Surface Influences 8.1

The use or application of weather forecasts is…

mainly at or near the surface

Surface conditions are often closely interacting with…

lower tropospheric cloud, turbulence, and radiative effects at small, poorly sampled scales

Surface influences on the atmosphere above

Vertical fluxes

Complex interdisciplinary parameterization

Aggregation from heterogeneous conditions

Layers

Surface (interface)
Surface layer

PBL

The surface processes and properties…

influence the atmosphere above (fluxes into the PBL and free atmosphere)

influence the near-surface weather that people experience and measure

Surface fluxes are important for

convective initiation and organization of cloud patterns

“Local effects” on the surface weather observations can be partially addressed by

statistical processing of model conditions based on characterization of a long record of point measurements

Diurnal effects on convective development

Precipitation recycling

Soil moisture memory

Automated surface observing sites are able to provide… at …. and…

high temporal resolution data; little additional cost; often have dense spatial distribution over land areas

What makes in situ data difficult to determine?

The spatial variability of land cover and terrain

Remote sensing (by satellite)

Improves spatial representativeness of land cover and clouds

not well suited for near-surface conditions below clouds or forest canopies

Some datasets from field projects

AMMA - Land-sea interactions in West African monsoons

OWLES - Lake effect snow around Lake Ontario

CHEESEHEAD - Multi-scale interactions in forested environements

The “surface”

The solid or liquid interface of the earth with the atmosphere

"The “surface layer”

The first layer of the atmosphere above the surface

Typical depth of the PBL

1 km

varies from < 100 m in stable conditions to thousands of meters in convective conditions

At higher latitudes, the near-surface environment is often dominated by

intense shallow inversions and nearly horizontal solar angles

Low latitudes are characterized by

Complex vegetation structure and humidity variations