Polarimetric , dual Doppler and cloud radar observations for climate
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Polarimetric , dual Doppler and cloud radar observations for climate. www.cawcr.gov.au. 17 December,2008 Taiwan. Peter May with contributions from Alain Protat, Scott Collis, VN Bringi, Chris Williams, M. Thurai, Tom Keenan, Brad Atkinson, Ken Glasson, Mike Whimpey …. Background.

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Peter may with contributions from

Polarimetric , dual Doppler and cloud radar observations for climate

www.cawcr.gov.au

17 December,2008

Taiwan

Peter May

with contributions from

Alain Protat, Scott Collis, VN Bringi, Chris Williams, M. Thurai, Tom Keenan, Brad Atkinson, Ken Glasson, Mike Whimpey …


Background

Background

  • Centre for Australian Weather and Climate Research

  • A partnership between the Bureau of Meteorology (old BMRC)

  • CSIRO (parts of CSIRO Marine and Atmospheric Research)

  • ~ 250 scientists at 4 main sites (Melbourne, Aspendale, Canberra, Hobart)

  • Tackling Earth System Science:

  • World class Earth system numerical modelling (NWP and Climate)

  • World class observations that inform decisions

  • Understand, characterise and preedict the water cycle in Australia

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Polarimetric radar applications

Polarimetric radar applications

  • Projects on nowcasting

  • QPE and precipitation microphysics for both weather and climate

  • Cloud process studies including dual Doppler

  • Cloud statistics (cloud radar, profilers and weather radar)

  • Model validation

  • Two sites:

  • Darwin Climate Research Station

  • CP 2 Radar in Brisbane

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Peter may with contributions from

CP2 radar in Brisbane


Capability for dsd s

Capability for DSD’s

From Bringi et al (submitted)

Compare DDSD from profiler and

C-POL

Builds on Williams and May, 2008

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


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  • D0 histograms for the Monsoon regime (left panel) and the build up phase (right panel). In both cases, the dashed line represents the regions identified as being convective and the solid line represents the regions identified as being stratiform in the CPOL

(a)

(b)

Just one example, extending to large sample, to examine regime dependence,

Land/ocean statistics, potential aerosol impacts, BL impacts

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Peter may with contributions from

Microphysical classification with polarimetric radar

Use combinations of estimators and fuzzy logic to estimate most

Likely hydrometeor type:

Z:45-80dBZZDR: -1-6 dB ρHV(0): >0.9

KDP: 0-20 o/kmT:-10 – 10oCRain/hail mix

Classification types:

DrizzleRain

Snow (dry low density)Snow (dry high density)Snow(melting)

Graupel (dry)Graupel (wet)

Hail (D < 2 cm)Hail (D > 2cm)Rain/Hail mix


Peter may with contributions from

Example of C-pol classification

Rain

Rain/hail mix and wet graupel


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Microphysical classification : 4 Nov. 2001

Mis-classification of melting

aggregates

Strongest updraft in cloud, but on edge of heavy precipitation

Over-turning at top of updraft

Rain/hail mix and graupel

Brightband contamination

High fall speeds imply

graupel and hail

Evaporation of drops in downdraft part of overturning sample produces apparent upward moving drops


Physics multi doppler synthesis

µphysics + Multi Doppler Synthesis

  • Uses a variational method based on the work by Protat and Zawadzki (see Protat, A. and I. Zawadzki 1999: A semi-adjoint method for real time retrieval of three-dimensional wind field from multiple-Doppler bistatic radar network data. J. Atmos. Oceanic Tech., 16, 432-449 )

  • Retrieval of U and V components is performed by minimising difference between guess fields and measurements

  • Retrieval of W is performed by minimising difference between guess field and W derived from the integration of the anelastic mass continuity equitation (one of the adjoint models)

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Sample result

Sample result

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Peter may with contributions from

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Peter may with contributions from

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Peter may with contributions from

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Peter may with contributions from

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Peter may with contributions from

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Peter may with contributions from

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Convective core statistics

Convective Core statistics

CRM comparison

From Jing Bo, NASA GISS

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Peter may with contributions from

  • More weather radar applications

  • Examine environmental controls

  • Model validation

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


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New Products – “3D coverage product”

Taking grids and calculating areal statistics as a function of

height and time, e.g. area Z> 10 dBZ, snow area etc

Metrics of cloud cover, convective activity …

  • Interpolate the radar reflectivity and

  • microphysical classifications from the

  • polarimetric radar data onto a

  • Cartesian grid and run a forward

  • reflectivity calculation on the model

  • fields to produce a matching grid.

