CloudSat-constrained cloud ice water path and cloud top height retrievals from MHS 157 and 183.3 GHz radiances

Abstract

Abstract. Ice water path (IWP) and cloud top height (h t ) are two of the key variables in determining cloud radiative and thermodynamical properties in climate models. Large uncertainty remains among IWP measurements from satellite sensors, in large part due to the assumptions made for cloud microphysics in these retrievals. In this study, we develop a fast algorithm to retrieve IWP from the 157, 183.3 ± 3 and 190.3 GHz radiances of the Microwave Humidity Sounder (MHS) such that the MHS cloud ice retrieval is consistent with CloudSat IWP measurements. This retrieval is obtained by constraining the empirical forward models between collocated and coincident measurements of CloudSat IWP and MHS cloud-induced radiance depression (T cir ) at these channels. The empirical forward model is represented by a lookup table (LUT) of T cir -IWP relationships as a function of h t and the frequency channel. With h t simultaneously retrieved, the IWP is found to be more accurate. The useful range of the MHS IWP retrieval is between 0.5 and 10 kg m −2 , and agrees well with CloudSat in terms of the normalized probability density function (PDF). Compared to the empirical model, current operational radiative transfer models (RTMs) still have significant uncertainties in characterizing the observed T cir -IWP relationships. Therefore, the empirical LUT method developed here remains an effective approach to retrieving ice cloud properties from the MHS-like microwave channels.

Microphysical properties of frozen particles inferred from Global Precipitation Measurement (GPM) Microwave Imager (GMI) polarimetric measurements

“…Although all three frequencies are window channels, they are still affected by water vapor abundance. But as found previously in Gong and Wu (2014), the water vapor attenuation effect is minor when cloud is present. The last plausible explanation of why the simulated 640 GHz peak amplitude is weaker than that of the other two frequencies with the same AR value originates from the background atmosphere lapse rate change.…”

“…Gong and Wu (2014) used an empirical IW-TB relationship derived from CloudSat-MHS (Microwave Humidity Sounder) measurements for the IWP retrieval, where they found this relationship is nearly linear for medium thick ice cloud (i.e., anvils). The observed PD value range in this study therefore can be translated into a 30 % IWP retrieval error if polarization is neglected.…”

“…Different from RT4, CRM allows the user to specify the vertical distribution of IWC or liquid water content (LWC) in the mixed-phase case, to study the sensitivity of the cloud-induced radiance to cloud layer height. Cloud height is another free parameter in addition to particle size and IWP, which can alter the cloud radiance amplitude significantly in a similar frequency range (Gong and Wu, 2014).…”

“…Another RTM for simulating frozen particle scattering, called the Cloud Radiance Model (CRM), is based on the cloudy-sky forward model in the Aura Microwave Limb Sounder (MLS) (Wu and Jiang, 2004;Gong and Wu, 2014). The CRM is a non-polarized model, and it assumes only spherical ice particles in the scattering calculation.…”

Ice crystal number concentration estimates from lidar-radar satellite remote sensing. Part 1: Method and evaluation

“…King et al, 1998;Sourdeval et al, 2013). Direct retrievals of the vertically integrated ice water content (IWC) -the ice water path (IWP) -can also be obtained from these channels (Sourdeval et al, 2015), passive microwave sensors (Gong and Wu, 2014), or a synergy of both (Holl et al, 2014). Vertical profiles of the cloud visible extinction (α ext ), IWC and ice crystal r eff are 10 commonly provided using lidar and/or radar measurements (e.g.…”