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3. What changes of temperature have occurred in the atmosphere and at the

3. What changes of temperature have occurred in the atmosphere and at the surface since the advent of modern measurement methods?. John Lanzante GFDL/NOAA. Upper-air/Radiosonde Perspective – esp. 2 studies: o LKS (Lanzante/Klein/Seidel, 2003, JCLIM)

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3. What changes of temperature have occurred in the atmosphere and at the

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  1. 3. What changes of temperature have occurred in the atmosphere and at the surface since the advent of modern measurement methods? John Lanzante GFDL/NOAA • Upper-air/Radiosonde Perspective – esp. 2 studies: • o LKS (Lanzante/Klein/Seidel, 2003, JCLIM) • * Homogenizes T for a global set of 87 stations • * Both unadjusted & adjusted data available • o Seidel et al. (2003, JCLIM, in review) • * Intercomparison of 5 radiosonde & 3 satellite (MSU) datasets Focus: o Stratosphere, Troposphere & (Troposphere-Surface) Difference o Trends andrange of estimates/uncertainties o Time periods: Radiosonde era ~1958 & Satellite era ~1979

  2. 1958-1997 – Global Trends(Seidel et al; in review, JCLIM) 5 Radiosonde Datasets(Angell-63 & 54, HadRT, LKS_adj, [RIHMI[) Stratosphere (100-50 hPa) ~ -.45 (~ -.55 to -.37 [-.22]) K/decade Troposphere (850-300 hPa) ~ +.10 (~ +.08 to +.12 [+.04]) K/decade 1979-1997 – Global Trends(Seidel et al; in review, JCLIM) Radiosonde Satellite HadRTLKS_adjUAH RSS Stratosphere (MSU4) -.93 -.76 -.53 -.45 Troposphere (MSU2) -.15 -.05 -.05 +.04 =>Limitation: Apples vs. Oranges Comparisons Inconsistent spatial & temporal sampling, data handling, etc. _________________________________________________________ Radiosonde: Angell-63= 63 Stations (Angell)Angell-54=54 Stations (Angell) HadRT=Gridded (Parker et al.)LKS=87 Stations (Lanzante et al.) RIHMI=Gridded (Sterin) Satellite-Microwave Sounding Unit (MSU): UAH=Gridded (Christy & Spencer)RSS=Gridded (Wentz et al.)

  3. 1979-1997 – Global Trends(LKS = Lanzante/Klein/Seidel) Identical sampling Radiosonde Satellite [spatial/temporal] LKS_unLKS_adjUAH Stratosphere (MSU4) -.86 -.65 -.57 Troposphere (MSU2) -.11 -.06 -.03 =>Homogeneity adjustment reduces disparity considerably =>But (from previous slide) RSS still warmer than UAH: Colder LKS_un < LKS_adj < UAH < RSS  Warmer => More radiosonde adjustment needed ? ________________________________________________________ Radiosonde: LKS_un =87 Stations (Lanzante et al.) – No homogeneity adjustments LKS_adj=87 Stations (Lanzante et al.) – Homogeneity adjusted Satellite-Microwave Sounding Unit (MSU): UAH=87 Stations (Christy & Spencer)

  4. Tropical Lower-Tropospheric Lapse (surface-700 hPa) Source: LKS Zone: 30N-30S Stations: 20 & 16 Lapse: Smooth monthly Trends: 1979-1997 Levels: Surface-700 => 1976/77 Jump down => ENSO (reduced amplitude after 1976/77) =>Satellite-era trends: Sensitive to radiosonde data homogenization

  5. 1979-97 Trend of Tropical Lapse (surface-700 hPa) [K/decade] (1) (2) (3) (Source: LKS) LKS Unadjusted .17 .17 .10 LKS Adjusted .10 .00 .00 Brown et al. (2000) ~.20 Gaffen et al. (2000) ~.08 (1) = Difference in separate trends surface & 700 (2) =Trend of monthly (surface-700) time series at each station (3) =Same as (2) except reduced network (1959-1997) => Caution in interpreting lapse trends: complexities & sensitivities

  6. Challenges – Issues Which Need To Be Resolved Reconcile trend differences between datasets: o Sonde vs. sonde, satellite vs. satellite, sonde vs. satellite o Sampling: spatial & temporal differences? o Better understanding of inhomogeneities & adjustment methods o Other data handling issues? {quality control, etc.} • Lapse rate variations: o Tropics: * How much of trend since 1979 is real? * What’s going on with 1976/77? o What about extratropics?

