Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.
-
Upload
sarah-dixon -
Category
Documents
-
view
222 -
download
1
Transcript of Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.
![Page 1: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/1.jpg)
Measurements of microphysical properties of convective clouds
in the tropics and the mid-latitudes
![Page 2: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/2.jpg)
• Introduction: recent projects in convective clouds- Megha-Tropiques (MT) - HYMEX- HAIC-HIWC
• Measurement objectives in convective clouds:Ice microphysical properties of tropical and mid-latitude convective clouds
- Measurements: PSD and radar reflectivity- Ice particle morphology from 2D images- Area-diameter and mass-diameter relations - Retrieved IWC: various approaches
® main question: quantifying the ice mass in clouds and precipitation
Outline
![Page 3: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/3.jpg)
2 aircraft campaigns have been performed in order to improve the rain rate retrieval in tropical convection.
MCS (squall lines) for MT1 MS for MT2 IC for MT2
13/08/2010 27/11/2011 08/12/2011
-Over West African Continent (Niamey/NIGER 08/2010), MT1.- All systems observed were Mesoscale Convective Systems
(MCS).
-Over Central Indian Ocean (Gan/MALDIVES , 11-12/2011), MT2.- 2 types of systems : the first 2 weeks, systems with Mesoscale expansion
(MS). the last 2 weeks, systems formed by Isolated Convection (IC).
Megha-Tropiques
![Page 4: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/4.jpg)
SOP1 aircraft campaign HyMeX-SOP1, the field campaign dedicated toheavy precipitation and flash-flooding in Northwestern Mediterranean
Heavy precipitation events: Balearic Islands (BA), Catalonia (CA) and Valencia (VA) regions in Spain, Cévennes-Vivarais (CV) and Corsica (CO) in France, Central Italy (CI), Liguria-Tuscany (LT) and North-Eastern Italy (NEI) in Italy.
HYMEX
10.8µm infrared brightness temperature from MSG at 0730 UTC 26 October 2012.
![Page 5: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/5.jpg)
Aircraft campaign performed out of Darwin for Aircraft Safety regulatory purposes (FAA, EASA) and scientific objectives
Primary objective is to provide 99th percentile total water content statistics, as a function of distance scale, to industry and regulators
Two types of convection for sampling :Oceanic convection (primary focus)Continental convection (secondary focus)
HAIC (High Altitude Ice Crystals)
Courtesy of HIWC
![Page 6: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/6.jpg)
F20 aircraft (SAFIRE): Possibilities, limitations• The flight crew consists of:
– 2 SAFIRE pilots– 1 SAFIRE flight engineer (jump
seat)
– 1 SAFIRE operator– 3 engineers/scientists to operate
scientific instrumentation and lead F20 mission
• F20 limitations:– 4 under wing pylons, limited
fuselage hardpoints and electrical cabling
– Available power for scientific instrumentation: 8.4 kVA
![Page 7: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/7.jpg)
Measurement challenges in convective clouds
Major requirements/challenges for instruments on F20: 1. A series of imaging instruments is needed to cover the range of expected cloud
particle sizes from µm to mm ➔ Particle Size Distribution (PSD)
2. Deploy instruments for maximum bulk IWC measurements: ROBUST probe (actually combination probe with CDP), redesigned IKP
3. Instruments to measure very small cloud particle properties (<100μm, <50µm, if possible): CDP, CPSPD, CPI, …
4. Discriminate phase of cloud particles (populations): CPSPD, CPI, OAPs….
5. Avoid possible small ice crystals contamination on spectrometer data: Anti-shattering tips, inter-arrival time measurement & post processing.
6. Retrieve microphysics beyond flight trajectory: remote sensing.
![Page 8: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/8.jpg)
Crystal growth after ice nucleation
Riming
Aggregation
Vapor diffusion
CPI (Cloud Particle Imager):data CNRS-LaMP
Crystal growth in convective clouds dominated by 3 major growth mechanisms:- diffusion ( fct (RHI, T): mostly small ice particles, sometimes up to 400 µm- riming (existing crystals collect supercooled droplets) - aggregation (important for high crystal concentrations)
have we understood these processes correctly?
are we able to describe themin an appropriate way for atmospheric models ?
