Precipitation Characteristics in Mid-Latitude East Asia as Observed by TRMM PR and TMI

Abstract

Precipitation radar and microwave radiometer data from the Tropical Rainfall Measuring Mission (TRMM) satellite during the spring and summer months of 1998 are used to study the precipitation characteristics in the mid-latitude East Asia region (20 -40 N, 100 -140 E), with particular emphasis on comparing the differences between stratiform and convective rains, and between rains during spring and summer. The characteristics in the mid-latitude are also compared with those in the tropics. The two-season mean results for the mid-latitudes show that the mean rainfall rate for stratiform clouds is @2 mm h À1 , at least 6 times lower than its convective counterpart. The mean convective rainfall rate is higher over land than over ocean, and higher in the mid-latitude than in the tropics. Generally, convective clouds generate more rain total for both mid-latitudes and tropics although they cover less area than stratiform clouds. Comparing between mid-latitude and tropical regions, the contribution of stratiform rains is larger in the mid-latitudes than in the tropics.There are distinct differences between stratiform and convective precipitation profiles, as well as noticeable seasonal variations of these profiles. The mean vertical profiles showed that stratiform rains have a quasi-constant rainfall rate below freezing level and a sharp drop-off above. Convective profiles, on the other hand, often have a maximum rainfall rate somewhere below the freezing level. Above the freezing level, precipitation layer for convective rains is thicker than for stratiform rains. For convective rains, significant differences are found between profiles over land and ocean, with a significant deeper layer for land convections given the same surface rainfall rate. Consistently, microwave scattering signature over land, expressed by polarization-corrected temperature at 85 GHz, is nearly twice as strong as that over ocean for the same surface rainfall rate. Precipitation profiles are similar in shape and depth between mid-latitude and tropical regions during summer when the freezing level heights are also similar between the two regions. However, compared to being no noticeable variation in the tropics during a year, there is a significant seasonal change for the precipitation profiles in mid-latitudes. The seasonal difference of precipitation profiles arises from the deeper precipitation layer in the summer than in Corresponding Author: Guosheng Liu, Department of Meteorology, Florida State University, Tallahassee, FL 32306-4520, USA. E-mail: liug@met.fsu.edu ( 2003, Meteorological Society of Japan the spring for a given surface rainfall rate, being in consistent with the seasonal variation of the freezing level height. This change in precipitation depth applies to both stratiform and convective rains, and to rains over both land and ocean. It should be mentioned that all the aforementioned results, except for the 85 GHz scattering signature, are derived from TRMM precipitation radar data.

Seasonal variability in tropical and subtropical convective and stratiform precipitation of the East Asian monsoon

“…In this article, 10-year (1998-2007) TRMM PR rain products (2A25) are used to determine properties of convective and stratiform rain [21]. Other precipitation in 2A25 accounts for about 1% of the rainfall amount and 5.8% of the rain area [22,23]. Therefore, it is common to only consider TRMM convective and stratiform rain in studying the spatial distribution [19,23], seasonal variation [24][25][26] and diurnal cycle [27,28] of precipitation.…”

An EOF‐based comparison and evaluation of simulated passive microwave signatures to observations over tropical oceans

“…Applying the cloud classification scheme to the observed rainy satellite FOVs yielded a distribution of about 12% convective, 14% mixed and 74% nonconvective with relatively little variability across the oceanic regions (Table 2). Although overall the convective clouds in all regions occupy a small portion, their contribution to total rain is significant because the mean rain rate is at about six times greater than that of stratiform rain [ Fu and Liu , 2003].…”

An examination of summer precipitation over Asia based on TRMM/TMI

“…However, researches aiming at the global scale are not feasible due to the limited location of measurements provided by individual radars and finite quantities of experiments. Fu et al analyzed the vertical profiles of precipitation by employing the TRMM PR data over East Asia in 1998 and presented the result that significant difference exists between convective and stratiform precipitation and there is a significant seasonal variability in mean profiles of mid-latitude precipitation caused by the different heights of freezing level in each season [41] . Another relevant study addressing the detailed variation in the vertical structure of precipitation indicated that on a logarithm scale the slopes of the rain profiles are approximately constants if the profiles are divided vertically into 3 or 4 layers, i.e.…”