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IBIS vs HF Observations:

IBIS vs HF Observations: When examined on a seasonal or monthly basis IBIS has systematic biases in NRG. But, seasonal biases cancel upon annual aggregation. Annual IBIS mean annual NEE close to observed 12-yr mean NEE

caitlyn-kinnerk
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IBIS vs HF Observations:

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  1. IBIS vs HF Observations: When examined on a seasonal or monthly basis IBIS has systematic biases in NRG. But, seasonal biases cancel upon annual aggregation. Annual IBIS mean annual NEE close to observed 12-yr mean NEE IBIS on average the systematically low GEE (1.4 MgC/ha/yr) balanced by systematically low R (-1.4 MgC/ha/yr) Summer IBIS R close to observed, GEE & NEE well below observed Spring (Apr/May): Very high GEE (~ 1MgC/ha/yr), partially offsets summer deficit. Uptake is way over predicted. Mostly May. Winter (Nov-Mar): IBIS under predicts efflux. Nov-Mar R low by 2MgC/ha.yr on average, Dec-Mar NEE low by about1 1MgC/ha/yr Fall (Nov-Oct): R low. 2000 – 2004 Abrupt up tick in summer R (+2.5MgC/ha/yr) and GEE (+3MgC/ha/yr). No similar jump in HF observed drivers: daily precipitation, solar, Tair, RH, Wspd.

  2. Spring (Apr/May): Very high GEE (~ 1MgC/ha/yr), partially offsets summer deficit. Uptake is way over predicted. Mostly May. This looks like the phenology scheme. Uptake starts too early. Summer IBIS R close to observed, GEE & NEE well below observed IBIS GEE typically low vs. obs IBIS R consistently high in June, mixed other months Seems to be over sensitivity to soil moisture (or soil is too dry in IBIS) For months of Jun-Aug, IBIS GEE, R errors correlate with soil moisture estimated with our simple hydrology model. Dry conditions supress GEE more than R Winter (Nov-Mar): IBIS under predicts efflux. Nov-Mar R low by 2MgC/ha.yr on average, Dec-Mar NEE low by about1 1MgC/ha/yr IBIS soil temperatures too low? Heterotrophic R pretty much shuts down in Jan & Feb.

  3. observed

  4. observed

  5. IBIS

  6. R2 = 0.49

  7. R2 = 0.39

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