theo brandsma royal netherlands met e orological institute (knmi)

Theo Brandsma

Royal Netherlands Meteorological Institute (KNMI)

6th Seminar for homogenization and qualtity control in climatological databases

COST-HOME meeting

Budapest, Hungary, 26-30 May 2008

Understanding of inter-site temperature differences at

the KNMI terrain in De Bilt (the Netherlands)

Contents

Background and methodology

Results

Overview of causes for inter-site temperature

differences

Background

KNMI terrain at De Bilt

Background and methodology

KNMI terrain at De Bilt

Background and methodology

(After the renovation of the nature area in Sep/Oct 2004)

Obstacle altitudeBackground and methodology

InstrumentsBackground and methodology

Daily maximum temperature

Results

Renovation

Daily minimum temperature

Results

Renovation

Diurnal cycle

Results

Diurnal cycle

Results

Wind direction dependence

Results

Overview of causes for inter-site temperature differences

1. Advection of warm/cold air related to local soil type/groundwater level differences

2. Local stability differences (especially for W < 1.0 m/s)

3. Screen ventilation differences (radiation error)

4. Sky-view factor/horizon differences

5. Radiation by surrounding objects

6. Instrumental errors