Cabauw Experimental Site forAtmospheric Research

- CESAR -

Henk Klein Baltink

Atmospheric Research Section

27 may 2002 Cloudnet Workshop Paris 2

Outline Overview Instruments at Cabauw Status 35 GHz Cloud Radar examples from BBC-campaign

27 may 2002 Cloudnet Workshop Paris 3

CESAR (Cabauw)

Objective:

to set-up and operate at the Cabauw site an observational facility with a comprehensive set of remote sensing and in-situ equipment to characterize the state of the atmosphere,its radiative properties and interaction with the land surface, for the study of physical processes, climate monitoring, and validation studies

27 may 2002 Cloudnet Workshop Paris 4

Remote Sensing Site

ProfilerSonicGPS

Cabauw Tower

27 may 2002 Cloudnet Workshop Paris 5

Status May 2002 (1) Tower (10, 20, 40, 80, 140, 200 m agl):

wind speed, direction, temp, dew temp (temp also at 0.6,1.6 m) turbulent fluxes at 180 m. (in progress) particle counters (in progress)

Surface: incoming/outgoing short & longwave radiation (BSRN in 20??) rain rate and duration DSD (in progress) soil temp. & hum. turbulent fluxes (at 4.5 m and 1 m. agl)

27 may 2002 Cloudnet Workshop Paris 6

Status May 2002 (2) Remote Sensing (passive)

IR-radiometers microwave radiometer (Univ.-Bonn, until ?)

Remote Sensing (active) 1290 MHz windprofiler/RASS 3.3 GHz FM-CW radar (TARA) 35 GHz Cloud Radar ceilometers (CT75,LD40) 1042 nm lidar GPS-receiver

27 may 2002 Cloudnet Workshop Paris 7

KNMI 35 GHz Radar

CT75 ceilometer

Heimann IR-radiometers

Video camera

27 may 2002 Cloudnet Workshop Paris 8

peak power 100 W (TWT transmitter) polarisation capability on receive spectral processing pulse-coding to enhance sensitivity 1.8 m antenna (0.36º beam angle) flexible parameter setting via GUI automated, unattended operation

Main Characteristics 35 GHz

27 may 2002 Cloudnet Workshop Paris 9

Status 35 GHz Cloud Radar In continuous operation since August 2001 2 week interrupt due to hardware failure (August) some minor software interrupts up to November no calibration and X-pol. (mid January - mid March) power output decreased by 10% since August absolute values not reliable when water on shroud plan 2002: upgrade DSP-board, fast V-H switch

27 may 2002 Cloudnet Workshop Paris 10

Acquisition cycle

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BBC

16 s

PRESENT

acquisition

processing

uncoded

coded

coded X-pol

27 may 2002 Cloudnet Workshop Paris 11

Sensitivity

2 modes:- 8-bit code (red)- uncoded (black)

ARM-SGP mode 2-54 dBZe @ 5 km

-42 dBZe @ 5 km

27 may 2002 Cloudnet Workshop Paris 12

Examples from BBC-campaign

TARA

35 GHz

MIRACLE

MICCY

27 may 2002 Cloudnet Workshop Paris 13

Ice Cloud

Reflectivity

Vertical Velocity

27 may 2002 Cloudnet Workshop Paris 14

WaterCloud

27 may 2002 Cloudnet Workshop Paris 15

35 GHz vs. TARA in rain

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KNMI, 19 Sep 2001

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Before rain event: good agreement

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3.3GHz radar

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During rain event: 20 – 30 dB difference20 50 80 110 140 170 200 230-40

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40Comparison between TARA and KNMI (Height: 2240m)

Minutes (start time: 05:09UTC)

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lect

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dBZ

)KNMITARA

Onset of precipitation at surface

27 may 2002 Cloudnet Workshop Paris 16

ModelcomparisonBBC 18/9/01

27 may 2002 Cloudnet Workshop Paris 17

Cloud Boundaries?

super cooled layer

27 may 2002 Cloudnet Workshop Paris 18

Ceilometer

Courtesy of Hannelore Bloemink, KNMI

27 may 2002 Cloudnet Workshop Paris 19

Spectra at 17:15

super cooled layer

noise

snr

signal

27 may 2002 Cloudnet Workshop Paris 20

Outlook (to do) Optimize acquisition cycle Calibration procedure (is it accurate

enough?) Mode-intercomparison and merging Water on shroud: no easy solution(?) Analysis of (all that) data