Stratospheric dryness: model simulations and satellite observations

Lelieveld, J.; Brühl, Christoph; Jöckel, Patrick; Steil, B.; Crutzen, Paul J.; Fischer, H.; Giorgetta, Marco; Hoor, Peter; Lawrence, M. G.; Sausen, R.; Tost, H.

doi:10.5194/acp-7-1313-2007

Cited by 114 publications

(90 citation statements)

References 101 publications

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“…3) the water vapour maxima observed by Odin/SMR occur one month earlier. A recent model study of the SSAO in water vapour by Lelieveld et al (2007) make a similar observation, when comparing their results to UARS/HALOE data. This is very likely explained by an under-sampling of the HALOE data due to the solar-occultation technique and the UARS orbit.…”

Section: Discussion and Summarysupporting

confidence: 56%

Observations of the mesospheric semi-annual oscillation (MSAO) in water vapour by Odin/SMR

et al. 2008

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Abstract. Mesospheric water vapour measurements taken by the SMR instrument aboard the Odin satellite between 2002 and 2006 have been analysed with focus on the mesospheric semi-annual circulation in the tropical and subtropical region. This analysis provides the first complete picture of mesospheric SAO in water vapour, covering altitudes above 80 km where previous studies were limited. Our analysis shows a clear semi-annual variation in the water vapour distribution in the entire altitude range between 65 km and 100 km in the equatorial area. Maxima occur near the equinoxes below 75 km and around the solstices above 80 km. The phase reversal occurs in the small layer inbetween, consistent with the downward propagation of the mesospheric SAO in the zonal wind in this altitude range. The SAO amplitude exhibits a double peak structure in the equatorial region, with maxima at about 75 km and 81 km. The observed amplitudes show higher values than an earlier analysis based on UARS/HALOE data. The upper peak amplitude remains relatively constant with latitude. The lower peak amplitude decreases towards higher latitudes, but recovers in the Southern Hemisphere subtropics. On the other hand, the annual variation is much more prominent in the Northern Hemisphere subtropics. Furthermore, higher volume mixing ratios during summer and lower values during winter are observed in the Northern Hemisphere subtropics, as compared to the corresponding latitude range in the Southern Hemisphere.

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Section: Discussion and Summarysupporting

confidence: 56%

Observations of the mesospheric semi-annual oscillation (MSAO) in water vapour by Odin/SMR

et al. 2008

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“…Very deep and overshooting convective clouds bring moisture to the upper troposphere lower stratosphere region. The critical issues like possible mechanisms/pathways of moistening or drying of the lower stratosphere are still undergoing research (Danielsen, 1982;Highwood and Hoskins, 1998;Sherwood and Dessler, 2000;Dessler, 2002;Gettelman et al, 2002;Sherwood and Dessler, 2003;Jain et al, 2006;Jensen et al, 2007;Lelieveld et al, 2007;Rossow and Pearl, 2007;Horvath and Soden, 2008;James et al, 2008). But the first step in investigating these issues further is to pinpoint the locations and frequency of the events when convection reaches and/or penetrates the TTL (Rossow and Pearl, 2007).…”

Section: Convection Reaching the Tropical Tropopause Layer (Ttl)mentioning

confidence: 99%

A daytime climatological distribution of high opaque ice cloud classes over the Indian summer monsoon region observed from 25-year AVHRR data

Devasthale

Graßl

2009

Atmos. Chem. Phys.

