Global observations of HNO₃ from the High Resolution Dynamics Limb Sounder (HIRDLS): First results

The HIRDLS instrument obtains between 5000 and 7000 HNO₃ profiles per day. HIRDLS HNO₃ data are generally good over the latitude range of 64°S to 80°N and pressure range 100 to 10 hPa, with some profiles, depending on latitude, having useful information between 100 to 161 hPa.

The individual profile "measured" precision is between 10 and 15%, but can be much larger if the HNO₃ abundance is low or outside the 100 hPa to 10 hPa range. Global results are compared with the HNO₃ observations from version 2.2 of the EOS Aura Microwave Limb Sounder (MLS), and it is found that large-scale features are consistent between the two instruments. HIRDLS HNO₃ is biased 0-20% low relative to Aura MLS in the mid-to-high latitudes and biased high in the tropical stratosphere.