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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  [2467 journals]
  • Intensified Impact of the Equatorial QBO in August–September on the
           Northern Stratospheric Polar Vortex in December–January since the Late
           1990s

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      Abstract: Abstract This study reveals an intensified impact of the equatorial quasi-biennial oscillation (QBO) in August–September (QBO_AS) on the northern stratospheric polar vortex (SPV) in December–January (SPV_DJ) since the late 1990s. The unstable relationship may be related to the differences in the deep convection anomaly over the tropical western Pacific and Indian Oceans in October–November (ON) related to the QBO_AS prior to and after the late 1990s. During 1998–2017, the easterly phase of the QBO_AS is accompanied by a colder tropical tropopause in ON, which enhances the deep convective activity over the tropical western Pacific and suppresses it over the Indian Ocean. The deep convection anomaly generates anomalous Rossby waves that propagate into the northern mid-to-high latitudes to constructively interfere with the climatological wavenumber-1 and wavenumber-2 components, thereby resulting in enhanced upward-propagating tropospheric planetary-scale waves and a weakened SPV_DJ anomaly. During 1979–1997, however, the deep convection anomaly over the tropical western Pacific and Indian Oceans in ON related to the easterly phase of the QBO_AS is weaker and shifts eastward, which excites the anomalous Rossby waves to constructively/destructively interfere with the climatological wavenumber-1 component in the midlatitudes/high latitudes, thereby weakening the upward-propagating planetary-scale waves and leading to a weaker linkage with the SPV_DJ. Further analyses reveal that the unstable relationship may be associated with the interdecadal differences in deep convection over the tropical western Pacific and Indian Oceans and the upward-propagating tropospheric planetary-scale waves in ON.
      PubDate: 2022-10-01
       
  • Progress and Prospects of Research on Subseasonal to Seasonal Variability
           and Prediction of the East Asian Monsoon

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      Abstract: Abstract Subseasonal to seasonal (S2S) variability represents the atmospheric disturbance on the 10–90-day timescale, which is an important bridge linking weather and climate. In 2015, China Meteorological Administration (CMA) listed the S2S prediction project that was initiated by WMO programs three years ago as one of its key tasks. After five years of research, significant progress has been made on the mechanisms of the East Asian monsoon (EAM) S2S variability, related impact of climate change, as well as the predictability on the S2S timescale of numerical models. The S2S variability of the EAM is closely linked to extreme persistent climate events in China and is an important target for seasonal climate prediction. However, under the influence of global warming and the interactions among climate systems, the S2S variability of the EAM is so complex that its prediction remains a great challenge. This paper reviews the past achievement and summarizes the recent progress in research of the EAM S2S variability and prediction, including characteristics of the main S2S modes of the EAM, their impact on the extreme events in China, effects of external and internal forcing on the S2S variability, as well as uncertainties of climate models in predicting the S2S variability, with a focus on the progress achieved by the S2S research team of the Chinese Academy of Meteorological Sciences. The present bottlenecks, future directions, and critical research recommendations are also analyzed and presented.
      PubDate: 2022-10-01
       
  • Interannual Relationship between Summer North Atlantic Oscillation and
           Subsequent November Precipitation Anomalies over Yunnan in Southwest China
           

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      Abstract: Abstract The summer North Atlantic Oscillation (SNAO) strongly affects the climate variability over Europe and downstream East Asia similar to its winter counterpart. This study thus investigates the interannual relationship between SNAO and the subsequent autumn precipitation anomalies over Yunnan, Southwest China and related physical mechanisms based on reanalysis data during 1958–2020. The results show that the interannual variations in SNAO exhibit a significant positive correlation with anomalies of Yunnan precipitation in November. Composite analyses demonstrate that for the positive SNAO phase, the positive sea surface temperature anomalies (SSTAs) in midlatitude North Atlantic as part of a tripole SSTA tend to weaken from summer to November through changes in surface heat fluxes. In turn, the predominately negative SSTA in tropical North Atlantic that persists into November induces an anomalous cyclone at midlatitudes, which triggers two middle-upper tropospheric wave trains propagating from midlatitude North Atlantic to Yunnan. The subtropical wave train propagates eastward along the subtropical westerly jet, and the mid-high latitude wave train follows the great circle path across Scandinavia and central Asia to the Tibetan Plateau. Both wave trains favor development of an anomalous cyclone over the southern Tibetan Plateau. The upper-tropospheric divergent condition on the southeastern side of the anomalous cyclone is dynamically conducive to locally ascending motion over Yunnan, thus producing above-normal precipitation. The opposite situation occurs in the negative SNAO phase. A coupled model reproduces well the wave train propagation and thereby confirms the positive relationship between SNAO and Yunnan precipitation in November.
      PubDate: 2022-10-01
       
