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  Subjects -> METEOROLOGY (Total: 113 journals)
Showing 1 - 36 of 36 Journals sorted alphabetically
Acta Meteorologica Sinica     Hybrid Journal   (Followers: 4)
Advances in Atmospheric Sciences     Hybrid Journal   (Followers: 45)
Advances in Climate Change Research     Open Access   (Followers: 39)
Advances in Meteorology     Open Access   (Followers: 28)
Advances in Statistical Climatology, Meteorology and Oceanography     Open Access   (Followers: 10)
Aeolian Research     Hybrid Journal   (Followers: 6)
Agricultural and Forest Meteorology     Hybrid Journal   (Followers: 20)
American Journal of Climate Change     Open Access   (Followers: 34)
Atmósfera     Open Access   (Followers: 3)
Atmosphere     Open Access   (Followers: 29)
Atmosphere-Ocean     Full-text available via subscription   (Followers: 16)
Atmospheric and Oceanic Science Letters     Open Access   (Followers: 13)
Atmospheric Chemistry and Physics (ACP)     Open Access   (Followers: 48)
Atmospheric Chemistry and Physics Discussions (ACPD)     Open Access   (Followers: 16)
Atmospheric Environment     Hybrid Journal   (Followers: 75)
Atmospheric Environment : X     Open Access   (Followers: 3)
Atmospheric Research     Hybrid Journal   (Followers: 71)
Atmospheric Science Letters     Open Access   (Followers: 40)
Boundary-Layer Meteorology     Hybrid Journal   (Followers: 32)
Bulletin of Atmospheric Science and Technology     Hybrid Journal   (Followers: 5)
Bulletin of the American Meteorological Society     Open Access   (Followers: 51)
Carbon Balance and Management     Open Access   (Followers: 5)
Ciencia, Ambiente y Clima     Open Access   (Followers: 3)
Climate     Open Access   (Followers: 6)
Climate and Energy     Full-text available via subscription   (Followers: 7)
Climate Change Economics     Hybrid Journal   (Followers: 33)
Climate Change Responses     Open Access   (Followers: 18)
Climate Dynamics     Hybrid Journal   (Followers: 44)
Climate of the Past (CP)     Open Access   (Followers: 5)
Climate of the Past Discussions (CPD)     Open Access  
Climate Policy     Hybrid Journal   (Followers: 51)
Climate Research     Hybrid Journal   (Followers: 6)
Climate Resilience and Sustainability     Open Access   (Followers: 21)
Climate Risk Management     Open Access   (Followers: 7)
Climate Services     Open Access   (Followers: 3)
Climatic Change     Open Access   (Followers: 68)
Current Climate Change Reports     Hybrid Journal   (Followers: 10)
Developments in Atmospheric Science     Full-text available via subscription   (Followers: 31)
Dynamics and Statistics of the Climate System     Open Access   (Followers: 5)
Dynamics of Atmospheres and Oceans     Hybrid Journal   (Followers: 19)
Earth Perspectives - Transdisciplinarity Enabled     Open Access  
Economics of Disasters and Climate Change     Hybrid Journal   (Followers: 9)
Energy & Environment     Hybrid Journal   (Followers: 24)
Environmental and Climate Technologies     Open Access   (Followers: 4)
Environmental Dynamics and Global Climate Change     Open Access   (Followers: 17)
Frontiers in Climate     Open Access   (Followers: 3)
GeoHazards     Open Access   (Followers: 2)
Global Meteorology     Open Access   (Followers: 18)
International Journal of Atmospheric Sciences     Open Access   (Followers: 23)
International Journal of Biometeorology     Hybrid Journal   (Followers: 1)
International Journal of Climate Change Strategies and Management     Hybrid Journal   (Followers: 27)
International Journal of Climatology     Hybrid Journal   (Followers: 30)
International Journal of Environment and Climate Change     Open Access   (Followers: 12)
International Journal of Image and Data Fusion     Hybrid Journal   (Followers: 2)
Journal of Agricultural Meteorology     Open Access  
Journal of Applied Meteorology and Climatology     Hybrid Journal   (Followers: 36)
Journal of Atmospheric and Oceanic Technology     Hybrid Journal   (Followers: 34)
Journal of Atmospheric and Solar-Terrestrial Physics     Hybrid Journal   (Followers: 210)
Journal of Atmospheric Chemistry     Hybrid Journal   (Followers: 22)
Journal of Climate     Hybrid Journal   (Followers: 57)
Journal of Climate Change     Full-text available via subscription   (Followers: 16)
Journal of Climatology     Open Access   (Followers: 3)
Journal of Hydrology and Meteorology     Open Access   (Followers: 36)
Journal of Hydrometeorology     Hybrid Journal   (Followers: 11)
Journal of Integrative Environmental Sciences     Hybrid Journal   (Followers: 4)
Journal of Meteorological Research     Full-text available via subscription   (Followers: 1)
Journal of Meteorology and Climate Science     Full-text available via subscription   (Followers: 17)
Journal of Space Weather and Space Climate     Open Access   (Followers: 28)
Journal of the Atmospheric Sciences     Hybrid Journal   (Followers: 84)
Journal of the Meteorological Society of Japan     Partially Free   (Followers: 6)
Journal of Weather Modification     Full-text available via subscription   (Followers: 2)
Large Marine Ecosystems     Full-text available via subscription   (Followers: 1)
Mediterranean Marine Science     Open Access   (Followers: 1)
Meteorologica     Open Access   (Followers: 2)
Meteorological Applications     Hybrid Journal   (Followers: 4)
Meteorological Monographs     Hybrid Journal   (Followers: 2)
Meteorologische Zeitschrift     Full-text available via subscription   (Followers: 3)
Meteorology and Atmospheric Physics     Hybrid Journal   (Followers: 27)
Mètode Science Studies Journal : Annual Review     Open Access  
Michigan Journal of Sustainability     Open Access   (Followers: 1)
Modeling Earth Systems and Environment     Hybrid Journal   (Followers: 1)
Monthly Notices of the Royal Astronomical Society     Hybrid Journal   (Followers: 16)
Monthly Weather Review     Hybrid Journal   (Followers: 33)
Nature Climate Change     Full-text available via subscription   (Followers: 144)
Nature Reports Climate Change     Full-text available via subscription   (Followers: 39)
Nīvār     Open Access  
npj Climate and Atmospheric Science     Open Access   (Followers: 6)
Open Atmospheric Science Journal     Open Access   (Followers: 4)
Open Journal of Modern Hydrology     Open Access   (Followers: 7)
Revista Brasileira de Meteorologia     Open Access  
Revista Iberoamericana de Bioeconomía y Cambio Climático     Open Access  
Russian Meteorology and Hydrology     Hybrid Journal   (Followers: 3)
Space Weather     Full-text available via subscription   (Followers: 25)
Studia Geophysica et Geodaetica     Hybrid Journal  
Tellus A     Open Access   (Followers: 22)
Tellus B     Open Access   (Followers: 21)
The Cryosphere (TC)     Open Access   (Followers: 6)
The Quarterly Journal of the Royal Meteorological Society     Hybrid Journal   (Followers: 28)
Theoretical and Applied Climatology     Hybrid Journal   (Followers: 13)
Tropical Cyclone Research and Review     Open Access  
Urban Climate     Hybrid Journal   (Followers: 4)
Weather     Hybrid Journal   (Followers: 18)
Weather and Climate Dynamics     Open Access  
Weather and Climate Extremes     Open Access   (Followers: 16)
Weather and Forecasting     Hybrid Journal   (Followers: 27)
Weatherwise     Hybrid Journal   (Followers: 4)
气候与环境研究     Full-text available via subscription   (Followers: 1)

