Instrument location
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Instrument location. Ground-based remote sensing instruments of clouds and precip at Princess Elisabeth. ceilo pyro radar. 10m. Cloud properties. Ceilometer. Infrared Radiation Pyrometer. pulsed diode laser in near IR (910nm)

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Instrument location

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Instrument location

Instrument location

Ground-based remote sensing

instruments of clouds and precip

at Princess Elisabeth

ceilo

pyro

radar

10m


Instrument location

Cloud properties

Ceilometer

Infrared Radiation

Pyrometer

  • pulsed diode laser in near IR (910nm)

  • vertical backscatter profiles and cloud base height detection up to 7.5 km

  • range resolution = 10m

  • report interval = 15s (transfer time of

  • accumulated signal)

  • passive radiometer: equivalent blackbody brightness temperature in 8-13 micron atm window

  • cloud base temperature

    (assuming =1)


Instrument location

  • - visibility below threshold (as defined for pilots)

  • sharp change in visibility

  • If these criteria not met => VV

“cloud bottom” exists

  • Vaisala algorithm is used for cloud base detection

  • - lidar equation is inverted using Klett (1981) algorithm assuming

where k2=1 - assumptionvalid for optically thick liquid clouds

(Krasnov and Russchenberg 2002;

Rocadenbosch et al. 1999)

=> remote visibility

  • Applied to PE:

  • liquid cloud bottom well defined

  • problems with ice clouds: algorithm identifies cloud top as cloud bottom

  • during precipitation/drifting snow - fake cloud bottom heights (=>low cloud bias during storm)


Apply new algorithm to cloud base detection tht temporal height tracking martucci et al 2010

Apply new algorithm to cloud base detection:THT (Temporal Height Tracking)Martucci et al. 2010)

  • The THT scheme is based on the information about the mutual positions of the local

  • maxima in the attenuated backscatter coefficient vertical profile and it’s vertical gradient:

where

1) lidar equation =>

2) gradient

  • i = single successive measurements in the selected period (eg, 10min) with time

  • resolution of recorded profile (3 s) => temporal evolution of GSi (average over 10min

  • ensures relatively invariable cloud base initiating the algorithm

  • heights of the largest 10min-mean(GS) and 10-minmean(beta) maxima => reference height

  • look for principal maxima of GS and beta in a limited interval around href

=> find GS(max) > threshold

and beta(max)

=> mean between the two = CBH


Jan 25 16 utc mid level cloud containing liquid from se

Jan 25, 16 utc:mid level cloud containing liquid from SE

cloud height = 3km

optically thick liquid clouds

- well defined cloud bottom height


Jan 31 15 utc ice cloud precip in the 500 2000m layer

Jan 31, 15 utc:ice cloud/precip in the 500-2000m layer

ice clouds/virga: errors in Vaisala-detected CBH

(precipitation-type profile; Vaisala algorithm

gives cloud top instead of cloud bottom)


Jan 31 15 utc virga in the 500 2000m layer detected by mrr

Jan 31, 15 utc:virga in the ~500-2000m layerdetected by MRR

Radar equivalent reflectivity


Clouds during february 6 7 2010 storm

Clouds duringFebruary 6-7, 2010storm


Synoptic chart 7 feb 2010 storm

500hPa

near surface (10m)

Synoptic chart: 7 Feb, 2010 storm

Feb 6

pe

pe

Feb 7

pe

Operational meteo information from Neumayer station (ECMWF)


Ir composite image feb 7 2010 09 utc

IR composite imageFeb 7, 201009 UTC:

pe

AMRC, UW-Madison

thanks to Matthew Lazzara

and his team


6 feb 8 utc

6 Feb, 8 utc

2 cloud layers detected:

~1.2 km, CBT = -18 C

~3 km, CBT = -35 C

liquid?

virga-type ice crystals


6 feb 15utc

6 Feb, 15utc

icy cloud

liquid?

CBH = 2.5km

CBT = -35 C


Feb 7 01utc

Feb 7, 01utc

CBH = 1.5 and 3-4 km

CBT = -25 C

glaciated cloud

light

precipitation


Feb 7 3utc ceilo detects beginning of precipitation

Feb 7, ~3utc: ceilo detectsbeginning of precipitation

cloud probably with liquid

very light precip

4

5

Height, m

data gap

very weak

radar signal...


Feb 7 8utc blowing snow

Height, m

data gap

Feb 7, ~8utc: blowing snow

blowing snow attenuates lidar signal

radar detects intensive

precipitation, while

ceilo completely attenuated


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