  • Assessing 10 Satellite Precipitation Products in Capturing the July 2021
           Extreme Heavy Rain in Henan, China

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      Abstract: Abstract On 20 July 2021, a sudden rainstorm happened in central and northern Henan Province, China, killing at least 302 people. This extreme precipitation event incurred substantial socioeconomic impacts and resulted in serious losses. Accurate monitoring of such rainstorm events is crucial. In this study, qualitative and quantitative methods are used to comprehensively evaluate the abilities of 10 high-resolution satellite precipitation products [CMORPH-Raw (Climate Prediction Center morphing technique), CMORPH-RT, PERSIANN-CCS (Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks), GPM IMERG-Early (Integrated Multisatellite Retrievals for Global Precipitation Measurement), GPM IMERG-Late, GSMaP-Now (Global Satellite Mapping of Precipitation), GSMaP-NRT, FY-2F, FY-2G, and FY-2H] in capturing this extreme rainstorm event, as well as their performances in monitoring different precipitation intensities. The results show that these satellite precipitation products are able to capture the spatial distributions of the rainstorm (e.g., its location in central and northern Henan), but all products have underestimated the amount of precipitation in the rainstorm center. With the increase in precipitation intensity, the hit rate decreases, the threat score decreases, and the false alarm rate increases. CMORPH-RT is better at capturing the rainstorm than CMORPH-Raw, and it depictes the rainstorm process well; GPM IMERG-Late is more accurate than GPM IMERG-Early; GSMaP-NRT has performed better than GSMaP-Now; and PERSIANN-CCS and FY-2F perform poorly. Among the products, CMORPH-RT performs the best, which has accurately captured the center of the rainstorm, and is also the closest to the station-based observations. In general, the satellite precipitation products that integrate infrared and passive microwave data are found to be better than those that only make use of infrared data. The satellite precipitation retrieval algorithm and the amount of passive microwave data have a relatively greater impact on the accuracy of satellite precipitation products.
      PubDate: 2022-10-01
       
  • An Empirical Model of Tropical Cyclone Intensity Forecast in the Western
           North Pacific

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      Abstract: Abstract The relative impact of environmental parameters on tropical cyclone (TC) intensification rate (IR) was investigated through a box difference index (BDI) method, using TC best track data from Joint Typhoon Warning Center and environmental fields from the NCEP final analysis data over the western North Pacific (WNP) during 2000–2018. There are total 6307 TC samples with a 6-h interval, of which about 14% belong to rapid intensification (RI) category. The analysis shows that RI occurs more frequently with higher environmental sea surface temperature, higher oceanic heat content, and lower upper-tropospheric temperature. A moderate easterly shear is more favorable for TC intensification. TC intensification happens mostly equatorward of 20°N while TC weakening happens mostly when TCs are located in the northwest of the basin. Mid-tropospheric relative humidity and vertical velocity are good indicators separating the intensification and non-intensification groups. A statistical model for TC intensity prediction was constructed based on six environmental predictors, with or without initial TC intensity. Both models are skillful based on Brier skill score (BSS) relative to climatology and in comparison with other statistical models, for both a training period (2000–2018) and an independent forecast period (2019–2020).
      PubDate: 2022-10-01
       
  • Refined Evaluation of Satellite Precipitation Products against Rain Gauge
           Observations along the Sichuan—Tibet Railway

