Cloud statistics over eastern China during GAME-IOP as seen from TRMM TMI*Nobuhiko ENDO
*Frontier Research Center for Global Change, JAMSTEC, Japan, 3173-25 Showa-machi,Kanazawa-ku, Yokohama, Kanagawa, 236-0001, Japan. e-mail: nobu@jamstec.go.jp
Abstract
We compare spatial and vertical distribution of clouds observed from TRMM TMI, ISCCP, surface and upper-air soundings
over eastern China during GAME-IOP. Spatial distribution of clouds from TRMM TMI and that from ISCCP were wellcorresponded with each other, while amount of cloud water and ice water was quit different. Cloud vertical structure
estimated from RAOB often exhibited multilayer structure, while TRMM TMI showed unimodal vertical structure.
Keyword: Cloud distribution, TRMM TMI, ISCCP.

1. Introduction
Cloud plays key roles in climate system. Climatology ofspatial distribution of clouds was compiled from surface
visual cloud observation (Warren et al., 1986; 1988) andfrom the International Satellite Cloud Climatology Project(ISCCP)(Rossow and Schiffer, 1991; 1999). However,surface observer often missed high clouds because lowerclouds spread over the sky. Further ISCCP cannot observe
lower clouds when high- and/or mid-level clouds arecovered broad area. TRMM TMI provides not only rainfall
rate, but also vertical distribution of cloud water and cloudice. TRMM TMI gives opportunity to makeinter-comparison between cloud statistics from TRMM
TMI, ISCCP, and conventional observation.

2. Data
An integrated data set with simultaneous observations at
the surface, from radiosonde and from satellites, werecollected over eastern China during the GAME-IOP. We
used the TRMM TMI standard product 2A12 from May toJuly 1998. TRMM 2A12 includes rainfall rates and thevertical structure of hydrometeors based upon the ninechannels of the TRMM TMI (Kummerow, et al, 1998).
ISCCP DX product (Rossow and Schiffer, 1999) fromGMS-5 was also employed. ISCCP DX products provide
cloud top pressure, cloud top temperature, and cloudoptical thickness during daytime. Four times per daily
radiosonde observation data at 27 stations in eastern China
were provided by TIPEX, HUBEX, JEXAM and SCSMEX.
Routine visual cloud observation data from surface wereprovided by TIPEX and obtained from SCSMEX dataarchive.
We selected TRMM orbits passed over eastern China
near 00 and 06 UTC. Then TRMM 2A12 and ISCCP DX
data were regrided on 0.5 degree boxes. ISCCP cloudoptical depth was converted into cloud water path. Cloudvertical structure was evaluated from radiosonde data at
daylight hours with the algorithm of Wang and Rossow(1995). We compiled collocated dataset from two satellite
products, surface weather observations and cloud verticalstructure evaluated from radiosonde observations at 27stations in eastern China except near the coast.

Fig. 1: Spatial distribution of cloud water path of
ISCCP DX (upper panel) and vertical integrated liquidwater content of TRMM TMI at 06UTC, June 24, 1998.

3. Results
3.1.
Spatial variation of clouds
Figure 1 shows spatial distribution of cloud water path of
ISCCP DX (upper panel) and vertical integrated liquidwater content of TRMM TMI at 06UTC, June 24, 1998.
According to ISCCP cloud classification table, larger cloudwater areas are corresponded with vigorous deep
convective clouds. Spatial distribution of cloudy pixels arewell corresponded with TMI and ISCCP DX during
daytime.

However, spatial distribution of cloud water and cloud
ice are very different between two satellites products.
Figure 2 indicates difference of vertical integrated cloudwater and vertical integrated cloud ice at 06UTC, June 24,
1998. Vertical integrated cloud water of TMI are larger
than that of ISCCP around and in deep convective clouds.
On the other hand, vertical integrated cloud water of TMI
is smaller in other area. Vertical integrated cloud ice isgenerally smaller in TRMM TMI in and around convective
cloud area. One cause of these cloud water/ice differences
between two satellite products may due to the use ofdifferent frequency of sensors. ISCCP (GMS-5) received
infra-red and visible bands, while TRMM TMI uses nine
microwave bands. Further ISCCP

3.2.

Cloud vertical structure

Clouds are often formed in different levels. Cloudvertical structure estimated from radiosonde clearly
indicate that there are single-layer and multi-layered cloud
distribution. We first compare cloud vertical structure
between surface visual observation and radiosonde
observation, and cloud vertical structures are quit similar.
Cloud vertical structure from radiosonde was comparedwith cloud vertical structure from 9 grids around theupper-air station in TRMM TMI and ISCCP DX data.
TRMM TMI frequently missed lower shallow clouds
observed by surface observer and estimated CVS fromradiosonde. ISCCP DX also does not captured in lower
clouds in Meiyu frontal zone because deep convective
cloud covers broad region. Furthermore, multilayered
clouds are often captured in radiosonde, while TRMM TMI
indicates unimodal cloud vertical structure. ISCCP DX alsofrequently missed multilayered structure in and around
active convective cloud systems.

4. Summary
An integrated data set with simultaneous observations at
the surface, from radiosonde and from satellites, wascollected over eastern China during the GAME-IOP. We
analyze the cloud type, cloud amount, cloud verticalstructure (CVS), and so on. We select orbits which TRMM
pass over eastern China near 00/06 UTC. Spatial
distribution of cloudy pixels are well corresponded withTMI and ISCCP DX during daytime. However, cloud water
path (column total cloud water) is very different between
two satellites products. Cloud water path of TMI are larger
than that of ISCCP around and in deep convective clouds.
Cloud vertical structure estimated from radiosonde clearly
indicate that there are single-layer and multi-layered cloud
distribution. TMI frequently missed lower shallow clouds
observed by surface observer and estimated CVS fromradiosonde. ISCCP DX also does not captured in lower
clouds. Further TRMM TMI shows unimodal structure ofvertical distribution of cloud water.

Fig. 2: Difference of vertical integrated cloud water(upper panel) and vertical integrated cloud ice (lowerpanel) between TRMM TMI and ISCCP DX at 06UTC,
June 24, 1998.

References
Kummerow, C., W. Barnes, T. Kozu, J. Shiue, and J. Simpson,
The Tropical Rainfall Measuring Mission (TRMM) sensor
package. J. Atmos. and Ocean Tech., 15, 808-816, 1998.
Rossow, W.B. and R.A. Schiffer, ISCCP cloud data products. Bull.
Amer. Meteor. Soc., 72, 2-20, 1991.
Rossow, W.B. and R.A. Schiffer, Advances in understanding
clouds from ISCCP. Bull. Amer. Meteor. Soc., 80,2261-2287, 1999.
Wang, J. and W.B. Rossow, Determination of cloud verticalstructure from upper-air observations, J. Appl. Meteor., 34,2243-2258, 1995.
Warren, S.G., C.J. Hahn, R.M. Chervin, and R.L. Jenne, Global
distribution of total cloud cover and cloud type amounts
over land. NCAR Tech. Note NCAR/TN-273+STR, 29pp.,
plus 200 maps, 1986
Warren, S.G., C.J. Hahn, R.M. Chervin, and R.L. Jenne, Global
distribution of total cloud cover and cloud type amounts
over ocean. NCAR Tech. Note NCAR/TN-317+STR, 42pp., plus 170 maps, 1988.