower than that from the 1990s to the 2000s and () the gains and losses of solar radiation at each level were in different conditions. The poor, normal, and comparatively abundant levels were transferred to higher levels, whereas the abundant level was transferred to lower levels. We believe our findings contribute to implementing ad hoc energy management strategies to optimize the use of solar radiation resources and provide scientific suggestions for policy planning. Xiangqian Li, Zhijun Tong, Enliang Guo, and Xiaolong Luo Copyright © 2017 Xiangqian Li et al. All rights reserved. Land Surface Temperature and Emissivity Separation from Cross-Track Infrared Sounder Data with Atmospheric Reanalysis Data and ISSTES Algorithm Mon, 21 Aug 2017 00:00:00 +0000 The Cross-track Infrared Sounder (CrIS) is one of the most advanced hyperspectral instruments and has been used for various atmospheric applications such as atmospheric retrievals and weather forecast modeling. However, because of the specific design purpose of CrIS, little attention has been paid to retrieving land surface parameters from CrIS data. To take full advantage of the rich spectral information in CrIS data to improve the land surface retrievals, particularly the acquisition of a continuous Land Surface Emissivity (LSE) spectrum, this paper attempts to simultaneously retrieve a continuous LSE spectrum and the Land Surface Temperature (LST) from CrIS data with the atmospheric reanalysis data and the Iterative Spectrally Smooth Temperature and Emissivity Separation (ISSTES) algorithm. The results show that the accuracy of the retrieved LSEs and LST is comparable with the current land products. The overall differences of the LST and LSE retrievals are approximately 1.3 K and 1.48%, respectively. However, the LSEs in our study can be provided as a continuum spectrum instead of the single-channel values in traditional products. The retrieved LST and LSEs now can be better used to further analyze the surface properties or improve the retrieval of atmospheric parameters. Yu-Ze Zhang, Xiao-Guang Jiang, Hua Wu, Ya-Zhen Jiang, Zhao-Xia Liu, and Cheng Huang Copyright © 2017 Yu-Ze Zhang et al. All rights reserved. Monitoring Water Resources over the Kotmale Reservoir in Sri Lanka Using ENSO Phases Thu, 17 Aug 2017 08:23:47 +0000 In this study, the El Nino Southern Oscillation (ENSO) phase index is used for water management over the Kotmale reservoir in Sri Lanka. Daily rainfall data of 9 stations over the Kotmale catchment during 1960–2005 June-September (JJAS) season is investigated over the Kotmale catchment. The ENSO phases are identified based on the 0.5°C sea surface temperature (SST) anomaly over Nino 3 region. The study has brought out few stations showing increasing and a few decreasing seasonal rainfall trends for JJAS season, while there is no change in the annual rainfall for the catchment. Monthly and seasonal rainfall of all the selected stations showed negative correlation with the sea surface temperature (SST) over the Nino-3 region index during JJAS season with varying magnitudes. During the warm phase of ENSO, below average rainfall is prominent for JJAS season over many stations. The rainfall especially during early September showed a significant below average rainfall during the warm ENSO phase. The seasonal rainfall during neutral and cold ENSO phases does not experience similar significant changes as seen during warm ENSO phase. Inflow of the Kotmale reservoir shows decreasing trend for the period of 1960–2005 in the observation from all stations collectively. Sewwandhi Chandrasekara, Venkatraman Prasanna, and Hyun-Han Kwon Copyright © 2017 Sewwandhi Chandrasekara et al. All rights reserved. The Role of Rossby-Wave Propagation in a North American Extreme Cold Event Thu, 17 Aug 2017 08:18:48 +0000 The Eliassen–Palm flux and Plumb wave activity flux are calculated using the European Centre for Medium-Range Weather Forecasts interim reanalysis daily dataset to determine the propagation of Rossby waves before a North American cold wave in January 2014. The results show that the upward wave activity fluxes mainly come from planetary waves 1 and 2, which provide a stable circulation background for the influence of the subplanetary-scale waves 3 and 4. The Rossby-wave propagation anomalies between the troposphere and the stratosphere are due to the modulating effects of waves 3 and 4 on waves 1 and 2. During 9–14 January 2014, the modulating effects helped strengthen upward and eastward wave activity fluxes over the Atlantic region and enhance the Pacific high in the stratosphere in its early stage. Later in 19–24 January, the downward wave activity fluxes over the east Pacific due to the modulating effects were beneficial to downward development of the stratospheric high over the Pacific and the formation of a blocking high over the west coast of North America in the troposphere accompanied by a strong adjacent cold low on the east side. These circulations benefit the southward invasion of polar cold air reaching the lower latitudes of east North America, leading to the cold wave outbreak. Chunhua Shi, Ting Xu, Hui Li, and Yannan Gao Copyright © 2017 Chunhua Shi et al. All rights reserved. Spatial-Temporal Patterns and Controls of Evapotranspiration across the Tibetan Plateau (2000–2012) Wed, 09 Aug 2017 07:51:42 +0000 Evapotranspiration (ET) is a key factor to further our understanding of climate change processes, especially on the Tibetan Plateau, which is sensitive to global change. Herein, the spatial patterns of ET are examined, and the effects of environmental factors on ET at different scales are explored from the years 2000 to 2012. The results indicated that a steady trend in ET was detected over the past decade. Meanwhile, the spatial distribution shows an increase of ET from the northwest to the southeast, and the rate of change in ET is lower in the middle part of the Tibetan Plateau. Besides, the positive effect of radiation on ET existed mainly in the southwest. Based on the environment gradient transects, the ET had positive correlations with temperature (, ), precipitation (R > 0.89, p < 0.0001), and NDVI (R > 0.75, p < 0.0001), but a negative correlation between ET and radiation (R = 0.76, p < 0.0001) was observed. We also found that the relationships between environmental factors and ET differed in the different grassland ecosystems, which indicated that vegetation type is one factor that can affect ET. Generally, the results indicate that ET can serve as a valuable ecological indicator. Hao Zhang, Jian Sun, and Junnan Xiong Copyright © 2017 Hao Zhang et al. All rights reserved. Geospatial Analysis of Extreme Weather Events in Nigeria (1985–2015) Using Self-Organizing Maps Wed, 09 Aug 2017 00:00:00 +0000 The explosion of data in the information age has provided an opportunity to explore the possibility of characterizing the climate patterns using data mining techniques. Nigeria has a unique tropical climate with two precipitation regimes: low precipitation in the north leading to aridity and desertification and high precipitation in parts of the southwest and southeast leading to large scale flooding. In this research, four indices have been used to characterize the intensity, frequency, and amount of rainfall over Nigeria. A type of Artificial Neural Network called the self-organizing map has been used to reduce the multiplicity of dimensions and produce four unique zones characterizing extreme precipitation conditions in Nigeria. This approach allowed for the assessment of spatial and temporal patterns in extreme precipitation in the last three decades. Precipitation properties in each cluster are discussed. The cluster closest to the Atlantic has high values of precipitation intensity, frequency, and duration, whereas the cluster closest to the Sahara Desert has low values. A significant increasing trend has been observed in the frequency of rainy days at the center of the northern region of Nigeria. Adeoluwa Akande, Ana Cristina Costa, Jorge Mateu, and Roberto Henriques Copyright © 2017 Adeoluwa Akande et al. All rights reserved.