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      Abstract: Abstract Being constructed in southwestern China, the Sichuan—Tibet Railway (STR) travels across the eastern Tibetan Plateau where there is the most complex terrain and changeable weather in the world. Due to sparse ground-based observations over the Tibetan Plateau, precipitation products retrieved by remote sensing are more widely used; however, satellite-based precipitation products (SPPs) have not yet been strictly and systematically evaluated along the STR. This study aims to evaluate the performance of six SPPs by a series of metrics with available ground observations along the STR during 1998–2020. The six SPPs include the datasets derived from the Tropical Rainfall Measuring Mission (TRMM), Climate Prediction Center morphing technique (CMORPH), Global Precipitation Measurement (GPM), Global Satellite Mapping of Precipitation (GSMaP), Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks (PERSIANN), and Fengyun-2 satellites precipitation estimate (FY2PRE). The results indicate that most of the SPPs can capture the precipitation characteristics on multiple timescales (monthly, daily, hourly, and diurnal cycle) as shown by the evaluated metrics. The probability density functions of the daily and hourly precipitation are also well represented by the SPPs, and 30 mm day−1 and 16 mm h−1 are identified as the daily and hourly thresholds of extreme precipitation events along the STR. The best SPP varies at different timescales: GPM and GSMaP are suitable for the monthly and daily scale, and FY2PRE and GPM are suited to the hourly scale. In general, GPM is relatively optimum on multiple timescales, and PERSIANN gives the worst performance. In addition, the SPPs perform worse at higher altitudes and for more intense precipitation. Overall, the results from this study are expected to provide essential reference for using the SPPs in meteorological services and disaster prevention in the STR construction and its future operation.
      PubDate: 2022-10-01
       
  • Stochastically Perturbed Parameterizations for the Process-Level
           Representation of Model Uncertainties in the CMA Global Ensemble
           Prediction System

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      Abstract: Abstract To represent model uncertainties at the physical process level in the China Meteorological Administration global ensemble prediction system (CMA-GEPS), a stochastically perturbed parameterization (SPP) scheme is developed by perturbing 16 parameters or variables selected from three physical parameterization schemes for the planetary boundary layer, cumulus convection, and cloud microphysics. Each chosen quantity is perturbed independently with temporally and spatially correlated perturbations sampled from log-normal distributions. Impacts of the SPP scheme on CMA-GEPS are investigated comprehensively by using the stochastically perturbed parametrization tendencies (SPPT) scheme as a benchmark. In the absence of initial-condition perturbations, perturbation structures introduced by the two schemes are investigated by analyzing the ensemble spread of three forecast variables’ physical tendencies and perturbation energy in ensembles generated by the separate use of SPP and SPPT. It is revealed that both schemes yield different perturbation structures and can simulate different sources of model uncertainty. When initial-condition perturbations are activated, the influences of the two schemes on the performance of CMA-GEPS are assessed by calculating verification scores for both upper-air and surface variables. The improvements in ensemble reliability and probabilistic skill introduced by SPP and SPPT are mainly located in the tropics. Besides, the vast majority of the reliability improvements (including increases in ensemble spread and reductions in outliers) are statistically significant, and a smaller proportion of the improvements in probabilistic skill (i.e., decreases in continuously ranked probability score) reach statistical significance. Compared with SPPT, SPP generally has more beneficial impacts on 200-hPa and 2-m temperature, along with 925-hPa and 2-m specific humidity, during the whole 15-day forecast range. For other examined variables, such as 850-hPa zonal wind, 850-hPa temperature, and 700-hPa humidity, SPP tends to yield more reliable ensembles at lead times beyond day 7, and to display comparable probabilistic skills with SPPT. Both SPP and SPPT have small impacts in the extratropics, primarily due to the dominant role of the singular vectors-based initial perturbations.
      PubDate: 2022-10-01
       
  • Direct Radiative Effects of Dust Aerosols over Northwest China Revealed by
           Satellite-Derived Aerosol Three-Dimensional Distribution

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      Abstract: Abstract Northwest China is recognized as a main source and a major transport channel of dust aerosols in East Asia. With a fragile ecological environment, this region is quite sensitive to global climate change. Based on the satellite-derived aerosol three-dimensional distribution, the direct radiative effects of dust aerosols over Northwest China are evaluated. Aerosols over Northwest China are mainly distributed in the Tarim Basin, Junggar Basin, Gobi Desert, and Loess Plateau. The aerosol extinction coefficients are greater than 0.36 km−1 over the Tarim Basin and 0.16 km−1 over the Gobi Desert and Loess Plateau, decreasing with height. Aerosols over Northwest China are mainly composed of pure dust and polluted dust. These dust aerosols can modify the horizontal temperature gradient, vertical thermodynamic structure, and diurnal temperature range by absorbing and scattering shortwave radiation and emitting longwave radiation. For the column atmosphere, the radiative effect of dust aerosols shows heating effect of approximately 0.3 K day−1 during the daytime and cooling effect of approximately −0.4 K day−1 at night. In the vertical direction, dust aerosols can heat up the lower atmosphere (0.5–1.5 K day−1) and cool down the upper atmosphere (about −1.0 K day−1) during the daytime, while they cool down the lower atmosphere (−3 to −1.5 K day−1) and heat up the upper atmosphere (1–1.5 K day−1) at night. There are also significant lateral and vertical variations in the dust radiative effects corresponding to their spatial distributions. This study provides some scientific basis for reducing uncertainty in the investigation of aerosol radiative effects and provides observation evidence for simulation studies.
      PubDate: 2022-10-01
       
