Subjects -> METEOROLOGY (Total: 106 journals)
 Showing 1 - 36 of 36 Journals sorted by number of followers Journal of Atmospheric and Solar-Terrestrial Physics       (Followers: 164) Nature Climate Change       (Followers: 151) Journal of the Atmospheric Sciences       (Followers: 80) Atmospheric Environment       (Followers: 72) Atmospheric Research       (Followers: 72) Climatic Change       (Followers: 71) Bulletin of the American Meteorological Society       (Followers: 62) Advances in Climate Change Research       (Followers: 59) Climate Policy       (Followers: 56) Journal of Climate       (Followers: 55) Climate Change Economics       (Followers: 50) Climate Dynamics       (Followers: 44) Advances in Atmospheric Sciences       (Followers: 43) Atmospheric Chemistry and Physics (ACP)       (Followers: 43) Weather and Forecasting       (Followers: 42) Journal of Applied Meteorology and Climatology       (Followers: 42) American Journal of Climate Change       (Followers: 41) Atmospheric Science Letters       (Followers: 40) 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Risk Management       (Followers: 12) Advances in Statistical Climatology, Meteorology and Oceanography       (Followers: 11) Atmospheric and Oceanic Science Letters       (Followers: 10) Journal of Hydrometeorology       (Followers: 9) Climate Research       (Followers: 8) The Cryosphere (TC)       (Followers: 8) Climate Law       (Followers: 7) Journal of the Meteorological Society of Japan       (Followers: 7) Aeolian Research       (Followers: 7) Climate of the Past (CP)       (Followers: 7) Climate and Energy       (Followers: 7) Dynamics and Statistics of the Climate System       (Followers: 6) Journal of Climate Change and Health       (Followers: 6) Bulletin of Atmospheric Science and Technology       (Followers: 6) Oxford Open Climate Change       (Followers: 6) Carbon Balance and Management       (Followers: 6) Climate       (Followers: 6) Open Atmospheric Science Journal       (Followers: 5) Open Journal of Modern Hydrology       (Followers: 5) Urban Climate       (Followers: 4) Meteorological Applications       (Followers: 4) Frontiers in Climate       (Followers: 4) Acta Meteorologica Sinica       (Followers: 4) npj Climate and Atmospheric Science       (Followers: 4) Journal of Integrative Environmental Sciences       (Followers: 4) Climate Services       (Followers: 4) Meteorologische Zeitschrift       (Followers: 4) Russian Meteorology and Hydrology       (Followers: 3) Journal of Climatology       (Followers: 3) Journal of Meteorological Research       (Followers: 3) International Journal of Image and Data Fusion       (Followers: 3) Atmospheric Environment : X       (Followers: 3) Environmental and Climate Technologies       (Followers: 3) Journal of Weather Modification       (Followers: 3) International Journal of Biometeorology       (Followers: 3) GeoHazards       (Followers: 2) 气候与环境研究       (Followers: 2) Atmósfera       (Followers: 2) Mediterranean Marine Science       (Followers: 2) Meteorologica       (Followers: 2) 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 Acta Meteorologica SinicaJournal Prestige (SJR): 0.638 Citation Impact (citeScore): 1Number of Followers: 4      Hybrid journal (It can contain Open Access articles) ISSN (Print) 0894-0525 Published by Springer-Verlag  [2469 journals]
• Simulations of a Persistent Heat Wave Event in Missouri in Summer 2012
Using a High-Resolution WRF Model

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

• Identifying Supercooled Liquid Water in Cloud Based on Airborne
Observations: Correlation of Cloud Particle Number Concentration with
Icing Probability and Proportion of Spherical Particles

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

• Decadal Change of the Linkage between Sea Ice over the Barents-Kara Seas
in November-December and the Stratospheric Polar Vortex in Subsequent
January

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

• Role of Intraseasonal Oscillation in a Compound Drought and Heat Event
over the Middle of the Yangtze River Basin during Midsummer 2018

