a multi-year data-set of arctic mixed-phase stratus...

Instrument DescriptionsAHSRLWavelength: 532 nmLaser Pulse Width: 40 nsReceiver Field of View: 45 µradReceiver Aperture: 40 cmAltitude Resolution: 7.5 mTemporal Resolution: 2.5 s

MMCRWavelength: 8.6 mmDoppler Velocity: yesSensitivity: ~ -40 dBZAntenna: 1.8 mAltitude Resolution: 45 mTransmit Power: 100 W peak

The seatainer housing for the AHSRL in Barrow (left) and Eureka (right). The map of the western Arctic (top) shows the differences in location between Barrow and Eureka. (Bathymetric chart courtesy of the NOAA IBCAO program. Also visible in the Eureka picture is the antenna for the NOAA millimeter cloud radar (MMCR).

N NBarrow(09/04-11/04)

Eureka(08/05-present)

Observation Sites

Long-Term Stratus Properties

PRECIPITATION

CLOUD

SURFACE

0 1000 2000 3000 4000 50000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Cloud Base Altitude (m)

Nor

mal

ized

#

BARROWEUREKA

0 20 40 60 80 100 1200

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Effective Diameter (µm)

Nor

mal

ized

#

BARROWEUREKA

0 0.02 0.04 0.06 0.08 0.10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Ice Water Content (g/m3)

Nor

mal

ized

#

BARROWEUREKA

230 235 240 245 250 255 260 265 270 2750

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Cloud Minimum Temperature (K)

Nor

mal

ized

#

BARROWEUREKA

0.5 1 1.5 2 2.5 3 3.5 4x 105

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Number Density (#/L)

Nor

mal

ized

#

BARROWEUREKA

0 1 2 3 4 50

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Cloud Optical Depth

Nor

mal

ized

#

BARROWEUREKA

0 500 1000 15000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Cloud Thickness (m)

Nor

mal

ized

#

BARROWEUREKA

0 0.2 0.4 0.6 0.8 10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Water Content (g/m3)

Nor

mal

ized

#

BARROWEUREKA

0 0.5 1 1.50

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Sub−Cloud Optical Depth

Nor

mal

ized

#

BARROWEUREKA

0 0.02 0.04 0.06 0.08 0.10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Ice Water Content (g/m3)

Nor

mal

ized

#

BARROWEUREKA

0 0.02 0.04 0.06 0.08 0.10

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


Nor

mal

ized

#

BARROWEUREKA

10 20 30 40 50 60 70 80 90 1000

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Number Density (#/L)

Nor

mal

ized

#

BARROWEUREKA

0 50 100 150 200 2500

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1


Nor

mal

ized

#

BARROWEUREKA

220 230 240 250 260 270 280 2900

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Surface Temperature (K)

Nor

mal

ized

#

BARROWEUREKA

0 50 100 150 200 250 300 3500

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Surface Wind Direction (degrees)

Nor

mal

ized

#

BARROWEUREKA

0 5 10 15 20 25 300

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

Surface Wind Speed (m/s)

Nor

mal

ized

#

BARROWEUREKA

09 October, 2004: Barrow

15 February, 2006: EurekaTime (UT)

Altit

ude

(km

)

Lidar backscatter cross section (Masked values shown in black and white)

23:05 23:10 23:15 23:20 23:25

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

1/(m str)1e−8

1e−7

1e−6

1e−5

1e−4

1e−3

Time (UT)

Altit

ude

(km

)

Radar backscatter cross section (Masked values shown in black and white)

23:05 23:10 23:15 23:20 23:25

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

1/(m str)1e−14

1e−13

1e−12

1e−11

1e−10

1e−9

1e−8

1e−7

Time (UT)

Altit

ude

(km

)

Depolarization (Masked values shown in black and white)

23:05 23:10 23:15 23:20 23:25

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Percent1e−2

2e−2

5e−2

1e−1

2e−1

5e−1

1

Time (UT)

Altit

ude

(km

)

Lidar backscatter cross section (Masked values shown in black and white)

12:05 12:10 12:15 12:20 12:25

0.20.40.60.81.01.21.41.61.82.02.22.42.62.8

1/(m str)1e−8

1e−7

1e−6

1e−5

1e−4

1e−3

Time (UT)

Altit

ude

(km

)

Radar backscatter cross section (Masked values shown in black and white)

12:05 12:10 12:15 12:20 12:25

0.20.40.60.81.01.21.41.61.82.02.22.42.62.8

1/(m str)1e−14

1e−13

1e−12

1e−11

1e−10

1e−9

1e−8

1e−7

Time (UT)

Altit

ude

(km

)

Depolarization (Masked values shown in black and white)

12:05 12:10 12:15 12:20 12:25

0.20.40.60.81.01.21.41.61.82.02.22.42.62.8

Percent1e−2

2e−2

5e−2

1e−1

2e−1

5e−1

1

Single-Layer Mixed-Phase Arctic Stratus

Introduction

Mixed-phase clouds remain a difficult problem for both the observational and modeling com-munities. In particular, improved understanding of mixed-phase clouds in the Arctic is crucial because of radiative effects they impart on a region that is particularly sensitive to change. In order to better understand these cloud structures, the University of Wisconsin Arctic High Spec-tral Resolution Lidar (AHSRL) has been deployed to two different Arctic locations. The first de-ployment lasted two months and was to Barrow, AK in support of the ARM Mixed-Phase Arctic Clouds Experiment (M-PACE). The second deployment is ongoing, and to date almost three years of data have been collected at Eureka, Canada. In both locations, the lidar was co-located with a NOAA Millimeter Cloud Radar (MMCR). Mixed phase stratus has been readily detected at both locations, measurements from 2004-2007 contain nearly 1000 hours of single-layer mixed-phase stratus observations.