  • Assimilation of All-Sky Radiance from the FY-3 MWHS-2 with the Yinhe
           4D-Var System

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      Abstract: Abstract Compared with traditional microwave humidity sounding capabilities at 183 GHz, new channels at 118 GHz have been mounted on the second generation of the Microwave Humidity Sounder (MWHS-2) onboard the Chinese FY-3C and FY-3D polar orbit meteorological satellites, which helps to perform moisture sounding. In this study, as the all-sky approach can manage non-linear and non-Gaussian behavior in cloud- and precipitation-affected satellite radiances, the MWHS-2 radiances in all-sky conditions were first assimilated in the Yinhe four-dimensional variational data assimilation (YH4DVAR) system. The data quality from MWHS-2 was evaluated based on observation minus background statistics. It is found that the MWHS-2 data of both FY-3C and FY-3D are of good quality in general. Six months of MWHS-2 radiances in all-sky conditions were then assimilated in the YH4DVAR system. Based on the forecast scores and observation fits, we conclude that the all-sky assimilation of the MWHS-2 at 118- and 183-GHz channels on FY-3C/D is beneficial to the analysis and forecast fields of the temperature and humidity, and the impact on the forecast skill scores is neutral to positive. Additionally, we compared the impacts of assimilating the 118-GHz channels and the equivalent Advanced Microwave Sounding Unit-A (AMSUA) channels on global forecast accuracy in the absence of other satellite observations. Overall, the impact of the 118-GHz channels on the forecast accuracy is not as large as that for the equivalent AMSUA channels. Nevertheless, all-sky radiance assimilation of MWHS-2 in the YH4DVAR system has indeed benefited from the 118-GHz channels.
      PubDate: 2022-10-01
       
  • Simulations of a Persistent Heat Wave Event in Missouri in Summer 2012
           Using a High-Resolution WRF Model

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      Abstract: Abstract An extreme and persistent heat wave event hit Missouri in summer 2012. Current operational forecast models failed to predict such an event at a long lead. The objective of the current study is to simulate this extreme event using a high-resolution Weather Research and Forecasting (WRF) model with eight combined physical (including longwave/shortwave radiation, microphysics, and planetary boundary layer) parameterization packages. Integrated for one month, the model successfully simulates the spatial pattern and temporal evolution of surface air temperature, compared to in-situ observations. The interesting feature is an oscillatory development of the surface air temperature, with a pronounced synoptic timescale. Such a temperature evolution is consistent with the local zonal wind fluctuation, implying the important role of anomalous temperature advection. An overall skill score that combines the performance of 2-m air temperature, relative humidity, and precipitation fields is defined. The result shows that the combination of Thompson, Rapid Radiative Transfer Model for GCMs (RRTMG), and Mellor-Yamada-Nakanishi-Niino level-3 (MYNN3) schemes presents the best WRF simulation. A further analysis of this best simulation shows that the model successfully reproduces the urban heat island (UHI) effect in the Kansas City Metropolitan Area with realistic diurnal variation of 2-m air temperature in the urban and nonurban areas with a larger UHI effect at nighttime.
      PubDate: 2022-08-01
      DOI: 10.1007/s13351-022-2039-9
       
  • Identifying Supercooled Liquid Water in Cloud Based on Airborne
           Observations: Correlation of Cloud Particle Number Concentration with
           Icing Probability and Proportion of Spherical Particles