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Acta Meteorologica Sinica
Journal Prestige (SJR): 0.638
Citation Impact (citeScore): 1
Number of Followers: 4  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0894-0525
Published by Springer-Verlag Homepage  [2658 journals]
  • Summer Monsoon Rainfall Variability in Central China over the Past 4700
           Years and Its Possible Link to Solar Activity

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      Abstract: Based on 467 pairs of δ18O and δ13C records and 8 230Th dates from a stalagmite (BF4) from Xiniu Cave, central China, we present a reconstruction of ∼9-yr resolution monsoon rainfall record for the past 4700 years. Our δ18O record shows good coherence with East Asian summer monsoon (EASM) rainfall proxies from adjacent regions during the overlapping intervals, suggesting that δ18O signal in BF4 can be interpreted as a monsoon rainfall proxy. The δ13C variations are related to changes in local processes at the cave site, and regional rainfall and temperature changes. Based on the δ18O record, a series of dry periods can be identified at 4500–1200, 3500–3200, 2800–2500, 1900–1600, 1400–1200, 700–500, and 400–200 yr BP, while a series of wet periods can be identified at 4200–3600, 2400–2200, 3200–2800, 1100–900, 600–400, and 200–100 yr BP. Power spectrum analysis on our δ18O record reveals significant cycles at ∼470 and ∼80 yr, coinciding with the typical solar periodic variations. This result suggests that changes in solar activity play a dominant role in driving centennial-decadal monsoon rainfall variation in central China. Due to minor changes in solar irradiance (less than 1.5 W m−2) over the past 4700 years, our record was further compared to the El Niño-Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO) proxies, confirming that solar forcing on monsoon rainfall changes might be amplified by the ENSO and PDO variations. From 600 to 150 yr BP (the Little Ice Age, LIA), a positive shift of ∼2‰ can be revealed in both the δ18O and δ13C records, indicating a cold/dry climatic pattern. By comparing our δ18O and δ13C records with historical documents, we suggest that the climatic deteriorations between 450 and 250 yr BP may have caused serious social unrest at the end of the Ming Dynasty.
      PubDate: 2021-08-01
       
