The Impact of Spectral Nudging on Cloud Simulation with a Regional Atmospheric Model

Abstract The impact of spectral nudging on cloud simulation with a regional atmospheric model was examined. Simulated cloudiness of the Regional Model (REMO) and the Spectrally Nudged REMO (SN-REMO) were intercompared and evaluated with satellite-derived cloudiness from the International Satellite Cloud Climatology Project (ISCCP). In general, the additional spectral nudging does not affect the mean cloud simulation. However, for particular weather regimes the introduction of spectral nudging causes notable differences in cloud simulation. Two weather conditions for these large differences in cloud simulation were derived: 1) change of the general circulation patterns, or 2) strong anticyclonic circulation within the model domain. Case studies of these weather situations indicated a better agreement of simulated and satellite-derived cloudiness when spectral nudging has been applied to the regional model.

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Impact of COVID-19 Lockdown and Atmospheric Circulation on the Air Quality in Wuhan During Early 2020

E3S Web of Conferences ◽

10.1051/e3sconf/202129902011 ◽

2021 ◽

Vol 299 ◽

pp. 02011

Author(s):

Youyong Xie ◽

Xiefei Zhi

Keyword(s):

Air Quality ◽

Atmospheric Circulation ◽

Air Pollutants ◽

General Circulation ◽

Circulation Pattern ◽

Atmospheric Circulation Patterns ◽

Atmospheric General Circulation ◽

Circulation Patterns ◽

The Impact

Previous studies indicated that the air quality was improved in Wuhan during COVID-19 lockdown. However, the impact of atmospheric general circulation on the changes of air quality has not been taken into account. The present study aims to discuss the improvement of air quality in Wuhan and its possible reasons during COVID-19 lockdown. The results showed that all air pollutants except O3 decreased in Wuhan during early 2020. The occurrence days of A, C, W and NW types’ circulation pattern during early 2020 are more than those during the same period of 1979-2020. The occurrence days of SW type’s circulation pattern is slightly less than those during early 1979-2020. With more occurrence days of these dominant atmospheric circulation patterns, the number of polluted days could rise in Wuhan during early 2020. Nevertheless, this scenario didn’t occur. The COVID-19 lockdown did improve the air quality in Wuhan during early 2020.

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Global atmospheric response to specific linear combinations of the main SST modes. Part I: numerical experiments and preliminary results

Annales Geophysicae ◽

10.1007/s00585-996-1066-7 ◽

1996 ◽

Vol 14 (10) ◽

pp. 1066-1077 ◽

Cited By ~ 1

Author(s):

S. Trzaska ◽

V. Moron ◽

B. Fontaine

Keyword(s):

Numerical Experiments ◽

General Circulation ◽

Large Scale ◽

Southern Oscillation ◽

Regional Scale ◽

Circulation Model ◽

Atmospheric Model ◽

Equatorial Atlantic ◽

Preliminary Results ◽

The Impact

Abstract. This article investigates through numerical experiments the controversial question of the impact of El Niño-Southern Oscillation (ENSO) phenomena on climate according to large-scale and regional-scale interhemispheric thermal contrast. Eight experiments (two considering only inversed Atlantic thermal anomalies and six combining ENSO warm phase with large-scale interhemispheric contrast and Atlantic anomaly patterns) were performed with the Météo-France atmospheric general circulation model. The definition of boundary conditions from observed composites and principal components is presented and preliminary results concerning the month of August, especially over West Africa and the equatorial Atlantic are discussed. Results are coherent with observations and show that interhemispheric and regional scale sea-surface-temperature anomaly (SST) patterns could significantly modulate the impact of ENSO phenomena: the impact of warm-phase ENSO, relative to the atmospheric model intercomparison project (AMIP) climatology, seems stronger when embedded in global and regional SSTA patterns representative of the post-1970 conditions [i.e. with temperatures warmer (colder) than the long-term mean in the southern hemisphere (northern hemisphere)]. Atlantic SSTAs may also play a significant role.

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Architectural traits of fruiting shoots in Juglans regia (Juglandaceae) related to fruiting habit and environmental conditions

Australian Journal of Botany ◽

10.1071/bt09095 ◽

2010 ◽

Vol 58 (2) ◽

pp. 141 ◽

Cited By ~ 3

Author(s):

Damijan Kelc ◽

Franci Stampar ◽

Anita Solar

Keyword(s):

