• DOI:10.1175/2009JCLI2847.1
• Corpus ID: 53962903

Maintenance of Lower Tropospheric Temperature Inversion in the Saharan Air Layer by Dust and Dry Anomaly

@article{Wong2009MaintenanceOL,
  title={Maintenance of Lower Tropospheric Temperature Inversion in the Saharan Air Layer by Dust and Dry Anomaly},
  author={Sun Wong and Andrew E. Dessler and Natalie M. Mahowald and Ping Yang and Q. Feng},
  journal={Journal of Climate},
  year={2009},
  volume={22},
  pages={5149-5162}
}

• Sun Wong, A. Dessler, +2 authors Q. Feng
• Published 1 October 2009
• Environmental Science
• Journal of Climate

The role of Saharan dust and dry anomalyin maintaining the temperature inversion in the Saharan air layer (SAL) is investigated. The dust aerosol optical thickness (AOT) in the SAL is inferred from the measurements taken by Aqua Moderate Resolution Imaging Spectroradiometer (MODIS), and the corresponding temperature and specific humidity anomalies are identified using the National Centers for Environmental Prediction (NCEP) data in August‐September over the North Atlantic tropical cyclone (TC) main developmentregion(MDR;108‐208N,408‐608W).TheauthorsalsostudytheSALsimulatedintheNationalCenter of Atmospheric Research (NCAR) Community Atmosphere Model, version 3 (CAM3), coupled with dust radiative effect. It is found that higher AOT is associated with warmer and dryer anomalies below 700 hPa, which increases the atmospheric stability. The calculated instantaneous radiative heating anomalies from a radiative transfer model indicate that both the dust and low humidity are essential to maintaining the temperaturestructureintheSALagainstthermalrelaxation.At850hPa,heatinganomaliescausedbyboththedust and dry anomalies (for AOT . 0.8) are 0.2‐0.4 K day 21 . The dust heats the atmosphere below 600 hPa, while the dry anomaly cools the atmosphere below 925 hPa, resulting in a peak of heating rate anomaly located at 700‐850 hPa. In the eastern Atlantic, dust contributes about 50% of the heating rate anomaly. Westward of 408W, when the dust content becomes small (AOT , 0.6), the heating rates are more sensitive to the water vapor profile used in the radiative transfer calculation. Retrieving or simulating correct water vapor profiles is essential to the assessment of the SAL heating budgets in regions where the dust content in the SAL is small.