# Presentation: 744683

## Using Large Ensembles of Low-Cost Lagrangian
Drifters for Tropical Cyclone 
Analysis & Forecasting

John Manobianco, Joseph G. Dreher, Mark L. Adams, and Jonathan L. Case 
ENSCO, Inc.

21 March 2006
60th Interdepartmental Hurricane Conference
(Mobile, AL)

Outline
Concept Description
Motivation
Methodology
PRELIMINARY Results
Summary/Future Efforts

**Drifters for Tropical Cyclone **
**Analysis & Forecasting**
**John Manobianco, Joseph G. Dreher, Mark L. Adams, and Jonathan L. Case **
- ENSCO, Inc.
**21 March 2006**
**60****th**** Interdepartmental Hurricane Conference**
**(Mobile, AL)**
- _Outline_
- Concept Description
- Motivation
- Methodology
- PRELIMINARY Results
- Summary/Future Efforts

## Concept Description

- Ensemble of super pressure, constant density balloons (Lagrangian drifters)
- Drastically reduce mass, size, and cost by integrating micro and eventually nanotechnology
- Components
- Balloon material (12.5-m MylarTM GL-AE)
- Current (70 gm; 40 cm; beach ball)
- Target (<1 gm; 10 cm; grapefruit)
- Self-contained with power source for
- Sensing
- Dropsonde quality micro sensors
- T, p, RH, velocity (micro GPS)
- Communication (Iridium-class satellites)
- Limited signal processing/computation

## Motivation

- Improve density / distribution of in situ observations especially over data sparse oceanic regions
- Significantly enhance adaptive or targeted observing campaigns
- Research & operational missions
- Synoptic observing capabilities spanning a broad range of time/space scales
- Tropical cyclone reconnaissance where it is only cost effective & practical to obtain in situ, high-resolution, measurements over limited domains

## Preliminary Data Impact Study

- Dynamic simulation models
- Virtual weather scenarios - ARPS (Advanced Regional Prediction System)
- Probe deployment & dispersion - Lagrangian particle model
- Data assimilation (DA) - NCAR/PSU MM5 (Mesoscale Model v5)
- Hurricane Floyd case (Sep 1999)
- Simulated observations
- GEMS probes deployed from aircraft
- 1140 probes every 12 h
- 1 per minute during typical recon flight pattern
- 5-min observation frequency
- No measurement errors or instrument failures
- No simulated aircraft, satellite, or dropsonde data
- Value added of probe data
- Observe/analyze 4D tropical cyclone structure
- Initialize tropical cyclones using high resolution models

## Experiment Design

- 15-km ARPS

- 3-km ARPS

- Floyd Best Track

| Experiment | Avg # obs per ingest time |
| --- | --- |
| Full | 4785  |
| 10% | 478 |
| 1%  | 47 |

## Simulated “Truth”

- 15-km ARPS clouds & probes
- 6-day loop with 1 frame every hour

- 3-km ARPS clouds & probes
- 29-h loop with 1 frame every 5 min

## Simulated “Truth” (2)

## DA Results

- B

- A

**ARPS 3-km**

**MM5 12-km (all obs)**

**MM5 12-km (10% obs)**

**MM5 12-km (1% obs)**

- 900 hPa
- Velocity (m s-1)
- 0000 UTC
- 11 Sep 1999

- B

- B

- B

- A

- A

- A

## DA Results (2)

- Speed (m s-1)
- Theta (K)
- 0000 UTC
- 11 Sep 1999

**ARPS 3-km**

**MM5 12-km (all obs)**

**MM5 12-km (10% obs)**

**MM5 12-km (1% obs)**

- B

- A

- B

- A

- B

- A

- B

- A

- 40 km

## DA Results (3)

## Summary & Future Efforts

- Summary
- Low cost, low mass, ensemble of Lagrangian drifters (GEMS)
- Map 4D tropical cyclone structure including intensity changes
- Initialize high resolution models without bogus vortex
- Operational Issues
- Deployment scenarios (cost, practicality, etc.)
- Aviation hazards
- Robustness to harsh conditions in tropical cyclones (e.g. rain out)
- Future Efforts
- Prototype development in progress (functional device by fall 2006)
- Expand data impact studies
- Limitations of a single case
- Use more advanced modeling/assimilation systems (e.g. H-WRF, 3D/4DVAR)
- Include full data suite & assess impact relative to track/intensity forecasts over broader range of space/time scales