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      Abstract: Abstract Identifying supercooled liquid water (SLW) in clouds is critical for weather modification, aviation safety, and atmospheric radiation calculations. Currently, aircraft identification in the SLW area mostly depends on empirical estimation of cloud particle number concentration (Nc) in China, and scientific verification and quantitative identification criteria are urgently needed. In this study, the observations are from the Fast Cloud Droplets Probe, Rosemount ice detector (RICE), and Cloud Particle Imager (CPI) onboard a King Air aircraft during seven flights in 2018 and 2019 over central and eastern China. Based on this, the correlation among Nc, the proportion of spherical particles (Ps), and the probability of icing (Pi) in supercooled stratiform and cumulus-stratus clouds is statistically analyzed. Subsequently, this study proposes a method to identify SLW areas using Nc in combination with ambient temperature. The reliability of this method is evaluated through the true skill statistics (TSS) and threat score (TS) methods. Numerous airborne observations during the seven flights reveal a strong correlation among Nc, Ps, and Pi at the temperature from 0 to -18°C. When Nc is greater than a certain threshold of 5 cm-3, there is always the SLW, i.e., Pi and Ps are high. Evaluation results demonstrate that the TSS and TS values for Nc = 5 cm-3 are higher than those for Nc < 5 cm-3, and a larger Nc threshold (> 5 cm-3) corresponds to a higher SLW identification hit rate and a higher SLW content. Therefore, Nc = 5 cm-3 can be used as the minimum criterion for identifying the SLW in clouds at temperature lower than 0°C. The SLW identification method proposed in this study is especially helpful in common situations where aircraft are equipped with only Nc probes and without the CPI and RICE.
      PubDate: 2022-08-01
      DOI: 10.1007/s13351-022-1064-z
       
  • Decadal Change of the Linkage between Sea Ice over the Barents-Kara Seas
           in November-December and the Stratospheric Polar Vortex in Subsequent
           January

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      Abstract: Abstract The linkage between the sea ice concentration (SIC) over the Barents-Kara Seas in November–December (SIC_BKS_ND) and the stratospheric polar vortex (SPV) in subsequent January (SPV_Jan) is investigated. It is found that SIC_BKS_ND is positively (negatively) correlated with SPV_Jan for the period 1979–1995 (1996–2009). Further analyses reveal that, during 1979–1995 (1996–2009), SIC_BKS_ND is relatively higher (lower), accompanied by smaller (larger) interannual variability with its center shifting northwest (southeast). Meanwhile, the polar front jet waveguide is relatively stronger (weaker). The simultaneous anomalous eastward-propagating Rossby waves excited by anomalously low SIC_BKS_ND are stronger (weaker), which results in the stronger (weaker) negative-positive-negative wave-train structure of geopotential height anomalies over Eurasia, with the location of these anomalous height centers shifting remarkably westward (eastward). Such changes tend to enhance (suppress) vertically propagating tropospheric planetary waves into the lower stratosphere at high-latitude via constructive (destructive) interference of anomalous tropospheric wave-train structure with the climatological planetary waves, subsequently weakening (strengthening) SPV_Jan. However, in conjunction with anomalously high SIC_BKS_ND, the interference of the tropospheric wave-train structure anomalies and their climatologies shows an opposite distribution to that of low SIC_BKS_ND anomalies, which leads to a strong (weak) SPV_Jan anomaly during 1979–1995 (1996–2009).
      PubDate: 2022-08-01
      DOI: 10.1007/s13351-022-1225-0
       
  • Role of Intraseasonal Oscillation in a Compound Drought and Heat Event
           over the Middle of the Yangtze River Basin during Midsummer 2018

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      Abstract: Abstract In late July 2018, a compound drought and heat event (CDHE) occurred in the middle of the Yangtze River basin (MYRB) and caused great damage to the national economy. The CDHE over the MYRB has been documented to be linked with intraseasonal oscillations (ISOs) from different regions. However, specific roles of different ISOs on the development of the CDHE cannot be separated in the observational analysis. By using partial lateral forcing experiments driven by ISO in the Weather Research and Forecasting (WRF) model, we found that the midlatitude ISO generated by a westerly wave train in the upper troposphere played an important role in this heatwave and drought event in the northern MYRB, causing a regional average temperature rise of 1.65°C and intensification of drought over 23.49% of the MYRB area. On the other hand, the ISO associated with the Pacific-Japan (PJ)-like teleconnection wave train in the lower troposphere induced a more pronounced impact on the event, causing an average temperature rise of 2.44°C, intensifying drought over 29.62% of the MYRB area. The MYRB was mainly affected by northward warm advection driven by the westward extension of the western North Pacific subtropical high in the early period of the CDHE development. In the late period, because of the establishment of a deep positive geopotential height field through the troposphere leading to intensive local subsidence, there was a remarkable temperature rise and moisture decrease in the MYRB. The results will facilitate a better understanding of the occurrence of CDHE and provide empirical precursory signals for subseasonal forecast of CDHE.
      PubDate: 2022-08-01
      DOI: 10.1007/s13351-022-2008-3
       
