COOPERATIVE HUNTSVILLEAREA RAINFALL MEASUREMENT CHARM NETWORK

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COOPERATIVE HUNTSVILLE-AREA RAINFALL MEASUREMENT
(CHARM) NETWORK

• Local precipitation network ( est. 1/2001)
• 157 sites in Huntsville Madison County, AL
• NASA, Army, USGS, and NWS sites and weather
  enthusiasts
• Daily rainfall totals (1200UTC reports)
• 3600 km2 coverage (1 gauge per 6x6 km)
• Primarily 4 manual gauges (65) with remaining
  (35) manual or automated tipping bucket (6 and
  8)
• 1-5 minute data from 30 automated sites

• Supports local weather and climate research
• validate weather radar and lightning data from
  satellites
• monitor spatial distributions of precipitation
  for modeling activities
• various satellite remote sensing studies of
  soil moisture and energy fluxes

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ACCESS TO CHARM (http//weather.msfc.nasa.gov/char
m)
Data entry and display Access historical data How
to take measurements FAQs Whats new
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TYPES OF RAIN GAUGES IN CHARM
4 non-recording all-weather
plastic
6, 8 non- recording (metal)
6, 8 tipping bucket recorded electronically
6, 8 recording weekly paper charts
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CHARM OBSERVERS
2001 Total 96 76 manual, 3 recording
(manual), and 17 automated
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USE AND APPLICATIONS

• CHARM86 supported NASA meteorological
  experiment over Huntsville
• Existing measurements systems
• Aldridge Creek flood of 1999
• Flooding of the AXAF clean room out at MSFC
  (1997)
• Environmental studies for MSFC Redstone Arsenal
• CHARM observations are part of the NWS (SHEF)
  data stream
• LMRFC (Slidell) and SERFC (Atlanta) for
  hydrological studies
• Local WFOs (HUN)
• Satellite and ground based (radar)
  intercomparison studies
• Short-term precipitation climatology studies

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• CHARM data has been used to validate forecast
  model estimates of precipitation

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PRECIPITATION INTERCOMPARISON

• Forecast 24h accumulated rainfall for
  April 12-13, 2001, 0700 LDT.
• Regional MM5 model (left) and early Eta
  (right)

Validation 24h accumulated rainfall derived from
NWS radars, April 12-13, 2001, ending 700a LST.
next
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PRECIPITATION ESTIMATE FROM RADAR CHARM data
indicates smaller scale variability
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• CHARM data has been used to validate radar
  estimates of precipitation

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DIGITAL PRECIPITATION PRODUCT

• NWS offices produce their own precipitation
  estimates from their local WSR-88D radar. The
  Nashville and Hytop (northeast of Huntsville)
  radars captured this storm event.
• Figures present storm totals (sum of hourly
  product over storm lifetime 4-6 hours).
• Same general structure
• Nashville radar - more intense / widespread
  rainfall
• Radar calibration, elevation, scan patterns,
  distance from storm may all contribute to the
  difference.

4-5
3
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CHARM DATA ANALYSIS

• June 4-5, 2001 Case Study
• Isolated heavy thunderstorm moves
• through the CHARM network
• Slow west-to-east movement over
• Huntsville

Rainfall totals reported at 1200UTC for the
preceding 24h . For June 4-5, the 24h totals
capture only this storm event.

• Details
• Strong north-south gradient on
• either side of the storm track
• Width of heavy rainfall area - 10 km
• Maximum of 2.96 on east of
• region, secondary max (2.73) in
• the western half of network

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• CHARM data has been used to verify and enhance
  special rainfall products used for climate studies

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Example of stage III radar product for June 4,
2001 over Northern Alabama Hourly stage III
product summed from 2100 0300 UTC.
NWS HDP PRODUCTS

• Stage I - integrated precipitation from local
  radar using standard or tropical Z-R
  relationships on
• 4 km grid dependent on Z-R relationship used
• Stage II - adjusted stage I product for bias
  using local (hourly) rain gauges
• Stage III - combination of stage II HDP from
  individual radars to produce a regional
  precipitation estimate
• minimal bias due to mis-calibration and
  different Z-R, local and seasonal adjustments
• regional continuity and consistency

Rainfall (cm)
Note the dual rainfall maximum in the stage III
radar product corresponds nicely both in position
and magnitude to the CHARM data.
CHARM
Stellman et al. 2001 (Wea. Fore.)
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STAGE III vs. CHARM