Juglans Regia ◽

Weather Conditions ◽

Basal Diameter ◽

Shoot Morphology ◽

Vegetative Buds ◽

Shoot Architecture ◽

The Mean ◽

Hot Weather ◽

The Impact ◽

Architectural Traits

The objective of the present study was to compare some basic architectural traits of annual shoots (1YS) in common walnut (Juglans regia L.), and to evaluate the impact of extreme drought and heat on the fruiting and growing response of the annual shoots. Measurements were conducted on three cultivars that have a terminal-bearing fruiting habit (Franquette), intermediate fruiting behaviour (Zdole-59) and a lateral-bearing fruiting habit (Fernor). Across 3 years, the mean 1YS of Franquette were one-third longer than those of the other two cultivars and their mean basal diameter was larger than that in Fernor and almost equal to that in Zdole-59. For Franquette, the length : diameter ratio showed a slender shoot morphology, whereas the shoot morphology was more compact in Fernor and Zdole-59. The 1YS of Franquette and Fernor had equal fruiting potential, with 2.8 and 2.7 fruits per shoot, respectively. Short but thick 1YS with the highest number of vegetative buds indicated dense branching and the good growing capacity of Zdole-59. The number of vegetative buds per 1YS changed during the 3 years in all cultivars, whereas the number of flowering buds per 1YS did not change in Franquette. Extreme dry and hot weather during the spring and summer of 2003 caused a reduction of 35–58% in length and a reduction of 2–16% in the basal diameter of the 1YS, regardless of fruiting behaviour. In the less vigorous, but highly productive lateral-bearer Fernor, unsuitable weather conditions in 2003 affected flower differentiation and resulted in significantly fewer fruits in 2004. The mean daily temperature in the period March–August was negatively correlated with the 1YS diameter and the number of vegetative buds per 1YS, whereas the mean precipitation during the same period showed a positive relationship with the length and diameter of the 1YS. Information obtained through shoot-architecture analysis could be useful in cultivar choice for new orchards, especially at a time of great climatic changes. Simple predictions for further development of the annual shoots could also be made.

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The Impact of the State of the Troposphere on the Response to Stratospheric Heating in a Simplified GCM

Journal of Climate ◽

10.1175/2010jcli3792.1 ◽

2010 ◽

Vol 23 (23) ◽

pp. 6166-6185 ◽

Cited By ~ 17

Author(s):

Isla R. Simpson ◽

Michael Blackburn ◽

Joanna D. Haigh ◽

Sarah N. Sparrow

Keyword(s):

General Circulation ◽

General Circulation Models ◽

Lower Latitude ◽

Mean Flow ◽

Magnitude Response ◽

Stratospheric Temperature ◽

The Mean ◽

Climate Forcings ◽

The Impact ◽

Jet Structure

Abstract Previous studies have made use of simplified general circulation models (sGCMs) to investigate the atmospheric response to various forcings. In particular, several studies have investigated the tropospheric response to changes in stratospheric temperature. This is potentially relevant for many climate forcings. Here the impact of changing the tropospheric climatology on the modeled response to perturbations in stratospheric temperature is investigated by the introduction of topography into the model and altering the tropospheric jet structure. The results highlight the need for very long integrations so as to determine accurately the magnitude of response. It is found that introducing topography into the model and thus removing the zonally symmetric nature of the model’s boundary conditions reduces the magnitude of response to stratospheric heating. However, this reduction is of comparable size to the variability in the magnitude of response between different ensemble members of the same 5000-day experiment. Investigations into the impact of varying tropospheric jet structure reveal a trend with lower-latitude/narrower jets having a much larger magnitude response to stratospheric heating than higher-latitude/wider jets. The jet structures that respond more strongly to stratospheric heating also exhibit longer time scale variability in their control run simulations, consistent with the idea that a feedback between the eddies and the mean flow is both responsible for the persistence of the control run variability and important in producing the tropospheric response to stratospheric temperature perturbations.

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Impact of Horizontal Resolution on Indian Summer Monsoon in coupled Atmosphere-Ocean Regional Model over CORDEX-SA

10.5194/egusphere-egu21-15990 ◽

2021 ◽

Author(s):

Pankaj Kumar ◽

Alok Kumar Mishra ◽

Aditya Kumar Dubey ◽

Md. Saquib Saharwardi ◽

Dimitry Sein

Keyword(s):

Summer Monsoon ◽

Indian Summer Monsoon ◽

Coupled System ◽

Regional Model ◽

Horizontal Resolution ◽

Ocean Model ◽

Global Ocean ◽

Russian Science ◽

The Mean ◽

The Impact

The correct representation of air-sea coupling is crucial towards improving the Indian summer monsoon. In this study, a coupled atmosphere-ocean regional model ROM is employed to investigate the impact of horizontal resolution (0.440 and 0.220) in simulating the mean Indian summer monsoon characteristics and associated dynamical and thermodynamical processes. Regional model, REMO, and global ocean model, MPIOM is taken as atmospheric and ocean components of the coupled system. Interestingly, ROM at both resolutions performs well in simulating the mean monsoonal characteristics. However, increasing horizontal resolution from 0.440 to 0.220 adds value in simulating the JJAS mean precipitation by reducing the biases both over ocean and land. The detailed results from the analysis will be discussed in the general assembly.Keywords: Indian summer monsoon, coupled regional model, horizontal-resolution, CORDEX-SA&#160;Acknowledgement: This work is jointly supported by the Department of Science and Technology (DST), Govt. of India, grant number DST/INT/RUS/RSF/P-33/G and the Russian Science Foundation (Project No.: 19-47-02015).

