In Press

Articles in press have been peer-reviewed and accepted, which are not yet assigned to volumes/issues, but are citable by Digital Object Identifier (DOI).
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Original Paper
Influence of the Arctic on the Predictability of Eurasian Winter Extreme Weather Events
Guokun DAI, Mu MU
, Available online   , Manuscript accepted  26 December 2019, doi: 10.1007/s00376-019-9222-7
The linkage between the Arctic and midlatitudes has received much attention recently due to the rapidly changing climate. Many investigations have been conducted to reveal the relationship between the Arctic and Eurasian extreme events from the perspective of climatological statistics. As a prediction source for extreme events in Eurasia, Arctic conditions are crucial for extreme event predictions. Therefore, it is urgent to explore the Arctic influence on the predictability of Eurasian extreme events due to the large uncertainties in Arctic conditions. Considering the sensitivity and nonlinearity of the atmospheric circulations in midlatitude to Arctic conditions, it is necessary to investigate the Arctic influences on Eurasian extreme weather events in case studies at weather time scales. Previous studies indicate that only perturbations in specific patterns have fast growth. Thus, the conditional nonlinear optimal perturbation approach is recommended for exploring the uncertainties in Arctic initial and boundary conditions and their synergistic effect on Eurasian extreme events. Moreover, the mechanism for extreme event formation may differ in different cases. Therefore, more extreme cases should be investigated to reach robust conclusions.
Verification of Subseasonal-to-Seasonal Forecasts for Major Stratospheric Sudden Warmings in Northern Winter from 1998/99 to 2012/13
Masakazu TAGUCHI
, Available online   , Manuscript accepted  02 December 2019, doi: 10.1007/s00376-019-9195-6
This study reports verification results of hindcast data of four systems in the subseasonal-to-seasonal (S2S) prediction project for major stratospheric sudden warmings (MSSWs) in northern winter from 1998/99 to 2012/13. This report deals with average features across all MSSWs, and possible differences between two MSSW types (vortex displacement and split types). Results for the average features show that stratospheric forecast verifications, when further averaged among the four systems, are judged to be successful for lead times around 10 d or shorter. All systems are skillful for lead times around 5 d, whereas the results vary among the systems for longer lead times. A comparison between the MSSW types overall suggests larger forecast errors or lower skill for MSSWs of the vortex split type, although the differences do not have strong statistical significance for almost all cases. This limitation is likely to at least partly reflect the small sample size of the MSSWs available.
Towards More Snow Days in Summer since 2001 at the Great Wall Station, Antarctic Peninsula: The Role of the Amundsen Sea Low
Minghu DING, Wei HAN, Tong ZHANG, Xiaoyuan YUE, Jeremy FYKE, Ge LIU, Cunde XIAO
, Available online   , Manuscript accepted  21 November 2019, doi: 10.1007/s00376-019-9196-5
The variation in the precipitation phase in polar regions represents an important indicator of climate change and variability. We studied the precipitation phase at the Great Wall Station and Antarctic Peninsula (AP) region, based on daily precipitation, synoptic records and ERA-Interim data during the austral summers of 1985−2014. Overall, there was no trend in the total precipitation amount or days, but the phase of summer precipitation (rainfall days versus snowfall days) showed opposite trends before and after 2001 at the AP. The total summer rain days/snow days increased/decreased during 1985−2001 and significantly decreased at a rate of −14.13 d (10 yr)−1/increased at a rate of 14.31 d (10 yr)−1 during 2001−2014, agreeing well with corresponding variations in the surface air temperature. Further, we found that the longitudinal location of the Amundsen Sea low (ASL) should account for the change in the precipitation phase since 2001, as it has shown a westward drift after 2001 [−41.1° (10 yr)−1], leading to stronger cold southerly winds, colder water vapor flux, and more snow over the AP region during summertime. This study points out a supplementary factor for the climate variation on the AP.