  • Heavy Precipitation over the Jing-Jin-Ji Region in Early October: What
           Controls Its Interannual Variability'

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      Abstract: Abstract Heavy regional precipitation (HRP) over Beijing, Tianjin, and Hebei Province (the Jing-Jin-Ji region or JJJ) in early October (1-10 October) is a high-impact climate event because of travel and outdoor activities by exceptionally large population during the Chinese National Day Holidays (CNDH). What causes the year-to-year variation of the HRP during early October is investigated through an observational analysis. It is found that the HRP arises from moisture transport by southerly anomalies to the west of an anomalous low-level anticyclone over the subtropical northwestern Pacific (SNWP). Sensitivity numerical experiments reveal that the low-level anticyclonic anomaly is caused by a dipole heating pattern over tropical western and central Pacific associated with a La Niña-like SST anomaly (SSTA) pattern in the Pacific and by a negative heating anomaly over North Europe. The latter connects the SNWP anticyclone through a Rossby wave train. Anomalous ascent associated with a positive heating anomaly over the tropical western Pacific may strengthen the local Hadley Cell, contributing to maintenance of the low-level anomalous anticyclone over SNWP and extending westwards of the western Pacific subtropical high (WPSH). Therefore, both the tropical Pacific and midlatitude heating signals over North Europe may be potential predictors for HRP forecast in the JJJ region in early October.
      PubDate: 2022-08-01
      DOI: 10.1007/s13351-022-1181-8
       
  • FY-4A/GIIRS Temperature Validation in Winter and Application to Cold Wave
           Monitoring

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      Abstract: Abstract In order to improve the operational application ability of the Fengyun-4A (FY-4A) new sounding dataset, in this paper, validation of the FY-4A Geosynchronous Interferometric Infrared Sounder (FY-4A/GIIRS) temperature was carried out using the balloon sounding temperature from meteorological sounding stations. More than 350,000 samples were obtained through time-space matching, and the results show that the FY-4A/GIIRS temperature mean bias (MB) is 0.07°C, the mean absolute error (MAE) is 1.80°C, the root-mean-square error (RMSE) is 2.546°C, and the correlation coefficient (RR) is 0.95. The FY-4A/GIIRS temperature error is relatively larger in the upper and lower troposphere, and relatively smaller in the middle troposphere; that is, the temperature at 500 hPa is better than that at 850 hPa. The temporal variation is smaller in the upper and middle troposphere than in the lower troposphere. The reconstruction of missing data of FY-4A/GIIRS temperature in cloudy areas is also carried out and the results are evaluated. The spatial distribution of reconstructed FY-4A/GIIRS temperature and the fifth generation ECMWF reanalysis (ERA5) data is consistent and completely retains the minimum temperature center with high precision of FY-4A/GIIRS. There are more detailed characteristics of intensity and position at the cold center than that of the reanalysis data. Therefore, an operational satellite retrieval temperature product with time-space continuity and high accuracy is formed. The reconstructed FY-4A/GIIRS temperature is used to monitor a strong cold wave event in November 2021. The results show that the product effectively monitors the movement and intensity of cold air activities, and it also has good indication for the phase transition of rain and snow triggered by cold wave.
      PubDate: 2022-08-01
      DOI: 10.1007/s13351-022-2015-4
       
  • Updated Simulation of Tropospheric Ozone and Its Radiative Forcing over
           the Globe and China Based on a Newly Developed Chemistry-Climate Model

