Variation of upper tropospheric clouds and water vapor over the Indian ocean
Item
Title (Dublin Core)
Variation of upper tropospheric clouds and water vapor over the Indian ocean
Description (Dublin Core)
The upper tropospheric (UT) ice water content (IWC) and water vapor (H<sub>2</sub>O) observed by the Microwave Limb Sounder (MLS) show dominant dipole mode variability over the Indian Ocean. This is characterized by the oscillating differences between the Western and Eastern Indian Ocean (WIO and EIO) with greater amplitude in JJA and SON than in other seasons. We denote δ <i>X</i> = <i>X</i>_WIO–<i>X</i>_EIO, with <i>X</i> being H<sub>2</sub>O and IWC at three UT levels (215 hPa, 147 hPa and 100 hPa) as well as sea surface temperature (SST), following the definition for previously identified Indian Ocean Dipole (IOD) variability. We found a strong positive correlation of δIWC at three UT levels with δSST, and a relatively weak positive correlation of δIWC with Nino 3.4 SST, suggesting that the UT clouds over the Indian Ocean are largely controlled by local thermally-driven circulation while teleconnection to ENSO plays a secondary role. The change per degree of δSST for δIWC in SON is 5.5 mg m<sup>−3</sup> C<sup>−1</sup> at 215 hPa, 1.6 mg m<sup>−3</sup> C<sup>−1</sup> at 147 hPa and 0.13 mg m<sup>−3</sup> C<sup>−1</sup> at 100 hPa (the 7-yr mean δIWC is −4.7 mg m<sup>−3</sup>, −1.6 mg m<sup>−3</sup> and −0.13 mg m<sup>−3</sup> at 215 hPa, 147 hPa and 100 hPa respectively). For δH<sub>2</sub>O, the per degree δSST change of 41.2 ppmv C<sup>−1</sup> corresponds to a strong increase at 215 hPa and a decrease of −0.23 ppmv C<sup>−1</sup> (−0.18 ppmv C<sup>−1</sup>) at 100 hPa (147 hPa), respectively. The Nino 3.4 SST has a relatively weak positive (negative) correlation with δ H<sub>2</sub>O at 215 hPa (100 hPa). The increase of δH<sub>2</sub>O at 215 hPa with increasing δSST is associated with the sharper contrast in convective intensity while the decrease of δH<sub>2</sub>O at 100 hPa with increasing δSST is a signature of the "convective cold top" and temperature control of 100 hPa H<sub>2</sub>O. For H<sub>2</sub>O, the 147 hPa marks a transition from the convection-controlled 215 hPa to the temperature-controlled 100 hPa.
Creator (Dublin Core)
Bhawar, R. L.
Jiang, J. H.
Su, H.
Date (Dublin Core)
2018-08-10
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acpd-11-21769-2011
https://acp.copernicus.org/preprints/acp-2011-578/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