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

• Heavy Precipitation over the Jing-Jin-Ji Region in Early October: What
Controls Its Interannual Variability'

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

• FY-4A/GIIRS Temperature Validation in Winter and Application to Cold Wave
Monitoring

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

• Updated Simulation of Tropospheric Ozone and Its Radiative Forcing over
the Globe and China Based on a Newly Developed Chemistry-Climate Model

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

• Height Variation in the Summer Quasi-Zero Wind Layer over Dunhuang,
Northwest China: A Diagnostic Study

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

• Cause-Effect Relationship between Meso-γ-Scale Rotation and Extreme
Short-Term Precipitation: Observational Analyses at Minute and
Sub-Kilometer Scales

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

• Estimation of Terrestrial Net Primary Productivity in China from
Fengyun-3D Satellite Data

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

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

• On the Increased Precipitation Recycling by Large-Scale Irrigation over
the Haihe Plain

Abstract: Abstract Irrigation not only plays an important role in global food security, but it also affects aspects of the regional climate, including precipitation. In this study, we proposed a simple and convenient method to quantify the contribution of large-scale irrigation to precipitation by distinguishing the amount of evaporation generated by irrigation from local evaporation based on the precipitation recycling method. A case study was presented to show the increased precipitation recycling ratio and the contribution of irrigation to precipitation during the main irrigation period in the Haihe Plain from 1961 to 2016. We found that the average precipitation recycling rates in the Haihe Plain are 8.32%, 9.74%, and 10.36% in April, May, and June, respectively. The contribution rates of irrigation to precipitation in the Haihe Plain are 3.76%, 5.12%, and 2.29% in April, May, and June, respectively. The total contribution of irrigation to precipitation during the main irrigation period is 3.77 mm; the respective contributions in April, May, and June are 0.72, 1.70, and 1.35 mm. The contribution of irrigation to local precipitation is relatively small as the inflow of atmospheric moisture during the irrigation period is still the main factor affecting local precipitation. Nevertheless, this part of the precipitation during the irrigation period alleviates the water shortage in the Haihe Plain to some extent.
PubDate: 2022-06-01
DOI: 10.1007/s13351-022-1220-5

• Forty Years of Air Temperature Change over Iran Reveals Linear and
Nonlinear Warming

Abstract: Abstract Spatiotemporal analysis of long-term changes in air temperature is of prime importance for climate change research and the development of effective mitigation and adaptation strategies. Although there are considerable studies on air temperature change across the globe, most of them have been on linear trends and time series analysis of nonlinear trends have not received enough attention. Here, spatiotemporal patterns of monthly and annual mean (Tmean), maximum (Tmax), and minimum (Tmin) air temperature at 47 synoptic stations across climate zones in Iran for a 40-yr period (1978–2017) are analyzed. A polynomial fitting scheme (Polytrend) is used to both monthly and annual air temperature data to detect trends and classify them into linear and nonlinear (quadratic and cubic) categories. The significant (non-significant) trends in Tmean, Tmax, and Tmin across all climate zones are 41.1% (58.9%), 34.1% (65.9%), and 46% (54%), respectively. The highest magnitude of increasing trends is observed in the annual Tmin (0.47°C decade−1) and the lowest magnitude is for the annual Tmax (0.4°C decade−1). Across the country, increasing trends $$(\bar x = 37.2\% )$$ have higher spatial coverage than the decreasing trends $$(\bar x = 3.2\% )$$ . Warming trends in Tmean (65.3%) and Tmin (73.1%) are mainly observed in humid climate zone while warming trends in Tmax are in semi-arid (43.9%) and arid (34.1%) climates. Linear change with a positive trend is predominant in all Tmean (56.7%), Tmax (67.8%), and Tmin (71.2%) and for both monthly and annual data. Further, the linear trends have the highest warming rate in annual Tmin (0.83°C decade−1) and Tmean (0.46°C decade−1) whereas the nonlinear trends have the highest warming rate in annual Tmax (0.52°C decade−1). The linear trend type is predominant across the country especially in humid climate zones whereas the nonlinear trends (quadratic and cubic) are mainly observed in the arid climate zones. This study highlights nonlinear changes and spatiotemporal trends in air temperature in Iran and contributes to a growing body of climate change literature that is necessary for the development of effective mitigation and adaptation strategies in the Middle East.
PubDate: 2022-06-01
DOI: 10.1007/s13351-022-1184-5