  7. * THE END *

  8. Source: LKS= Lanzante/Klein/Seidel Region: Global= (87 Stations) Temperature: Smooth monthly Arrows: Major volcanoes Levels: 400 hPa & 70 hPa Stratosphere: Cooling trend ~1980, Volcanoes, QBO Troposphere: Quasi-linear warming trend ~ 1960s, ENSO & other

  9. Source: LKS= Lanzante/Klein/Seidel Zones/Stations: NH= 30-90N / 37 TP= 30N-30S / 24 SH= 30-90S / 8 Temperature: Smooth monthly Vertical Bar: 1976/77 Level: 400 hPa NH: Warming since ~1980 SH: Warming ~1960s to ~1980 [very few stations] Tropics: Jump up ~1976/77

  10. 1958-1997 – Global Trends(Seidel et al; in review, JCLIM) [K/decade] 5 Radiosonde DatasetsAng63 Ang54 HadRT LKS_adj RIHMI Stratosphere (100-50 hPa) -.55 -.48 -.44 -.37 -.22 Troposphere (850-300 hPa) +.08 +.11 +.09 +.12 +.04 1979-2001 – Global Trends(Seidel et al; in review, JCLIM) Radiosonde Satellite HadRTLKS_adjUAH RSS Stratosphere (MSU4) -.88 -- -.52 -.43 Troposphere (MSU2) -.08 -- +.01 +.10 Supplementary material: Seidel et al. 2003 Radiosonde: Angell-63= 63 Stations (Angell)Angell-54=54 Stations (Angell) HadRT=Gridded (Parker et al.)LKS=87 Stations (Lanzante et al.) RIHMI=Gridded (Sterin) Satellite-Microwave Sounding Unit (MSU): UAH=Gridded (Christy & Spencer)RSS=Gridded (Wentz et al.)

  11. Lapse (surface-700 hPa) Trends 1979-1997 * Unadjusted= red*Adjusted= blue *Arrow up/down= 0.2 K/decade *Blue only: no adjustment *Red only: delete (too little data for trend)

  12. Surface Temperature Trends 1979-1997 * Unadjusted= red*Adjusted= blue *Arrow up/down= 0.2 K/decade *Blue only: no adjustment *Red only: delete (too little data for trend)

  13. Lower Tropospheric Lapse Rate 1979-97 Controversy (Debate & NRC Committee) o +CO2 GCMs  more warming aloft than surface (tropics) o Satellite era  more warming at surface Q: Are lapse rate trends sensitive to adjustment & other details? Trend of Surface-700 hPa T (1979-97) [K/decade] (1) (2) (3) NH Un .25 .17 .15Low sensitivity NH Adj .18 .16 .16 SH Un -.11 -.04 -.23Small number of stations SH Adj .15 .14 .05Surface T sensitive to adjustment Tropics Un .17 .17 .10 Surface T sensitive to adjustment Tropics Adj .10 .00 .00 Brown et al. ~.20; Gaffen et al. ~.08 Globe Un .13 .16 .11 Some sensitivity Globe Adj .10 .14 .07 * Caution in interpreting lapse trends[spatial & temporal complexities] (1) = Difference in separate trends surface & 700 (2) = Trend of monthly time series: surface-700 (3) = Same as (2) except reduced network (1959-97)

  14. Lower Tropospheric Lapse Rate 1959-97 Trend of Surface-700 hPa T (1979-97) [K/decade] (1) (2) (3) NH Un .06 .06 .06 NH Adj .03 .00 .00 SH Un -.41 .01 -.02 SH Adj -.23 .04 .-06 Tropics Un .00 -.06 -.08 Tropics Adj -.08 -.05 -.07 Globe Un .01 .02 .00Globe Adj -.05 .00 -.04 • = Difference in separate trends surface & 700 • (2) = Trend of monthly time series: surface-700 • (3) = Same as (2) except reduced network (1959-97)

  15. Lower Tropospheric Lapse Rate Time Series Ticks: 0.2 K o Median sfc-700 over all stations in a zone (smoothed) [1959-97 stations] o Red = Unadjusted o Colored= Adjusted o SH: Very sensitive to adjustment; limited spatial sampling o NH: 1979-97 trend is fortuitous; multi-year time scales dominate o Tropics:Lags SOI ~ 6 mon. (weaker after ‘76); 1976-77 dominates 1979-97 trend is a subtle feature!

  16. 87 Station Network Latitude Zones (for analyses): NH(30-90N) ~ 35 stations Tropics(30N-30S)~ 25-30 stations SH(30-90S)~ 8-15 stations

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