Publications

The simple adjoint (SA) method of Qiu and Xu (1992, henceforth referred to as QX92) was recently upgraded and tested with the Phoenix-II data for retrieving the low-altitude winds from single-Doppler scans (Xu et al. 1993a,b henceforth referred to as XQY93a,b). The major results can be briefly reviewed as follows: (i) Using multiple time-level data with the adjoint formulation makes the retrieval more accurate and less sensitive to the observational error. (ii) Imposing a weak nondivergence constraint can suppress the spurious divergence caused by the data noise and improve the retrieval. (iii) Retrieving the eddy coefficients improves the wind retrieval. (iv) Retrieving the time-man residual term improves the wind retrieval. Although the results in XQY93a,b were encouraging, the Phoenix-II data used in XQY93a,b were collected on non-storm days with chaff dispensed from an aircraft. The real challenge is to test the SA method with storm data. A microburst case is selected for the test in this paper.