Subject: instrument-maintenance Detail: During the indicated period, the GRAS receiver onboard Metop-A will undergo a series of tracking parameter tests aiming at improving the signal characteristics of rising occultations. In particular, the campaign aims at reducing vertical error correlations of bending angles in the lower stratosphere, at the same time minimizing side effects. During this period, the number of daily occultations from Metop-A as well as the penetration of rising occultations into the mid and lower troposphere might vary more than usual. [Rev. 2]: End Time updated. Status: scheduled Issue Time: 2017-12-07 16:11:46.0 Services: GRAS Level 1 - Metop-A GRAS AHRPT Metop-A Type: Planned Maintenance Ann Nr: 3478 Rev: 1 Start Time: 2018-01-22 14:48:00.0 End Time: 2018-01-22 14:55:00.0 Satellites: Metop-A Subsystem: ASCAT