• Three-Dimensional Urban Thermal Effect across a Large City Cluster during
an Extreme Heat Wave: Observational Analysis

Abstract: Abstract Given extensive and rapid urbanization globally, assessing regional urban thermal effects (UTE) in both canopy and boundary layers under extreme weather/climate conditions is of significant interest. Rapid population and economic growth in the Yangtze River Delta (YRD) have made it one of the largest city clusters in China. Here, we explore the three-dimensional (3D) UTE in the YRD using multi-source observations from high-resolution automatic weather stations, radiosondes, and eddy covariance sensors during the record-setting heat wave (HW) of July–August 2013. It is found that the regional canopy layer UTE is up to 0.6–1.2°C, and the nocturnal UTE (0.7–1.6°C) is larger than daytime UTE (0.2–0.5°C) during the HW. The regional canopy layer UTE is enhanced and expanded northwards, with some rural sites contaminated by the urban influences, especially at night. In the boundary layer, the strengthened regional UTE extends vertically to at least 925 hPa (∼750 m) during this HW. The strengthened 3D UTE in the YRD is associated with an enlarged Bowen ratio difference between urban and non-urban areas. These findings about the 3D UTE are beneficial for better understanding of the thermal environment of large city clusters under HW and for more appropriate adaption and mitigation strategies.
PubDate: 2022-06-01
DOI: 10.1007/s13351-022-1171-x

• Variations of Raindrop Size Distribution and Radar Retrieval in Outer
Rainbands of Typhoon Mangkhut (2018)

Abstract: Abstract The evolution of the microphysical properties of raindrops from Typhoon Mangkhut’s outer rainbands as the storm made landfall in South China in September 2018 was investigated. The observations by three two-dimensional video disdrometers deployed in central Guangdong Province were analyzed concurrently. It was found that the radial distribution of the median volume diameter (D0) and normalized intercept parameter (Nw) varied in different stages, and that raindrops smaller than 3.0 mm contributed more than 99% of the total precipitation. Considering the characteristics of precipitation in the typhoon outer rainband, a modified stratiform rain (SR)—convective rain (CR) separator line is proposed based on D0 and Nw scatterplots. Meanwhile, an “S—C likelihood index” is introduced, which was used to classify three rain types (SR, CR, and mixed rain). The CR results were highly consistent with those of the improved typhoon precipitation classification method based on rain rate. By calculating effectively the radar reflectivity factor (Ze) in the Ku and Ka bands, D0—Ze and Nw—D0 empirical relations were thereby derived for improving the accuracy of rainfall retrieval. Among the four quantitative precipitation estimators using S-band dual-polarimetric radar parameters simulated by the T-matrix method, the estimator that adopted the specific differential phase and differential reflectivity was found to be the most effective for both SR and CR.
PubDate: 2022-06-01
DOI: 10.1007/s13351-022-1134-2

