consistent msu radiance dataset for reanalysis cheng-zhi zou

Consistent MSU Radiance Dataset for Reanalysis Consistent MSU Radiance Dataset for Reanalysis

Cheng-Zhi ZouCheng-Zhi Zou

CFSRR First Advisory Board Meeting, NOAA Science Center, November 7, 2007

NOAA/NESDIS/Center for Satellite Applications and research

NOAA MSU SatellitesNOAA MSU Satellites

4 channels to measure the atmospheric temperature profiles

No cloud contamination

Each satellite has a life cycle of a few years

Each satellite overlaps With other satellites—good for bias

correction

LECT gradually changes With time– orbital drift phenomenon

Satellite Local Equator Crossing Time (LECT) vs time

MSU Scan Pattern and footprint sizes

Time series based on Time series based on pre-launch calibrated radiance datapre-launch calibrated radiance data

Different bias correction yield different trend results (Christy and Spenser, Mears and Wentz, Vinnikov and Grody, Zou et al.) Reanalysis has its own bias correction procedure, how to ensure the reanalysis trend to represent the real atmospheric trend?

Simultaneous Nadir OverpassSimultaneous Nadir Overpass

Method to find SNO matchups:

Use Cao’s (2004) method

to find the orbits that

have intersections

Use time and location

information in the 1B

file to determine

simultaneity between

two pixels

Schematic viewing the overpasses between two NOAA satellites

SNO LocationsSNO Locations

MSU In-Orbit Calibration ProcessMSU In-Orbit Calibration Process

Earth

Cold Space T=2.73K

MSU Sensor

Warm TargetTemperature is measured by PRT

Conceptual diagram of MSU observational procedure

Level 0 Calibration

Digital Counts (C)

Rad

ian

ce

(R)

(Cc , 2.73K)

(Cw, Rw)

(Ce, RL)

(Ce, Re)

Onboard Warm Target

Cosmic Cold Target

Earth View

k j

jjkkL ZZRRR

Radiance Error Model for SNO Matchup K and J :

kkkkLk ZRRR ,

jjjjLj ZRRR ,

SNO Radiance Error Model

Consider colinearity between Zk and Zj choose the coefficients that completely remove the warm target temperature contamination

Tb comparison for SNO matchupsTb comparison for SNO matchups

After pre-launch calibration After SNO calibration

Comparison Between Pre-launch Comparison Between Pre-launch and SNO calibrationand SNO calibration

Inter-satellite differences after SNO calibration

std=0.04K

Time series differences for pre-launch calibration Std=0.1K

Anomaly time seriesAnomaly time series

Independent validation dataset for reanalysis Independent validation dataset for reanalysis

Website address: http://www.orbit.nesdis.noaa.gov/smcd/emb/mscat/mscatmain.htm

Datasets available: Level 2 radiance:

pre-launch (operationally) calibrated SNO calibrated Level 3 SNO calibrated gridded products: 2.502.50

pentad T2, T3, and T4, 1987-present pentad anomaly T2, T3, and T4, 1987-present monthly T2, T3, and T4, 1987-present monthly anomaly T2, T3, and T4,1987-present

Trend patternsTrend patterns

T23, Mid-tropospheric temperature trend, 1987-2006

T3 trend

T4, Lower Stratospheric temperature trend1987-2006

Remaining issuesRemaining issues

• Efforts needed to resolve short overlap problem between NOAA 10 and 9 for accurate bias removal

• more calibration coefficients (higher order calibration equation) maybe needed to solve Channel 3 for NOAA 11 and 12

• Different frequencies between MSU and AMSU