Orographic Land-Atmosphere Interactions and the Diurnal Cycle of Low Level Clouds and Fog

Orographic Land-Atmosphere Interactions and the Diurnal Cycle of Low Level Clouds and Fog AbstractPrevious work illuminated landform controls on moisture convergence in the Southern Appalachian Mountains (SAM) promoting heterogeneity in the vertical structure of low level clouds (LLC) and seeder-feeder interactions (SFI) that significantly impact warm season precipitation. Here, the focus is on elucidating orographic land-atmosphere interactions associated with the observed diurnal cycle of LLC and fog in the region. Three distinct hydrometeorological regimes during the Integrated Precipitation and Hydrology Experiment (IPHEx) are examined using the Weather Research and Forecasting model. Sensitivity to the choice of planetary boundary layer parameterization was investigated in the light of IPHEx observations. Simulations using the MYNN (Mellor-Yamada-Nakanishi-Niino) scheme exhibit LLC and fog patterns most consistent with observations albeit without capturing SFI. Independently of synoptic regime, the simulations reveal two distinct modes of orographic controls on atmospheric moisture convergence patterns that explain the diurnal cycle of LLC and fog. First, a stationary nocturnal mode at meso-α scales associated with an extended flow separation zone supports low level pooling and trapping of cold, moist, stable air in the inner mountain on the lee side of the western topographic divide. Second, a dynamic daytime mode that results from the co-organization of ridge valley-circulations at the meso-γ scale and Rayleigh-Bénard convection at the meso-β scale is associated with widespread low level instability below the envelope orography. Orographic decoupling results in the formation of a shallow stagnation zone between the western and eastern topographic divides at night that contracts westward during daytime. Predominantly easterly and southeasterly low level moisture convergence patterns support early afternoon LLC formation in the inner SAM. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Hydrometeorology American Meteorological Society

Orographic Land-Atmosphere Interactions and the Diurnal Cycle of Low Level Clouds and Fog

Loading next page...
 
/lp/ams/orographic-land-atmosphere-interactions-and-the-diurnal-cycle-of-low-eJyWRBrAC4
Publisher
American Meteorological Society
Copyright
Copyright © American Meteorological Society
ISSN
1525-7541
eISSN
1525-7541
D.O.I.
10.1175/JHM-D-16-0186.1
Publisher site
See Article on Publisher Site

Abstract

AbstractPrevious work illuminated landform controls on moisture convergence in the Southern Appalachian Mountains (SAM) promoting heterogeneity in the vertical structure of low level clouds (LLC) and seeder-feeder interactions (SFI) that significantly impact warm season precipitation. Here, the focus is on elucidating orographic land-atmosphere interactions associated with the observed diurnal cycle of LLC and fog in the region. Three distinct hydrometeorological regimes during the Integrated Precipitation and Hydrology Experiment (IPHEx) are examined using the Weather Research and Forecasting model. Sensitivity to the choice of planetary boundary layer parameterization was investigated in the light of IPHEx observations. Simulations using the MYNN (Mellor-Yamada-Nakanishi-Niino) scheme exhibit LLC and fog patterns most consistent with observations albeit without capturing SFI. Independently of synoptic regime, the simulations reveal two distinct modes of orographic controls on atmospheric moisture convergence patterns that explain the diurnal cycle of LLC and fog. First, a stationary nocturnal mode at meso-α scales associated with an extended flow separation zone supports low level pooling and trapping of cold, moist, stable air in the inner mountain on the lee side of the western topographic divide. Second, a dynamic daytime mode that results from the co-organization of ridge valley-circulations at the meso-γ scale and Rayleigh-Bénard convection at the meso-β scale is associated with widespread low level instability below the envelope orography. Orographic decoupling results in the formation of a shallow stagnation zone between the western and eastern topographic divides at night that contracts westward during daytime. Predominantly easterly and southeasterly low level moisture convergence patterns support early afternoon LLC formation in the inner SAM.

Journal

Journal of HydrometeorologyAmerican Meteorological Society

Published: Mar 8, 2017

There are no references for this article.

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 12 million articles from more than
10,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Unlimited reading

Read as many articles as you need. Full articles with original layout, charts and figures. Read online, from anywhere.

Stay up to date

Keep up with your field with Personalized Recommendations and Follow Journals to get automatic updates.

Organize your research

It’s easy to organize your research with our built-in tools.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

Monthly Plan

  • Read unlimited articles
  • Personalized recommendations
  • No expiration
  • Print 20 pages per month
  • 20% off on PDF purchases
  • Organize your research
  • Get updates on your journals and topic searches

$49/month

Start Free Trial

14-day Free Trial

Best Deal — 39% off

Annual Plan

  • All the features of the Professional Plan, but for 39% off!
  • Billed annually
  • No expiration
  • For the normal price of 10 articles elsewhere, you get one full year of unlimited access to articles.

$588

$360/year

billed annually
Start Free Trial

14-day Free Trial