• Present-Day PM2.5 over Asia: Simulation and Uncertainty in CMIP6 ESMs

Abstract: Abstract This study assesses the ability of 10 Earth System Models (ESMs) that participated in the Coupled Model Inter-comparison Project Phase 6 (CMIP6) to reproduce the present-day inhalable particles with diameters less than 2.5 micrometers (PM2.5) over Asia and discusses the uncertainty. PM2.5 accounts for more than 30% of the surface total aerosol (fine and coarse) concentration over Asia, except for central Asia. The simulated spatial distributions of PM2.5 and its components, averaged from 2005 to 2020, are consistent with the Modern-Era Retrospective Analysis for Research and Applications version 2 (MERRA-2) reanalysis. They are characterized by the high PM2.5 concentrations in eastern China and northern India where anthropogenic components such as sulfate and organic aerosol dominate, and in northwestern China where the mineral dust in PM2.5 fine particles (PM2.5DU) dominates. The present-day multi-model mean (MME) PM2.5 concentrations slightly underestimate ground-based observations in the same period of 2014–2019, although observations are affected by the limited coverage of observation sites and the urban areas. Those model biases partly come from other aerosols (such as nitrate and ammonium) not involved in our analyses, and also are contributed by large uncertainty in PM2.5 simulations on local scale among ESMs. The model uncertainties over East Asia are mainly attributed to sulfate and PM2.5DU; over South Asia, they are attributed to sulfate, organic aerosol, and PM2.5DU; over Southeast Asia, they are attributed to sea salt in PM2.5 fine particles (PM2.5SS); and over central Asia, they are attributed to PM2.5DU. They are mainly caused by the different representations of aerosols within individual ESMs including the representation of aerosol size distributions, dynamic transport, and physical and chemistry mechanisms.
PubDate: 2022-06-01
DOI: 10.1007/s13351-022-1202-7

• Cloud Water Resource in North China in 2017 Simulated by the CMA-CPEFS
Cloud Resolving Model: Validation and Quantification

Abstract: Abstract Based on the concept of cloud water resource (CWR) and the cloud microphysical scheme developed by the Chinese Academy of Meteorological Sciences (CAMS), a coupled mesoscale and cloud-resolving model system is developed in the study for CWR numerical quantification (CWR-NQ) in North China for 2017. The results show that (1) the model system is stable and capable for performing 1-yr continuous simulation with a water budget error of less than 0.2%, which indicates a good water balance. (2) Compared with the observational data, it is confirmed that the simulating capability of the CWR-NQ approach is decent for the spatial distribution of yearly cumulative precipitation, daily precipitation intensity, yearly average spatial distribution of water vapor. (3) Compared with the CWR diagnostic quantification (CWR-DQ), the results from the CWR-NQ differ mainly in cloud condensation and cloud evaporation. However, the deviation of the net condensation (condensation minus evaporation) between the two methods is less than 1%. For other composition variables, such as water vapor advection, surface evaporation, precipitation, cloud condensation, and total atmospheric water substances, the relative differences between the CWR-NQ and the CWR-DQ are less than 5%. (4) The spatiotemporal features of the CWR in North China are also studied. The positive correlation between water vapor convergence and precipitation on monthly and seasonal scales, and the lag of precipitation relative to water vapor convergence on hourly and daily scales are analyzed in detail, indicating the significance of the state term on hourly and daily scales. The effects of different spatial scales on the state term, advection term, source—sink term, and total amount are analyzed. It is shown that the advective term varies greatly at different spatiotemporal scales, which leads to differences at different spatiotemporal scales in CWR and related characteristic quantities.
PubDate: 2022-06-01
DOI: 10.1007/s13351-022-1118-2

• Evaluation of Reprocessed Fengyun-3B Global Outgoing Longwave Radiation
Data: Comparison with CERES OLR