  • Performance of the CRA-40/Land, CMFD, and ERA-Interim Datasets in
           Reflecting Changes in Surface Air Temperature over the Tibetan Plateau

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      Abstract: We analyzed the spatiotemporal variations in surface air temperature and key climate change indicators over the Tibetan Plateau during a common valid period from 1979 to 2018 to evaluate the performance of different datasets on various timescales. We used observations from 22 in-situ observation sites, the CRA-40/Land (CRA) reanalysis dataset, the China Meteorological Forcing Dataset (CMFD), and the ERA-Interim (ERA) reanalysis dataset. The three datasets are spatially consistent with the in-situ observations, but slightly underestimate the annual mean surface air temperature. The daily mean surface air temperature estimated by the CRA, CMFD, and ERA datasets is closer to the in-situ observations after correction for elevation. The CMFD shows the best performance in simulating the annual mean surface air temperature over the Tibetan Plateau, followed by the CRA and ERA datasets with comparable performances. The CMFD is relatively accurate in simulating the daily mean surface air temperature over the Tibetan Plateau on an annual scale, whereas both the CRA and ERA datasets perform better in summer than in winter. The increasing trends in the annual mean surface air temperature over the Tibetan Plateau from 1979 to 2018 reflected by the CRA dataset and the CMFD are 0.5°C (10 yr)−1, similar to the in-situ observations, whereas the warming rate in the ERA dataset is only 0.3°C (10 yr)−1. The trends in the length of the growing season derived from the in-situ observations, the CRA, CMFD, and ERA datasets are 5.3, 4.8, 6.1, and 3.2 day (10 yr)−1, respectively. Our analyses suggest that both the CRA dataset and the CMFD perform better than the ERA dataset in modeling the changes in surface air temperature over the Tibetan Plateau.
      PubDate: 2021-08-01
       
  • Combining Monte Carlo and Ensemble Probabilities in Tropical Cyclone
           Forecasts near Landfall

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      Abstract: The Monte Carlo probability (MCP) model, which has been used for official tropical cyclone (TC) warnings to the public by the United States’ National Hurricane Center (NHC), can estimate the probability of wind speed in the vicinity of a TC during the forecast period. It has been successful in the operational environment for many years. However, due to its strong dependence on a given forecast track (e.g., forecast from the NCEP Global Forecast System), the MCP model may generate a poor probability map for TCs near landfall. In this study, we proposed and tested a modified MCP method for TC forecasts near landfall. We first adjusted the MCP model by adding limits to the direction angle and motion distance to deal with the substantial change in TC moving direction and the low wind speeds during landfall. Then, we combined ensemble probability maps generated from ECMWF, United Kingdom MetOffice(UKMO), and NCEP ensemble forecasts, obtained from The International Grand Global Ensemble (TIGGE), into the MCP model to configure a modified MCP model. Wind speed probability maps for the 0–120-h forecast from both the original and modified MCP models are compared. It is found that the modified MCP model can provide a better wind speed probability map during landfall, especially at wind speeds of 20–64 kt near TC landfall. The results from this study prove the benefits of combining the MCP model with ensemble forecasting in potential applications for improved TC forecasts.
      PubDate: 2021-08-01
       
  • Visibility Characteristics over the South China Sea during 1980–2018
           Based on Gridded Data Generated by Artificial Neural Network

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      Abstract: This paper generated gridded visibility (Vis) data from 1980 to 2018 over the South China Sea (SCS) based on artificial neural network (ANN), and the accuracy of the generated data was tested. Then, temporal and spatial characteristics of Vis in the area were analyzed based on the generated Vis data. The results showed that Vis in the southern SCS was generally better than that in the northern SCS. In the past 39 years, Vis in both spring and winter has improved, especially in winter at a significant increased speed of 0.37 km decade−1. However, Vis in both summer and autumn has decreased, especially in summer with an obvious reduction of 0.84 km decade−1. Overall, Vis is best in summer and worst in winter, averaging 31.89 km in summer and 20.96 km in winter, which may be related to the difference of climatic conditions and wind speed in different seasons. At the same time, probability of low Vis in spring is significantly higher than that in other seasons, especially in the northwest of Hainan Island and the northwest of Malaysia.
      PubDate: 2021-08-01
       
  • Dynamical and Machine Learning Hybrid Seasonal Prediction of Summer
           Rainfall in China