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Abstract.A daytime climatological spatio-temporal distribution of high opaque ice cloud (HOIC) classes over the Indian subcontinent (0-40 • N, 60 • E-100 • E) is presented using 25-year data from the Advanced Very High Resolution Radiometers (AVHRRs) for the summer monsoon months. The HOICs are important for regional radiative balance, precipitation and troposphere-stratosphere exchange. In this study, HOICs are sub-divided into three classes based on their cloud top brightness temperatures (BT ). Class I represents very deep convection (BT <220 K). Class II represents deep convection (220 K<=BT <233 K) and Class III background convection (233 K<=BT <253 K). Apart from presenting finest spatial resolution (0.1×0.1 degrees) and long-term climatology of such cloud classes from AVHRRs to date, this study for the first time illustrates on (1) how these three cloud classes are climatologically distributed during monsoon months, and (2) how their distribution changes during active and break monsoon conditions. It is also investigated that how many deep convective clouds reach the tropopause layer during individual monsoon months. It is seen that Class I and Class II clouds dominate the Indian subcontinent during monsoon. The movement of monsoon over continent is very well reflected in these cloud classes. During monsoon breaks strong suppression of convective activity is observed over the Arabian Sea and the western coast of India. On the other hand, the presence of such convective activity is crucial for active monsoon conditions and all-IndiaCorrespondence to: A. Devasthale (abhay.devasthale@smhi.se) rainfall. It is found that a significant fraction of HOICs (3-5%) reach the tropopause layer over the Bay of Bengal during June and over the north and northeast India during July and August. Many cases are observed when clouds penetrate the tropopause layer and reach the lower stratosphere. Such cases mostly occur during June compared to the other months.

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“…The model dynamics has been weakly nudged (Jeuken et al, 1996;Jöckel et al, 2006;Lelieveld et al, 2007) towards the analysis data of the European Centre for MediumRange Weather Forecasts (ECMWF) operational model (up to 100 hPa) to represent the actual day-to-day meteorology in the troposphere. This allows a direct comparison with observations.…”

Section: A Pozzer Et Al: Aerosol Simulation With Emac 963mentioning

confidence: 99%

Distributions and regional budgets of aerosols and their precursors simulated with the EMAC chemistry-climate model

et al. 2012

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Abstract.The new global anthropogenic emission inventory (EDGAR-CIRCE) of gas and aerosol pollutants has been incorporated in the chemistry general circulation model EMAC (ECHAM5/MESSy Atmospheric Chemistry). A relatively high horizontal resolution simulation is performed for the years [2005][2006][2007][2008] to evaluate the capability of the model and the emissions to reproduce observed aerosol concentrations and aerosol optical depth (AOD) values. Model output is compared with observations from different measurement networks (CASTNET, EMEP and EANET) and AODs from remote sensing instruments (MODIS and MISR). A good spatial agreement of the distribution of sulfate and ammonium aerosol is found when compared to observations, while calculated nitrate aerosol concentrations show some discrepancies. The simulated temporal development of the inorganic aerosols is in line with measurements of sulfate and nitrate aerosol, while for ammonium aerosol some deviations from observations occur over the USA, due to the wrong temporal distribution of ammonia gas emissions. The calculated AODs agree well with the satellite observations in most regions, while negative biases are found for the equatorial area and in the dust outflow regions (i.e. Central Atlantic and Northern Indian Ocean), due to an underestimation of biomass burning and aeolian dust emissions, respectively. Aerosols and precursors budgets for five different regions (North America, Europe, East Asia, Central Africa and South America) are calculated. Over East-Asia most of the emitted aerosols (precursors) are also deposited within the region, while in North America and Europe transport plays a larger role. Further, it is shown that a simulation with monthly varying anthropogenic emissions typically improves the temporal correlation by 5-10 % compared to one with constant annual emissions.

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Stratospheric dryness: model simulations and satellite observations

Cited by 114 publications

References 101 publications

Observations of the mesospheric semi-annual oscillation (MSAO) in water vapour by Odin/SMR

Observations of the mesospheric semi-annual oscillation (MSAO) in water vapour by Odin/SMR

A daytime climatological distribution of high opaque ice cloud classes over the Indian summer monsoon region observed from 25-year AVHRR data

Distributions and regional budgets of aerosols and their precursors simulated with the EMAC chemistry-climate model

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