CASA Update for MPAR Group

David McLaughlinUniversity of Massachusetts – Amherst

V. ChandrasakarColorado State University

March 20, 2007 – OFCM/Silver Spring, MD

Three Key points

1. The disruptive technology CASA is pursuing is not limited to the lower troposphere.

2. Key technologies Phased array technologies – CASA and partner Raytheon

(this session) Beam resource allocation Multifunction inversion algorithms (eg, Dual Doppler).

3. CASA plans a substantial spring experiment to investigate & demonstrate many key system components & attributes and benefits to sensing, detecting, predicting, warning, and responding to hazardous weather events.

CASA: collaborative adaptive sensing of the atmosphere

10,000 ft

tornado

wind

earth surface

snow

3.05

km

3.05

km

0 40 80 120 160 200 240

RANGE (km)

Critical gap

Gap filler or lower-troposphere concept – works with lo-band complement

15o

Network & System Trades

30km

22km37km

Low-level coverage

38 beam steps 0-560

30 km

22 km altitude

coverage

Full volume coverage

CASA: collaborative adaptive sensing of the atmosphere

40,000 ft

tornadosnow

12.0

km

RANGE (km)

0 20 40 60 80 100

wind

earth surface

3 or 4 Face Phased Array

45°

45°

Full volume concept: all X-band

Project IP1: CASA’s Initial 4-Node Test Bed Users: NWS Forecast Office Oklahoma Emergency Managers Association CASA researchers, themselves

WSR88D

Attributes - Resolution; Coverage height; Update time; Multiple Doppler; multi-use

3350

30/1.6 km 40/2 km 70/3.6 km

90/4.6 km 110/5.7 km 140/7.2 km

20060815-222919

20060815-222906

20060815-222924 20060815-222928

20060815-222911 20060815-222915

Dual-Doppler Analysis

KSAO-KCYR winds

KRSP-KCYR winds

KRSP-KSAO winds

Multiple-Doppler Analysis

Overview of IP1 Spring 2007experiment

Intense Operational Period (IOP) of data collection: April 9 – June 10

• IOP 2007 operations include: - Daily meetings and weather briefings- Real-time, near-24 hour monitoring of the system- Hardware support in the field and on stand-by- Ground survey team on stand-by- Real-time assimilation of data into NWP (ARPS) models

• End-users include:- The National Weather Service- Local emergency managers- News9 (OKC media)- CASA Researchers- Private sector (e.g., Vieux & Associates)

Overview of IP1 Spring 2007 Data Collection

• IOP 2007 data collection summary: - Continuous, real-time DCAS mode.- Automated DCAS system driven by end-user rules and needs.

- Real-time data dissemination to end-users via LDM.- Real-time visualization- Real-time attenuation-correction.- Dual-PRF signal processing.- All data archived permanently,

stored on tape.

Spring Experiment Leadership Team:

V. Chandrasakar (CSU) – Lead

J. Brotzge (OU) – Lead Forecaster

B. Philips (UMass) – End User Integration Leader

For more details, see:

• http://www-net.cs.umass.edu/mclaughlin/

• http://www.casa.umass.edu

Low Cost, Low Power Radars

Specifications: 1 m x 1 m X-band antennas Mechanical scanning (2005) Electronic scanning (2009) 2 degree pencil beam Single and dual V & H polarization

configurations 15+ degree elevation; 90 degree azimuth

scan 10’s Watt average power $50k target cost (in 2005 dollars,

projected 10 years ahead)

Deploying networks of these today

Will deploy networks like this in 2009

Phase-Phase EScan Antennas

1.7 cm

1 m

~3,000 T/R Modules performs electronic beam scanning in azimuth and elevation

Challenge: 100:1 cost reduction compared to today’s high-power military phased array radars

- Raytheon Briefing-

Frequency-Phase EScan Antennas

1 m

Phase-steered in az direction (±45 deg or ±60 deg)

Freq-steered in elevation (0-56 degrees)

Requires excessive bandwidth (> 1 GHz) for frequency-scan. Deemed impractical.

Phase-tilt EScan Antenna

1 m

Phase-steered in az direction (±45 deg or ±60 deg)

Mechanical tilt in elevation (15 degrees)

-11º to 0º

0 to +11º

12” deep

Dual Polarized Phase-Tilt EScan Array

T/R MODULE

BACKPLANE

FEED ANTENNA

DUAL POLARIZED LINEAR ARRAY

ANTENNA

64 sticks dx=1.6cm, L=1 m

64 e

lem

ents

/stic

k dy

=1.

6 cm

, L=

1 m

RADIATING ELEMENT

square patch

slots

feeds

ground plane

T/R MODULE ARCHITECTURE

ANTENNA

SP2T PA

LNA

CONTROLUNIT

SP2T SP2T

MA

PS

AT

SP2T

SP2T

ADRESS / DATA

SITCK

ANTENNA FEED

Single Pol Prototype: 40 W panel $20k Spring ’08

Dual Pol Prototype: 10-40W $30-$50k Spring ‘09

Backup slides

Ground Clutter Filtering

Rush Springs 30-Dec-2006 05:03:47 UTC

Reflectivity before filtering Reflectivity after filtering

• Adaptive spectral ground clutter filtering (Chandra/CSU)

Rush Springs 30-Dec-2006 05:03:47 UTC

Velocity before filtering Velocity after filtering

Ground Clutter Filtering

Dual-PRF waveform

• Velocity measurements greater than 30 m/s with dual-PRF

• Nyquist velocity of 38 m/s

• Range overlay suppression up to 93 km

• Data from August 15 at 23:35:30 UTC• 3 dual-Doppler syntheses

– KRSP-KSAO– KRSP-KCYR– KCYR-KSAO

• All 3 radar scans start within 2 seconds of one another, so advection not really an issue

• All 3 radar scans were 360º at 2 elevation angles (3º and 4º)

Dual-Doppler Synthesis

Dual-Polarized Attenuation Mitigation

Before Attenuation Correction After Attenuation Correction