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      Abstract: Seasonal prediction of summer rainfall is crucial to reduction of regional disasters, but currently it has a low prediction skill. We developed a dynamical and machine learning hybrid (MLD) seasonal prediction method for summer rainfall in China based on circulation fields from the Chinese Academy of Sciences (CAS) Flexible Global Ocean-Atmosphere-Land System Model finite volume version 2 (FGOALS-f2) operational dynamical prediction model. Through selecting optimum hyperparameters for three machine learning methods to obtain the best fit and least overfitting, an ensemble mean of the random forest and gradient boosting regression tree methods was shown to have the highest prediction skill measured by the anomalous correlation coefficient. The skill has an average value of 0.34 in the historical cross-validation period (1981–2010) and 0.20 in the 10-yr period (2011–2020) of independent prediction, which significantly improves the dynamical prediction skill by 400%. Both reducing overfitting and using the best dynamical prediction are important in applications of the MLD method and in-depth analysis of these warrants a further investigation.
      PubDate: 2021-08-01
       
  • Decreasing Trend of Western North Pacific Tropical Cyclone Inner-Core Size
           over the Past Decades

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      Abstract: Studies on tropical cyclone (TC) inner-core size have become increasingly active in recent years. However, few studies have investigated the trend of TC inner-core size. Here, we introduce a new index to measure TC inner-core size and calculate the observed trend. This index can greatly reduce the influence of data heterogeneity and uncertainty. It also considers public concern because the new index is mainly determined by the inner-core size of strong TCs, which attract more public attention than weak TCs. The results show that in the past decades, TC inner-core size has a significant downtrend that is significant above the 99% confidence level when the new index is used. We also show that this trend is probably related to the increase in TC intensity and relatively small inner-core size of strong TCs. Moreover, relative sea surface temperature (SST) is assumed to make contributions to the downtrend of TC inner-core size, which has a significant negative correlation with the new index.
      PubDate: 2021-08-01
       
  • Contribution of Water Vapor to the Record-Breaking Extreme Meiyu Rainfall
           along the Yangtze River Valley in 2020

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      Abstract: A record-breaking extreme Meiyu rainfall occurred along the Yangtze River valley (YRV) in 2020 since 1961, persisting from 11 June to 31 July with the largest amount and the highest intensity. From the aspect of water vapor, the causes of its formation are revealed in this study. The 2020 Meiyu rainfall amount is directly attributed to the greatly enhanced vertically integrated water vapor transport (IVT) convergence, which is in turn primarily determined by the mean circulation dynamic (MCD) contribution associated with anomalous East Asian summer monsoon (EASM) and the thermodynamic component (TH) contribution due to water vapor anomaly. The MCD contribution is mainly responsible for the extreme Meiyu rainfall amount and abundant water vapor convergence in the YRV, whereas the TH contribution tends to shift Meiyu rain belt northward to the Yangtze-Huaihe River valley, extending the Meiyu rainfall coverage area. Furthermore, the excessive moist static energy (MSE) associated with the largest water vapor anomaly could substantially increase the atmospheric instability, favoring the extreme 2020 Meiyu rainfall intensity. In terms of the tremendous IVT to the YRV from both the South China Sea and Bay of Bengal during the 2020 Meiyu period, the low-level anticyclone anomalies over the western North Pacific (WNP) and Bay of Bengal provide appropriate atmospheric circulation conditions, and they are generated by the super suppressed WNP convective activities as a Matsuno-Gill type response, which are further attributed to the combined warm SST anomalies in both the tropical western Indian Ocean (TWIO) and tropical Atlantic Ocean (TAO) eventually.
      PubDate: 2021-08-01
       
  • Boreal Summer Intraseasonal Oscillation and Its Possible Impact on
           Precipitation over Southern China in 2019

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      Abstract: Based on daily precipitation observation data in China, the intraseasonal oscillation (ISO) features of summer precipitation over southern China in 2019 have been investigated by wavelet and band-pass filtering analyses. The results show that enhanced (suppressed) precipitation occurred over southern China during early (late) boreal summer 2019. The signals of both 10–20- and 30–60-day ISO in southern China are remarkable, with the amplitude of the 10–20-day ISO larger than the 30–60-day ISO in boreal summer 2019. The synergistic effect of the 10–20- and 30–60-day ISO wet phases was found to exert a tremendous influence on persistent heavy precipitation in July 2019, when the amount of precipitation reached its maximum in southern China since 1981. The atmospheric circulation and convection evolution characteristics of both 10–20- and 30–60-day ISO are further investigated. An anomalous low-level anticyclone over the South China Sea is prominently linked to the wet phase of the 10–20-day ISO, whereas an anomalous low-level cyclone over southern China is dominantly associated with the wet phase of the 30–60-day ISO. Both events enhance the water vapor convergence and ascending motion over southern China. Thus, the atmospheric circulation that accompanied the synergism of the wet phases of the 10–20- and 30–60-day ISO resulted in persistent heavy precipitation over southern China in July 2019.
      PubDate: 2021-08-01
       
  • Comparison of Controlling Parameters for Near-Equatorial Tropical Cyclone
           Formation between Western North Pacific and North Atlantic

