# Presentation: 118083

## Variability of Graupel and Ice Crystal Aggregates Observed by Aircraft during TRMM KWAJEX

**David E. Kingsmill ****1,2****, Sandra E. Yuter ****3****, and **
**Ellen M. Sukovich ****1,2**
**1 ****University of Colorado, CIRES**
**2 ****NOAA Earth System Research Laboratory**
**3 ****North Carolina State University**

- Presented at the 3nd TRMM International Science Conference
- Las Vegas, NV    February 4-8, 2008

## KWAJEX

**KWAJEX**

- 23 July-15 September 1999
- Kwajalein Atoll (167.7 E, 8.7 N)
- Ground, ship and air based datasets
- UND Citation
- NASA DC-8
- KPOL

- KPOL

- NASA DC-8

- UND Citation

- Kwajalein

## Two-dimensional optical array probes

- UND Citation 2DC

- NASA DC-8 2D-CIP

- UND Citation HVPS

- X

- Y

- Z

- Y

- X

## TRMM Common Microphysics ProductsKingsmill et al. (2004, JAM)

- Customized for analysis of microphysics data collected from aircraft during the TRMM field campaigns.
- Formatted with a common and relatively simple structure and processed using a consensus algorithm.
- Developed to aid in the refinement of TRMM precipitation retrieval algorithms.
- Data averaged over ~1 km distances (Number concentrations, size spectra, ice and liquid water contents)

## TRMM Common Microphysics Products

- Habit identification using Area Ratio (AR) thresholds
- Graupel were over-estimated using this technique!
*AR* of aggregates biased high for partial images

- Graupel

- 0.7 ≤ *AR *< 0.95

- Aggregates

- 0.3 ≤ *AR *< 0.7

## Alternative habit identification techniqueKorolev and Sussman (2000, JTech)

- Ensemble-based
- Does not identify habit of individual particles
- More statistically robust
- Employs several geometric parameters of an image, including both perimeter and area
- Identifies four general habit categories:
- Spheres,   dendrites,   needles   and    irregulars
- Habit category fractions are provided for each ensemble

## KWAJEX Habit Identification Results

- Temperature Distribution
- of Aircraft Sampling (T < 0°C)

- UND Citation (7625 ensembles, T < 0oC)

- Dendrite Fraction

- Sphere Fraction

- Needle Fraction

**Graupel**

**Aggr.**

**Mixed**

- NASA DC8 (7882 ensembles, T < 0o)

- Dendrite Fraction

- Sphere Fraction

- Needle Fraction

**Graupel**

**Aggr.**

**Mixed**

- 2D-C

- 2D-CIP

## Extension of algorithm for identificationof graupel and aggregates

- Sphere
- Fraction (SF)

- Dendrite
- Fraction (DF)

- Needle/Column
- Fraction (NF)

## Habit Identification Results  

**Habit Identification Results**

- UND Citation (7625 ensembles)

- Dendrite Fraction

- Sphere Fraction

- Needle Fraction

**Graupel**

**Aggr.**

**Mixed**

- NASA DC8 (7882 ensembles)

- Dendrite Fraction

- Sphere Fraction

- Needle Fraction

**Graupel**

**Aggr.**

**Mixed**

## Habit ID vs. Precip. Structure

- Weak

- Convective

- Stratiform

- UND Citation

- NASA
- DC8

## Habit ID vs. Temperature Distribution 

- UND Citation

## Habit ID vs. Particle Size

- UND Citation

## Summary (Part 1)

- KWAJEX
- UND Citation, NASA DC8
- 2D-OAP Habit ID
- Habit Variability
- UND Citation (0 > T > -45C)
- Graupel (~5%), Aggregate (~80%), Mixed (~15%)
- NASA DC8 (-35 > T > -65C)
- Graupel (0%), Aggregate (~98%), Mixed (~2%)
- Habit vs. Precipitation Structure
- Graupel most closely associated with convective precipitation
- Most aggregates within stratiform precipitation
- Mixed graupel/aggregates evenly divided between conv/strat

## Habit vs. Temperature
Aggregates and mixed evident over entire temperature range
Most graupel evident 0 < T < -10C
Habit vs. Particle Size
Aggregates appear across a wide range of sizes (up to 5 mm)
Graupel and mixed are most prevalent at sizes less than 2 mm 

- Aggregates and mixed evident over entire temperature range
- Most graupel evident 0 < T < -10C
- Habit vs. Particle Size
- Aggregates appear across a wide range of sizes (up to 5 mm)
- Graupel and mixed are most prevalent at sizes less than 2 mm

- Summary (Part 2)

- This research was supported by NASA Grants
- NAG5-9716 and NNG04GJ15G (Kingsmill and Sukovich)
- and NASA Grant NNG04GA65G and NSF ATM-0544766 (Yuter).