• Resolution issues will affect comparison
• Radar
• radar volume varies with distance
• 4km grid cells arbitrary selection
• Rain gauge
• point measurement microscale variability
  greatest in convective storms
• multiple rain gauges for each grid cell (a
  single best comparison used in analysis below)

Comparison shows little or no bias (0.19)
between CHARM measurements and radar estimates.
Scatter is considerable especially for amounts
1.00.
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CHARM data is regularly used to evaluate
short-term variations in precipitation
climatology.
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HUNTSVILLE DROUGHT OF 2005 OR WAS
IT?Huntsville had one significant rain event
from 9/1 through 11/15 (2.5 months) hottest
time of year in a year with minimum Springtime
rainfall? despite numerous tropical storms
impinging on the ValleyYet there is significant
variability between reported rainfall over the
region!
Only 4 real rain events in 3 months
Note absence of any rain events
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VARIABILITY IN MONTHLY RAINFALL - Fall
2005 Normal Actual RangeSeptember 4.3
2.9 (2.0 - 5.5in)October 3.5 0.1
(0.0 - 0.5in)November 5.3
3.0 (3.0 - 6.5in)Note
difference in spatial variability! Does it even
out over the long term?


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CHARM 2005 selected station monthly rainfall and
anomalies (departure from normal).
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2005 RAINFALL

• SE HSV (blue) and airport (red) show below
  average rainfall most months

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2005 RAINFALL

• SE HSV (blue) and airport (red) show below
  average rainfall most months
• NSSTC location (orange) similar to airport
  trends, Big Cove area (cyan) had a surplus during
  the summer

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2005 RAINFALL

• SE HSV (blue) and airport (red) show below
  average rainfall most months
• NSSTC location (orange) similar to airport
  trends, Big Cove area (cyan) had a surplus during
  the summer
• Madison area (green) shows large summer surplus,
  Cullman (grey) was dry

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CHARM 2005 selected station monthly rainfall
anomalies and yearly deficit (sum of departure
from normal).
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2005 ANOMALY AND DEFICIT

• At the airport (red), 2005 starts out dry and
  stays dry (-17 in).

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2005 ANOMALY AND DEFICIT

• At the airport (red), 2005 starts out dry and
  stays dry (-17 in).
• SE HSV (blue) tracks airport but Big Cove area
  (cyan) only down -9 in for year.

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2005 ANOMALY AND DEFICIT

• At the airport (red), 2005 starts out dry and
  stays dry (-17 in).
• SE HSV (blue) tracks airport but Big Cove area
  (cyan) only down -9 in for year.
• Summer rains keep Madison (green) with little
  (-3 in) deficit for the year.

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CHARM 2005 rainfall deficit pattern shows large
deficit throughout most of the region, however
Madison and surrounding regions were not as hard
hit with the drought.
Are the 2005 patterns a continuation of past
trends?
-7.8
-2.7
-7.2
-16.3
-13.5
-17.2
-8.9
-
-15.3
-14.6
2005 Deficit
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CHARM can be used to look at short-term climate
trends in rainfall. The following analysis
highlights the 2001-2005 period.
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2001-2005 ANOMALY/DEFICIT

• 2001 was wet. 2002-2005 experience growing
  deficits at airport (red).

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2001-2005 ANOMALY/DEFICIT

• 2001 was wet. 2002-2005 experience growing
  deficits at airport (red).
• NSSTC (orange) tracks airport deficit, but trend
  not as sharp in SE HSV (blue). Rainfall surplus
  grows throughout the period in Big Cove region
  (cyan, 13 in).

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2001-2005 ANOMALY/DEFICIT

• 2001 was wet. 2002-2005 experience growing
  deficits at airport (red).
• NSSTC (orange) tracks airport deficit, but trend
  not as sharp in SE HSV (blue). Rainfall surplus
  grows throughout the period in Big Cove region
  (cyan, 13 in).
• While Madison stays most, Cullman shows extreme
  drought over last 4 years.

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Trends in quality controlled CHARM observations
show distinctive patterns in 2001-2005 cumulative
anomaly fields.
Process 5-8 more sites with continuous
records Need more long term precipitation
observations
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FUTURE OF CHARM

• Long-term activity to support NASA research
  projects
• permanent (?) to support Tennessee Valley weather
  resources
• possible field program or GPM validation site
• Encourage long-term precipitation observations
  from existing participants
• annual CHARM meeting of all participants
• workshop on equipment and observation methods,
  scientific analysis
• picnic or other gathering to share experiences
• more recording gauges
• Expand network
• outlying areas fill in gaps (NE Madison Co,
  south of River, east of HSV)
• weather enthusiasts