25-28 October 2004 2nd IPWG
Monterey, CA
The Status of the NOAA/NESDIS Operational
AMSU Precipitation AlgorithmRalph FerraroNOAA/NESDIS
College Park, MD USA
Fuzhong Weng, Norman Grody, Limin Zhao, Paul Pellegrino, Cezar Kongoli, Huan Meng, Mark Liu
25-28 October 2004 2nd IPWG
Monterey, CA
Outline
• Review of AMSU and NOAA POES• Current AMSU Algorithm
– 89/150 GHz Scattering Technique• Performance and limitations
– Applications • Example: Tropical Rainfall Potential
– Solid Precipitation over land• Performance and limitations
• Future:– Algorithm improvements– NOAA-N, N’ and METOP
25-28 October 2004 2nd IPWG
Monterey, CA
NOAA AMSU Sensor•Flown on NOAA-15 (5/98), NOAA-16 (9/00) & NOAA-17 (5/02) satellites•Contains 20 channels:
•AMSU-A (45 km nadir FOV)•15 channels•23 – 89 GHz
•AMSU-B (15 km nadir FOV)•5 channels•89 – 183 GHz
•Operational “imaging” products:•TPW, CLW, rain rate, snow cover, sea-ice, etc.
•~4-hour temporal sampling:•130, 730, 1030, 1330, 1930, 2230 LST
25-28 October 2004 2nd IPWG
Monterey, CA
25-28 October 2004 2nd IPWG
Monterey, CA
AMSU Rain Rate Algorithm• Basis for algorithm – work of Weng, Grody and Zhao
– Physical retrieval of IWP and De – 89 & 150 GHz
• Algorithm adopted for use with AMSU-B– Use of other window and sounding channels
• Derive needed parameters• Filters for false signatures
– Use of ancillary data– Use of other AMSU derived products
• IWP to rain rate based on limited MM5 model data and RTE calculations:– RR = A0 + A1*IWP + A2*IWP2
25-28 October 2004 2nd IPWG
Monterey, CA
25-28 October 2004 2nd IPWG
Monterey, CA
25-28 October 2004 2nd IPWG
Monterey, CA
AMSU-ATb’s
AMSU-BTb’s
Ancillary
Land or Water? Land or
Water?
Land Water
Sea-IceConc.
TPW &CLW
Ice?No
Yes
Emissivity
SurfaceTemperature
AMSU-ASwath
LandWater
AMSU-BSwath
IWP & De
SnowIce?
No
Snow?Yes
No
Rain Rate IWP & De
PrecipitationRate
25-28 October 2004 2nd IPWG
Monterey, CA
25-28 October 2004 2nd IPWG
Monterey, CA
AMSU Rain Rate Algorithm - Chronology
• Original algorithm suffered from several problems– Unrealistic PDF’s in IWP and rain rate– Too low rain in convection, too high in stratiform– Large discontinuities between land and ocean– Over sensitivity to small IWP
• Improvements developed and implemented 8/03:– Two stream corrections for TB89 & TB150 as function of Θ– Two sets of coefficients based on size of De – Utilization of 183 GHz bands to determine depth of
precipitation• Developed a “Convective Index” (CI) based on differences
and magnitudes of TB183+1, TB183+3, TB183 +7
• Developed two IWP to RR relationships based on CI
25-28 October 2004 2nd IPWG
Monterey, CA
Example of Real Time Data
25-28 October 2004 2nd IPWG
Monterey, CA
Example of Monthly Data
25-28 October 2004 2nd IPWG
Monterey, CA
Web Sitehttp://www.orbit.nesdis.noaa.gov/corp/scsb/mspps/main.
html
25-28 October 2004 2nd IPWG
Monterey, CA
Validation/Evaluation• Land:
– Instantaneous – NCEP Stage IV (Janowiak)– Monthly – GPCC Gauges (Rudolph) & SSM/I – Monthly – Australia (Ebert)– Monthly - AMSR-E
• Ocean:– Monthly – SSM/I– Monthly – AMSR-E
• User Feedback– Joyce, Huffman, Turk, etc.