![Page 9: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/9.jpg)
French Falcon 20 (SAFIRE) in Niamey (NIGER)
Megha-Tropiques
CPI Cloud particle imager
RASTA (Cloud RADAR (94GHz)*
FSSP-ER (cloud droplet PSD)
PIP Precip. Imag. Probe
2DStereo 2D/3D imaging
Instruments used within MT
CIP Cloud. Imager. Probe
2010/2011
![Page 10: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/10.jpg)
Bulk TWC and PSD from optical spectrometersIKP, ROBUST, 2mmLWC: TWC
CDP: PSD smallest particles
![Page 11: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/11.jpg)
PSD from particle images
1 mm
2D-S: Intermediate size particles (PSD < 1mm)
6 mm
PIP: Largest particlesPSD > 1mm
![Page 12: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/12.jpg)
Combined PSD covering entire size range of hydrometeors
![Page 13: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/13.jpg)
Combined PSD covering entire size range of hydrometeors
A series of instruments needed to cover the entire range of expected cloud particle sizes: µm to mm range for PSD of hydrometeors!!
100
101
102
103
104
10-6
10-4
10-2
100
102
104
Deq(µm)
#/L/
µm
Merging different instruments to retrieve total PSD
PIP
CIP2DS
PSD composition
« Pristine » range fit(80 µm,250 µm)
« Drizzle » range fit(250 µm,1500 µm)
Precipitation range fit(1500 µm,5000 µm)
![Page 14: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/14.jpg)
MT1
MT2
Measurements: Averaged PSD and radar reflectivity
T [°
C]T
[°C]
Dmax [µm]
Dmax [µm]
![Page 15: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/15.jpg)
Comparing radar reflectivity from ground observations with in-situ microphysics
MT1 (Niger, 2010) , observed reflectivity range : 10 – 35 dBZ
![Page 16: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/16.jpg)
Comparing radar reflectivity from ground observations with in-situ microphysics
by co-localization of aircraft and radar pulse volume
![Page 17: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/17.jpg)
Analyzing the microphysics behind reflectivity from ground observations
3 number distributions of solid hydrometeors ( 1 min averages) ➝ different in number
IWC = 0.6 g m-3
IWC = 1.2 g m-3
IWC = 1.9 g m-3
➝ different in mass
but,in all 3 cases the surface radar gives the same reflectivity of 28-29 dBZ
however,Cloud Radar reflectivity(94GHz) well distinguishes the microphysicaldifferences of the 3 spectra
![Page 18: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/18.jpg)
2D images => density & m(Dmax) ?
Ice particle morphology from 2D images
![Page 19: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/19.jpg)
max.DAreaprojected
Þn(Dmax) (PSD)
Ice particle morphology from 2D images
Area
[cm
²]
Dmax [cm]
#/L/
µm
Dmax [µm]
![Page 20: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/20.jpg)
Calculation of the Mass-Diameter Relationship :
• PSD and reflectivity at 95GHz (RASTA) measured.• β is calculated with s from A(D) relationship:
=> α is calculated while matching simulated and measured 94GHz reflectivity (Tmatrix calculations for oblate particle with a flattening of 0.8).
Here: Results for MT1
5.125.2
α
β
α vs β vs Temperature
Area-diameter and mass-diameter relations
maxm D
![Page 21: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/21.jpg)
Calculation of the IWC (CWC)
Comparison of IWC retrievals:
- Matching measured with simulated reflectivities via T-matrix- Baker & Lawson* method
Retrieved IWC: various approaches
*Baker, Brad, and R. Paul Lawson. “Improvement in Determination of Ice Water Content from Two-Dimensional Particle Imagery. Part I: Image-to-Mass Relationships.” Journal of Applied Meteorology and Climatology 45, no. 9 (September 2006): 1282–1290.Lawson, R. Paul, and Brad A. Baker. “Improvement in Determination of Ice Water Content from Two-Dimensional Particle Imagery. Part II: Applications to Collected Data.” Journal of Applied Meteorology and Climatology 45, no. 9 (September 2006): 1291–1303.
![Page 22: Measurements of microphysical properties of convective clouds in the tropics and the mid-latitudes.](https://reader035.fdocuments.net/reader035/viewer/2022062407/56649e245503460f94b123af/html5/thumbnails/22.jpg)
Calculation of the IWC (CWC) from T-matrix compared with IKP reference bulk IWCRetrieved IWC: various approaches