  • At each altitude level of the grid

  • calculate:

    • The fraction of the total area

    • covered by Z> [10, 20, 30, 40] dBZ

    • The fraction of the total area

    • covered by rain, snow, graupel, hail

    • The maximum reflectivity

    • anywhere in the grid


Scm product

SCM product

  • . Examples of observed reflectivity fields and how they map onto the SCP product. The reflectivity fields are CAPPI (reflectivity fields at a constant altitude) for 11 km (0750 UT) and 3 km (0630 UT) on 10 February, 2006. The 10 dBZ (40 dBZ) fraction at these times and heights are 34.7 % and 4.4 % respectively.

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Application for cloud physics

Application for cloud physics

  • Look at statistics for island thunderstorms to study question of what

  • Controls thunderstorm characteristics?

  • Similar forcing, just sort by environment i.e CAPE, CIN, Shear, aerosol

  • Note CAPE, shear and aerosol are independent, CAPE-CIN correlated

  • In press May et al ACP, 2008

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Application for cloud physics1

Application for cloud physics

  • Sorted by CAPE

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Peter may with contributions from

  • Sorted by CIN

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Peter may with contributions from

  • Sorted by shear

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


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  • Sorted by aerosol

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


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  • So is there an aerosol effect?

  • But thermodynamics are also different.

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Application for model testing

`Application for model testing

  • Radar Observations Model statistics

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Statistical approach for radar analysis

Statistical approach for radar analysis

  • Time series of the domain average

    total rain rate (solid) and convective

    rain rate (dotted) for the radar

    observations (top panel) and model

    simulations (lower panel).

    The time axis has been shifted by 4

    hours for the models to bring them

    into reasonable phase agreement

    as discussed in the May and Lane

    2008.

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Summary of section

Summary of section

  • Robust detailed kinematic and microphysical descriptions of storm systems in 4D

  • Useful for case studies and statistical analysis

  • Statistics :

    To describe regime dependence for better understanding

    Paramaterisation development

    Model testing

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Cloud radar profiles motivation

Cloud radar profiles: Motivation

Characterize the tropical ice cloud properties from different radar-lidar observations at different sites :

  • to evaluate the variability of these properties along the tropical belt, as a function of large-scale environment, cloud regime, in the vertical, interannual, etc …

  • to better understand the cloud / radiation feedback mechanisms

  • to provide an observational basis for model evaluation

  • to provide a reference to evaluate new spaceborne sensors (A-Train)

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Ground based radar lidar observations

Ground-based radar-lidar observations

  • ARM Sites : Darwin  2006/2007 monsoon season

    (other seasons soon for interannual variability)

  • AMF Sites : Niamey (West-Africa, 2006 monsoon season)

    Mather et al. (2007) and Mace et al. (2006) already documented

    the Manus and Nauru ARM sites – this study adds up two sites.

    Radars are degraded to the same sensitivity in all comparisons

    “Ice cloud” and “convective ice” profiles are separated in both datasets

    Which radius should we consider around these sites ?

    Impact of diurnal cycle of cloud properties around these sites ?

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Darwin vs niamey

Darwin vs Niamey

  • Compare statistics from two tropical sites

  • 1. Darwin – coastal monsoon environment

  • Intense storm activity is nearby

  • 2. Niamey, Niger – inland for AMMA

  • Most intense storms in Congo to the east, cloud systems propagate in

  • Compare the two – monsoon vs continental, site representativeness for

    CLOUDSAT interpretation,

    Diurnal cycles, radiative differences etc.

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Frequency of ice cloud occurrence

Frequency of Ice Cloud Occurrence

Similar profiles

but very large

difference

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Ice cloud fraction

Ice Cloud Fraction

Cloud fraction corresponds to the UM model (12 km horizontal, 50 vertical levels)

which will be used for regional Australian forecast from January 2009

Both sites are characterized by similar cloud fraction distributions (0.05 to 0.3 / 0.9 to 1)

Main differences are in the upper-levels (more high CFs in Darwin cirrus)

and above melting layer (more small CFs in Darwin)

A large-scale model should be able to reproduce that

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Ice cloud top height base thickness

Ice Cloud Top Height, Base, Thickness

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Microphysical properties

Microphysical Properties

PDFs

Mean Vertical Profiles

Microphysical processes - Two regions

From top to 8 km – aggregation dominating

From 8 km to Melting Layer – sublimation dominating

Darwin vs Niamey : ice clouds over Niamey consist of smaller-sized particles

but in much larger concentrations, thereby carrying more ice water and producing

more visible extinction than the ice clouds over Darwin. Heating rates ?

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Peter may with contributions from

  • Climate observations with radar

  • Fundamental cloud physics:

    DSD, cloud properties, kinematics

  • Model testing and diagnosis

The Centre for Australian Weather and Climate ResearchA partnership between CSIRO and the Bureau of Meteorology


Thank you

Thank you

The Centre for Australian Weather and Climate Research

A partnership between CSIRO and the Bureau of Meteorology

Peter May

Phone: +61 3 9669 4490

Email: [email protected]

Web: www.cawcr.gov.au

Thank you

www.cawcr.gov.au


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