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Good bye!! Cold tropopause

Good bye!! Cold tropopause. ?. 気候物理コアモデル改良サブグループ 渡辺真吾. What ’ s cold bias?. JJA Temperature biases. -10 K. -5 K. UM - ERA40. 5.7b - ERA40. -10 +10. mstrn8. UM. Underestimation of shortwave heating rate?. Shortwave heating rate [K/day] in the tropics (10S-10N) ; Jan. GSM/JMA.

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Good bye!! Cold tropopause

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  1. Good bye!!Cold tropopause ? 気候物理コアモデル改良サブグループ 渡辺真吾

  2. What’s cold bias? • JJA Temperature biases -10 K -5 K UM - ERA40 5.7b - ERA40 -10 +10

  3. mstrn8 UM Underestimation of shortwave heating rate? • Shortwave heating rate [K/day] in the tropics (10S-10N) ; Jan GSM/JMA

  4. New radiation codemstrnX (radX) • Newer release of HITRAN (HIgh-resolution TRANsmission molecular absorption database) HITRAN`92 ⇒HITRAN`00 • Highly optimized integration scheme for K-distribution method

  5. mstrnX mstrn8 UM Improvement in theshortwave heating rate • Shortwave heating rate [K/day] in the tropics (10S-10N) ; Jan GSM/JMA

  6. mstrnX mstrnX_noGWD mstrn8 ERA40 • Temperature profiles in the tropics (10S-10N); January

  7. -10 K noGWD - ERA40 5.7b - ERA40 Meridional structure? • JJA Temperature biases radX - ERA40 -10 +10

  8. radX - ERA40 CH4 oxidation Moist / Dry biases • JJA humidity biases [%difference] 5.7b - ERA40 -100 +100

  9. Summary #.1 • The cold tropopause has been caused by shortcomings of the previous radiation code. • Temperature and humidity biases were significantly reduced. • Some tuning parameters (e.g., GWD) must be re-concerned.

  10. How about lower resolution models? mstrn8 • JJA Temperature biases -10 K -10 K -15 K -5 K T21L40 - ERA40 5.7b - ERA40 -10 +10

  11. mstrnX • JJA Temperature biases -6 K -12 K T21L40 - ERA40 T106L56 - ERA40 -10 +10

  12. Moist / Dry biases mstrnX • JJA humidity biases [%difference] T21L40 - ERA40 T106L56 - ERA40 -100 +100

  13. Cloud water distribution mstrnX • JJA cloud water [kg/kg] T21L40 - ERA40 T106L56 - ERA40 0 5x10-5

  14. Why cold & moist biases are still significant in T21L40? • Lower vertical resolution near the tropopause (dZ=~1.5 km) • Lower horizontal resolution; 5.6 • Insufficient GWD? • Physical processes (all parameters are tuned for T106+full physics)

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