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      Abstract: In this study, the differences in spatial distribution and controlling parameters for the formation of near-equatorial tropical cyclones (NETCs) between the western North Pacific (WNP) and the North Atlantic (NA) are investigated. NETCs exhibit distinctive spatial variabilities in different basins. Over the past few decades, the majority of NETCs took place in WNP while none was observed in NA. The mechanism behind such a distinguishing spatial distribution difference is analyzed by using statistical methods. It is noted that the dynamical variables such as low-level relative vorticity and vertical wind shear (VWS) are likely the primary controlling parameters. Compared with NA, larger low-level vorticity and smaller VWS appear over WNP. The increase of vorticity attributes a lot to the turning of northeast trade wind. NETCs in WNP tend to occur in the areas with VWS less than 9 m s−1, while the VWS in NA generally exceeds 10 m s−1. On the other hand, the sea surface temperature in the near-equatorial region of both of the two oceans exceeds 26.5°C and the difference of mid-level moisture is not significant; thus, thermal factors have little contribution to the distinction of NETC activities between WNP and NA. Intraseasonal oscillation (ISO) and synoptic-scale disturbances in WNP are also shown to be more favorable for NETC genesis. More NETCs were generated in ISO active phase. Synoptic-scale disturbances in WNP obtain more energy from the mean flows through the barotropic energy conversion process. The overall unfavorable thermal and dynamic conditions lead to the absence of NETCs in NA.
      PubDate: 2021-08-01
       
  • Uncertainty in Projection of Climate Extremes: A Comparison of CMIP5 and
           CMIP6

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      Abstract: Climate projections by global climate models (GCMs) are subject to considerable and multi-source uncertainties. This study aims to compare the uncertainty in projection of precipitation and temperature extremes between Coupled Model Intercomparison Project (CMIP) phase 5 (CMIP5) and phase 6 (CMIP6), using 24 GCMs forced by 3 emission scenarios in each phase of CMIP. In this study, the total uncertainty (T) of climate projections is decomposed into the greenhouse gas emission scenario uncertainty (S, mean inter-scenario variance of the signals over all the models), GCM uncertainty (M, mean inter-model variance of signals over all emission scenarios), and internal climate variability uncertainty (V, variance in noises over all models, emission scenarios, and projection lead times); namely, T = S + M + V. The results of analysis demonstrate that the magnitudes of S, M, and T present similarly increasing trends over the 21st century. The magnitudes of S, M, V, and T in CMIP6 are 0.94–0.96, 1.38–2.07, 1.04–1.69, and 1.20–1.93 times as high as those in CMIP5. Both CMIP5 and CMIP6 exhibit similar spatial variation patterns of uncertainties and similar ranks of contributions from different sources of uncertainties. The uncertainty for precipitation is lower in midlatitudes and parts of the equatorial region, but higher in low latitudes and the polar region. The uncertainty for temperature is higher over land areas than oceans, and higher in the Northern Hemisphere than the Southern Hemisphere. For precipitation, T is mainly determined by M and V in the early 21st century, by M and S at the end of the 21st century; and the turning point will appear in the 2070s. For temperature, T is dominated by M in the early 21st century, and by S at the end of the 21st century, with the turning point occuring in the 2060s. The relative contributions of S to T in CMIP6 (12.5%–14.3% for precipitation and 31.6%–36.2% for temperature) are lower than those in CMIP5 (15.1%–17.5% for precipitation and 38.6%–43.8% for temperature). By contrast, the relative contributions of M in CMIP6 (50.6%–59.8% for precipitation and 59.4%–60.3% for temperature) are higher than those in CMIP5 (47.5%–57.9% for precipitation and 51.7%–53.6% for temperature). The higher magnitude and relative contributions of M in CMIP6 indicate larger difference among projections of various GCMs. Therefore, more GCMs are needed to ensure the robustness of climate projections.
      PubDate: 2021-08-01
       
  • Lower Stratospheric Water Vapor Variations Diagnosed from Satellite
           Observations, Reanalysis Data, and a Chemistry—Climate Model

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      Abstract: Stratospheric water vapor variations, which may play an important role in surface climate, have drawn extensive studies. Here, the variation in stratospheric water vapor is investigated by using data from observations of the Microwave Limb Sounder (MLS) on the Aura satellite, from the ECMWF Interim Reanalysis (ERAI), and simulations by the Whole Atmosphere Community Climate Model (WACCM). We find that the differences of annual mean stratospheric water vapor among these datasets may be partly caused by the differences in vertical transports. Using budget analysis, we find that the upward transport of water vapor at 100 hPa is mainly located over the Pacific warm pool region and South America in the equatorial tropics in boreal winter and over the southeast of the South Asian high and south of North America in boreal summer. It is found that temperature averaged over regions with upward transport is a better indicator of interannual variability of tropical mean stratospheric water vapor than the tropical mean temperature. It seems that the distributions of the seasonal cycle amplitude of lower stratospheric water vapor in the tropics can also be impacted by the vertical transport. The radiative effects of the interannual changes in water vapor in the lowermost stratosphere are underestimated by approximately 29% in both ERAI and WACCM compared to MLS, although the interannual variations of water vapor in the lowermost stratosphere are dramatically overestimated in ERAI and WACCM. The results here indicate that the radiative effect of long-term changes in water vapor in the lowermost stratosphere may be underestimated in both ERAI and WACCM simulations.
      PubDate: 2021-08-01
       