25-28 October 2004 2nd IPWG
Monterey, CA
25-28 October 2004 2nd IPWG
Monterey, CA
25-28 October 2004 2nd IPWG
Monterey, CA
25-28 October 2004 2nd IPWG
Monterey, CA
N15N16N17 AMSU vs. GPCC - 8/03 to 7/0460 S - 60 N
y = 0.7922x + 8.2134R2 = 0.4975
0
100
200
300
400
500
600
700
800
0 100 200 300 400 500 600 700 800
GPCC (mm/month)
AM
SU
(m
m/m
on
th)
F13F15 SSMI vs. GPCC - 8/03 to 7/0460 S - 60 N
y = 0.6778x + 7.8219R2 = 0.4326
0
100
200
300
400
500
600
700
800
0 100 200 300 400 500 600 700 800
GPCC (mm/month)
SS
MI
(mm
/mo
nt
25-28 October 2004 2nd IPWG
Monterey, CA
Mean Mean Mean Bias Bias
SSMI AMSU GPCC SSMI AMSU
60S-60N 58.54 67.50 74.84 0.78 0.90
40S-40N 71.43 80.76 80.47 0.89 1.00
20S-20N 98.25 117.47 128.87 0.76 0.91
R R
SSMI AMSU
60S-60N 0.66 0.71
40S-40N 0.71 0.76
20S-20N 0.76 0.79
Performance vs. GPCC (8/03 – 7/04)
25-28 October 2004 2nd IPWG
Monterey, CA
Zonal Mean Land Rainfall (8/03 - 7/04)
0
20
40
60
80
100
120
140
160
180
-45 -35 -25 -15 -5 5 15 25 35 45 55
Latitude
Rai
nfa
ll (
mm
)
SSMI
AMSU
GPCC
25-28 October 2004 2nd IPWG
Monterey, CA
AMSR-E and SSM/I Comparisons
25-28 October 2004 2nd IPWG
Monterey, CA
N-16 vs. AMSR-E
Land Ocean
25-28 October 2004 2nd IPWG
Monterey, CA
Summary/Limitations• Land
– In general, performs well• Too high in convective situations?• Regional biases (of course!), esp. too high in drier regimes
– 3-satellite estimates outperform (dual SSM/I)– Better sensitivity to lighter rain rates
• Ocean– Restricted to convective precipitation
• Overall, too low due to missing precipitation without ice (generally lighter rain intensities)• Rain coverage less than other sensors
– Conditional rain rates too high?• Cloud base temperature estimate incorrect?
• Coastlines– Not adequately handled
• View angle dependencies– Larger FOV on scan edges results in varying rain rate distributions
• Larger errors due to beam filling likely• Lower rain rates expected over larger area, but makes more difficult for users• May miss detecting some rain at scan edge
25-28 October 2004 2nd IPWG
Monterey, CA
Applications at NOAA
•Weather forecasting & analysis•Tropical Cyclones•Climate Monitoring•Development of merged
precipitation analysis
25-28 October 2004 2nd IPWG
Monterey, CA
Hurricane Ivan – 15 Sept 04
25-28 October 2004 2nd IPWG
Monterey, CA
NOAA/NESDIS TRaPHurricane Ivan – 15 Sept 04
25-28 October 2004 2nd IPWG
Monterey, CA
Ground Truth
25-28 October 2004 2nd IPWG
Monterey, CA
Falling Snow over Land from AMSU• Use of AMSU-B 183 GHz bands along with
AMSU-A 53.6 GHz allows for expansion of current algorithm to over cold and snow covered surfaces:– AMSU-B channels allow for detection of scattering
associated with precipitation, but surface blind when “sufficient moisture” exists
– AMSU-A channel 5 allows for discrimination between “rain” and “snow”
• Feature added in 11/03, snowfall detection only (assigned arbitrary rate of 0.1 mm/hr)
• Validation over CONUS winter 2003-04
25-28 October 2004 2nd IPWG
Monterey, CA
1200 UTC 25 January 2004 1300 UTC 25 January 2004
25-28 October 2004 2nd IPWG
Monterey, CA
Snowfall Detection Algorithm
Snow on groundor
Tsfc < 269K?
MSPPSLand
Rain Rate
No
YesTB54L <
Cold Snow*?
*Note:Cold Snow is240 or 245 K
Yes
NoTB89-TB150>4 ?
No
NoPrecipitati
on
Yes TB176 < 255and
TB180 < 253and
TB182<250?
Yes
TB176 > 255and
TB180 < 253and
TB23<262?
No
TB150-TB176> -16and
TB176-TB180 > -3and
TB89-TB150<10 ?
Yes
No
Precipitation=
MSPPS Rain Rate
Value
PrecipitationIs
Indeterminate
Snow Is
Falling
No
Yes
25-28 October 2004 2nd IPWG
Monterey, CA
January 2004 – Snowfall Frequency
ALG245
ALG240
x
x
x
x
xx
25-28 October 2004 2nd IPWG
Monterey, CA
CONUS Validation Statistics
ALG245 ALG240 ALG245 ALG240 ALG245 ALG240
CXY CXY ROA ROA MIT MIT
POD 0.48 0.52 0.69 0.64 0.17 0.07
FAR 0.17 0.20 0.00 0.07 0.00 0.25
TS 0.44 0.46 0.69 0.61 0.17 0.07
ETS 0.41 0.43 0.68 0.59 0.16 0.05
HSS 0.94 0.94 0.98 0.97 0.95 0.87
25-28 October 2004 2nd IPWG
Monterey, CA
Summary/Limitations• Algorithm Performance
– Can detect snowfall associated with synoptic scale systems– Low false alarms– Can increase region of application by lowering TB54L
threshold up to 5 K• Some increase in false alarms
• Limitations– Relative moist atmospheres - -5 to 0 C– Southern extent of snow pack/temperate latitudes– Precip layer needs to extend to ~4-5 km or higher– No signal in extreme cold climate regimes and shallow
snow
25-28 October 2004 2nd IPWG
Monterey, CA
Future• Near term algorithm improvements
– FOV issues – L3 nadir equivalent product– Coastlines– Incorporation of CLW into ocean (1DVar)– Snowfall rates; land & ocean
• Longer term– 1DVar, including land surface emissivity (with JCSDA)– Climate regime classification– Snowfall rates
• Upcoming launches– NOAA-N (Feb 05)
• MHS replaces AMSU-B– METOP-1 (Jan 06?)
• Pipeline processing• Continued interactions with NASA and international partners on GPM
– NOAA funds FY08?