Cloud liquid water path （ L ） （i.e. vertically integrated cloud liquid water） is an important parameter in meteorology and in the study on cloud radiation interaction. It has already been demonstrated that the space borne microwave radiometer is a powerful tool for monitoring the distribution and variation of L on global scale. However

the L retrieval algorithm for on orbit SSM/I still has to be improved or renewed

and in parallel the algorithm is being developed for AMSR on board the ADEOS Ⅱ which will be launched in the near future. The aim of this work is to develop an algorithm for determining over ocean cloud L using the physico statistical method. A simple relationship is obtained between liquid water path and the difference of brightness temperatures （Δ T B） in cloudy and clear atmospheres from the simulation data with a radiative transfer model. In the algorithm

only the relationship L Δ T B in channel of vertically polarized 37 GHz （37 V） is used because it has smaller rms error. The T B at 37 V in ‘clear’ atmosphere is derived through a relationship with T B at 19.35 V obtained by regression of SSM/I observation data in really clear atmospheres. The L results retrieved from SSM/I measurements by the present algorithm and two other algorithms are compared to the ISCCP L data. It is shown that the present L retrieval algorithm yields quite reliable retrievals of cloud liquid water path.