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      Abstract: Abstract This study evaluates the performance of a newly developed atmospheric chemistry-climate model, BCCAGCM_CUACE2.0 (Beijing Climate Center Atmospheric General Circulation Model_China Meteorological Administration Unified Atmospheric Chemistry Environment) model, for determining past (2010) and future (2050) tropospheric ozone (O3) levels. The radiative forcing (RF), effective radiative forcing (ERF), and rapid adjustments (RAs, both atmospheric and cloud) due to changes in tropospheric O3 are then simulated by using the model. The results show that the model reproduces the tropospheric O3 distribution and the seasonal changes in O3 surface concentration in 2010 reasonably compared with site observations throughout China. The global annual mean burden of tropospheric O3 is simulated to have increased by 14.1 DU in 2010 relative to pre-industrial time, particularly in the Northern Hemisphere. Over the same period, tropospheric O3 burden has increased by 21.1 DU in China, with the largest increase occurring over Southeast China. Although the simulated tropospheric O3 burden exhibits a declining trend in global mean in the future, it increases over South Asia and Africa, according to the Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios. The global annual mean ERF of tropospheric O3 is estimated to be 0.25 W m-2 in 1850–2010, and it is 0.50 W m-2 over China. The corresponding atmospheric and cloud RAs caused by the increase of tropospheric O3 are estimated to be 0.02 and 0.03 W m-2, respectively. Under the RCP2.6, RCP4.5, RCP6.0, and RCP8.5 scenarios, the annual mean tropospheric O3 ERFs are projected to be 0.29 (0.24), 0.18 (0.32), 0.23 (0.32), and 0.25 (0.01) W m-2 over the globe (China), respectively.
      PubDate: 2022-08-01
      DOI: 10.1007/s13351-022-1187-2
       
  • Height Variation in the Summer Quasi-Zero Wind Layer over Dunhuang,
           Northwest China: A Diagnostic Study

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      Abstract: Abstract This study investigates the variation in the stratospheric quasi-zero wind layer (QZWL) over Dunhuang, Gansu Province, China, on 9 August 2020 using sounding observations from the Dunhuang national reference station and the fifth generation of ECMWF atmospheric reanalysis data (ERA5). The QZWL over Dunhuang was located between 18.6 and 20.4 km on 9 August 2020. The South Asian high (SAH) and subtropical westerly jet jointly affected the QZWL. As the SAH retreated westward, the upper-level westerly jet over Dunhuang strengthened, and the jet axis height increased. As a result, the zonal westerly wind was lifted to a higher altitude, and the wind speed of 100-70 hPa increased, raising the QZWL. In addition, the east-west oscillation of the SAH occurred earlier than the adjustment of the QZWL altitude, which can be used as a forecasting indicator for the QZWL. To further explore the mechanism responsible for the QZWL adjustment, the forcing terms in the equations for zonal wind, kinetic energy, and vertical wind shear were analyzed. The results showed that the upper-level geopotential gradient was the basic physical factor forcing the local change in zonal wind and kinetic energy. The change in zonal wind and kinetic energy led to the uplift of the QZWL. The results revealed that the vertical shear of horizontal wind could adequately indicate the stratospheric QZWL location.
      PubDate: 2022-08-01
      DOI: 10.1007/s13351-022-1207-2
       
  • Cause-Effect Relationship between Meso-γ-Scale Rotation and Extreme
           Short-Term Precipitation: Observational Analyses at Minute and
           Sub-Kilometer Scales

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      Abstract: Abstract The cause-effect relationship between meso-γ-scale rotation and extreme short-term precipitation events remains elusive in mesoscale meteorological research. We aimed to elucidate this relationship by analyzing a rainstorm over the Pearl River Delta during the nocturnal hours of 15 May 2017 based on 6-min radar observations and 1-min rain gauge data. This rainstorm had a maximum hourly rainfall of 100.1 mm, with 26 stations recording hourly rainfall > 60 mm h.1 in 5 h. Extreme heavy precipitation was produced in association with a convergence zone along the southern side of a synoptic low-level shear line, where southwesterly warm, humid airflows with precipitable water of > 60 mm, little convection inhibition (< 10 J kg-1), and a low lifting condensation level (about 300 m) dominated. A meso-γ-scale vortex was quantitatively identified during the hour with the largest number of gauges observing extreme hourly rainfall. The vortex had a mean diameter of 6.1 km and a peak intensity of 3.1 × 10-3 s-1 during its lifetime of 54 min. The vortex initialized and remained inside the region of extreme rain rates (radar-retrieved rain rates > 100 mm h-1), reached its peak intensity after the peak of the collocated 6-min rainfall accumulation, and then weakened rapidly after the extreme rainfall region moved away. The radar-retrieved liquid water path was about five to seven times the ice water path and the specific differential phase (Kdp) below 0°C increased sharply downward during the lifetime of the vortex, suggesting the presence of active warm rain microphysical processes. These results indicate that the release of the latent heat of condensation induced by extreme rainfall could have contributed to the formation of the vortex in an environment with a weak 0.1-km vertical wind shear (about 4–5 m s-1) through enhanced lowlevel convergence, although the strengthening of low-level updrafts by rotational dynamic effects and short-term rainfall cannot be ruled out.
      PubDate: 2022-08-01
      DOI: 10.1007/s13351-022-2028-z
       