  • Evaluation of Global Gridded Precipitation and Temperature Datasets
           against Gauged Observations over the Upper Tekeze River Basin, Ethiopia

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      Abstract: The availability of satellite and reanalysis climate datasets and their applicability have been greatly promoted in hydro-climatic studies. However, such climatic products are still subject to considerable uncertainties and an evaluation of the products is necessary for applications in specific regions. This study aims to evaluate the reliability of nine gridded precipitation and temperature datasets against ground-based observations in the upper Tekeze River basin (UTB) of Ethiopia from 1982 to 2016. Precipitation, maximum temperature (Tmax), minimum temperature (Tmin), and mean temperature (Tmean) were evaluated at daily and monthly timescales. The results show that the best estimates of precipitation are from the EartH2Observe, WFDEI, and ERA-Interim reanalysis data Merged and Bias-corrected for the Inter-Sectoral Impact Model Intercomparison Project (EWEMBI), and the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) datasets. The percentage biases and correlation coefficients (CCs) are within ± 15% and > 0.5, respectively, for both EWEMBI and CHIRPS at the two timescales. All products underestimate the drought conditions indicated by the standardized precipitation index (SPI), while the EWEMBI and CHIRPS datasets show higher agreement with the observations than other datasets. The Tmean estimates produced by the ECMWF Re-Analysis version 5 (ERA5) and the Climate Hazards Group InfraRed Temperature with Station data (CHIRTS) are the closest to the observations, with CCs of 0.65 and 0.55, respectively, at the daily timescale. The CHIRTS and EWEMBI datasets show better representations of Tmax (Tmin), with CCs of 0.69 (0.72) and 0.62 (0.68), respectively, at the monthly timescale. The temperature extremes are better captured by the ERA5 (Tmean), CHIRTS (Tmax), and EWEMBI (Tmin) datasets. The findings of this study provide useful information to select the most appropriate dataset for hydrometeorological studies in the UTB and could help to improve the regional representation of global datasets.
      PubDate: 2021-08-01
       
  • Comparison of Sunshine Duration Measurements between a Jordan Sunshine
           Recorder and Three Automatic Sensors at Shangdianzi GAW Station

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      Abstract: We used parallel sunshine duration datasets obtained with a Jordan sunshine recorder and three automatic sunshine duration sensors to investigate the differences between these instruments. We used measurements obtained at Shangdianzi (SDZ) regional Global Atmosphere Watch (GAW) station with a Jordan sunshine recorder, a DFC2 photoelectric sunshine meter, a CHP1 pyrheliometer, and two CMP11 pyranometers from 1 January to 5 July 2019 and from 3 November 2020 to 28 February 2021. The results showed that the daily sunshine duration measurements obtained from the Jordan sunshine recorder were comparable with those from the DFC2 meter and the CMP11 pyranometers under all-sky conditions, but were considerably different from those observed by the CHP1 pyrheliometer. An analysis of potential influencing factors showed that the solar zenith angle, the spectral range of the automatic sensors, the relative humidity, and the sky conditions were the main factors affecting the measurements of sunshine duration between the Jordan sunshine recorder and three automatic sensors. We proposed a simple linear regression function—the DFC2-equivalent sunshine duration estimation (DFCESD) model—to guarantee the consistency of the long-term sunshine duration series observed by the Jordan sunshine recorder at SDZ and the measurements from the DFC2 meter. Validation of the DFCESD model showed that the mean absolute difference (MAD) between the daily sunshine duration observed by the Jordan sunshine recorder and those from the DFC2 meter improved from −0.7 to −0.2 h day−1, the relative deviation (RD) improved from −9.3% to −2.3%, and the root-mean-square deviation (RMSD) decreased from 1.0 to 0.8 h day−1.
      PubDate: 2021-08-01
       
  • Influence of Strong Tropical Volcanic Eruptions on Daily Temperature and
           Precipitation Extremes Across the Globe

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      Abstract: This study investigates the influences of strong tropical volcanic eruptions (SVEs) on daily temperature and precipitation extreme events using long-term simulations from the Hadley Centre Coupled Model version 3 (HadCM3) and the Community Earth System Model version 1.1 (CESM1). The results indicate that the occurrences of daily hot extremes and daily heavy precipitation extremes decrease over most parts of the world in the peak forcing years of SVEs. Due to the volcanic cooling effect, the average probability of daily hot extremes decreases by approximately 50% across the globe. The decrease in intensity is stronger for midlatitude land regions and tropical South America. In contrast, daily cold extremes occur more frequently over most parts of continental regions. Globally, a cold extreme event expected once every 3 years under non-volcanic conditions can be expected every 1.5 years on average in the peak forcing years. Overall, the SVE-induced cooling effect plays a dominant role in regulating daily cold and hot extremes. Over high-latitude Eurasian regions, in contrast to other continental regions, the probability and intensity of daily cold extremes decrease due to an SVE-strengthened polar vortex and the associated temperature advection anomalies. With regard to daily heavy precipitation extremes, the probability and intensity both decrease over most monsoon areas. Further analysis suggests that the reduced probability and intensity of daily heavy precipitation extremes are mainly due to the SVE-induced global decrease in the water-holding capacity.
      PubDate: 2021-06-01
       
