The performance of the EarthCARE Cloud Profiling Radar in marine stratiform clouds

Burns, David H.; Kollias, Pavlos; Tatarevic, Aleksandra; Battaglia, Alessandro; Tanelli, Simone

doi:10.1002/2016jd025090

Cited by 29 publications

(23 citation statements)

References 27 publications

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“…For missed detections above 1 km, besides those caused definitely by cloud microphysics that are labeled as missing type III, small or broken clouds that partially fill in the CPR FOV contribute a lot (King et al, ; Burns et al, ;Liu et al, ). Among these nonovercast ones, the clouds thicker than 480 m are considered to be affected by nonovercast factor only and classified into missing type IIB.…”

Section: Methodsmentioning

confidence: 99%

“…In addition, CPR has practical difficulties in detecting optically thin clouds with optical thickness <0.3, which are mostly thin cirrus (Marchand et al, ; Stephens et al, ). Low‐level stratiform clouds that significantly contribute to the planetary albedo are also great challenges for CPR, which is attributed to their very low altitude that is possibly within the radar blind zone (Bennartz, ; Burns et al, ; Liu et al, ; Sassen & Wang, ). Since the climatology of shallow cloud systems and their interactions with aerosols have been extensively concerned by applying spaceborne radar measurements (Rosenfeld et al, ; Turner et al, ; Winker et al, ), it is essential to clarify the performance of CPR cloud detection, especially in lower atmosphere.…”

Section: Introductionmentioning

confidence: 99%

“…More than one factor can cause the CPR missed detection on warm clouds, which include surface clutter, vertical/horizontal resolution, and sensitivity (Mace et al, ; Marchand et al, ; Stephens et al, ; Burns et al, ). In the very low altitude, spaceborne radar tends to suffer from the contamination of surface clutters, for which the radar signals are wholly invalid.…”

Section: Introductionmentioning

confidence: 99%

“…Given the CPR spatial resolution, ~1.4 × 1.7 km and 480 m on horizontal and vertical orientation, respectively, clouds without sufficient area or thickness account much for these failures. These nonovercast effects have considerable impacts on spaceborne radar for cloud measurements (Burns et al, ). Excluding the above factors that are closely related to the external features of clouds, i.e., very low location and small volume, there are still many clouds that are completely missed by CPR.…”

Section: Introductionmentioning

confidence: 99%

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Multiple Factors Explaining the Deficiency of Cloud Profiling Radar on Detecting Oceanic Warm Clouds

Liu

et al. 2018

JGR Atmospheres

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The Cloud Profiling Radar (CPR) detecting efficiency on low-level clouds is affected by many situations, including surface clutter, spatial resolution, and radar sensitivity. These factors can uniquely or jointly result in missed detections of oceanic single-layer warm clouds. Fifty-seven percent of missed detections are attributed to a single factor, and the rest are attributed to two or more factors that are indistinguishable. For missed warm clouds above 1 km, 30% result from the nonovercast effect, while the CPR range resolution is the major cause for the overcast ones. In particular, 18.4% are attributed exclusively to specific cloud microphysics, which is characterized by droplet effective radius (DER) and cloud optical thickness (COT). Compared to COT, the CPR detection is more dependent on DER, with a critical value standing around 10 μm. It is only for larger DER that the effects from COT turn to arise. Given liquid water path, clouds with larger DER and smaller COT are more likely to generate sufficient reflectivity and be detected than their counterpart. For clouds with the same DER and COT, opposite detecting results are primarily determined by the different droplet size distributions that lead to a variable reflectivity across the CPR detecting limit. Over global oceans, total miss rate of cloud occurrences approaches 0.73, while the loss rate of cloud water mass is 0.42 due to the smaller liquid water path of CPR-missed clouds. The CPR-missed detections also lead to uncertainties in cloud radiative forcing estimations. A notable overestimation of shortwave cloud forcing at 160% is found at bottom and top of atmosphere.The 94-GHz Cloud Profiling Radar (CPR) aboard CloudSat is the first spaceborne millimeter-wavelength radar, which began operational data collection since 2006. It is able to detect shallow convective clouds and drizzle that centimeter-wavelength radar remains insensitive. By virtue of its À28 dBZ sensitivity and the resulting cloud water resolving capability, CPR's observations have been involved in considerable investigations as an important data source for cloud and precipitation studies (Behrangi et al., 2012; Haynes et al., 2013; Key Points: • CPR-missed detections that are uniquely or jointly caused by different factors are identified and examined over global oceans • CPR cloud detection is more dependent on DER, with a critical value around 10 μm, and the effects from COT arise for only larger DER • Opposite detection for clouds with the same DER and COT results from variable reflectivity across the CPR detecting limit Supporting Information: • Supporting Information S1 . (2018). Multiple factors explaining the deficiency of cloud profiling radar on detecting oceanic warm clouds.Figure 5. (a) Zonal distribution of each missing type and (b) the respective fractions from south to north. Histogram of the pixel amount of all missing types in (a) and the averaged frozen layer height in (b).

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Multiple Factors Explaining the Deficiency of Cloud Profiling Radar on Detecting Oceanic Warm Clouds

Liu

et al. 2018

JGR Atmospheres

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“…It is not uncommon to rely on observations collected by highly sensitive airborne and ground-based millimeter radar observations to assess the performance of coarser less sensitive radars (e.g., [Burns et al, 2016;). Such observations have allowed Stephens et al [2002] to conclude that, based-on sensitivity alone, the CloudSat-CPR should only be able to detect 70% of marine boundary layer cloud segments.…”

Section: Introductionmentioning

confidence: 99%