  • Estimation of Terrestrial Net Primary Productivity in China from
           Fengyun-3D Satellite Data

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      Abstract: Abstract Currently, the satellite data used to estimate terrestrial net primary productivity (NPP) in China are predominantly from foreign satellites, and very few studies have based their estimates on data from China’s Fengyun satellites. Moreover, despite their importance, the influence of land cover types and the normalized difference vegetation index (NDVI) on NPP estimation has not been clarified. This study employs the Carnegie—Ames—Stanford approach (CASA) model to compute the fraction of absorbed photosynthetically active radiation and the maximum light use efficiency suitable for the main vegetation types in China in accordance with the finer resolution observation and monitoring-global land cover (FROM-GLC) classification product. Then, the NPP is estimated from the Fengyun-3D (FY-3D) data and compared with the Moderate Resolution Imaging Spectroradiometer (MODIS) NPP product. The FY-3D NPP is also validated with existing research results and historical field-measured NPP data. In addition, the effects of land cover types and the NDVI on NPP estimation are analyzed. The results show that the CASA model and the FY-3D satellite data estimate an average NPP of 441.2 g C m−2 yr−1 in 2019 for China’s terrestrial vegetation, while the total NPP is 3.19 Pg C yr−1. Compared with the MODIS NPP, the FY-3D NPP is overestimated in areas of low vegetation productivity and is underestimated in high-productivity areas. These discrepancies are largely due to the differences between the FY-3D NDVI and MODIS NDVI. Compared with historical field-measured data, the FY-3D NPP estimation results outperformed the MODIS NPP results, although the deviation between the FY-3D NPP estimate and the in-situ measurement was large and may exceed 20% at the pixel scale. The land cover types and the NDVI significantly affected the spatial distribution of NPP and accounted for NPP deviations of 17.0% and 18.1%, respectively. Additionally, the total deviation resulting from the two factors reached 29.5%. These results show that accurate NDVI products and land cover types are important prerequisites for NPP estimation.
      PubDate: 2022-06-01
      DOI: 10.1007/s13351-022-1183-6
       
  • Dynamic Trigger and Moisture Source of Two Typical Meiyu Front Rainstorms
           Associated with Eastward-Moving Cloud Clusters from the Tibetan Plateau

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      Abstract: Abstract Eastward-moving cloud clusters from the Tibetan Plateau (TP) often trigger heavy rainfall events in the Yangtze River basin in summer. Forecasting these events in an operational environment remains a challenging task. Here, dynamical diagnosis and a Lagrangian trajectory model are used to analyze the background atmospheric circulation, maintenance mechanism, and moisture transport of two Meiyu front rainstorms (MYFR) during 30 June–2 July 2016 and 17–19 June 2018 associated with eastward-moving cloud clusters from the TP. It is shown that in both cases heavy rainfall is characterized by semi-continuous rainbelts extending from the eastern TP to the Yangtze River valleys with eastward-spreading convective clouds weakening and strengthening alternately from the eastern TP to downstream regions. Following the track of positive water vapor advection, centers of positive vorticity propagate downstream through the Sichuan basin. The baroclinic thermodynamic—dynamical interaction and the barotropic non-equilibrium force work against each other in the development of the MYFR. Specifically, during the early stage of precipitation development, the barotropic non-equilibrium force dominates, while during the period of heavy precipitation the baroclinic thermodynamic—dynamical interaction dominates. The convergence associated with the baroclinic thermodynamic—dynamical interaction guarantees the persistence of heavy precipitation. Compared to the climate mean state (1988–2018), both MYFR events associated with eastward-moving cloud clusters from the eastern TP are characterized by increased moisture transport from the southwest. One of the major paths of moisture transport in both cases is along the south side of the TP, directly connected to the eastward movement of cloud clusters.
      PubDate: 2022-06-01
      DOI: 10.1007/s13351-022-1179-2
       
 
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