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Impact of Shortened Winter Road Access on Costs of Forest Operations

Forests ◽

10.3390/f10050447 ◽

2019 ◽

Vol 10 (5) ◽

pp. 447 ◽

Cited By ~ 2

Author(s):

Tevfik Z. Kuloglu ◽

Victor J. Lieffers ◽

Axel E. Anderson

Keyword(s):

General Circulation ◽

Unit Cost ◽

Weather Conditions ◽

General Circulation Models ◽

Forest Harvesting ◽

Frozen Soil ◽

Annual Number ◽

Soil Conditions ◽

Frozen Ground ◽

The Impact

A significant portion of the forest harvesting in the cooler regions of North America occurs in the winter when the ground is frozen and can support machine traffic. Climate change may influence the cost of forestry operations by reducing the period of winter access in those cold regions. In this study, we examined the impact of a shortened period of frozen ground conditions on logging operation and costs. To adapt to shorter period of frozen soil conditions, logging contractors might need to provide more machines and labor to complete logging in a shorter period of frozen conditions. The objectives were to calculate the costs of logging operations of a hypothetical forestry company in Alberta, Canada under two conditions: first, when the wood was hauled to the mill directly; and second, when part of the wood was hauled to satellite yards close to the logging area, thereby minimizing the annual number of idle hauling trucks. General Circulation Models were used to predict future winter weather conditions. Using the current type of harvesting machines and hauling directly to the mill, the unit cost of logging operations ($/m3) was projected to increase by an average of 1.6% to 2.5% in 2030s, 2.8% to 5.3% in the 2050s and 4.8% to 10.9% in the 2080s compared to the base year of 2015–2016. With use of satellite yards during the winter logging, the total logging cost will increase over direct haul, by 1.8% to 2.8% in the 2030s, 3.1% to 5.7% in the 2050s and 5.2% to 11.4% in the 2080s. Using satellite yards, however, will provide year-around employment for hauling truckers and more consistent and reliable hauling operations.

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The Precipitation Response to an Idealized Subtropical Continent

Journal of Climate ◽

10.1175/jcli-d-15-0616.1 ◽

2016 ◽

Vol 29 (12) ◽

pp. 4543-4564 ◽

Cited By ~ 9

Author(s):

Elizabeth A. Maroon ◽

Dargan M. W. Frierson ◽

Sarah M. Kang ◽

Jacob Scheff

Keyword(s):

General Circulation ◽

Hadley Circulation ◽

General Circulation Models ◽

Atmospheric Model ◽

Opposite Hemisphere ◽

Clear Sky ◽

Tropical Precipitation ◽

Precipitation Response ◽

Atmospheric General Circulation Models ◽

The Impact

Abstract A subtropical continent is added to two aquaplanet atmospheric general circulation models (AGCMs) to better understand the influence of land on tropical circulation and precipitation. The first model, the gray-radiation moist (GRaM) AGCM, has simplified physics, while the second model, the GFDL Atmospheric Model version 2.1 (AM2.1), is a fully comprehensive AGCM. Both models have a continent that is 60° wide in longitude from 10° to 30°N, in an otherwise slab-ocean-covered world. The precipitation response varies with cloudy- and clear-sky feedbacks and depends on continental albedo. In GRaM simulations with a continent, precipitation in the Northern Hemisphere decreases mostly as a result of decreased evaporation. In AM2.1 simulations, precipitation also shifts southward via Hadley circulation changes due to increasing albedo, but the radiative impact of clouds and moisture creates a more complex response. Results are similar when a seasonal cycle of insolation is included in AM2.1 simulations. The impact of a large, bright subtropical continent is to shift precipitation to the opposite hemisphere. In these simulations, the hemisphere of greater tropical precipitation is better predicted by the hemisphere with greater atmospheric energy input, as has been shown in previous literature, rather than the hemisphere that has higher surface temperature.

