NCEP/EMC Land-Surface and PBL Parameterization Schemes

Outline of Presentation

Land-Surface Physics

Is the Land Surface Important to NWP?

Goals of Improved Land-Surface Physics

Notable Examples

Atmospheric signature over Oklahoma wheat fields (dark green area from north-central through southwest Oklahoma) during peak greenness.

"Relatively moist,"

1998 Texas /Oklahoma Drought
10% Moisture Availability over Region by late July 1998

Parched, dry ground heats quickly under afternoon insolation.  Note very warm Eta model soil temperatures over the Red River Valley

The hot, dry ground results in large sensible heat flux into the PBL, with very hot 2 meter temperatures (>40 C) over the area

So what does a land-surface scheme do?

Attributes of Eta Land-Surface Physics

Slide 14

"Key Assumption:"

Prognostic Equations

Operational Soil Texture Database

Evapotranspiration Treatment

Evapotranspiration (continued)

Canopy Resistance Issues

Canopy Resistance (continued)

Operational Vegetation Type Database at NCEP

December Green Vegetation Fraction

June Green Vegetation Fraction

Annual Time Series of Green Fraction Over Oklahoma Wheat Country

Annual Time Series of Green Fraction over Iowa Corn Fields

Annual Time Series of Green Fraction over Arizona Desert

Eta Model Albedo (snow free)

Snow Cover Treatment

More Snow Information

Milestones of Eta Land-Surface Physics

PBL Physics

Purpose of PBL Scheme

Attributes of PBL Treatment

Atmospheric Surface Layer

What the heck is “Similarity Theory”?

PBL Above the Surface Layer

Recent Verification and New Initiatives

EMC Forecast Verification System (FVS) Regions

February 1999 Northern Plains (NPL) 2m TAIR

April 1999 NPL 2m TAIR and RELH

August 1999 NPL 2m TAIR and RELH

Use of OK Mesonet to examine land-surface physics

Oklahoma Vegetation Fraction During July

Humidity bias over OK Mesonet in July 1997

Improved soil moisture via continuous self-cycling

Validation of Surface Fluxes

Validation of Surface Fluxes (continued)

Validation of Surface Fluxes (continued)

Validation of Surface Fluxes (continued)

Areas Needing Improvement

Major Initiative:  LDAS

Improvement in soil moisture from using observed precipitation

LDAS High-Resolution Vegetation

Conclusions