  • Lagged Responses of the Tropical Pacific to the 11-yr Solar Cycle Forcing
           and Possible Mechanisms

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      Abstract: This paper uses two subsets of ensemble historical-Nat simulations and pi-Control simulations from CMIP5 as well as observational/reanalysis datasets to investigate responses of the tropical Pacific to the 11-yr solar cycle. A statistically significant 11-yr solar signal is found in the upper-ocean layers above the thermocline and tropospheric circulations. A warming response initially appears in the upper layers of the central equatorial Pacific in the solar maximum years in observations, then increases and shifts into the eastern Pacific at lagged 1–3 yr. Meanwhile, an anomalous updraft arises over the western equatorial Pacific and shifts eastwards in the following years with anomalous subsidence over the Maritime Continent. These lagged responses are confirmed by the historical-Nat simulations, except that the initial signal is located more to the west and all the responses are weaker than the observed. A simplified mixed-layer heat budget analysis based on the historical-Nat simulations suggests that the atmospheric forcing, especially the shortwave radiation, is the major contributor to the initial warming response, and the ocean heat transport effect is responsible for the eastward displacement of the lagged warming responses. In the solar maximum years, the zonal ocean temperature gradient in the western-central Pacific is reduced by the initial warming, and anomalous westerly winds appear over the western equatorial Pacific and extend into the eastern Pacific during the lagged years. These anomalous westerly winds reduce the wind-driven ocean dynamical transport, resulting in the initial warming in the central equatorial Pacific being amplified and the surface warming shifting eastward during the lagged 1–3 yr.
      PubDate: 2021-06-01
       
  • Historical Changes and Future Projections of Extreme Temperature and
           Precipitation along the Sichuan-Tibet Railway

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      Abstract: Based on multiresource high-resolution in situ and satellite merged observations along with model simulations from the Coordinated Regional Climate Downscaling Experiment (CORDEX), this study first investigated historical changes in extreme temperature and precipitation during the period of 1979–2018 in areas along the Sichuan-Tibet Railway, and then projected the future changes in the frequency and intensity of extreme temperature and precipitation under the RCP (Representative Concentration Pathway) 4.5 and 8.5 scenarios. This paper is expected to enhance our understanding of the spatiotemporal variability in the extreme temperature and precipitation along the Sichuan-Tibet Railway, and to provide scientific basis to advance the Sichuan-Tibet Railway construction and operation. The results show that temperatures in the Sichuan-Tibet region display a noticeable warming trend in the past 40 years, and the increase of minimum temperature is significantly higher than that of maximum temperature in the northwest of the region. Significant increase of precipitation is found mainly over the northwest of the Tibetan Plateau. Except for Lhasa and its surrounding areas, precipitation over other areas along the Sichuan-Tibet Railway shows no significant change in the past 40 years, as indicated in five datasets; however, precipitation along the railway has shown a remarkable decrease in the past 20 years in the TRMM satellite dataset. The warm days and nights have clearly increased by 6 and 5 day decade−1 for 1979–2019, while cold days and nights have markedly decreased by about 6.6 and 3.6 day decade−1, respectively. In the past 20 years, the areas with increased precipitation from very wet days and extremely wet days are mainly distributed to the north of the Sichuan-Tibet Railway, while in the areas along the railway itself, the very wet days and extremely wet days are decreasing. Under RCPs 4.5 and 8.5, the temperature in the Sichuan-Tibet region will increase significantly, and the frequency of extreme high (low) temperature events in the late 21st century (2070–2099) will greatly increase (decrease) by about 50%–80% (10%) compared with occurrences in the late 20th century (1970–1999). Meanwhile, the frequency of very wet days and extremely wet days in the Sichuan-Tibet region will increase by about 2%–19% and 2%–5%, respectively, and the areas along the Sichuan-Tibet Railway will be affected by more extreme high temperature and extreme precipitation events.
      PubDate: 2021-06-01
       
  • Terrestrial Near-Surface Wind Speed Variations in China: Research Progress
           and Prospects