Comparison of Advanced Technology Microwave Sounder Biases Estimated Using Radio Occultation and Hurricane Florence (2018) captured by NOAA-20 and S-NPP
Xiaoxu TIAN, Xiaolei ZOU
, Available online   , Manuscript accepted  19 November 2019, doi: 10.1007/s00376-019-9119-5
The second Advanced Technology Microwave Sounder (ATMS) was onboard the National Oceanic and Atmospheric Administration (NOAA)-20 satellite when launched on 18 November 2017. Using nearly six months of the earliest NOAA-20 observations, the biases of the ATMS instrument were compared between NOAA-20 and the Suomi National Polar-Orbiting Partnership (S-NPP) satellite. The biases of ATMS channels 8 to 13 were estimated from the differences between antenna temperature observations and model simulations generated from Meteorological Operational (MetOp)-A and MetOp-B satellites’ Global Positioning System (GPS) radio occultation (RO) temperature and water vapor profiles. It was found that the ATMS onboard the NOAA-20 satellite has generally larger cold biases in the brightness temperature measurements at channels 8 to 13 and small standard deviations. The observations from ATMS on both S-NPP and NOAA-20 are shown to demonstrate an ability to capture a less than 1-h temporal evolution of Hurricane Florence (2018) due to the fact that the S-NPP orbits closely follow those of NOAA-20.
Sensitivity to Tendency Perturbations of Tropical Cyclone Short-range Intensity Forecasts Generated by WRF
Xiaohao QIN, Wansuo DUAN, Hui XU
, Available online   , Manuscript accepted  19 November 2019, doi: 10.1007/s00376-019-9187-6
The present study uses the nonlinear singular vector (NFSV) approach to identify the optimally-growing tendency perturbations of the Weather Research and Forecasting (WRF) model for tropical cyclone (TC) intensity forecasts. For nine selected TC cases, the NFSV-tendency perturbations of the WRF model, including components of potential temperature and/or moisture, are calculated when TC intensities are forecasted with a 24-hour lead time, and their respective potential temperature components are demonstrated to have more impact on the TC intensity forecasts. The perturbations coherently show barotropic structure around the central location of the TCs at the 24-hour lead time, and their dominant energies concentrate in the middle layers of the atmosphere. Moreover, such structures do not depend on TC intensities and subsequent development of the TC. The NFSV-tendency perturbations may indicate that the model uncertainty that is represented by tendency perturbations but associated with the inner-core of TCs, makes larger contributions to the TC intensity forecast uncertainty. Further analysis shows that the TC intensity forecast skill could be greatly improved as preferentially superimposing an appropriate tendency perturbation associated with the sensitivity of NFSVs to correct the model, even if using a WRF with coarse resolution.
Contributions to the Interannual Summer Rainfall Variability in the Mountainous Area of Central China and Their Decadal Changes
Kaiming HU, Yingxue LIU, Gang HUANG, Zhuoqi HE, Shang-Min LONG
, Available online   , Manuscript accepted  18 November 2019, doi: 10.1007/s00376-019-9099-5
Using a high-resolution precipitation dataset, the present study detected that the mountainous area of central China (MACA) is a hotspot of ENSO’s impact on the summer rainfall variability. Further analysis suggests that both ENSO and atmospheric forcing make contributions to the summer rainfall variability in MACA. The dominant rainfall-related SST mode features as a seasonal transition from an El Niño-like warming in the preceding winter to a La Nina-like cooling in the following autumn, and it explains about 29% of the total variance of the rainfall during 1951–2018. It indicates that ENSO with a rapid phase transition is responsible for inducing summer rainfall anomalies in MACA. Besides, an upper-level circumglobal wave mode in the Northern Hemisphere during summer also explains about 29% of the summer rainfall variance. Contributions of both the SST and the atmospheric modes have experienced interdecadal changes. The influence of the SST mode gradually increases and plays a dominant role in the recent decades, suggesting that ENSO with a rapid phase transition becomes more important for rainfall prediction in MACA.