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Reaching the lower stratosphere: validating an extended vertical grid for COSMO

Geoscientific Model Development Discussions ◽

10.5194/gmdd-8-483-2015 ◽

2015 ◽

Vol 8 (1) ◽

pp. 483-520

Author(s):

J. Eckstein ◽

S. Schmitz ◽

R. Ruhnke

Keyword(s):

Relative Humidity ◽

Lower Stratosphere ◽

Weather Prediction ◽

Atmospheric Model ◽

Northern Europe ◽

Time Period ◽

Regional Atmospheric Model ◽

Lee Waves ◽

Vertical Grid ◽

The Mean

Abstract. This study presents an extended vertical grid for the regional atmospheric model COSMO, used for numerical weather prediction, reaching up to 33 km. The extended setup has been used to stably simulate eleven months in a domain covering central and northern Europe. Temperature and relative humidity have been validated using radio sonde data in polar and temperate latitudes, focussing on the stratosphere. Temperature values are reproduced very well by the model. Relative humidity could only be met in the mean over the whole time period after excluding data from Russian stations, which showed significantly higher values. A study of orographically induced lee waves over Iceland, well visible in the model but not in the regridded boundary data (ERA-Interim and NCEP reanalysis), showcases the advantage and applicability of the model in the extended vertical grid.

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Impact of SSTA in the East Indian Ocean on the Frequency of Northwest Pacific Tropical Cyclones: A Regional Atmospheric Model Study

Journal of Climate ◽

10.1175/jcli-d-10-05014.1 ◽

2011 ◽

Vol 24 (23) ◽

pp. 6227-6242 ◽

Cited By ~ 54

Author(s):

Ruifen Zhan ◽

Yuqing Wang ◽

Chun-Chieh Wu

Keyword(s):

Indian Ocean ◽

Atmospheric Model ◽

Western Pacific ◽

Northwest Pacific ◽

East Indian ◽

Regional Atmospheric Model ◽

The Impact ◽

East Indian Ocean ◽

The Western Pacific ◽

Genesis Frequency

Abstract The impact of the sea surface temperature anomaly (SSTA) in the East Indian Ocean (EIO) on the tropical cyclone (TC) frequency over the western North Pacific (WNP) and the involved physical mechanisms are examined using the International Pacific Research Center (IPRC) Regional Atmospheric Model (iRAM) driven by the reanalysis and the observed SSTs. The model reproduces generally quite realistic climatic features of the WNP TC activity, including the interannual variability of the WNP TC genesis frequency, the geographical distributions of TC genesis and frequency of occurrence. In particular, the model reproduces the observed statistical (negatively correlated) relationship between the WNP TC frequency and the EIO SSTA, as recently studied by Zhan et al. The experiments with artificially imposed SSTA in the EIO in the year 2004 with normal EIO SST and WNP TC activity confirm that the EIO SSTA does affect the TC genesis frequency in the entire genesis region over the WNP by significantly modulating both the western Pacific summer monsoon and the equatorial Kelvin wave activity over the western Pacific, two major large-scale dynamical controls of TC genesis over the WNP. Additional sensitivity experiments are performed for two extreme years: one (1994) with the highest and one (1998) with the lowest TC annual frequencies in the studied period. The results reveal that after the EIO SSTAs in the two extreme years are removed, the TC frequency in 1998 is close to the climatological mean, while the excessive TCs in 1994 are still simulated. The model results suggest that the warm EIO might be a major factor contributing to the unusually few TCs formed over the WNP in 1998, but the cold EIO seemed to contribute little to the excessive WNP TCs in 1994.

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Impact of ocean-atmosphere coupling on regional climate: the Iberian Peninsula case

10.5194/egusphere-egu2020-13098 ◽

2020 ◽

Author(s):

William Cabos ◽

Dmitry Sein ◽

Alba de la Vara ◽

Francisco Alvarez Garcia

Keyword(s):

Atlantic Ocean ◽

Iberian Peninsula ◽

North Atlantic ◽

Global Climate Model ◽

Regional Climate ◽

Atmospheric Model ◽

The North ◽

Regional Atmospheric Model ◽

The North Atlantic ◽

The Impact

Regional models used for downscaling the European climate usually include a relatively small area of the Atlantic Ocean and are uncoupled, with the SST used as lower boundary conditions much coarser than the mesh of the regional atmospheric model. Concerns thus arise about the proper representation of the oceanic influence and the role of air-sea coupling in such experiments.&#160; A complex orography and the exposure to different air and ocean masses make the Iberian Peninsula (IP) an ideal test case for exploring the impact of including explicitly the North Atlantic in the regional domain and the added value that coupling brings to regional climate modeling. To this end, the regionally-coupled model ROM and its atmospheric component, the regional atmospheric model REMO are used in a set of coupled and uncoupled experiments forced by the ERA-Interim reanalysis and by the global climate model MPI-ESM. The atmospheric domain is the same in all simulations and includes the North Atlantic and the ocean component is global and eddy permitting. Results show that the impact of air-sea coupling on the IP winter biases can be traced back to the features of the simulated North Atlantic Ocean circulation. In summer, it is the air-sea interactions in the Mediterranean that exert the largest influence on the regional biases. Despite improvements introduced by the eddy-permitting ocean, it is suggested that a higher resolution could be needed for a correct simulation of the features of the large-scale atmospheric circulation that impact the climate of the IP.&#160;&#160;&#160;&#160;&#160;

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