Abstract: Abstract Outgoing longwave radiation (OLR) at the top of the atmosphere (TOA) is a key parameter for understanding and interpreting the relationship between clouds, radiation, and climate interactions. It has been one of the operational products of the Fengyun (FY) meteorological satellites. OLR accuracy has gradually improved with advancements in satellite payload performance and the OLR retrieval algorithm. Supported by the National Key R&D Program Retrospective Calibration of Historical Chinese Earth Observation Satellite data (Richceos) project, a long-term OLR climate data record (CDR) was reprocessed based on the recalibrated Level 1 data of FY series satellites using the latest OLR retrieval algorithm. In this study, Fengyun-3B (FY-3B)’s reprocessed global OLR data from 2010 to 2018 were evaluated by using the Clouds and the Earth’s Radiant Energy System (CERES) global daily OLR data. The results showed that there was a high consistency between the FY-3B instantaneous OLR and CERES Single Scanner Footprint (SSF) OLR. Globally, between the two CDR datasets, the correlation coefficient reached 0.98, and the root-mean-square error (RMSE) was approximately 8–9 W m−2. The bias mainly came from the edge regions of the satellite orbit, which may be related to the satellite zenith angle and cloud cover distribution. It was shown that the long-term FY-3B OLR had temporal stability compared to CERES OLR long-term data. In terms of spatial distribution, the mean deviations showed zonal and seasonal characteristics, although seasonal fluctuations were observed in the differences between the two datasets. Effects of FY-3B OLR application to the South China Sea monsoon region and ENSO were demonstrated and analyzed, and the results showed that the seasonal deviation of FY-3B’s OLR comes mainly from the retrieval algorithm. However, it has little effect on the analysis of climate events.
PubDate: 2022-06-01
DOI: 10.1007/s13351-022-1132-4

• CMIP6 Projections of the “Warming-Wetting” Trend in Northwest China
and Related Extreme Events Based on Observational Constraints

Abstract: Abstract This study presents the improved future projections of the climate “warming—wetting” trend and climate extremes with different return periods in Northwest China at different global warming levels. The projections are based on the Coupled Model Intercomparison Project phase 6 (CMIP6) simulations constrained by the high-resolution observation dataset using the equidistant cumulative distribution functions (EDCDF) method. The results indicate that the climate will experience continuous warming and wetting as reflected by average temperature and total precipitation over Northwest China, especially under the scenario of the shared socioeconomic pathway 5—representative concentration pathway 8.5 (SSP5–8.5). Most parts of Northwest China will continue to warm in the future more than global average. Spatially, areas with prominent “warming—wetting” trends will be mainly distributed in western Northwest China. It is worth noting that extreme heat and precipitation events will also increase with the climate warming and wetting over Northwest China. Moreover, frequencies of rarer extreme events will increase more apparently than weaker extreme events and frequency increase of extreme heat events responds to global warming faster than that of extreme precipitation events. Limiting global warming within 2°C relative to 1850–1900 would slowdown the increase in extreme heat events and considerably suppress the increase in frequencies of extreme precipitation events, especially the rare (i.e., 50-yr) extreme events.
PubDate: 2022-04-01
DOI: 10.1007/s13351-022-1157-8

• Sensitivity of Lake-Effect Convection to the Lake Surface Temperature over
Poyang Lake in China

Abstract: Abstract In this study, high-resolution weather research and forecasting (WRF) simulations are used to explore the sensitivity of lake-effect convection over Poyang Lake (PL) to the change of lake surface temperature (LST). A control experiment (CTR) with climate mean LST (303 K) is compared with six sensitivity experiments (CTR−1/2/3K and CTR+1/2/3K) in which the LSTs are set based on the mean LST difference of 6 K between the maximum and minimum. The results show that the CTR experiment reasonably reproduces the lake-effect convection, and the lake-effect convection in sensitivity experiments is significantly influenced by the LST. With the increase of LST, the initiation time of the lake-effect convection is advanced gradually, while the initiation location moves PL from its shore. The lake-effect convection strengthens (weakens) in the increase-temperature CTR+1/2/3K (decrease-temperature CTR−1/2/3K) experiments, but the lake-effect convection does not monotonically strengthen with the LST, for the strongest one occurring in the CTR+1K experiment. The corresponding diagnostic analysis shows that the upward sensible heat flux and latent heat flux over PL increase with the LST, resulting in the enhancement of the lake-land breeze and the enlargement of the convective available potential energy (CAPE). This is the main reason for the changes in the initiation time and location, as well as the intensity of lake-effect convection in different experiments. In addition, the non-monotonous variation of the level of free convection, which is mainly induced by the non-monotonous variation of the lifting condensation level, is responsible for the non-monotonous variation of the lake-effect convection intensity with the LST.
PubDate: 2022-04-01
DOI: 10.1007/s13351-022-1142-2

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