The effect of the Zagros Mountains on the formation and maintenance of the Iran Anticyclone using RegCM4

Zarrin, Azar; Ghaemi, Hooshang; Azadi, Majid; Mofidi, Abbas; Mirzaei, E

doi:10.1007/s00703-011-0134-z

Cited by 29 publications

(23 citation statements)

References 20 publications

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“…9d). This agrees with previous studies (Wu et al 2012;Zaitchik et al 2007;Zarrin et al 2011), which emphasize the importance of diabatic heating of the Zagros Mountains in lowering the sea level pressure and inducing the low-level cyclonic wind surround the mountains that may reinforce the ISM, particularly over northwestern India. However, such heating effect is relatively small compared to the full impact of the Zagros Mountains (cf.…”

Section: Thermal Effect: Elevated Heating Versus Thermal Insulationsupporting

confidence: 82%

Asynchronous responses of East Asian and Indian summer monsoons to mountain uplift shown by regional climate modelling experiments

et al. 2012

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It has been demonstrated in climate models that both the Indian and East Asian summer monsoons (ISM and EASM) are strengthened by the uplift of the entire Asian orography or Tibetan Plateau (TP) (i.e. bulk mountain uplift). Such an effect is widely perceived as the major mechanism contributing to the evolution of Asian summer monsoons in the Neogene. However, geological evidence suggests more diachronous growth of the Asian orography (i.e. regional mountain uplift) than bulk mountain uplift. This demands a re-evaluation of the relation between mountain uplift and the Asian monsoon in the geological periods. In this study, sensitivity experiments considering the diachronous growth of different parts of the Asian orography are performed using the regional climate model COSMO-CLM to investigate their effects on the Asian summer monsoons. The results show that, different from the bulk mountain uplift, the regional mountain uplift can lead to an asynchronous development of the ISM and EASM. While the ISM is primarily intensified by the thermal insulation (mechanical blocking) effect of the southern TP (Zagros Mountains), the EASM is mainly enhanced by the surface sensible heating of the central, northern and eastern TP. Such elevated surface heating can induce a low-level cyclonic anomaly around the TP that reduces the ISM by suppressing the lower tropospheric monsoon vorticity, but promotes the EASM by strengthening the warm advection from the south of the TP that sustains the monsoon convection. Our findings provide new insights to the evolution of the Asian summer monsoons and their interaction with the tectonic changes in the Neogene.

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Section: Thermal Effect: Elevated Heating Versus Thermal Insulationsupporting

confidence: 82%

Asynchronous responses of East Asian and Indian summer monsoons to mountain uplift shown by regional climate modelling experiments

et al. 2012

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“…A significant positive correlation of 0.9 between AP 2mT and SLP is also found over Iran. The positive surface pressure anomaly over Iran and the negative pressure anomaly over the AP create a southerly wind anomaly over the AP, which weakens the northerly winds (Zarrin et al, 2011;Giannakopoulou and Touni, 2012;Yu et al, 2016). This prevailing southerly wind anomaly blowing from the warm Indian Ocean advects warm temperatures towards the AP.…”

Section: Resultsmentioning

confidence: 99%

Prominent mode of summer surface air temperature variability and associated circulation anomalies over the Arabian Peninsula

Attada

Yadav

Kunchala

et al. 2018

Atmospheric Science Letters

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This study investigates the dominant modes of surface air temperature (SAT) variability and associated circulation changes over the Arabian Peninsula (AP) during summer for the period 1979–2016 based on an empirical orthogonal function (EOF) analysis. The analysis results reveal that the first leading EOF mode is related to the weakening of the subtropical westerly jet stream, which may impact the AP temperature variability through the mid‐latitude Rossby wave trains (successive troughs and ridges). This can be explained by the high correlation of the AP summer temperatures with the quasi‐stationary mid‐latitude/extratropical Eurasian Rossby wave train type patterns, which influences the air temperature variability by modulating the Asian Jets. Furthermore, the high AP SAT variability is also closely associated with strong middle to lower tropospheric descent (subsidence) anomalies, which cause warm temperature anomalies over this region.

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“…The relations between CasHKI and meteorological parameters in Zabol (Figures ) are strongly affected by several local factors, such as local wind driven by orography, thermal lows, convection, local dust re‐suspension and mesoscale convective systems, besides changes in land use – land cover and hydro‐meteorological conditions (Rashki et al ., ; Kaskaoutis et al ., ). Regional Climate Model (RegCM4) simulations revealed that the intensification of the Levar wind due to the channelling effect over Sistan and the local thermal convection cells modify the mean synoptic atmospheric circulation at local‐to‐regional scales (Zarrin et al ., ; Kaskaoutis et al ., ), resulting in weakening of the correlation between CasHKI and wind speed at Zabol (Figures and ). The modification in the vertical wind profile due to topography, surface heating and dust radiative warming affects the convection, vertical movement and shear over Sistan, which are important factors for dust uplift (Alizadeh Choobari et al ., ).…”

Section: Resultsmentioning

confidence: 99%

Assessment of changes in atmospheric dynamics and dust activity over southwest Asia using the Caspian Sea–Hindu Kush Index

Kaskaoutis

Rashki

Houssos

et al. 2017

Intl Journal of Climatology

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This study examines the influence of the Caspian Sea–Hindu Kush Index (CasHKI) on local and synoptic meteorology as well as on dust emissions over southwest (SW) Asia by means of National Center for Environmental Prediction/National Center for Atmospheric Research (NCEP‐NCAR) re‐analysed mean sea‐level pressure (MSLP), geopotential height at 700 hPa and surface meridional wind, along with meteorological data at Zabol, east Iran and Meteosat/Infrared Difference Dust Index (IDDI) retrievals. The analysis focuses on the summer period (June to September) of 2000–2014 and the winter period (November to March) of 1963–2014. The CasHKI values are mostly controlled by the MSLP anomalies over the Caspian Sea (CS) domain, varying from approximately −25 to +35 hPa in winter and from approximately−10 to +14 hPa in summer, but without a clear annual pattern. The CasHKI values are classified into four modes for each month depending on their intensity. In the summer months, the high CasHKI mode is associated with enhanced MSLP over central Asia and deepening of the Indo‐Pakistan thermal low associated with the Indian summer monsoon. At 700‐hPa level, the high CasHKI mode shows an enhancement of the Arabian ridge, expanding it to the north over Iran and the CS, with a concurrent strengthening of the Indian trough, leading to intensification of northerly winds along east Iran. This results in significant increase in dust activity over SW Asia, which is also apparent in the winter months. Furthermore, the intensification of the northerly flow associated with the high CasHKI modes drops the temperature and increases the relative humidity over Zabol, especially during winter. The SPRINTARS‐model simulations also show increased dust emissions and concentrations for the high CasHKI values, confirming that the CasHKI variations modulate the dust activity over SW Asia throughout the year.

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The effect of the Zagros Mountains on the formation and maintenance of the Iran Anticyclone using RegCM4

Cited by 29 publications

References 20 publications

Asynchronous responses of East Asian and Indian summer monsoons to mountain uplift shown by regional climate modelling experiments

Asynchronous responses of East Asian and Indian summer monsoons to mountain uplift shown by regional climate modelling experiments

Prominent mode of summer surface air temperature variability and associated circulation anomalies over the Arabian Peninsula

Assessment of changes in atmospheric dynamics and dust activity over southwest Asia using the Caspian Sea–Hindu Kush Index

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