A Multi-Year Data-Set of Arctic Mixed-Phase Stratus Properties as Derived by a Combination of High-Spectral Resolution Lidar and Millimeter Cloud Radar

Gijs de Boer, Edwin W. ElorantaThe University of Wisconsin - Madison

Motivation

0 100 200 300 400 500−600

−400

−200

0

200

400

600

800

1000


)m( esa

B duolC

morF th gieH

Effective Diameter 10/09/04

Lidar−Radar RetrievalIn−Situ Measurements (water)In−Situ Measurements (ice)

10−2 100 102 104 106−600

−400

−200

0

200

400

600

800

1000

Number Density 10/09/04

Number Density (1/L)

)m( esa

B d uolC

m orF th gieH


−0.1 0 0.1 0.2 0.3 0.4 0.5 0.6−600

−400

−200

0

200

400

600

800

1000

Water Content 10/09/04


)m( esa

B du olC

morF t hgieH


Comparison With other Measurements

Longitude (deg)

Alti

tude

(km

)

CALIOP Derived Cloud Mask and Ground−Based Cloud−Top Height

−86.5 −86 −85.5 −850

0.5

1

1.5

2

2.5

3

Longitude (deg)

Alti

tude

(km

)

CALIOP Derived Cloud Mask and Ground−Based Cloud−Top Height

−86.5 −86 −85.5 −850

0.5

1

1.5

2

2.5

3

Left: Comparisons of MMCR cloud-top height retrievals (black line) with a cloud-mask derived from CALIOP data (red). Below: Comparisons of the lidar-radar microphysical retrievals (black) with in-situ data from Barrow (blue and red).

* EU

REK

A

* EU

REK

A

AcknowledgementsThis work was supported by the United States Department of Energy and NASA. Special thanks to the ILRC travel grant committee for assist-ing with travel expenses associated with attending this meeting.

Many microphysical retrievals obtained from satellite instruments require a priori information about the observed cloud. The same is true for parameterizations used for numerical simula-tions of cloud structures. Observations of this kind for Arctic clouds are very limited.

Methodology

Time (UT)

)mk( eduti tl A

Radar Backscatter Cross−Section

13:00 14:00 15:00 16:00 17:00 18:00 19:000.20.40.60.81.01.21.41.61.82.02.22.42.62.83.03.23.43.63.8

1/(m str)1e−14

1e−13

1e−12

1e−11

1e−10

1e−9

1e−8

1e−7

Time (UT)

)mk( eduti t lA

Lidar Backscatter Cross−Section

13:00 14:00 15:00 16:00 17:00 18:00 19:000.20.40.60.81.01.21.41.61.82.02.22.42.62.83.03.23.43.63.8

1/(m str)1e−6

1e−5

1e−4

1e−3Cloud Top: altitude > altitude of cloud baseO.D. < 1.5 -- HSRL backscatter cross-section < 5x10-⁵ 1/(m str)O.D. > 1.5 -- MMCR backscatter cross-section <1x10-¹⁸ 1/(m str)

Cloud Base: HSRL backscatter cross-section > 5x10-⁵ 1/(m str) HSRL depolarization < 0.03

The HSRL and MMCR are utilized together to locate cloud boundaries. Above (left), plots of the two data products are overlaid, and criteria for cloud-base and cloud top are given. HSRL and MMCR measurements are then combined to retrieve cloud microphysical quanti-ties (Donovan and Van Lammeren, 2001; Shupe, 2005). Temperature and wind data are re-trieved from cloud structures observed within 20 minutes of radiosonde launches. All infor-mation is averaged over half hour periods and distributions of long-term statistics are cre-ated as shown at right.

Time (UT)

Number Density

13:00 14:00 15:00 16:00 17:00 18:00 19:000.20.40.60.81.01.21.41.61.82.02.22.42.62.83.03.23.43.63.8

1/L1

10

1e2

1e3

1e4

Time (UT)

)mk( edutitlA

Water Content

13:00 14:00 15:00 16:00 17:00 18:00 19:000.20.40.60.81.01.21.41.61.82.02.22.42.62.83.03.23.43.63.8

g/m^3

0.02

0.04

0.06

0.08

0.1

0.12

0.14

Time (UT)

)mk( edutitl A

Effective Diameter

13:00 14:00 15:00 16:00 17:00 18:00 19:000.20.40.60.81.01.21.41.61.82.02.22.42.62.83.03.23.43.63.8

microns

20

40

60

80

100

120

140

160

180

200

Assumptions for retrievals:- gamma distribution of particles- spherical shape under presence of liquid, and variable shape elsewhere

a multi-year data-set of arctic mixed-phase stratus...

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