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      Abstract: Changes in terrestrial near-surface wind speed (NSWS) are indicative of the concentrated net effect of climate change and anthropogenic activities. Investigating change mechanisms of NSWS not only furthers the understanding of how the atmosphere changes and improves the climate analysis and projection, but also aids the evaluation and application of wind energy resources. Recent advances in studies of the changes and associated mechanisms of the NSWS over China are reviewed in this paper. Some new results have been achieved in understanding the behaviors of the NSWS changes. The NSWS over China has experienced a decrease in the past 40 years and a recovery in the recent decade, exhibiting large regional and seasonal differences. Understanding of the mechanisms of the NSWS changes has been improved in several aspects; for example, it is found that the reduced NSWS over China is due to the weakening of the pressure-gradient force (PGF) attributed to variations in large-scale ocean-atmosphere circulations (LOACs) as well as the increase of surface roughness due to the land use and cover change (LUCC). The main methods used to analyze the NSWS changes and corresponding mechanisms are also elucidated and discussed. However, studies are still lacking on the mechanisms for multi-timescale (seasonal, interannual, decadal, multi-decadal) variations in the NSWS over China, and it remains unknown about the contributions of different forcing factors to the NSWS changes. Finally, key scientific issues regarding our understanding of the NSWS changes are proposed for future investigation.
      PubDate: 2021-06-01
       
  • Influence of Near Real-Time Green Vegetation Fraction Data on Numerical
           Weather Prediction by WRF over North China

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      Abstract: The green vegetation fraction (GVF) can greatly influence the partitioning of surface sensible and latent heat fluxes in numerical weather prediction (NWP) models. However, the multiyear averaged monthly GVF climatology—the most commonly used representation of the vegetation state in models—cannot capture the real-time vegetation state well. In this study, a near real-time (NRT) GVF dataset generated from an 8-day composite of the normalized difference vegetation index is compared with the 10-yr averaged monthly GVF provided by the WRF model. The annual variability of the GVF over North China is examined in detail. Many differences between the two GVF datasets are found over dryland, grassland, and cropland/grassland mosaic areas. Two experiments using different GVF datasets are performed to assess the impacts of GVF on forecasts of screen-level temperature and humidity. The results show that using NRT GVF can lead to a widespread reduction of 2-m temperature forecast errors from April to October. Evaluation against in-situ observations shows that the positive impact on 2-m temperature forecasts in the morning is more distinct than that in the afternoon. Our study demonstrates that NRT GVF can provide a more realistic representation of the vegetation state, which in turn helps to improve short-range forecasts in arid and semiarid regions of North China. Moreover, our study shows that the negative effect of using NRT GVF is closely related to the initial soil moisture.
      PubDate: 2021-06-01
       
  • Statistical Characteristics and Long-Term Variations of Major Sudden
           Stratospheric Warming Events

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      Abstract: Using NCEP/NCAR reanalysis data, we investigate the statistical characteristics and the long-term variations of major sudden stratospheric warming (SSW) events in the Northern Hemisphere. We find that the strength and duration of major SSW events have increased from 1958 to 2019 because of the strengthening of winter planetary wave activity. The frequency of the SSW events related to displacement or split of the polar vortex differs between early, middle, and late winter. Early (middle) winter is dominated by displacement (split) SSW events, while late winter sees almost equal frequency of these two types of events. This is due to the differences in the relative strength of wavenumber-1 and wavenumber-2 planetary wave activity among the three winter periods. As a result of the increase in upward planetary wave activity and the decrease in westerly winds around the polar vortex in middle winter, more SSW events tend to occur in middle winter. In addition, we reveal the influence of the downward propagation of different types of SSW events on the surface temperature anomaly. Compared with early displacement SSW events, middle split SSW events are followed by more surface cold centers in Russia, northern China, and North America.
      PubDate: 2021-06-01
       
  • Application of Gaussian Weight to Improve Perturbation Features of
           Convection-Permitting Ensemble Forecast Based on Local Breeding of Growing
           Modes

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      Abstract: Local breeding of growing modes (LBGM) is a method used to generate initial condition perturbation (ICP) for convection-permitting ensemble forecasts. Equal weights (EWs) are usually presumed in LBGM during the localization of ICP, without considering different contributions of the grid points within the local radius. To address this problem, Gaussian weights (GWs) are proposed in this study, which can accommodate the varied influences of the grids inside the local radius on the central grid through a Gaussian function. Specifically, two convection-permitting ensemble forecast experiments based on LBGM with GWs and EWs are compared and analyzed respectively for two squall line cases. The results showed that the use of the GWs intensified the local characteristics of the ICP and made the distribution of the ICP fields more flow-dependent. Kinetic energy spectrum of the ICP indicated that there could be more large-scale information in the ICP by using the GWs. In addition, mesoscale information also improved slightly. For forecast of nonprecipitation variables, GWs improved the relationship between the root-mean-square error and the spread and contributed to the forecasting accuracy of wind, temperature, geopotential height, and humidity. For the precipitation forecast, GWs simulated the precipitation structure successfully and provided better probability forecasting during the evolution of the two squall line processes than the EWs.
      PubDate: 2021-06-01
       
 
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