Uncertainty in Tropical Cyclone Intensity Predictions due to Uncertainty in Initial Conditions
Chenxi WANG, Zhihua ZENG, Ming YING
, Available online   , Manuscript accepted  04 November 2019, doi: 10.1007/s00376-019-9126-6
Focusing on the role of initial condition uncertainty, we use WRF initial perturbation ensemble forecasts to investigate the uncertainty in intensity forecasts of Tropical Cyclone (TC) Rammasun (1409), which is the strongest TC to have made landfall in China during the past 50 years. Forecast results indicate that initial condition uncertainty leads to TC forecast uncertainty, particularly for TC intensity. This uncertainty increases with forecast time, with a more rapid and significant increase after 24 h. The predicted TC develops slowly before 24 h, and at this stage the TC in the member forecasting the strongest final TC is not the strongest among all members. However, after 24 h, the TC in this member strengthens much more than that the TC in other members. The variations in convective instability, precipitation, surface upward heat flux, and surface upward water vapor flux show similar characteristics to the variation in TC intensity, and there is a strong correlation between TC intensity and both the surface upward heat flux and the surface upward water vapor flux. The initial condition differences that result in the maximum intensity difference are smaller than the errors in the analysis system. Differences in initial humidity, and to a lesser extent initial temperature differences, at the surface and at lower heights are the key factors leading to differences in the forecasted TC intensity. These differences in initial humidity and temperature relate to both the overall values and distribution of these parameters.
Refractory Black Carbon Results and a Method Comparison between Solid-state Cutting and Continuous Melting Sampling of a West Antarctic Snow and Firn Core
Luciano MARQUETTO, Susan KASPARI, Jefferson Cardia SIMÕES, Emil BABIK
, Available online   , Manuscript accepted  24 October 2019, doi: 10.1007/s00376-019-9124-8
This work presents the refractory black carbon (rBC) results of a snow and firn core drilled in West Antarctica (79°55'34.6"S, 94°21'13.3"W) during the 2014−15 austral summer, collected by Brazilian researchers as part of the First Brazilian West Antarctic Ice Sheet Traverse. The core was drilled to a depth of 20 m, and we present the results of the first 8 m by comparing two subsampling methods—solid-state cutting and continuous melting—both with discrete sampling. The core was analyzed at the Department of Geological Sciences, Central Washington University (CWU), WA, USA, using a single particle soot photometer (SP2) coupled to a CETAC Marin-5 nebulizer. The continuous melting system was recently assembled at CWU and these are its first results. We also present experimental results regarding SP2 reproducibility, indicating that sample concentration has a greater influence than the analysis time on the reproducibility for low rBC concentrations, like those found in the Antarctic core. Dating was carried out using mainly the rBC variation and sulfur, sodium and strontium as secondary parameters, giving the core 17 years (1998−2014). The data show a well-defined seasonality of rBC concentrations for these first meters, with geometric mean summer/fall concentrations of 0.016 μg L−1 and geometric mean winter/spring concentrations of 0.063 μg L−1. The annual rBC concentration geometric mean was 0.029 μg L−1 (the lowest of all rBC cores in Antarctica referenced in this work), while the annual rBC flux was 6.1 μg m−2 yr−1 (the lowest flux in West Antarctica records so far).
