Comparing rain retrievals from GPROF with ECMWF 1D‐Var products

Abstract

Both the Goddard Profiling Algorithm (GPROF) and European Centre for MediumRange Weather Forecasts (ECMWF) one-dimensional + four-dimensional variational analysis (1D+4D-Var) rainfall retrievals are inversion algorithms based on Bayes' theorem. Differences stem primarily from the a priori information. The GPROF uses an observationally generated a priori database whereas ECMWF 1D-Var uses the model forecast first guess (FG) fields. The relative similarity in the two approaches means that comparisons can shed light on the differences that are produced by the a priori information. Case studies have found that differences can be classified into four categories based upon the agreement in the brightness temperatures (T b s) and in the microphysical properties of cloud water path (CWP) and rainwater path (RWP) space. A category of special interest is when both retrievals converge to similar T b through minimization procedures but produce different CWP and RWP. The similarity in T b can be attributed to comparable total water path (TWP) between the two retrievals while the disagreement in the microphysics is caused by their different degrees of constraint of the cloud/rain ratio by the observations. This situation occurs frequently and takes up 46.9% in the 1 month 1D-Var retrievals examined. The two retrievals produce similar spatial patterns but with different magnitude. The allocation of a large amount of CWP in the 1D-Var retrieval seems to be related to the stratiform portion of rain, which is produced by the large-scale condensation scheme. To attain better-constrained cloud/rain ratios and improved retrieval quality, this study suggests the implementation of higher microwave frequency channels in the 1D-Var algorithm.

Towards variational retrieval of warm rain from passive microwave observations

“…Figure 1 shows the drizzle onset values of liquid water path (LWP) used in this study, subset by TPW and SST. These drizzle onset values are in general agreement with some in the literature (Chen et al, 2011;Lebsock et al, 2008;Mülmenstädt et al, 2015;Wentz and Spencer, 1998;Wang et al, 2017) and lower than some others (Iturbide-Sanchez et al, 2011;Kida et al, 2010), though direct comparison is difficult due to the subdivision by environmental regime done here. The GPM V05 passive algorithm (i.e.…”

“…Successful assimilation of "all-sky" radiances from microwave radiometers can yield a more accurate analysis state from which numerical weather prediction (NWP) models can run (Geer et al, 2017). However, the same factors that cause the retrieval problem to be under-constrained are also relevant for DA schemes (Wang et al, 2012). Thus, microwave radiances from raining or cloudy pixels are often not included in the data assimilation.…”

Towards variational retrieval of warm rain from passive microwave observations

“…Figure 1 shows the drizzle onset values of liquid water path (LWP) used in this study, subset by TPW and SST. These drizzle onset values are in general agreement with some in the literature Lebsock et al, 2008;Mülmenstädt et al, 2015;Wentz and Spencer, 1998;Wang et al, 2017) and lower than some others (Iturbide-Sanchez et al, 2011;Kida et al, 2010), though direct comparison is difficult due to the subdivision by environmental regime done here. The GPM V05 passive algorithm (i.e.…”

“…Successful assimilation of "all-sky" radiances from microwave radiometers can yield a more accurate analysis state from which numerical weather prediction (NWP) models can run . However, the same factors that cause the retrieval problem to be under-constrained are also relevant for DA schemes (Wang et al, 2012). Thus, microwave radiances from raining or cloudy pixels are often not included in the data assimilation.…”

Evaluating the sustainability of production in terms of environmental dimension

“…According to this fact, much more business support and apply green principles such as using environmentally friendly raw materials and recycled paper for packaging and reducing their use of fossil fuels. These green principles have been expanded to many areas, including supply chains (Chung and Wee, 2008;Lin et al, 2011;Wang et al, 2012Wang et al, , 2010. Including the 'green' notion to the 'supply chain' definition generates a new paradigm where the supply chain involves a direct connection to the environment (Diabat and Govindan, 2011;Wang et al, 2010;Zhu and Sarkis, 2006;Eltayeb et al, 2011 …”