## Backup Slides

## KWAJEX Habit Identification Results

- Dendrite Fraction

- Dendrite Fraction

- Sphere Fraction

- Sphere Fraction

- Needle Fraction

- Needle Fraction

- UND Citation (7625 ensembles, T < 0°C)

- NASA DC8 (7882 ensembles, T < 0°C)

- Dendrite Fraction

- Dendrite Fraction

- Sphere Fraction

- Sphere Fraction

- Needle Fraction

- Needle Fraction

## KWAJEX Habit Identification Results

- Dendrite Fraction

- Dendrite Fraction

- Sphere Fraction

- Sphere Fraction

- Needle Fraction

- Needle Fraction

- UND Citation (7625 ensembles, T < 0°C)

- NASA DC8 (7882 ensembles, T < 0°C)

- Dendrite Fraction

- Dendrite Fraction

- Sphere Fraction

- Sphere Fraction

- Needle Fraction

- Needle Fraction

**Graupel**

**Aggr.**

**Mixed**

**Graupel**

**Aggr.**

**Mixed**

## KWAJEX Habit Identification Results

- Dendrite Fraction

- Dendrite Fraction

- Sphere Fraction

- Sphere Fraction

- Needle Fraction

- Needle Fraction

- UND Citation (7625 ensembles, T < 0°C)

- NASA DC8 (7882 ensembles, T < 0°C)

- Dendrite Fraction

- Dendrite Fraction

- Sphere Fraction

- Sphere Fraction

- Needle Fraction

- Needle Fraction

**Graupel/**
**Mixed**

**Aggr.**
**(Needle)**

**Aggr.**
**(Und.)**

**Aggr.**
**(Dendrite)**

**Graupel/**
**Mixed**

**Aggr.**
**(Needle)**

**Aggr.**
**(Und.)**

**Aggr.**
**(Dendrite)**

## Old Versions of Slides

## TRMM Common Microphysics Products

- Customized for analysis of microphysics data collected from aircraft during the TRMM field campaigns.
- Formatted with a common and relatively simply structure and processed using a consensus algorithm.
- Developed to aid in the refinement of TRMM precipitation retrieval algorithms.
- Data averaged over ~1 km distances (Number concentrations, size spectra, ice and liquid water contents)
- Habit identification using Area Ratio (AR) thresholds
- Graupel were over-estimated using this technique!

- Graupel

- 0.7 ≤ *AR *< 0.95

- Aggregates

- 0.3 ≤ *AR *< 0.7

## Alternative habit identification techniqueKorolev and Sussman (2000, JTech)

- Ensemble-based
- More statistically robust
- Does not identify habit of individual particles
- Employs several geometric parameters of an image, including both perimeter and area
- Identifies four general habit categories:
- Spheres, dendrites, needles and irregulars
- Habit category fractions are provided for each ensemble
- Does not explicitly identify graupel and aggregates!

## Habit Identification vs.Precipitation Structure

|  | NASA DC-8
(4109 Ensembles) |  |  |
| --- | --- | --- | --- |
|  | Graupel | Aggregate | Mixed |
| CONV | 0 | 684 | 9 |
| STRAT | 0 | 3373 | 43 |

- Weak

- Convective

- Stratiform

- UND Citation

- NASA
- DC8

|  | UND Citation
(5324 Ensembles) |  |  |
| --- | --- | --- | --- |
|  | Graupel | Aggregate | Mixed |
| CONV | 196 | 921 | 370 |
| STRAT | 112 | 3349 | 376 |

## Summary

- KWAJEX
- UND Citation, NASA DC8
- 2D-OAP Habit ID
- Habit Variability
- UND Citation (0 > T > -45C)
- Graupel (~5%), Aggregate (~80%), Mixed (~15%)
- NASA DC8 (-35 > T > -65C)
- Graupel (0%), Aggregate (~98%), Mixed (~2%)
- Habit vs. Precipitation Structure
- Graupel most closely associated with convective precipitation
- Most aggregates within stratiform precipitation
- Mixed graupel/aggregates evenly divided between conv/strat
- Habit vs. Temperature
- Aggregates and mixed evident over entire temperature range
- Most graupel evident 0 < T < -10C
- Habit vs. Particle Size
- Aggregates appear across a wide range of sizes (up to 5 mm)
- Graupel and mixed are most prevalent at sizes less than 2 mm