Antarctic Radiosonde Observations Reduce Uncertainties and Errors in Reanalyses and Forecasts over the Southern Ocean: An Extreme Cyclone Case
Kazutoshi SATO, Jun INOUE, Akira YAMAZAKI, Naohiko HIRASAWA, Konosuke SUGIURA, Kyohei YAMADA
, Available online   , Manuscript accepted  30 April 2019, doi: 10.1007/s00376-019-8231-x
Cyclones with strong winds can make the Southern Ocean and the Antarctic a dangerous environment. Accurate weather forecasts are essential for safe shipping in the Southern Ocean and observational and logistical operations at Antarctic research stations. This study investigated the impact of additional radiosonde observations from Research Vessel "Shirase" over the Southern Ocean and Dome Fuji Station in Antarctica on reanalysis data and forecast experiments using an ensemble data assimilation system comprising the Atmospheric General Circulation Model for the Earth Simulator and the Local Ensemble Transform Kalman Filter Experimental Ensemble Reanalysis, version 2. A 63-member ensemble forecast experiment was conducted focusing on an unusually strong Antarctic cyclonic event. Reanalysis data with (observing system experiment) and without (control) additional radiosonde data were used as initial values. The observing system experiment correctly captured the central pressure of the cyclone, which led to the reliable prediction of the strong winds and moisture transport near the coast. Conversely, the control experiment predicted lower wind speeds because it failed to forecast the central pressure of the cyclone adequately. Differences were found in cyclone predictions of operational forecast systems with and without assimilation of radiosonde observations from Dome Fuji Station.
Stratospheric Ozone-induced Cloud Radiative Effects On Antarctic Sea Ice
Yan XIA, Yongyun HU, Jiping LIU, Yi HUANG, Fei XIE, Jintai LIN
, Available online   , Manuscript accepted  19 April 2019, doi: 10.1007/s00376-019-8251-6
Recent studies demonstrate that the Antarctic Ozone Hole has important influences on Antarctic sea ice. While most of these works have focused on effects associated with atmospheric and oceanic dynamic processes caused by stratospheric ozone changes, here we show that stratospheric ozone-induced cloud radiative effects also play important roles in causing changes in Antarctic sea ice. Our simulations demonstrate that the recovery of the Antarctic Ozone Hole causes decreases in clouds over Southern Hemisphere (SH) high latitudes and increases in clouds over the SH extratropics. The decrease in clouds leads to a reduction in downward infrared radiation, especially in austral autumn. This results in cooling of the Southern Ocean surface and increasing Antarctic sea ice. Surface cooling also involves ice-albedo feedback. Increasing sea ice reflects solar radiation and causes further cooling and more increases in Antarctic sea ice.
Data Description Article
LICOM Model Datasets for the CMIP6 Ocean Model Intercomparison Project
Pengfei LIN, Zhipeng YU, Hailong LIU, Yongqiang YU, Yiwen LI, Jirong JIANG, Wei XUE, Kangjun CHEN, Qian YANG, Bowen ZHAO, Jilin WEI, Mengrong DING, Zhikuo SUN, Yaqi WANG, Yao MENG, Weipeng ZHENG, Jinfeng MA
, Available online   , Manuscript accepted  05 December 2019, doi: 10.1007/s00376-019-9208-5
The datasets of two Ocean Model Intercomparison Project (OMIP) simulation experiments from the LASG/IAP Climate Ocean Model, version 3 (LICOM3), forced by two different sets of atmospheric surface data, are described in this paper. The experiment forced by CORE-II (Co-ordinated Ocean–Ice Reference Experiments, Phase II) data (1948–2009) is called OMIP1, and that forced by JRA55-do (surface dataset for driving ocean–sea-ice models based on Japanese 55-year atmospheric reanalysis) data (1958–2018) is called OMIP2. First, the improvement of LICOM from CMIP5 to CMIP6 and the configurations of the two experiments are described. Second, the basic performances of the two experiments are validated using the climatological-mean and interannual time scales from observation. We find that the mean states, interannual variabilities, and long-term linear trends can be reproduced well by the two experiments. The differences between the two datasets are also discussed. Finally, the usage of these data is described. These datasets are helpful toward understanding the origin system bias of the fully coupled model.
News & Views
The 13th and 14th Workshops on Antarctic Meteorology and Climate
Matthew A. LAZZARA, Sophie A. ORENDORF, Taylor P. NORTON, Jordan G. POWERS, David H. BROMWICH, Scott CARPENTIER, John J. CASSANO, Steven R. COLWELL, Arthur M. CAYETTE, Kirstin WERNER
, Available online   , Manuscript accepted  27 November 2019, doi: 10.1007/s00376-019-9215-6